Deep Analysis of Text Rendering ProjectPublic

Plan updated

>git clone https://github.com/chenglou/pretext.git

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Output:
Cloning into 'pretext'...

>pwd

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Output:
/Users/maxgeorgopoulos/Documents/blook/experiments/pretext

>rg --files

Command: /bin/zsh -lc 'rg --files'
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Output:
src/analysis.ts
src/layout.test.ts
src/layout.ts
src/measurement.ts
src/test-data.ts
src/line-break.ts
src/text-modules.d.ts
src/bidi.ts
research-data/system-ui-size-scan.json
corpora/th-nithan-vetal-story-7.txt
corpora/th-nithan-vetal-story-1.txt
corpora/ja-rashomon.txt
corpora/hi-eidgah.txt
corpora/ja-kumo-no-ito.txt
corpora/dashboard.json
corpora/README.md
corpora/zh-zhufu.txt
corpora/ur-chughd.txt
corpora/chrome-sampled.json
corpora/mixed-app-text.txt
corpora/zh-guxiang.txt
corpora/en-gatsby-opening.txt
corpora/he-masaot-binyamin-metudela.txt
corpora/STATUS.md
corpora/representative.json
corpora/my-bad-deeds-return-to-you-teacher.txt
corpora/chrome-step10.json
corpora/TAXONOMY.md
corpora/ko-unsu-joh-eun-nal.txt
corpora/km-prachum-reuang-preng-khmer-volume-7-stories-1-10.txt
corpora/sources.json
corpora/my-cunning-heron-teacher.txt
corpora/ar-risalat-al-ghufran-part-1.txt
corpora/ar-al-bukhala.txt
pages/demos/bubbles.html
pages/demos/variable-typographic-ascii.ts
pages/demos/justification-comparison.model.ts
pages/demos/justification-comparison.ts
pages/demos/editorial-engine.ts
pages/demos/dynamic-layout-text.ts
pages/demos/justification-comparison.ui.ts
pages/demos/bubbles.ts
pages/demos/justification-comparison.data.ts
pages/demos/wrap-geometry.ts
pages/demos/variable-typographic-ascii.html
pages/demos/svg.d.ts
pages/demos/editorial-engine.html
pages/demos/dynamic-layout.html
pages/demos/rich-note.html
pages/demos/masonry/index.ts
pages/demos/masonry/shower-thoughts.json
pages/demos/masonry/index.html
pages/demos/accordion.ts
pages/demos/accordion.html
pages/demos/bubbles-shared.ts
pages/demos/justification-comparison.html
pages/demos/rich-note.ts
pages/demos/index.html
pages/demos/dynamic-layout.ts
pages/assets/claude-symbol.svg
pages/assets/openai-symbol.svg
pages/corpus.html
pages/benchmark.ts
pages/diagnostic-utils.ts
pages/benchmark.html
pages/emoji-test.html
pages/gatsby.ts
pages/probe.html
pages/probe.ts
pages/report-utils.ts
pages/accuracy.html
pages/justification-comparison.html
pages/accuracy.ts
pages/corpus.ts
pages/gatsby.html
DEVELOPMENT.md
AGENTS.md
oxlintrc.json
tsconfig.json
scripts/corpus-check.ts
scripts/probe-check.ts
scripts/gatsby-sweep.ts
scripts/report-server.ts
scripts/corpus-font-matrix.ts
scripts/build-demo-site.ts
scripts/pre-wrap-check.ts
scripts/status-dashboard.ts
scripts/accuracy-check.ts
scripts/gatsby-check.ts
scripts/corpus-taxonomy.ts
scripts/corpus-sweep.ts
scripts/corpus-representative.ts
scripts/corpus-status.ts
scripts/package-smoke-test.ts
scripts/benchmark-check.ts
scripts/browser-automation.ts
benchmarks/safari.json
benchmarks/chrome.json
tsconfig.build.json
package.json
thoughts.md
RESEARCH.md
README.md
accuracy/firefox.json
accuracy/safari.json
accuracy/chrome.json
TODO.md
status/dashboard.json
bun.lock
shared/navigation-state.ts
STATUS.md
CHANGELOG.md
LICENSE

>sed -n '1,220p' package.json

Command: /bin/zsh -lc "sed -n '1,220p' package.json"
Chunk ID: 9aed31
Wall time: 0.0000 seconds
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Output:
{
  "name": "@chenglou/pretext",
  "version": "0.0.3",
  "license": "MIT",
  "type": "module",
  "publishConfig": {
    "access": "public"
  },
  "main": "./dist/layout.js",
  "types": "./dist/layout.d.ts",
  "exports": {
    ".": {
      "types": "./dist/layout.d.ts",
      "import": "./dist/layout.js",
      "default": "./dist/layout.js"
    },
    "./demos/*": "./pages/demos/*",
    "./assets/*": "./pages/assets/*",
    "./package.json": "./package.json"
  },
  "files": [
    "CHANGELOG.md",
    "dist",
    "src",
    "!src/layout.test.ts",
    "!src/test-data.ts",
    "pages/demos",
    "pages/assets",
    "LICENSE"
  ],
  "scripts": {
    "accuracy-check": "bun run scripts/accuracy-check.ts",
    "accuracy-check:firefox": "ACCURACY_CHECK_BROWSER=firefox bun run scripts/accuracy-check.ts",
    "accuracy-check:safari": "ACCURACY_CHECK_BROWSER=safari bun run scripts/accuracy-check.ts",
    "accuracy-snapshot": "bun run scripts/accuracy-check.ts --full --output=accuracy/chrome.json",
    "accuracy-snapshot:firefox": "ACCURACY_CHECK_BROWSER=firefox bun run scripts/accuracy-check.ts --full --output=accuracy/firefox.json",
    "accuracy-snapshot:safari": "ACCURACY_CHECK_BROWSER=safari bun run scripts/accuracy-check.ts --full --output=accuracy/safari.json",
    "benchmark-check": "bun run scripts/benchmark-check.ts",
    "benchmark-check:safari": "BENCHMARK_CHECK_BROWSER=safari bun run scripts/benchmark-check.ts",
    "build:package": "rm -rf dist && tsc -p tsconfig.build.json",
    "check": "tsc && oxlint --type-aware src",
    "corpus-check": "bun run scripts/corpus-check.ts",
    "corpus-check:safari": "CORPUS_CHECK_BROWSER=safari bun run scripts/corpus-check.ts",
    "corpus-font-matrix": "bun run scripts/corpus-font-matrix.ts",
    "corpus-font-matrix:safari": "CORPUS_CHECK_BROWSER=safari bun run scripts/corpus-font-matrix.ts",
    "corpus-representative": "bun run scripts/corpus-representative.ts --output=corpora/representative.json",
    "corpus-status": "bun run scripts/corpus-status.ts",
    "corpus-status:refresh": "bun run scripts/corpus-representative.ts --output=corpora/representative.json && bun run scripts/corpus-sweep.ts --all --samples=9 --output=corpora/chrome-sampled.json && bun run scripts/corpus-sweep.ts --all --start=300 --end=900 --step=10 --output=corpora/chrome-step10.json && bun run scripts/corpus-status.ts",
    "corpus-sweep": "bun run scripts/corpus-sweep.ts",
    "corpus-sweep:safari": "CORPUS_CHECK_BROWSER=safari bun run scripts/corpus-sweep.ts",
    "corpus-taxonomy": "bun run scripts/corpus-taxonomy.ts",
    "gatsby-check": "bun run scripts/gatsby-check.ts",
    "gatsby-check:safari": "GATSBY_CHECK_BROWSER=safari bun run scripts/gatsby-check.ts",
    "gatsby-sweep": "bun run scripts/gatsby-sweep.ts",
    "gatsby-sweep:safari": "GATSBY_CHECK_BROWSER=safari bun run scripts/gatsby-sweep.ts",
    "package-smoke-test": "bun run scripts/package-smoke-test.ts",
    "prepack": "rm -rf dist && tsc -p tsconfig.build.json",
    "pre-wrap-check": "bun run scripts/pre-wrap-check.ts",
    "probe-check": "bun run scripts/probe-check.ts",
    "probe-check:safari": "PROBE_CHECK_BROWSER=safari bun run scripts/probe-check.ts",
    "status-dashboard": "bun run scripts/status-dashboard.ts",
    "site:build": "rm -rf site && bun run scripts/build-demo-site.ts",
    "start": "HOST=${HOST:-127.0.0.1}; PORT=3000; pids=$(lsof -tiTCP:$PORT -sTCP:LISTEN 2>/dev/null); if [ -n \"$pids\" ]; then echo \"Freeing port $PORT: terminating $pids\"; kill $pids 2>/dev/null || true; sleep 1; pids=$(lsof -tiTCP:$PORT -sTCP:LISTEN 2>/dev/null); if [ -n \"$pids\" ]; then echo \"Port $PORT still busy: killing $pids\"; kill -9 $pids 2>/dev/null || true; fi; fi; bun pages/*.html pages/demos/*.html pages/demos/*/index.html --host=$HOST:$PORT",
    "start:lan": "HOST=0.0.0.0 bun run start",
    "start:watch": "HOST=${HOST:-127.0.0.1}; PORT=3000; pids=$(lsof -tiTCP:$PORT -sTCP:LISTEN 2>/dev/null); if [ -n \"$pids\" ]; then echo \"Freeing port $PORT: terminating $pids\"; kill $pids 2>/dev/null || true; sleep 1; pids=$(lsof -tiTCP:$PORT -sTCP:LISTEN 2>/dev/null); if [ -n \"$pids\" ]; then echo \"Port $PORT still busy: killing $pids\"; kill -9 $pids 2>/dev/null || true; fi; fi; bun pages/*.html pages/demos/*.html pages/demos/*/index.html --watch --no-clear-screen --host=$HOST:$PORT"
  },
  "devDependencies": {
    "@types/bun": "latest",
    "oxlint": "^1.51.0",
    "oxlint-tsgolint": "^0.15.0",
    "tsgolint": "^0.0.1",
    "typescript": "6.0.2"
  }
}

>find src -maxdepth 2 -type f | sort

Command: /bin/zsh -lc 'find src -maxdepth 2 -type f | sort'
Chunk ID: 1530ac
Wall time: 0.0000 seconds
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Output:
src/analysis.ts
src/bidi.ts
src/layout.test.ts
src/layout.ts
src/line-break.ts
src/measurement.ts
src/test-data.ts
src/text-modules.d.ts

>wc -l src/*.ts README.md RESEARCH.md STATUS.md TODO.md thoughts.md

Command: /bin/zsh -lc 'wc -l src/*.ts README.md RESEARCH.md STATUS.md TODO.md thoughts.md'
Chunk ID: 00a5c3
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Output:
    1007 src/analysis.ts
     173 src/bidi.ts
     774 src/layout.test.ts
     717 src/layout.ts
    1084 src/line-break.ts
     231 src/measurement.ts
      59 src/test-data.ts
       4 src/text-modules.d.ts
     147 README.md
     344 RESEARCH.md
      46 STATUS.md
      43 TODO.md
      17 thoughts.md
    4646 total

>sed -n '1,260p' README.md

Command: /bin/zsh -lc "sed -n '1,260p' README.md"
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Output:
# Pretext

Pure JavaScript/TypeScript library for multiline text measurement & layout. Fast, accurate & supports all the languages you didn't even know about. Allows rendering to DOM, Canvas, SVG and soon, server-side.

Pretext side-steps the need for DOM measurements (e.g. `getBoundingClientRect`, `offsetHeight`), which trigger layout reflow, one of the most expensive operations in the browser. It implements its own text measurement logic, using the browsers' own font engine as ground truth (very AI-friendly iteration method).

## Installation

```sh
npm install @chenglou/pretext
```

## Demos

Clone the repo, run `bun install`, then `bun start`, and open the `/demos` in your browser (no trailing slash. Bun devserver bugs on those)
Alternatively, see them live at [chenglou.me/pretext](https://chenglou.me/pretext/). Some more at [somnai-dreams.github.io/pretext-demos](https://somnai-dreams.github.io/pretext-demos/)

## API

Pretext serves 2 use cases:

### 1. Measure a paragraph's height _without ever touching DOM_

```ts
import { prepare, layout } from '@chenglou/pretext'

const prepared = prepare('AGI 春天到了. بدأت الرحلة 🚀', '16px Inter')
const { height, lineCount } = layout(prepared, textWidth, 20) // pure arithmetics. No DOM layout & reflow!
```

`prepare()` does the one-time work: normalize whitespace, segment the text, apply glue rules, measure the segments with canvas, and return an opaque handle. `layout()` is the cheap hot path after that: pure arithmetic over cached widths. Do not rerun `prepare()` for the same text and configs; that'd defeat its precomputation. For example, on resize, only rerun `layout()`.

If you want textarea-like text where ordinary spaces, `\t` tabs, and `\n` hard breaks stay visible, pass `{ whiteSpace: 'pre-wrap' }` to `prepare()`:

```ts
const prepared = prepare(textareaValue, '16px Inter', { whiteSpace: 'pre-wrap' })
const { height } = layout(prepared, textareaWidth, 20)
```

On the current checked-in benchmark snapshot:
- `prepare()` is about `19ms` for the shared 500-text batch
- `layout()` is about `0.09ms` for that same batch

We support all the languages you can imagine, including emojis and mixed-bidi, and caters to specific browser quirks

The returned height is the crucial last piece for unlocking web UI's:
- proper virtualization/occlusion without guesstimates & caching
- fancy userland layouts: masonry, JS-driven flexbox-like implementations, nudging a few layout values without CSS hacks (imagine that), etc.
- _development time_ verification (especially now with AI) that labels on e.g. buttons don't overflow to the next line, browser-free
- prevent layout shift when new text loads and you wanna re-anchor the scroll position

### 2. Lay out the paragraph lines manually yourself

Switch out `prepare` with `prepareWithSegments`, then:

- `layoutWithLines()` gives you all the lines at a fixed width:

```ts
import { prepareWithSegments, layoutWithLines } from '@chenglou/pretext'

const prepared = prepareWithSegments('AGI 春天到了. بدأت الرحلة 🚀', '18px "Helvetica Neue"')
const { lines } = layoutWithLines(prepared, 320, 26) // 320px max width, 26px line height
for (let i = 0; i < lines.length; i++) ctx.fillText(lines[i].text, 0, i * 26)
```

- `walkLineRanges()` gives you line widths and cursors without building the text strings:

```ts
let maxW = 0
walkLineRanges(prepared, 320, line => { if (line.width > maxW) maxW = line.width })
// maxW is now the widest line — the tightest container width that still fits the text! This multiline "shrink wrap" has been missing from web
```

- `layoutNextLine()` lets you route text one row at a time when width changes as you go:

```ts
let cursor = { segmentIndex: 0, graphemeIndex: 0 }
let y = 0

// Flow text around a floated image: lines beside the image are narrower
while (true) {
  const width = y < image.bottom ? columnWidth - image.width : columnWidth
  const line = layoutNextLine(prepared, cursor, width)
  if (line === null) break
  ctx.fillText(line.text, 0, y)
  cursor = line.end
  y += 26
}
```

This usage allows rendering to canvas, SVG, WebGL and (eventually) server-side.

### API Glossary

Use-case 1 APIs:
```ts
prepare(text: string, font: string, options?: { whiteSpace?: 'normal' | 'pre-wrap' }): PreparedText // one-time text analysis + measurement pass, returns an opaque value to pass to `layout()`. Make sure `font` is synced with your css `font` declaration shorthand (e.g. size, weight, style, family) for the text you're measuring. `font` is the same format as what you'd use for `myCanvasContext.font = ...`, e.g. `16px Inter`.
layout(prepared: PreparedText, maxWidth: number, lineHeight: number): { height: number, lineCount: number } // calculates text height given a max width and lineHeight. Make sure `lineHeight` is synced with your css `line-height` declaration for the text you're measuring.
```

Use-case 2 APIs:
```ts
prepareWithSegments(text: string, font: string, options?: { whiteSpace?: 'normal' | 'pre-wrap' }): PreparedTextWithSegments // same as `prepare()`, but returns a richer structure for manual line layouts needs
layoutWithLines(prepared: PreparedTextWithSegments, maxWidth: number, lineHeight: number): { height: number, lineCount: number, lines: LayoutLine[] } // high-level api for manual layout needs. Accepts a fixed max width for all lines. Similar to `layout()`'s return, but additionally returns the lines info
walkLineRanges(prepared: PreparedTextWithSegments, maxWidth: number, onLine: (line: LayoutLineRange) => void): number // low-level api for manual layout needs. Accepts a fixed max width for all lines. Calls `onLine` once per line with its actual calculated line width and start/end cursors, without building line text strings. Very useful for certain cases where you wanna speculatively test a few width and height boundaries (e.g. binary search a nice width value by repeatedly calling walkLineRanges and checking the line count, and therefore height, is "nice" too. You can have text messages shrinkwrap and balanced text layout this way). After walkLineRanges calls, you'd call layoutWithLines once, with your satisfying max width, to get the actual lines info.
layoutNextLine(prepared: PreparedTextWithSegments, start: LayoutCursor, maxWidth: number): LayoutLine | null // iterator-like api for laying out each line with a different width! Returns the LayoutLine starting from `start`, or `null` when the paragraph's exhausted. Pass the previous line's `end` cursor as the next `start`.
type LayoutLine = {
  text: string // Full text content of this line, e.g. 'hello world'
  width: number // Measured width of this line, e.g. 87.5
  start: LayoutCursor // Inclusive start cursor in prepared segments/graphemes
  end: LayoutCursor // Exclusive end cursor in prepared segments/graphemes
}
type LayoutLineRange = {
  width: number // Measured width of this line, e.g. 87.5
  start: LayoutCursor // Inclusive start cursor in prepared segments/graphemes
  end: LayoutCursor // Exclusive end cursor in prepared segments/graphemes
}
type LayoutCursor = {
  segmentIndex: number // Segment index in prepareWithSegments' prepared rich segment stream
  graphemeIndex: number // Grapheme index within that segment; `0` at segment boundaries
}
```

Other helpers:
```ts
clearCache(): void // clears Pretext's shared internal caches used by prepare() and prepareWithSegments(). Useful if your app cycles through many different fonts or text variants and you want to release the accumulated cache
setLocale(locale?: string): void // optional (by default we use the current locale). Sets locale for future prepare() and prepareWithSegments(). Internally, it also calls clearCache(). Setting a new locale doesn't affect existing prepare() and prepareWithSegments() states (no mutations to them)
```

## Caveats

Pretext doesn't try to be a full font rendering engine (yet?). It currently targets the common text setup:
- `white-space: normal`
- `word-break: normal`
- `overflow-wrap: break-word`
- `line-break: auto`
- If you pass `{ whiteSpace: 'pre-wrap' }`, ordinary spaces, `\t` tabs, and `\n` hard breaks are preserved instead of collapsed. Tabs follow the default browser-style `tab-size: 8`. The other wrapping defaults stay the same: `word-break: normal`, `overflow-wrap: break-word`, and `line-break: auto`.
- `system-ui` is unsafe for `layout()` accuracy on macOS. Use a named font.
- Because the default target includes `overflow-wrap: break-word`, very narrow widths can still break inside words, but only at grapheme boundaries.

## Develop

See [DEVELOPMENT.md](DEVELOPMENT.md) for the dev setup and commands.

## Credits

Sebastian Markbage first planted the seed with [text-layout](https://github.com/chenglou/text-layout) last decade. His design — canvas `measureText` for shaping, bidi from pdf.js, streaming line breaking — informed the architecture we kept pushing forward here.

>sed -n '1,260p' RESEARCH.md

Command: /bin/zsh -lc "sed -n '1,260p' RESEARCH.md"
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Output:
# Research Log

Everything we tried, measured, and learned while building this library.

For the current compact browser-accuracy / benchmark snapshot, see `STATUS.md`.
For the current compact corpus / sweep snapshot, see `corpora/STATUS.md`.
For the shared mismatch vocabulary, see `corpora/TAXONOMY.md`.

## Current steering summary

This log is historical. The current practical steering picture is:

- Japanese has two real canaries (`羅生門`, `蜘蛛の糸`), both clean at anchor widths and both still exposing a small positive one-line field on broader Chrome sweeps.
- Chinese has two long-form canaries (`祝福`, `故鄉`) showing the same broad Chrome-positive / Safari-clean split, with real font sensitivity between `Songti SC` and `PingFang SC`.
- Myanmar still has two real canaries with residual Chrome/Safari disagreement around quote/follower-style classes, so it remains the main unresolved Southeast Asian frontier.
- Urdu has a real Nastaliq/Naskh canary (`چغد`) with the same narrow-width negative field in Chrome and Safari, so it is clearly a shaping/context class rather than dirty data or a browser-only quirk. It remains parked rather than actively tuned.
- Arabic coarse corpora are clean; the remaining work there is mostly a fine-width edge-fit class, not the old preprocessing/corpus-hygiene problems.
- Mixed app text still matters because it catches product-shaped classes that books miss, especially soft-hyphen and extractor-sensitive cases.

## The problem: DOM measurement interleaving

When UI components independently measure text heights with DOM reads like `getBoundingClientRect()`, each read can force synchronous layout. If those reads interleave with writes, the browser can end up relaying out the whole document repeatedly.

The goal here was always the same:
- do the expensive text work once in `prepare()`
- keep `layout()` arithmetic-only
- make resize-driven relayout cheap and coordination-free

## Approach 1: Canvas measureText + word-width caching

Canvas `measureText()` avoids DOM layout. It goes straight to the browser's font engine.

That led to the basic two-phase model:
- `prepare(text, font)` — segment text, measure segments, cache widths
- `layout(prepared, maxWidth, lineHeight)` — walk cached widths with pure arithmetic

That architecture held up. The broad browser sweeps are now clean in Chrome, Safari, and Firefox, and the hot `layout()` path is still the core product win.

## Rejected: DOM-based or string-reconstruction measurement in the hot path

Several alternatives were tried and rejected:

- measuring full candidate lines as strings during `layout()`
- moving measurement into hidden DOM elements during `prepare()`
- using SVG `getComputedTextLength()`

The pattern was consistent:
- they either reintroduced DOM reads
- or they were slower than the current two-phase model
- or they looked cleaner locally but regressed the actual benchmark path

The important keep was architectural, not algorithmic:
- `layout()` stayed arithmetic-only on cached widths

## Discovery: system-ui font resolution mismatch

Canvas and DOM resolve `system-ui` to different font variants on macOS at certain sizes:

Machine-readable scan:
- [research-data/system-ui-size-scan.json](/Users/chenglou/github/pretext/research-data/system-ui-size-scan.json)

In the recorded scan, mismatches clustered at `10-12px`, `14px`, and `26px`.
`13px`, `15-25px`, and `27-28px` were exact.

macOS uses SF Pro Text at smaller sizes and SF Pro Display at larger sizes. Canvas and DOM switch between them at different thresholds.

Practical conclusion:
- use a named font if accuracy matters
- keep `system-ui` documented as unsafe
- if we ever support it properly, the believable path is a narrow prepare-time DOM fallback for detected bad tuples

What did **not** look trustworthy enough:
- lookup tables
- naive scaling
- guessed resolved-font substitution

## Discovery: word-by-word sum accuracy

Canvas is internally consistent enough that summing measured segments works very well, but not perfectly. Over a full paragraph, tiny adjacency differences can accumulate into a line-edge error.

The keeps were small and semantic:
- merge punctuation into the preceding word before measuring
- let trailing collapsible spaces hang instead of forcing a break

What did **not** survive:
- full-string verification in `layout()`
- uniform rescaling
- generic pair-level correction models

The broad lesson was that local semantic preprocessing paid off more than clever runtime correction.

## Discovery: text-shaper is a useful reference, not a runtime replacement

`text-shaper` was useful reference material, especially for Unicode coverage and bidi ideas, but not a replacement for the current browser-facing model.

What was worth taking:
- broader Unicode coverage, e.g. missing CJK extension blocks

What was not worth taking:
- its segmentation as a runtime replacement for `Intl.Segmenter`
- its paragraph breaker as a substitute for browser-parity layout

Bottom line:
- good reference material
- wrong runtime center of gravity for this repo

## Discovery: preserving ordinary spaces, hard breaks, and numeric tab stops is viable

The smallest honest second whitespace mode turned out to be:
- preserve ordinary spaces
- preserve `\n` hard breaks
- preserve tabs with default browser-style tab stops
- leave the other wrapping defaults alone

That became:
- `{ whiteSpace: 'pre-wrap' }`

What mattered:
- preserved spaces still hang at line end
- consecutive hard breaks keep empty lines
- a trailing final hard break does **not** invent an extra empty line
- tabs advance to the next default browser tab stop from the current line start

The mode now covers the textarea-like cases we cared about, and the broad browser sweeps plus the dedicated `pre-wrap` oracle are green.

One important tooling lesson also came out of this:
- keep a small permanent oracle suite
- justify it once with a broader brute-force validation pass
- do not keep the brute-force pass forever once it has done its job

## Discovery: emoji canvas/DOM width discrepancy

Chrome and Firefox on macOS can measure emoji wider in canvas than in DOM at small sizes. Safari does not share the same discrepancy.

What held up:
- detect the discrepancy by comparing canvas emoji width against actual DOM emoji width per font
- cache that correction
- keep it outside the hot layout path

This is now one of the small browser-profile shims that is actually justified.

## Retired HarfBuzz probe path

We briefly kept a headless HarfBuzz backend in the repo for server-side measurement probes.

What it taught us:
- it was useful for research and algorithm probes
- it was not close enough to our active browser-grounded path to justify keeping it in the main repo
- isolated Arabic words in that probe path needed explicit LTR direction to avoid misleading widths

So if HarfBuzz comes up again later, treat it as explored territory:
- useful as a research reference
- not the runtime direction for Pretext
- not a substitute for browser-oracle or browser-canvas validation

## Final browser sweep closure

The last browser mismatches were not fixed by moving more work into `layout()`. That regressed the hot path and was reverted.

What actually held up:
- better preprocessing in `prepare()`
- better browser diagnostics pages and scripts
- a tiny browser-specific line-fit tolerance

What did **not** change:
- `layout()` stayed arithmetic-only

That remains the right center of gravity for the project.

## Arabic frontier

Arabic took several passes, but the pattern is clearer now.

What survived:
- merge no-space Arabic punctuation clusters during `prepare()`
  - e.g. `فيقول:وعليك`, `همزةٌ،ما`
- treat Arabic punctuation-plus-mark clusters like `،ٍ` as left-sticky too
- split `" " + combining marks` into plain space plus marks attached to the following word
- use normalized slices and the exact corpus font during probe work
- trust the better RTL diagnostics path instead of reconstructing offsets from rendered line text
- clean obvious corpus/source artifacts instead of inventing new engine rules for them
- allow a tiny non-Safari line-fit tolerance bump for the remaining positive fine-width field

What did **not** survive:
- pair correction models at segment boundaries
- larger Arabic run-slice width models
- broad phrase-level heuristics derived from one good-looking probe

Those failed for the same reason in different sizes:
- pair corrections were too local to move the real misses
- run-slice widths were much heavier and still did not move the hard widths enough
- both made `prepare()` or `layout()` materially worse without buying a clean Arabic field

So the useful guardrail is:
- if an Arabic idea starts by adding more shaping-aware width caches inside the current segment-sum architecture, be skeptical early
- the Arabic keeps so far have been preprocessing, corpus cleanup, diagnostics, and tiny tolerance shims, not richer width-cache models

Current read:
- Arabic coarse corpora are healthy
- the remaining work is much narrower now
- the unresolved class looks like a mix of fine-width edge-fit and shaping/context, not another obvious preprocessing hole

## Long-form corpus canaries

Once the main browser sweep became a regression gate, the long-form corpora became the real steering canaries.

### Mixed app text

This is the most product-shaped canary.

What it has been good for:
- URL/query-string handling
- escaped quote clusters
- numeric expressions like `२४×७`
- time ranges like `7:00-9:00`
- emoji ZWJ runs
- manual soft hyphens

Important keep:
- model URL/query strings as narrow structured units, not one giant breakable blob

Current status:
- almost entirely clean
- one remaining extractor-sensitive soft-hyphen miss around `710px` still looks paragraph-scale or accumulation-sensitive rather than like a neat local bug

### Thai

Thai exposed a product-shaped ASCII quote issue more than a dictionary-segmentation failure.

The keep:
- contextual ASCII quote glue during preprocessing

Result:
- two Thai prose corpora are healthy at anchor widths
- sampled sweeps stayed clean enough that Thai now looks broader than one lucky story

### Khmer

Khmer broadened the Southeast Asian class without immediately demanding new engine work.

The keep:
- preserve explicit zero-width separators from the source text

Result:
- anchors and sampled sweeps were clean enough to keep Khmer as a real canary

### Lao (rejected)

The Lao corpus attempt was a source problem, not an engine problem.

The raw text was wrapped print/legal text, which made it a dirty `white-space: normal` canary. We rejected it instead of normalizing nonsense into the repo.

### Myanmar

Myanmar is still the main unresolved Southeast Asian frontier.

What survived:
- treat `၊` / `။` / `၍` / `၌` / `၏` as left-sticky during preprocessing
- treat `၏` as medial glue in clusters like `ကျွန်ုပ်၏လက်မ`

>sed -n '1,260p' thoughts.md

Command: /bin/zsh -lc "sed -n '1,260p' thoughts.md"
Chunk ID: 059ab7
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 544
Output:
## Personal Thoughts, In No Particular Order

- My personal desire is to see end-developers being empowered to make all the layouts that makes UI more expressive, without sacrificing maintainability & performance, and without having to wait for permissions from the web committee. The current UI stereotypes across all platforms has been either:
  - a landing-page with few, floating text chunks, powered by GL
  - a blog article with mostly just text and no possible interactivity
  - a SaaS dashboard
  - a mobile UI with 2-3 rectangles' worth of UI

- If you dig deep enough, 80% of CSS spec could be avoided if userland had better control over text. The paradigm of web layout shoves our text into a single-direction black hole, and to crawl those text metrics back incurs huge maintenance and performance overhead (ask AI about this).

- The convenience angle of CSS is gradually being eroded by the fact that:
  - the more CSS expressivity we bake in, the worse the CSS perf becomes (against all wishes from everyone on the committee and userland), and "programming" in CSS (as opposed to just "declare things" in CSS) is something very few desire
  - AI alleviates the need of having more hard-coded CSS configs, which are becoming more dictionary-like rather compositional.

- It's very hard to have new competing web browser implementations, because the specs are gigantic, and many engines (grassroot efforts, gamers-driven rewrites, languages-driven rewrites, etc.) eagerly chase & premature perf improvements before realizing that the specs, often written decades ago and disregarding modern perf & feature needs,  throw a wrench in those architectures. As a first approximation, UI performance & developer ergonomics _cannot_ possibly have an order of magnitude improvement, because the bottleneck is in the specs themselves. The only way to circumvent this is to bring more capabilities to userland, in a hope to stop the spec from over-growing even more in the future. Stopping spec complexity is something every browser vendor can agree on (and ironically, sometime for completely opposing reasons).

- The cost of any verifiable software will trend toward 0

>rg -n "^(export |function |const |type |interface )" src/layout.ts src/analysis.ts src/line-break.ts src/measurement.ts src/bidi.ts

Command: /bin/zsh -lc 'rg -n "''^(export |function |const |type |interface )" src/layout.ts src/analysis.ts src/line-break.ts src/measurement.ts src/bidi.ts'
Chunk ID: c6a6f8
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2676
Output:
src/layout.ts:72:function getSharedGraphemeSegmenter(): Intl.Segmenter {
src/layout.ts:83:type PreparedCore = {
src/layout.ts:99:export type PreparedText = {
src/layout.ts:103:type InternalPreparedText = PreparedText & PreparedCore
src/layout.ts:107:export type PreparedTextWithSegments = InternalPreparedText & {
src/layout.ts:111:export type LayoutCursor = {
src/layout.ts:116:export type LayoutResult = {
src/layout.ts:121:export type LayoutLine = {
src/layout.ts:128:export type LayoutLineRange = {
src/layout.ts:134:export type LayoutLinesResult = LayoutResult & {
src/layout.ts:138:export type PrepareProfile = {
src/layout.ts:147:export type PrepareOptions = {
src/layout.ts:151:export type PreparedLineChunk = {
src/layout.ts:159:function createEmptyPrepared(includeSegments: boolean): InternalPreparedText | PreparedTextWithSegments {
src/layout.ts:191:function measureAnalysis(
src/layout.ts:394:function mapAnalysisChunksToPreparedChunks(
src/layout.ts:424:function prepareInternal(
src/layout.ts:436:export function profilePrepare(text: string, font: string, options?: PrepareOptions): PrepareProfile {
src/layout.ts:472:export function prepare(text: string, font: string, options?: PrepareOptions): PreparedText {
src/layout.ts:478:export function prepareWithSegments(text: string, font: string, options?: PrepareOptions): PreparedTextWithSegments {
src/layout.ts:482:function getInternalPrepared(prepared: PreparedText): InternalPreparedText {
src/layout.ts:495:export function layout(prepared: PreparedText, maxWidth: number, lineHeight: number): LayoutResult {
src/layout.ts:503:function getSegmentGraphemes(
src/layout.ts:520:function getLineTextCache(prepared: PreparedTextWithSegments): Map<number, string[]> {
src/layout.ts:529:function lineHasDiscretionaryHyphen(
src/layout.ts:542:function buildLineTextFromRange(
src/layout.ts:581:function createLayoutLine(
src/layout.ts:612:function materializeLayoutLine(
src/layout.ts:628:function toLayoutLineRange(line: InternalLayoutLine): LayoutLineRange {
src/layout.ts:642:function stepLineRange(
src/layout.ts:652:function materializeLine(
src/layout.ts:669:export function walkLineRanges(
src/layout.ts:681:export function layoutNextLine(
src/layout.ts:695:export function layoutWithLines(prepared: PreparedTextWithSegments, maxWidth: number, lineHeight: number): LayoutLinesResult {
src/layout.ts:707:export function clearCache(): void {
src/layout.ts:714:export function setLocale(locale?: string): void {
src/line-break.ts:4:export type LineBreakCursor = {
src/line-break.ts:9:export type PreparedLineBreakData = {
src/line-break.ts:26:export type InternalLayoutLine = {
src/line-break.ts:34:function canBreakAfter(kind: SegmentBreakKind): boolean {
src/line-break.ts:44:function isSimpleCollapsibleSpace(kind: SegmentBreakKind): boolean {
src/line-break.ts:48:function getTabAdvance(lineWidth: number, tabStopAdvance: number): number {
src/line-break.ts:56:function getBreakableAdvance(
src/line-break.ts:68:function fitSoftHyphenBreak(
src/line-break.ts:94:function findChunkIndexForStart(prepared: PreparedLineBreakData, segmentIndex: number): number {
src/line-break.ts:102:export function normalizeLineStart(
src/line-break.ts:133:export function countPreparedLines(prepared: PreparedLineBreakData, maxWidth: number): number {
src/line-break.ts:140:function countPreparedLinesSimple(prepared: PreparedLineBreakData, maxWidth: number): number {
src/line-break.ts:204:function walkPreparedLinesSimple(
src/line-break.ts:375:export function walkPreparedLines(
src/line-break.ts:673:export function layoutNextLineRange(
src/line-break.ts:937:function layoutNextLineRangeSimple(
src/measurement.ts:3:export type SegmentMetrics = {
src/measurement.ts:11:export type EngineProfile = {
src/measurement.ts:19:const segmentMetricCaches = new Map<string, Map<string, SegmentMetrics>>()
src/measurement.ts:22:const emojiPresentationRe = /\p{Emoji_Presentation}/u
src/measurement.ts:23:const maybeEmojiRe = /[\p{Emoji_Presentation}\p{Extended_Pictographic}\p{Regional_Indicator}\uFE0F\u20E3]/u
src/measurement.ts:25:const emojiCorrectionCache = new Map<string, number>()
src/measurement.ts:27:export function getMeasureContext(): CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D {
src/measurement.ts:43:export function getSegmentMetricCache(font: string): Map<string, SegmentMetrics> {
src/measurement.ts:52:export function getSegmentMetrics(seg: string, cache: Map<string, SegmentMetrics>): SegmentMetrics {
src/measurement.ts:65:export function getEngineProfile(): EngineProfile {
src/measurement.ts:103:export function parseFontSize(font: string): number {
src/measurement.ts:108:function getSharedGraphemeSegmenter(): Intl.Segmenter {
src/measurement.ts:115:function isEmojiGrapheme(g: string): boolean {
src/measurement.ts:119:export function textMayContainEmoji(text: string): boolean {
src/measurement.ts:123:function getEmojiCorrection(font: string, fontSize: number): number {
src/measurement.ts:153:function countEmojiGraphemes(text: string): number {
src/measurement.ts:162:function getEmojiCount(seg: string, metrics: SegmentMetrics): number {
src/measurement.ts:169:export function getCorrectedSegmentWidth(seg: string, metrics: SegmentMetrics, emojiCorrection: number): number {
src/measurement.ts:174:export function getSegmentGraphemeWidths(
src/measurement.ts:193:export function getSegmentGraphemePrefixWidths(
src/measurement.ts:214:export function getFontMeasurementState(font: string, needsEmojiCorrection: boolean): {
src/measurement.ts:227:export function clearMeasurementCaches(): void {
src/analysis.ts:1:export type WhiteSpaceMode = 'normal' | 'pre-wrap'
src/analysis.ts:3:export type SegmentBreakKind =
src/analysis.ts:13:type SegmentationPiece = {
src/analysis.ts:20:export type MergedSegmentation = {
src/analysis.ts:28:export type AnalysisChunk = {
src/analysis.ts:34:export type TextAnalysis = { normalized: string, chunks: AnalysisChunk[] } & MergedSegmentation
src/analysis.ts:36:export type AnalysisProfile = {
src/analysis.ts:40:const collapsibleWhitespaceRunRe = /[ \t\n\r\f]+/g
src/analysis.ts:41:const needsWhitespaceNormalizationRe = /[\t\n\r\f]| {2,}|^ | $/
src/analysis.ts:43:type WhiteSpaceProfile = {
src/analysis.ts:49:function getWhiteSpaceProfile(whiteSpace?: WhiteSpaceMode): WhiteSpaceProfile {
src/analysis.ts:56:export function normalizeWhitespaceNormal(text: string): string {
src/analysis.ts:69:function normalizeWhitespacePreWrap(text: string): string {
src/analysis.ts:79:function getSharedWordSegmenter(): Intl.Segmenter {
src/analysis.ts:86:export function clearAnalysisCaches(): void {
src/analysis.ts:90:export function setAnalysisLocale(locale?: string): void {
src/analysis.ts:97:const arabicScriptRe = /\p{Script=Arabic}/u
src/analysis.ts:98:const combiningMarkRe = /\p{M}/u
src/analysis.ts:99:const decimalDigitRe = /\p{Nd}/u
src/analysis.ts:101:function containsArabicScript(text: string): boolean {
src/analysis.ts:105:export function isCJK(s: string): boolean {
src/analysis.ts:129:export const kinsokuStart = new Set([
src/analysis.ts:158:export const kinsokuEnd = new Set([
src/analysis.ts:174:const forwardStickyGlue = new Set([
src/analysis.ts:178:export const leftStickyPunctuation = new Set([
src/analysis.ts:197:const arabicNoSpaceTrailingPunctuation = new Set([
src/analysis.ts:204:const myanmarMedialGlue = new Set([
src/analysis.ts:208:const closingQuoteChars = new Set([
src/analysis.ts:219:function isLeftStickyPunctuationSegment(segment: string): boolean {
src/analysis.ts:233:function isCJKLineStartProhibitedSegment(segment: string): boolean {
src/analysis.ts:240:function isForwardStickyClusterSegment(segment: string): boolean {
src/analysis.ts:248:function isEscapedQuoteClusterSegment(segment: string): boolean {
src/analysis.ts:261:function splitTrailingForwardStickyCluster(text: string): { head: string, tail: string } | null {
src/analysis.ts:285:function isRepeatedSingleCharRun(segment: string, ch: string): boolean {
src/analysis.ts:293:function endsWithArabicNoSpacePunctuation(segment: string): boolean {
src/analysis.ts:298:function endsWithMyanmarMedialGlue(segment: string): boolean {
src/analysis.ts:303:function splitLeadingSpaceAndMarks(segment: string): { space: string, marks: string } | null {
src/analysis.ts:312:export function endsWithClosingQuote(text: string): boolean {
src/analysis.ts:321:function classifySegmentBreakChar(ch: string, whiteSpaceProfile: WhiteSpaceProfile): SegmentBreakKind {
src/analysis.ts:336:function splitSegmentByBreakKind(
src/analysis.ts:387:function isTextRunBoundary(kind: SegmentBreakKind): boolean {
src/analysis.ts:396:const urlSchemeSegmentRe = /^[A-Za-z][A-Za-z0-9+.-]*:$/
src/analysis.ts:398:function isUrlLikeRunStart(segmentation: MergedSegmentation, index: number): boolean {
src/analysis.ts:409:function isUrlQueryBoundarySegment(text: string): boolean {
src/analysis.ts:413:function mergeUrlLikeRuns(segmentation: MergedSegmentation): MergedSegmentation {
src/analysis.ts:461:function mergeUrlQueryRuns(segmentation: MergedSegmentation): MergedSegmentation {
src/analysis.ts:510:const numericJoinerChars = new Set([
src/analysis.ts:516:const asciiPunctuationChainSegmentRe = /^[A-Za-z0-9_]+[,:;]*$/
src/analysis.ts:517:const asciiPunctuationChainTrailingJoinersRe = /[,:;]+$/
src/analysis.ts:519:function segmentContainsDecimalDigit(text: string): boolean {
src/analysis.ts:526:function isNumericRunSegment(text: string): boolean {
src/analysis.ts:535:function mergeNumericRuns(segmentation: MergedSegmentation): MergedSegmentation {
src/analysis.ts:580:function mergeAsciiPunctuationChains(segmentation: MergedSegmentation): MergedSegmentation {
src/analysis.ts:629:function splitHyphenatedNumericRuns(segmentation: MergedSegmentation): MergedSegmentation {
src/analysis.ts:682:function mergeGlueConnectedTextRuns(segmentation: MergedSegmentation): MergedSegmentation {
src/analysis.ts:755:function carryTrailingForwardStickyAcrossCJKBoundary(segmentation: MergedSegmentation): MergedSegmentation {
src/analysis.ts:783:function buildMergedSegmentation(
src/analysis.ts:946:function compileAnalysisChunks(segmentation: MergedSegmentation, whiteSpaceProfile: WhiteSpaceProfile): AnalysisChunk[] {
src/analysis.ts:981:export function analyzeText(
src/bidi.ts:7:type BidiType = 'L' | 'R' | 'AL' | 'AN' | 'EN' | 'ES' | 'ET' | 'CS' |
src/bidi.ts:10:const baseTypes: BidiType[] = [
src/bidi.ts:32:const arabicTypes: BidiType[] = [
src/bidi.ts:57:function classifyChar(charCode: number): BidiType {
src/bidi.ts:65:function computeBidiLevels(str: string): Int8Array | null {
src/bidi.ts:164:export function computeSegmentLevels(normalized: string, segStarts: number[]): Int8Array | null {

>sed -n '1,260p' src/measurement.ts

Command: /bin/zsh -lc "sed -n '1,260p' src/measurement.ts"
Chunk ID: bd68a7
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1795
Output:
import { isCJK } from './analysis.js'

export type SegmentMetrics = {
  width: number
  containsCJK: boolean
  emojiCount?: number
  graphemeWidths?: number[] | null
  graphemePrefixWidths?: number[] | null
}

export type EngineProfile = {
  lineFitEpsilon: number
  carryCJKAfterClosingQuote: boolean
  preferPrefixWidthsForBreakableRuns: boolean
  preferEarlySoftHyphenBreak: boolean
}

let measureContext: CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D | null = null
const segmentMetricCaches = new Map<string, Map<string, SegmentMetrics>>()
let cachedEngineProfile: EngineProfile | null = null

const emojiPresentationRe = /\p{Emoji_Presentation}/u
const maybeEmojiRe = /[\p{Emoji_Presentation}\p{Extended_Pictographic}\p{Regional_Indicator}\uFE0F\u20E3]/u
let sharedGraphemeSegmenter: Intl.Segmenter | null = null
const emojiCorrectionCache = new Map<string, number>()

export function getMeasureContext(): CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D {
  if (measureContext !== null) return measureContext

  if (typeof OffscreenCanvas !== 'undefined') {
    measureContext = new OffscreenCanvas(1, 1).getContext('2d')!
    return measureContext
  }

  if (typeof document !== 'undefined') {
    measureContext = document.createElement('canvas').getContext('2d')!
    return measureContext
  }

  throw new Error('Text measurement requires OffscreenCanvas or a DOM canvas context.')
}

export function getSegmentMetricCache(font: string): Map<string, SegmentMetrics> {
  let cache = segmentMetricCaches.get(font)
  if (!cache) {
    cache = new Map()
    segmentMetricCaches.set(font, cache)
  }
  return cache
}

export function getSegmentMetrics(seg: string, cache: Map<string, SegmentMetrics>): SegmentMetrics {
  let metrics = cache.get(seg)
  if (metrics === undefined) {
    const ctx = getMeasureContext()
    metrics = {
      width: ctx.measureText(seg).width,
      containsCJK: isCJK(seg),
    }
    cache.set(seg, metrics)
  }
  return metrics
}

export function getEngineProfile(): EngineProfile {
  if (cachedEngineProfile !== null) return cachedEngineProfile

  if (typeof navigator === 'undefined') {
    cachedEngineProfile = {
      lineFitEpsilon: 0.005,
      carryCJKAfterClosingQuote: false,
      preferPrefixWidthsForBreakableRuns: false,
      preferEarlySoftHyphenBreak: false,
    }
    return cachedEngineProfile
  }

  const ua = navigator.userAgent
  const vendor = navigator.vendor
  const isSafari =
    vendor === 'Apple Computer, Inc.' &&
    ua.includes('Safari/') &&
    !ua.includes('Chrome/') &&
    !ua.includes('Chromium/') &&
    !ua.includes('CriOS/') &&
    !ua.includes('FxiOS/') &&
    !ua.includes('EdgiOS/')
  const isChromium =
    ua.includes('Chrome/') ||
    ua.includes('Chromium/') ||
    ua.includes('CriOS/') ||
    ua.includes('Edg/')

  cachedEngineProfile = {
    lineFitEpsilon: isSafari ? 1 / 64 : 0.005,
    carryCJKAfterClosingQuote: isChromium,
    preferPrefixWidthsForBreakableRuns: isSafari,
    preferEarlySoftHyphenBreak: isSafari,
  }
  return cachedEngineProfile
}

export function parseFontSize(font: string): number {
  const m = font.match(/(\d+(?:\.\d+)?)\s*px/)
  return m ? parseFloat(m[1]!) : 16
}

function getSharedGraphemeSegmenter(): Intl.Segmenter {
  if (sharedGraphemeSegmenter === null) {
    sharedGraphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })
  }
  return sharedGraphemeSegmenter
}

function isEmojiGrapheme(g: string): boolean {
  return emojiPresentationRe.test(g) || g.includes('\uFE0F')
}

export function textMayContainEmoji(text: string): boolean {
  return maybeEmojiRe.test(text)
}

function getEmojiCorrection(font: string, fontSize: number): number {
  let correction = emojiCorrectionCache.get(font)
  if (correction !== undefined) return correction

  const ctx = getMeasureContext()
  ctx.font = font
  const canvasW = ctx.measureText('\u{1F600}').width
  correction = 0
  if (
    canvasW > fontSize + 0.5 &&
    typeof document !== 'undefined' &&
    document.body !== null
  ) {
    const span = document.createElement('span')
    span.style.font = font
    span.style.display = 'inline-block'
    span.style.visibility = 'hidden'
    span.style.position = 'absolute'
    span.textContent = '\u{1F600}'
    document.body.appendChild(span)
    const domW = span.getBoundingClientRect().width
    document.body.removeChild(span)
    if (canvasW - domW > 0.5) {
      correction = canvasW - domW
    }
  }
  emojiCorrectionCache.set(font, correction)
  return correction
}

function countEmojiGraphemes(text: string): number {
  let count = 0
  const graphemeSegmenter = getSharedGraphemeSegmenter()
  for (const g of graphemeSegmenter.segment(text)) {
    if (isEmojiGrapheme(g.segment)) count++
  }
  return count
}

function getEmojiCount(seg: string, metrics: SegmentMetrics): number {
  if (metrics.emojiCount === undefined) {
    metrics.emojiCount = countEmojiGraphemes(seg)
  }
  return metrics.emojiCount
}

export function getCorrectedSegmentWidth(seg: string, metrics: SegmentMetrics, emojiCorrection: number): number {
  if (emojiCorrection === 0) return metrics.width
  return metrics.width - getEmojiCount(seg, metrics) * emojiCorrection
}

export function getSegmentGraphemeWidths(
  seg: string,
  metrics: SegmentMetrics,
  cache: Map<string, SegmentMetrics>,
  emojiCorrection: number,
): number[] | null {
  if (metrics.graphemeWidths !== undefined) return metrics.graphemeWidths

  const widths: number[] = []
  const graphemeSegmenter = getSharedGraphemeSegmenter()
  for (const gs of graphemeSegmenter.segment(seg)) {
    const graphemeMetrics = getSegmentMetrics(gs.segment, cache)
    widths.push(getCorrectedSegmentWidth(gs.segment, graphemeMetrics, emojiCorrection))
  }

  metrics.graphemeWidths = widths.length > 1 ? widths : null
  return metrics.graphemeWidths
}

export function getSegmentGraphemePrefixWidths(
  seg: string,
  metrics: SegmentMetrics,
  cache: Map<string, SegmentMetrics>,
  emojiCorrection: number,
): number[] | null {
  if (metrics.graphemePrefixWidths !== undefined) return metrics.graphemePrefixWidths

  const prefixWidths: number[] = []
  const graphemeSegmenter = getSharedGraphemeSegmenter()
  let prefix = ''
  for (const gs of graphemeSegmenter.segment(seg)) {
    prefix += gs.segment
    const prefixMetrics = getSegmentMetrics(prefix, cache)
    prefixWidths.push(getCorrectedSegmentWidth(prefix, prefixMetrics, emojiCorrection))
  }

  metrics.graphemePrefixWidths = prefixWidths.length > 1 ? prefixWidths : null
  return metrics.graphemePrefixWidths
}

export function getFontMeasurementState(font: string, needsEmojiCorrection: boolean): {
  cache: Map<string, SegmentMetrics>
  fontSize: number
  emojiCorrection: number
} {
  const ctx = getMeasureContext()
  ctx.font = font
  const cache = getSegmentMetricCache(font)
  const fontSize = parseFontSize(font)
  const emojiCorrection = needsEmojiCorrection ? getEmojiCorrection(font, fontSize) : 0
  return { cache, fontSize, emojiCorrection }
}

export function clearMeasurementCaches(): void {
  segmentMetricCaches.clear()
  emojiCorrectionCache.clear()
  sharedGraphemeSegmenter = null
}

>sed -n '1,260p' src/bidi.ts

Command: /bin/zsh -lc "sed -n '1,260p' src/bidi.ts"
Chunk ID: 0b125e
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1654
Output:
// Simplified bidi metadata helper for the rich prepareWithSegments() path,
// forked from pdf.js via Sebastian's text-layout. It classifies characters
// into bidi types, computes embedding levels, and maps them onto prepared
// segments for custom rendering. The line-breaking engine does not consume
// these levels.

type BidiType = 'L' | 'R' | 'AL' | 'AN' | 'EN' | 'ES' | 'ET' | 'CS' |
                'ON' | 'BN' | 'B' | 'S' | 'WS' | 'NSM'

const baseTypes: BidiType[] = [
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','S','B','S','WS',
  'B','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','BN','B','B','B','S','WS','ON','ON','ET','ET','ET','ON',
  'ON','ON','ON','ON','ON','CS','ON','CS','ON','EN','EN','EN',
  'EN','EN','EN','EN','EN','EN','EN','ON','ON','ON','ON','ON',
  'ON','ON','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','ON','ON',
  'ON','ON','ON','ON','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','ON','ON','ON','ON','BN','BN','BN','BN','BN','BN','B','BN',
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','CS','ON','ET','ET','ET','ET','ON','ON','ON','ON','L','ON',
  'ON','ON','ON','ON','ET','ET','EN','EN','ON','L','ON','ON','ON',
  'EN','L','ON','ON','ON','ON','ON','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','ON','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','ON','L','L','L','L','L','L','L','L'
]

const arabicTypes: BidiType[] = [
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'CS','AL','ON','ON','NSM','NSM','NSM','NSM','NSM','NSM','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','NSM','NSM','NSM','NSM','NSM','NSM','NSM',
  'NSM','NSM','NSM','NSM','NSM','NSM','NSM','AL','AL','AL','AL',
  'AL','AL','AL','AN','AN','AN','AN','AN','AN','AN','AN','AN',
  'AN','ET','AN','AN','AL','AL','AL','NSM','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM',
  'NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','ON','NSM',
  'NSM','NSM','NSM','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL'
]

function classifyChar(charCode: number): BidiType {
  if (charCode <= 0x00ff) return baseTypes[charCode]!
  if (0x0590 <= charCode && charCode <= 0x05f4) return 'R'
  if (0x0600 <= charCode && charCode <= 0x06ff) return arabicTypes[charCode & 0xff]!
  if (0x0700 <= charCode && charCode <= 0x08AC) return 'AL'
  return 'L'
}

function computeBidiLevels(str: string): Int8Array | null {
  const len = str.length
  if (len === 0) return null

  // eslint-disable-next-line unicorn/no-new-array
  const types: BidiType[] = new Array(len)
  let numBidi = 0

  for (let i = 0; i < len; i++) {
    const t = classifyChar(str.charCodeAt(i))
    if (t === 'R' || t === 'AL' || t === 'AN') numBidi++
    types[i] = t
  }

  if (numBidi === 0) return null

  const startLevel = (len / numBidi) < 0.3 ? 0 : 1
  const levels = new Int8Array(len)
  for (let i = 0; i < len; i++) levels[i] = startLevel

  const e: BidiType = (startLevel & 1) ? 'R' : 'L'
  const sor = e

  // W1-W7
  let lastType: BidiType = sor
  for (let i = 0; i < len; i++) {
    if (types[i] === 'NSM') types[i] = lastType
    else lastType = types[i]!
  }
  lastType = sor
  for (let i = 0; i < len; i++) {
    const t = types[i]!
    if (t === 'EN') types[i] = lastType === 'AL' ? 'AN' : 'EN'
    else if (t === 'R' || t === 'L' || t === 'AL') lastType = t
  }
  for (let i = 0; i < len; i++) {
    if (types[i] === 'AL') types[i] = 'R'
  }
  for (let i = 1; i < len - 1; i++) {
    if (types[i] === 'ES' && types[i - 1] === 'EN' && types[i + 1] === 'EN') {
      types[i] = 'EN'
    }
    if (
      types[i] === 'CS' &&
      (types[i - 1] === 'EN' || types[i - 1] === 'AN') &&
      types[i + 1] === types[i - 1]
    ) {
      types[i] = types[i - 1]!
    }
  }
  for (let i = 0; i < len; i++) {
    if (types[i] !== 'EN') continue
    let j
    for (j = i - 1; j >= 0 && types[j] === 'ET'; j--) types[j] = 'EN'
    for (j = i + 1; j < len && types[j] === 'ET'; j++) types[j] = 'EN'
  }
  for (let i = 0; i < len; i++) {
    const t = types[i]!
    if (t === 'WS' || t === 'ES' || t === 'ET' || t === 'CS') types[i] = 'ON'
  }
  lastType = sor
  for (let i = 0; i < len; i++) {
    const t = types[i]!
    if (t === 'EN') types[i] = lastType === 'L' ? 'L' : 'EN'
    else if (t === 'R' || t === 'L') lastType = t
  }

  // N1-N2
  for (let i = 0; i < len; i++) {
    if (types[i] !== 'ON') continue
    let end = i + 1
    while (end < len && types[end] === 'ON') end++
    const before: BidiType = i > 0 ? types[i - 1]! : sor
    const after: BidiType = end < len ? types[end]! : sor
    const bDir: BidiType = before !== 'L' ? 'R' : 'L'
    const aDir: BidiType = after !== 'L' ? 'R' : 'L'
    if (bDir === aDir) {
      for (let j = i; j < end; j++) types[j] = bDir
    }
    i = end - 1
  }
  for (let i = 0; i < len; i++) {
    if (types[i] === 'ON') types[i] = e
  }

  // I1-I2
  for (let i = 0; i < len; i++) {
    const t = types[i]!
    if ((levels[i]! & 1) === 0) {
      if (t === 'R') levels[i]!++
      else if (t === 'AN' || t === 'EN') levels[i]! += 2
    } else if (t === 'L' || t === 'AN' || t === 'EN') {
      levels[i]!++
    }
  }

  return levels
}

export function computeSegmentLevels(normalized: string, segStarts: number[]): Int8Array | null {
  const bidiLevels = computeBidiLevels(normalized)
  if (bidiLevels === null) return null

  const segLevels = new Int8Array(segStarts.length)
  for (let i = 0; i < segStarts.length; i++) {
    segLevels[i] = bidiLevels[segStarts[i]!]!
  }
  return segLevels
}

>sed -n '1,260p' src/layout.ts

Command: /bin/zsh -lc "sed -n '1,260p' src/layout.ts"
Chunk ID: 2c61dd
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2434
Output:
// Text measurement for browser environments using canvas measureText.
//
// Problem: DOM-based text measurement (getBoundingClientRect, offsetHeight)
// forces synchronous layout reflow. When components independently measure text,
// each measurement triggers a reflow of the entire document. This creates
// read/write interleaving that can cost 30ms+ per frame for 500 text blocks.
//
// Solution: two-phase measurement centered around canvas measureText.
//   prepare(text, font) — segments text via Intl.Segmenter, measures each word
//     via canvas, caches widths, and does one cached DOM calibration read per
//     font when emoji correction is needed. Call once when text first appears.
//   layout(prepared, maxWidth, lineHeight) — walks cached word widths with pure
//     arithmetic to count lines and compute height. Call on every resize.
//     ~0.0002ms per text.
//
// i18n: Intl.Segmenter handles CJK (per-character breaking), Thai, Arabic, etc.
//   Bidi: simplified rich-path metadata for mixed LTR/RTL custom rendering.
//   Punctuation merging: "better." measured as one unit (matches CSS behavior).
//   Trailing whitespace: hangs past line edge without triggering breaks (CSS behavior).
//   overflow-wrap: pre-measured grapheme widths enable character-level word breaking.
//
// Emoji correction: Chrome/Firefox canvas measures emoji wider than DOM at font
//   sizes <24px on macOS (Apple Color Emoji). The inflation is constant per emoji
//   grapheme at a given size, font-independent. Auto-detected by comparing canvas
//   vs actual DOM emoji width (one cached DOM read per font). Safari canvas and
//   DOM agree (both wider than fontSize), so correction = 0 there.
//
// Limitations:
//   - system-ui font: canvas resolves to different optical variants than DOM on macOS.
//     Use named fonts (Helvetica, Inter, etc.) for guaranteed accuracy.
//     See RESEARCH.md "Discovery: system-ui font resolution mismatch".
//
// Based on Sebastian Markbage's text-layout research (github.com/chenglou/text-layout).

import { computeSegmentLevels } from './bidi.js'
import {
  analyzeText,
  clearAnalysisCaches,
  endsWithClosingQuote,
  isCJK,
  kinsokuEnd,
  kinsokuStart,
  leftStickyPunctuation,
  setAnalysisLocale,
  type AnalysisChunk,
  type SegmentBreakKind,
  type TextAnalysis,
  type WhiteSpaceMode,
} from './analysis.js'
import {
  clearMeasurementCaches,
  getCorrectedSegmentWidth,
  getEngineProfile,
  getFontMeasurementState,
  getSegmentGraphemePrefixWidths,
  getSegmentGraphemeWidths,
  getSegmentMetrics,
  textMayContainEmoji,
} from './measurement.js'
import {
  countPreparedLines,
  layoutNextLineRange as stepPreparedLineRange,
  walkPreparedLines,
  type InternalLayoutLine,
} from './line-break.js'

let sharedGraphemeSegmenter: Intl.Segmenter | null = null
// Rich-path only. Reuses grapheme splits while materializing multiple lines
// from the same prepared handle, without pushing that cache into the API.
let sharedLineTextCaches = new WeakMap<PreparedTextWithSegments, Map<number, string[]>>()

function getSharedGraphemeSegmenter(): Intl.Segmenter {
  if (sharedGraphemeSegmenter === null) {
    sharedGraphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })
  }
  return sharedGraphemeSegmenter
}

// --- Public types ---

declare const preparedTextBrand: unique symbol

type PreparedCore = {
  widths: number[] // Segment widths, e.g. [42.5, 4.4, 37.2]
  lineEndFitAdvances: number[] // Width contribution when a line ends after this segment
  lineEndPaintAdvances: number[] // Painted width contribution when a line ends after this segment
  kinds: SegmentBreakKind[] // Break behavior per segment, e.g. ['text', 'space', 'text']
  simpleLineWalkFastPath: boolean // Normal text can use the simpler old line walker across all layout APIs
  segLevels: Int8Array | null // Rich-path bidi metadata for custom rendering; layout() never reads it
  breakableWidths: (number[] | null)[] // Grapheme widths for overflow-wrap segments, else null
  breakablePrefixWidths: (number[] | null)[] // Cumulative grapheme prefix widths for narrow browser-policy shims
  discretionaryHyphenWidth: number // Visible width added when a soft hyphen is chosen as the break
  tabStopAdvance: number // Absolute advance between tab stops for pre-wrap tab segments
  chunks: PreparedLineChunk[] // Precompiled hard-break chunks for line walking
}

// Keep the main prepared handle opaque so the public API does not accidentally
// calcify around the current parallel-array representation.
export type PreparedText = {
  readonly [preparedTextBrand]: true
}

type InternalPreparedText = PreparedText & PreparedCore

// Rich/diagnostic variant that still exposes the structural segment data.
// Treat this as the unstable escape hatch for experiments and custom rendering.
export type PreparedTextWithSegments = InternalPreparedText & {
  segments: string[] // Segment text aligned with the parallel arrays, e.g. ['hello', ' ', 'world']
}

export type LayoutCursor = {
  segmentIndex: number // Segment index in `segments`
  graphemeIndex: number // Grapheme index within that segment; `0` at segment boundaries
}

export type LayoutResult = {
  lineCount: number // Number of wrapped lines, e.g. 3
  height: number // Total block height, e.g. lineCount * lineHeight = 57
}

export type LayoutLine = {
  text: string // Full text content of this line, e.g. 'hello world'
  width: number // Measured width of this line, e.g. 87.5
  start: LayoutCursor // Inclusive start cursor in prepared segments/graphemes
  end: LayoutCursor // Exclusive end cursor in prepared segments/graphemes
}

export type LayoutLineRange = {
  width: number // Measured width of this line, e.g. 87.5
  start: LayoutCursor // Inclusive start cursor in prepared segments/graphemes
  end: LayoutCursor // Exclusive end cursor in prepared segments/graphemes
}

export type LayoutLinesResult = LayoutResult & {
  lines: LayoutLine[] // Per-line text/width pairs for custom rendering
}

export type PrepareProfile = {
  analysisMs: number
  measureMs: number
  totalMs: number
  analysisSegments: number
  preparedSegments: number
  breakableSegments: number
}

export type PrepareOptions = {
  whiteSpace?: WhiteSpaceMode
}

export type PreparedLineChunk = {
  startSegmentIndex: number
  endSegmentIndex: number
  consumedEndSegmentIndex: number
}

// --- Public API ---

function createEmptyPrepared(includeSegments: boolean): InternalPreparedText | PreparedTextWithSegments {
  if (includeSegments) {
    return {
      widths: [],
      lineEndFitAdvances: [],
      lineEndPaintAdvances: [],
      kinds: [],
      simpleLineWalkFastPath: true,
      segLevels: null,
      breakableWidths: [],
      breakablePrefixWidths: [],
      discretionaryHyphenWidth: 0,
      tabStopAdvance: 0,
      chunks: [],
      segments: [],
    } as unknown as PreparedTextWithSegments
  }
  return {
    widths: [],
    lineEndFitAdvances: [],
    lineEndPaintAdvances: [],
    kinds: [],
    simpleLineWalkFastPath: true,
    segLevels: null,
    breakableWidths: [],
    breakablePrefixWidths: [],
    discretionaryHyphenWidth: 0,
    tabStopAdvance: 0,
    chunks: [],
  } as unknown as InternalPreparedText
}

function measureAnalysis(
  analysis: TextAnalysis,
  font: string,
  includeSegments: boolean,
): InternalPreparedText | PreparedTextWithSegments {
  const graphemeSegmenter = getSharedGraphemeSegmenter()
  const engineProfile = getEngineProfile()
  const { cache, emojiCorrection } = getFontMeasurementState(
    font,
    textMayContainEmoji(analysis.normalized),
  )
  const discretionaryHyphenWidth = getCorrectedSegmentWidth('-', getSegmentMetrics('-', cache), emojiCorrection)
  const spaceWidth = getCorrectedSegmentWidth(' ', getSegmentMetrics(' ', cache), emojiCorrection)
  const tabStopAdvance = spaceWidth * 8

  if (analysis.len === 0) return createEmptyPrepared(includeSegments)

  const widths: number[] = []
  const lineEndFitAdvances: number[] = []
  const lineEndPaintAdvances: number[] = []
  const kinds: SegmentBreakKind[] = []
  let simpleLineWalkFastPath = analysis.chunks.length <= 1
  const segStarts = includeSegments ? [] as number[] : null
  const breakableWidths: (number[] | null)[] = []
  const breakablePrefixWidths: (number[] | null)[] = []
  const segments = includeSegments ? [] as string[] : null
  const preparedStartByAnalysisIndex = Array.from<number>({ length: analysis.len })
  const preparedEndByAnalysisIndex = Array.from<number>({ length: analysis.len })

  function pushMeasuredSegment(
    text: string,
    width: number,
    lineEndFitAdvance: number,
    lineEndPaintAdvance: number,
    kind: SegmentBreakKind,
    start: number,
    breakable: number[] | null,
    breakablePrefix: number[] | null,
  ): void {
    if (kind !== 'text' && kind !== 'space' && kind !== 'zero-width-break') {
      simpleLineWalkFastPath = false
    }
    widths.push(width)
    lineEndFitAdvances.push(lineEndFitAdvance)
    lineEndPaintAdvances.push(lineEndPaintAdvance)
    kinds.push(kind)
    segStarts?.push(start)
    breakableWidths.push(breakable)
    breakablePrefixWidths.push(breakablePrefix)
    if (segments !== null) segments.push(text)
  }

  for (let mi = 0; mi < analysis.len; mi++) {
    preparedStartByAnalysisIndex[mi] = widths.length
    const segText = analysis.texts[mi]!
    const segWordLike = analysis.isWordLike[mi]!
    const segKind = analysis.kinds[mi]!
    const segStart = analysis.starts[mi]!

    if (segKind === 'soft-hyphen') {
      pushMeasuredSegment(
        segText,
        0,
        discretionaryHyphenWidth,
        discretionaryHyphenWidth,
        segKind,
        segStart,
        null,
        null,
      )

>sed -n '261,520p' src/layout.ts

Command: /bin/zsh -lc "sed -n '261,520p' src/layout.ts"
Chunk ID: e7c526
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2302
Output:
      preparedEndByAnalysisIndex[mi] = widths.length
      continue
    }

    if (segKind === 'hard-break') {
      pushMeasuredSegment(segText, 0, 0, 0, segKind, segStart, null, null)
      preparedEndByAnalysisIndex[mi] = widths.length
      continue
    }

    if (segKind === 'tab') {
      pushMeasuredSegment(segText, 0, 0, 0, segKind, segStart, null, null)
      preparedEndByAnalysisIndex[mi] = widths.length
      continue
    }

    const segMetrics = getSegmentMetrics(segText, cache)

    if (segKind === 'text' && segMetrics.containsCJK) {
      let unitText = ''
      let unitStart = 0

      for (const gs of graphemeSegmenter.segment(segText)) {
        const grapheme = gs.segment

        if (unitText.length === 0) {
          unitText = grapheme
          unitStart = gs.index
          continue
        }

        if (
          kinsokuEnd.has(unitText) ||
          kinsokuStart.has(grapheme) ||
          leftStickyPunctuation.has(grapheme) ||
          (engineProfile.carryCJKAfterClosingQuote &&
            isCJK(grapheme) &&
            endsWithClosingQuote(unitText))
        ) {
          unitText += grapheme
          continue
        }

        const unitMetrics = getSegmentMetrics(unitText, cache)
        const w = getCorrectedSegmentWidth(unitText, unitMetrics, emojiCorrection)
        pushMeasuredSegment(unitText, w, w, w, 'text', segStart + unitStart, null, null)

        unitText = grapheme
        unitStart = gs.index
      }

      if (unitText.length > 0) {
        const unitMetrics = getSegmentMetrics(unitText, cache)
        const w = getCorrectedSegmentWidth(unitText, unitMetrics, emojiCorrection)
        pushMeasuredSegment(unitText, w, w, w, 'text', segStart + unitStart, null, null)
      }
      preparedEndByAnalysisIndex[mi] = widths.length
      continue
    }

    const w = getCorrectedSegmentWidth(segText, segMetrics, emojiCorrection)
    const lineEndFitAdvance =
      segKind === 'space' || segKind === 'preserved-space' || segKind === 'zero-width-break'
        ? 0
        : w
    const lineEndPaintAdvance =
      segKind === 'space' || segKind === 'zero-width-break'
        ? 0
        : w

    if (segWordLike && segText.length > 1) {
      const graphemeWidths = getSegmentGraphemeWidths(segText, segMetrics, cache, emojiCorrection)
      const graphemePrefixWidths = engineProfile.preferPrefixWidthsForBreakableRuns
        ? getSegmentGraphemePrefixWidths(segText, segMetrics, cache, emojiCorrection)
        : null
      pushMeasuredSegment(
        segText,
        w,
        lineEndFitAdvance,
        lineEndPaintAdvance,
        segKind,
        segStart,
        graphemeWidths,
        graphemePrefixWidths,
      )
    } else {
      pushMeasuredSegment(
        segText,
        w,
        lineEndFitAdvance,
        lineEndPaintAdvance,
        segKind,
        segStart,
        null,
        null,
      )
    }
    preparedEndByAnalysisIndex[mi] = widths.length
  }

  const chunks = mapAnalysisChunksToPreparedChunks(analysis.chunks, preparedStartByAnalysisIndex, preparedEndByAnalysisIndex)
  const segLevels = segStarts === null ? null : computeSegmentLevels(analysis.normalized, segStarts)
  if (segments !== null) {
    return {
      widths,
      lineEndFitAdvances,
      lineEndPaintAdvances,
      kinds,
      simpleLineWalkFastPath,
      segLevels,
      breakableWidths,
      breakablePrefixWidths,
      discretionaryHyphenWidth,
      tabStopAdvance,
      chunks,
      segments,
    } as unknown as PreparedTextWithSegments
  }
  return {
    widths,
    lineEndFitAdvances,
    lineEndPaintAdvances,
    kinds,
    simpleLineWalkFastPath,
    segLevels,
    breakableWidths,
    breakablePrefixWidths,
    discretionaryHyphenWidth,
    tabStopAdvance,
    chunks,
  } as unknown as InternalPreparedText
}

function mapAnalysisChunksToPreparedChunks(
  chunks: AnalysisChunk[],
  preparedStartByAnalysisIndex: number[],
  preparedEndByAnalysisIndex: number[],
): PreparedLineChunk[] {
  const preparedChunks: PreparedLineChunk[] = []
  for (let i = 0; i < chunks.length; i++) {
    const chunk = chunks[i]!
    const startSegmentIndex =
      chunk.startSegmentIndex < preparedStartByAnalysisIndex.length
        ? preparedStartByAnalysisIndex[chunk.startSegmentIndex]!
        : preparedEndByAnalysisIndex[preparedEndByAnalysisIndex.length - 1] ?? 0
    const endSegmentIndex =
      chunk.endSegmentIndex < preparedStartByAnalysisIndex.length
        ? preparedStartByAnalysisIndex[chunk.endSegmentIndex]!
        : preparedEndByAnalysisIndex[preparedEndByAnalysisIndex.length - 1] ?? 0
    const consumedEndSegmentIndex =
      chunk.consumedEndSegmentIndex < preparedStartByAnalysisIndex.length
        ? preparedStartByAnalysisIndex[chunk.consumedEndSegmentIndex]!
        : preparedEndByAnalysisIndex[preparedEndByAnalysisIndex.length - 1] ?? 0

    preparedChunks.push({
      startSegmentIndex,
      endSegmentIndex,
      consumedEndSegmentIndex,
    })
  }
  return preparedChunks
}

function prepareInternal(
  text: string,
  font: string,
  includeSegments: boolean,
  options?: PrepareOptions,
): InternalPreparedText | PreparedTextWithSegments {
  const analysis = analyzeText(text, getEngineProfile(), options?.whiteSpace)
  return measureAnalysis(analysis, font, includeSegments)
}

// Diagnostic-only helper used by the browser benchmark harness to separate the
// text-analysis and measurement phases without duplicating the prepare logic.
export function profilePrepare(text: string, font: string, options?: PrepareOptions): PrepareProfile {
  const t0 = performance.now()
  const analysis = analyzeText(text, getEngineProfile(), options?.whiteSpace)
  const t1 = performance.now()
  const prepared = measureAnalysis(analysis, font, false) as InternalPreparedText
  const t2 = performance.now()

  let breakableSegments = 0
  for (const widths of prepared.breakableWidths) {
    if (widths !== null) breakableSegments++
  }

  return {
    analysisMs: t1 - t0,
    measureMs: t2 - t1,
    totalMs: t2 - t0,
    analysisSegments: analysis.len,
    preparedSegments: prepared.widths.length,
    breakableSegments,
  }
}

// Prepare text for layout. Segments the text, measures each segment via canvas,
// and stores the widths for fast relayout at any width. Call once per text block
// (e.g. when a comment first appears). The result is width-independent — the
// same PreparedText can be laid out at any maxWidth and lineHeight via layout().
//
// Steps:
//   1. Normalize collapsible whitespace (CSS white-space: normal behavior)
//   2. Segment via Intl.Segmenter (handles CJK, Thai, etc.)
//   3. Merge punctuation into preceding word ("better." as one unit)
//   4. Split CJK words into individual graphemes (per-character line breaks)
//   5. Measure each segment via canvas measureText, cache by (segment, font)
//   6. Pre-measure graphemes of long words (for overflow-wrap: break-word)
//   7. Correct emoji canvas inflation (auto-detected per font size)
//   8. Optionally compute rich-path bidi metadata for custom renderers
export function prepare(text: string, font: string, options?: PrepareOptions): PreparedText {
  return prepareInternal(text, font, false, options) as PreparedText
}

// Rich variant used by callers that need enough information to render the
// laid-out lines themselves.
export function prepareWithSegments(text: string, font: string, options?: PrepareOptions): PreparedTextWithSegments {
  return prepareInternal(text, font, true, options) as PreparedTextWithSegments
}

function getInternalPrepared(prepared: PreparedText): InternalPreparedText {
  return prepared as InternalPreparedText
}

// Layout prepared text at a given max width and caller-provided lineHeight.
// Pure arithmetic on cached widths — no canvas calls, no DOM reads, no string
// operations, no allocations.
// ~0.0002ms per text block. Call on every resize.
//
// Line breaking rules (matching CSS white-space: normal + overflow-wrap: break-word):
//   - Break before any non-space segment that would overflow the line
//   - Trailing whitespace hangs past the line edge (doesn't trigger breaks)
//   - Segments wider than maxWidth are broken at grapheme boundaries
export function layout(prepared: PreparedText, maxWidth: number, lineHeight: number): LayoutResult {
  // Keep the resize hot path specialized. `layoutWithLines()` shares the same
  // break semantics but also tracks line ranges; the extra bookkeeping is too
  // expensive to pay on every hot-path `layout()` call.
  const lineCount = countPreparedLines(getInternalPrepared(prepared), maxWidth)
  return { lineCount, height: lineCount * lineHeight }
}

function getSegmentGraphemes(
  segmentIndex: number,
  segments: string[],
  cache: Map<number, string[]>,
): string[] {
  let graphemes = cache.get(segmentIndex)
  if (graphemes !== undefined) return graphemes

  graphemes = []
  const graphemeSegmenter = getSharedGraphemeSegmenter()
  for (const gs of graphemeSegmenter.segment(segments[segmentIndex]!)) {
    graphemes.push(gs.segment)
  }
  cache.set(segmentIndex, graphemes)
  return graphemes
}

function getLineTextCache(prepared: PreparedTextWithSegments): Map<number, string[]> {

>sed -n '521,780p' src/layout.ts

Command: /bin/zsh -lc "sed -n '521,780p' src/layout.ts"
Chunk ID: a944f3
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1335
Output:
  let cache = sharedLineTextCaches.get(prepared)
  if (cache !== undefined) return cache

  cache = new Map<number, string[]>()
  sharedLineTextCaches.set(prepared, cache)
  return cache
}

function lineHasDiscretionaryHyphen(
  kinds: SegmentBreakKind[],
  startSegmentIndex: number,
  startGraphemeIndex: number,
  endSegmentIndex: number,
): boolean {
  return (
    endSegmentIndex > 0 &&
    kinds[endSegmentIndex - 1] === 'soft-hyphen' &&
    !(startSegmentIndex === endSegmentIndex && startGraphemeIndex > 0)
  )
}

function buildLineTextFromRange(
  segments: string[],
  kinds: SegmentBreakKind[],
  cache: Map<number, string[]>,
  startSegmentIndex: number,
  startGraphemeIndex: number,
  endSegmentIndex: number,
  endGraphemeIndex: number,
): string {
  let text = ''
  const endsWithDiscretionaryHyphen = lineHasDiscretionaryHyphen(
    kinds,
    startSegmentIndex,
    startGraphemeIndex,
    endSegmentIndex,
  )

  for (let i = startSegmentIndex; i < endSegmentIndex; i++) {
    if (kinds[i] === 'soft-hyphen' || kinds[i] === 'hard-break') continue
    if (i === startSegmentIndex && startGraphemeIndex > 0) {
      text += getSegmentGraphemes(i, segments, cache).slice(startGraphemeIndex).join('')
    } else {
      text += segments[i]!
    }
  }

  if (endGraphemeIndex > 0) {
    if (endsWithDiscretionaryHyphen) text += '-'
    text += getSegmentGraphemes(endSegmentIndex, segments, cache).slice(
      startSegmentIndex === endSegmentIndex ? startGraphemeIndex : 0,
      endGraphemeIndex,
    ).join('')
  } else if (endsWithDiscretionaryHyphen) {
    text += '-'
  }

  return text
}

function createLayoutLine(
  prepared: PreparedTextWithSegments,
  cache: Map<number, string[]>,
  width: number,
  startSegmentIndex: number,
  startGraphemeIndex: number,
  endSegmentIndex: number,
  endGraphemeIndex: number,
): LayoutLine {
  return {
    text: buildLineTextFromRange(
      prepared.segments,
      prepared.kinds,
      cache,
      startSegmentIndex,
      startGraphemeIndex,
      endSegmentIndex,
      endGraphemeIndex,
    ),
    width,
    start: {
      segmentIndex: startSegmentIndex,
      graphemeIndex: startGraphemeIndex,
    },
    end: {
      segmentIndex: endSegmentIndex,
      graphemeIndex: endGraphemeIndex,
    },
  }
}

function materializeLayoutLine(
  prepared: PreparedTextWithSegments,
  cache: Map<number, string[]>,
  line: InternalLayoutLine,
): LayoutLine {
  return createLayoutLine(
    prepared,
    cache,
    line.width,
    line.startSegmentIndex,
    line.startGraphemeIndex,
    line.endSegmentIndex,
    line.endGraphemeIndex,
  )
}

function toLayoutLineRange(line: InternalLayoutLine): LayoutLineRange {
  return {
    width: line.width,
    start: {
      segmentIndex: line.startSegmentIndex,
      graphemeIndex: line.startGraphemeIndex,
    },
    end: {
      segmentIndex: line.endSegmentIndex,
      graphemeIndex: line.endGraphemeIndex,
    },
  }
}

function stepLineRange(
  prepared: PreparedTextWithSegments,
  start: LayoutCursor,
  maxWidth: number,
): LayoutLineRange | null {
  const line = stepPreparedLineRange(prepared, start, maxWidth)
  if (line === null) return null
  return toLayoutLineRange(line)
}

function materializeLine(
  prepared: PreparedTextWithSegments,
  line: LayoutLineRange,
): LayoutLine {
  return createLayoutLine(
    prepared,
    getLineTextCache(prepared),
    line.width,
    line.start.segmentIndex,
    line.start.graphemeIndex,
    line.end.segmentIndex,
    line.end.graphemeIndex,
  )
}

// Batch low-level line geometry pass. This is the non-materializing counterpart
// to layoutWithLines(), useful for shrinkwrap and other aggregate geometry work.
export function walkLineRanges(
  prepared: PreparedTextWithSegments,
  maxWidth: number,
  onLine: (line: LayoutLineRange) => void,
): number {
  if (prepared.widths.length === 0) return 0

  return walkPreparedLines(getInternalPrepared(prepared), maxWidth, line => {
    onLine(toLayoutLineRange(line))
  })
}

export function layoutNextLine(
  prepared: PreparedTextWithSegments,
  start: LayoutCursor,
  maxWidth: number,
): LayoutLine | null {
  const line = stepLineRange(prepared, start, maxWidth)
  if (line === null) return null
  return materializeLine(prepared, line)
}

// Rich layout API for callers that want the actual line contents and widths.
// Caller still supplies lineHeight at layout time. Mirrors layout()'s break
// decisions, but keeps extra per-line bookkeeping so it should stay off the
// resize hot path.
export function layoutWithLines(prepared: PreparedTextWithSegments, maxWidth: number, lineHeight: number): LayoutLinesResult {
  const lines: LayoutLine[] = []
  if (prepared.widths.length === 0) return { lineCount: 0, height: 0, lines }

  const graphemeCache = getLineTextCache(prepared)
  const lineCount = walkPreparedLines(getInternalPrepared(prepared), maxWidth, line => {
    lines.push(materializeLayoutLine(prepared, graphemeCache, line))
  })

  return { lineCount, height: lineCount * lineHeight, lines }
}

export function clearCache(): void {
  clearAnalysisCaches()
  sharedGraphemeSegmenter = null
  sharedLineTextCaches = new WeakMap<PreparedTextWithSegments, Map<number, string[]>>()
  clearMeasurementCaches()
}

export function setLocale(locale?: string): void {
  setAnalysisLocale(locale)
  clearCache()
}

>sed -n '1,260p' src/line-break.ts

Command: /bin/zsh -lc "sed -n '1,260p' src/line-break.ts"
Chunk ID: 99c16f
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1841
Output:
import type { SegmentBreakKind } from './analysis.js'
import { getEngineProfile } from './measurement.js'

export type LineBreakCursor = {
  segmentIndex: number
  graphemeIndex: number
}

export type PreparedLineBreakData = {
  widths: number[]
  lineEndFitAdvances: number[]
  lineEndPaintAdvances: number[]
  kinds: SegmentBreakKind[]
  simpleLineWalkFastPath: boolean
  breakableWidths: (number[] | null)[]
  breakablePrefixWidths: (number[] | null)[]
  discretionaryHyphenWidth: number
  tabStopAdvance: number
  chunks: {
    startSegmentIndex: number
    endSegmentIndex: number
    consumedEndSegmentIndex: number
  }[]
}

export type InternalLayoutLine = {
  startSegmentIndex: number
  startGraphemeIndex: number
  endSegmentIndex: number
  endGraphemeIndex: number
  width: number
}

function canBreakAfter(kind: SegmentBreakKind): boolean {
  return (
    kind === 'space' ||
    kind === 'preserved-space' ||
    kind === 'tab' ||
    kind === 'zero-width-break' ||
    kind === 'soft-hyphen'
  )
}

function isSimpleCollapsibleSpace(kind: SegmentBreakKind): boolean {
  return kind === 'space'
}

function getTabAdvance(lineWidth: number, tabStopAdvance: number): number {
  if (tabStopAdvance <= 0) return 0

  const remainder = lineWidth % tabStopAdvance
  if (Math.abs(remainder) <= 1e-6) return tabStopAdvance
  return tabStopAdvance - remainder
}

function getBreakableAdvance(
  graphemeWidths: number[],
  graphemePrefixWidths: number[] | null,
  graphemeIndex: number,
  preferPrefixWidths: boolean,
): number {
  if (!preferPrefixWidths || graphemePrefixWidths === null) {
    return graphemeWidths[graphemeIndex]!
  }
  return graphemePrefixWidths[graphemeIndex]! - (graphemeIndex > 0 ? graphemePrefixWidths[graphemeIndex - 1]! : 0)
}

function fitSoftHyphenBreak(
  graphemeWidths: number[],
  initialWidth: number,
  maxWidth: number,
  lineFitEpsilon: number,
  discretionaryHyphenWidth: number,
  cumulativeWidths: boolean,
): { fitCount: number, fittedWidth: number } {
  let fitCount = 0
  let fittedWidth = initialWidth

  while (fitCount < graphemeWidths.length) {
    const nextWidth = cumulativeWidths
      ? initialWidth + graphemeWidths[fitCount]!
      : fittedWidth + graphemeWidths[fitCount]!
    const nextLineWidth = fitCount + 1 < graphemeWidths.length
      ? nextWidth + discretionaryHyphenWidth
      : nextWidth
    if (nextLineWidth > maxWidth + lineFitEpsilon) break
    fittedWidth = nextWidth
    fitCount++
  }

  return { fitCount, fittedWidth }
}

function findChunkIndexForStart(prepared: PreparedLineBreakData, segmentIndex: number): number {
  for (let i = 0; i < prepared.chunks.length; i++) {
    const chunk = prepared.chunks[i]!
    if (segmentIndex < chunk.consumedEndSegmentIndex) return i
  }
  return -1
}

export function normalizeLineStart(
  prepared: PreparedLineBreakData,
  start: LineBreakCursor,
): LineBreakCursor | null {
  let segmentIndex = start.segmentIndex
  const graphemeIndex = start.graphemeIndex

  if (segmentIndex >= prepared.widths.length) return null
  if (graphemeIndex > 0) return start

  const chunkIndex = findChunkIndexForStart(prepared, segmentIndex)
  if (chunkIndex < 0) return null

  const chunk = prepared.chunks[chunkIndex]!
  if (chunk.startSegmentIndex === chunk.endSegmentIndex && segmentIndex === chunk.startSegmentIndex) {
    return { segmentIndex, graphemeIndex: 0 }
  }

  if (segmentIndex < chunk.startSegmentIndex) segmentIndex = chunk.startSegmentIndex
  while (segmentIndex < chunk.endSegmentIndex) {
    const kind = prepared.kinds[segmentIndex]!
    if (kind !== 'space' && kind !== 'zero-width-break' && kind !== 'soft-hyphen') {
      return { segmentIndex, graphemeIndex: 0 }
    }
    segmentIndex++
  }

  if (chunk.consumedEndSegmentIndex >= prepared.widths.length) return null
  return { segmentIndex: chunk.consumedEndSegmentIndex, graphemeIndex: 0 }
}

export function countPreparedLines(prepared: PreparedLineBreakData, maxWidth: number): number {
  if (prepared.simpleLineWalkFastPath) {
    return countPreparedLinesSimple(prepared, maxWidth)
  }
  return walkPreparedLines(prepared, maxWidth)
}

function countPreparedLinesSimple(prepared: PreparedLineBreakData, maxWidth: number): number {
  const { widths, kinds, breakableWidths, breakablePrefixWidths } = prepared
  if (widths.length === 0) return 0

  const engineProfile = getEngineProfile()
  const lineFitEpsilon = engineProfile.lineFitEpsilon

  let lineCount = 0
  let lineW = 0
  let hasContent = false

  function placeOnFreshLine(segmentIndex: number): void {
    const w = widths[segmentIndex]!
    if (w > maxWidth && breakableWidths[segmentIndex] !== null) {
      const gWidths = breakableWidths[segmentIndex]!
      const gPrefixWidths = breakablePrefixWidths[segmentIndex] ?? null
      lineW = 0
      for (let g = 0; g < gWidths.length; g++) {
        const gw = getBreakableAdvance(
          gWidths,
          gPrefixWidths,
          g,
          engineProfile.preferPrefixWidthsForBreakableRuns,
        )
        if (lineW > 0 && lineW + gw > maxWidth + lineFitEpsilon) {
          lineCount++
          lineW = gw
        } else {
          if (lineW === 0) lineCount++
          lineW += gw
        }
      }
    } else {
      lineW = w
      lineCount++
    }
    hasContent = true
  }

  for (let i = 0; i < widths.length; i++) {
    const w = widths[i]!
    const kind = kinds[i]!

    if (!hasContent) {
      placeOnFreshLine(i)
      continue
    }

    const newW = lineW + w
    if (newW > maxWidth + lineFitEpsilon) {
      if (isSimpleCollapsibleSpace(kind)) continue
      lineW = 0
      hasContent = false
      placeOnFreshLine(i)
      continue
    }

    lineW = newW
  }

  if (!hasContent) return lineCount + 1
  return lineCount
}

function walkPreparedLinesSimple(
  prepared: PreparedLineBreakData,
  maxWidth: number,
  onLine?: (line: InternalLayoutLine) => void,
): number {
  const { widths, kinds, breakableWidths, breakablePrefixWidths } = prepared
  if (widths.length === 0) return 0

  const engineProfile = getEngineProfile()
  const lineFitEpsilon = engineProfile.lineFitEpsilon

  let lineCount = 0
  let lineW = 0
  let hasContent = false
  let lineStartSegmentIndex = 0
  let lineStartGraphemeIndex = 0
  let lineEndSegmentIndex = 0
  let lineEndGraphemeIndex = 0
  let pendingBreakSegmentIndex = -1
  let pendingBreakPaintWidth = 0

  function clearPendingBreak(): void {
    pendingBreakSegmentIndex = -1
    pendingBreakPaintWidth = 0
  }

  function emitCurrentLine(
    endSegmentIndex = lineEndSegmentIndex,
    endGraphemeIndex = lineEndGraphemeIndex,
    width = lineW,
  ): void {
    lineCount++
    onLine?.({
      startSegmentIndex: lineStartSegmentIndex,
      startGraphemeIndex: lineStartGraphemeIndex,
      endSegmentIndex,
      endGraphemeIndex,
      width,
    })
    lineW = 0
    hasContent = false
    clearPendingBreak()
  }

  function startLineAtSegment(segmentIndex: number, width: number): void {
    hasContent = true
    lineStartSegmentIndex = segmentIndex
    lineStartGraphemeIndex = 0
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
    lineW = width
  }

  function startLineAtGrapheme(segmentIndex: number, graphemeIndex: number, width: number): void {
    hasContent = true
    lineStartSegmentIndex = segmentIndex
    lineStartGraphemeIndex = graphemeIndex

>sed -n '261,520p' src/line-break.ts

Command: /bin/zsh -lc "sed -n '261,520p' src/line-break.ts"
Chunk ID: 7bbea1
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1878
Output:
    lineEndSegmentIndex = segmentIndex
    lineEndGraphemeIndex = graphemeIndex + 1
    lineW = width
  }

  function appendWholeSegment(segmentIndex: number, width: number): void {
    if (!hasContent) {
      startLineAtSegment(segmentIndex, width)
      return
    }
    lineW += width
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
  }

  function updatePendingBreak(segmentIndex: number, segmentWidth: number): void {
    if (!canBreakAfter(kinds[segmentIndex]!)) return
    pendingBreakSegmentIndex = segmentIndex + 1
    pendingBreakPaintWidth = lineW - segmentWidth
  }

  function appendBreakableSegment(segmentIndex: number): void {
    appendBreakableSegmentFrom(segmentIndex, 0)
  }

  function appendBreakableSegmentFrom(segmentIndex: number, startGraphemeIndex: number): void {
    const gWidths = breakableWidths[segmentIndex]!
    const gPrefixWidths = breakablePrefixWidths[segmentIndex] ?? null
    for (let g = startGraphemeIndex; g < gWidths.length; g++) {
      const gw = getBreakableAdvance(
        gWidths,
        gPrefixWidths,
        g,
        engineProfile.preferPrefixWidthsForBreakableRuns,
      )

      if (!hasContent) {
        startLineAtGrapheme(segmentIndex, g, gw)
        continue
      }

      if (lineW + gw > maxWidth + lineFitEpsilon) {
        emitCurrentLine()
        startLineAtGrapheme(segmentIndex, g, gw)
      } else {
        lineW += gw
        lineEndSegmentIndex = segmentIndex
        lineEndGraphemeIndex = g + 1
      }
    }

    if (hasContent && lineEndSegmentIndex === segmentIndex && lineEndGraphemeIndex === gWidths.length) {
      lineEndSegmentIndex = segmentIndex + 1
      lineEndGraphemeIndex = 0
    }
  }

  let i = 0
  while (i < widths.length) {
    const w = widths[i]!
    const kind = kinds[i]!

    if (!hasContent) {
      if (w > maxWidth && breakableWidths[i] !== null) {
        appendBreakableSegment(i)
      } else {
        startLineAtSegment(i, w)
      }
      updatePendingBreak(i, w)
      i++
      continue
    }

    const newW = lineW + w
    if (newW > maxWidth + lineFitEpsilon) {
      if (canBreakAfter(kind)) {
        appendWholeSegment(i, w)
        emitCurrentLine(i + 1, 0, lineW - w)
        i++
        continue
      }

      if (pendingBreakSegmentIndex >= 0) {
        if (
          lineEndSegmentIndex > pendingBreakSegmentIndex ||
          (lineEndSegmentIndex === pendingBreakSegmentIndex && lineEndGraphemeIndex > 0)
        ) {
          emitCurrentLine()
          continue
        }
        emitCurrentLine(pendingBreakSegmentIndex, 0, pendingBreakPaintWidth)
        continue
      }

      if (w > maxWidth && breakableWidths[i] !== null) {
        emitCurrentLine()
        appendBreakableSegment(i)
        i++
        continue
      }

      emitCurrentLine()
      continue
    }

    appendWholeSegment(i, w)
    updatePendingBreak(i, w)
    i++
  }

  if (hasContent) emitCurrentLine()
  return lineCount
}

export function walkPreparedLines(
  prepared: PreparedLineBreakData,
  maxWidth: number,
  onLine?: (line: InternalLayoutLine) => void,
): number {
  if (prepared.simpleLineWalkFastPath) {
    return walkPreparedLinesSimple(prepared, maxWidth, onLine)
  }

  const {
    widths,
    lineEndFitAdvances,
    lineEndPaintAdvances,
    kinds,
    breakableWidths,
    breakablePrefixWidths,
    discretionaryHyphenWidth,
    tabStopAdvance,
    chunks,
  } = prepared
  if (widths.length === 0 || chunks.length === 0) return 0

  const engineProfile = getEngineProfile()
  const lineFitEpsilon = engineProfile.lineFitEpsilon

  let lineCount = 0
  let lineW = 0
  let hasContent = false
  let lineStartSegmentIndex = 0
  let lineStartGraphemeIndex = 0
  let lineEndSegmentIndex = 0
  let lineEndGraphemeIndex = 0
  let pendingBreakSegmentIndex = -1
  let pendingBreakFitWidth = 0
  let pendingBreakPaintWidth = 0
  let pendingBreakKind: SegmentBreakKind | null = null

  function clearPendingBreak(): void {
    pendingBreakSegmentIndex = -1
    pendingBreakFitWidth = 0
    pendingBreakPaintWidth = 0
    pendingBreakKind = null
  }

  function emitCurrentLine(
    endSegmentIndex = lineEndSegmentIndex,
    endGraphemeIndex = lineEndGraphemeIndex,
    width = lineW,
  ): void {
    lineCount++
    onLine?.({
      startSegmentIndex: lineStartSegmentIndex,
      startGraphemeIndex: lineStartGraphemeIndex,
      endSegmentIndex,
      endGraphemeIndex,
      width,
    })
    lineW = 0
    hasContent = false
    clearPendingBreak()
  }

  function startLineAtSegment(segmentIndex: number, width: number): void {
    hasContent = true
    lineStartSegmentIndex = segmentIndex
    lineStartGraphemeIndex = 0
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
    lineW = width
  }

  function startLineAtGrapheme(segmentIndex: number, graphemeIndex: number, width: number): void {
    hasContent = true
    lineStartSegmentIndex = segmentIndex
    lineStartGraphemeIndex = graphemeIndex
    lineEndSegmentIndex = segmentIndex
    lineEndGraphemeIndex = graphemeIndex + 1
    lineW = width
  }

  function appendWholeSegment(segmentIndex: number, width: number): void {
    if (!hasContent) {
      startLineAtSegment(segmentIndex, width)
      return
    }
    lineW += width
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
  }

  function updatePendingBreakForWholeSegment(segmentIndex: number, segmentWidth: number): void {
    if (!canBreakAfter(kinds[segmentIndex]!)) return
    const fitAdvance = kinds[segmentIndex] === 'tab' ? 0 : lineEndFitAdvances[segmentIndex]!
    const paintAdvance = kinds[segmentIndex] === 'tab' ? segmentWidth : lineEndPaintAdvances[segmentIndex]!
    pendingBreakSegmentIndex = segmentIndex + 1
    pendingBreakFitWidth = lineW - segmentWidth + fitAdvance
    pendingBreakPaintWidth = lineW - segmentWidth + paintAdvance
    pendingBreakKind = kinds[segmentIndex]!
  }

  function appendBreakableSegment(segmentIndex: number): void {
    appendBreakableSegmentFrom(segmentIndex, 0)
  }

  function appendBreakableSegmentFrom(segmentIndex: number, startGraphemeIndex: number): void {
    const gWidths = breakableWidths[segmentIndex]!
    const gPrefixWidths = breakablePrefixWidths[segmentIndex] ?? null
    for (let g = startGraphemeIndex; g < gWidths.length; g++) {
      const gw = getBreakableAdvance(
        gWidths,
        gPrefixWidths,
        g,
        engineProfile.preferPrefixWidthsForBreakableRuns,
      )

      if (!hasContent) {
        startLineAtGrapheme(segmentIndex, g, gw)
        continue
      }

      if (lineW + gw > maxWidth + lineFitEpsilon) {
        emitCurrentLine()
        startLineAtGrapheme(segmentIndex, g, gw)
      } else {
        lineW += gw
        lineEndSegmentIndex = segmentIndex
        lineEndGraphemeIndex = g + 1
      }
    }

    if (hasContent && lineEndSegmentIndex === segmentIndex && lineEndGraphemeIndex === gWidths.length) {
      lineEndSegmentIndex = segmentIndex + 1
      lineEndGraphemeIndex = 0
    }
  }

  function continueSoftHyphenBreakableSegment(segmentIndex: number): boolean {
    if (pendingBreakKind !== 'soft-hyphen') return false
    const gWidths = breakableWidths[segmentIndex]!
    if (gWidths === null) return false
    const fitWidths = engineProfile.preferPrefixWidthsForBreakableRuns
      ? breakablePrefixWidths[segmentIndex] ?? gWidths
      : gWidths
    const usesPrefixWidths = fitWidths !== gWidths
    const { fitCount, fittedWidth } = fitSoftHyphenBreak(
      fitWidths,

>sed -n '521,780p' src/line-break.ts

Command: /bin/zsh -lc "sed -n '521,780p' src/line-break.ts"
Chunk ID: 2a4a71
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1930
Output:
      lineW,
      maxWidth,
      lineFitEpsilon,
      discretionaryHyphenWidth,
      usesPrefixWidths,
    )
    if (fitCount === 0) return false

    lineW = fittedWidth
    lineEndSegmentIndex = segmentIndex
    lineEndGraphemeIndex = fitCount
    clearPendingBreak()

    if (fitCount === gWidths.length) {
      lineEndSegmentIndex = segmentIndex + 1
      lineEndGraphemeIndex = 0
      return true
    }

    emitCurrentLine(
      segmentIndex,
      fitCount,
      fittedWidth + discretionaryHyphenWidth,
    )
    appendBreakableSegmentFrom(segmentIndex, fitCount)
    return true
  }

  function emitEmptyChunk(chunk: { startSegmentIndex: number, consumedEndSegmentIndex: number }): void {
    lineCount++
    onLine?.({
      startSegmentIndex: chunk.startSegmentIndex,
      startGraphemeIndex: 0,
      endSegmentIndex: chunk.consumedEndSegmentIndex,
      endGraphemeIndex: 0,
      width: 0,
    })
    clearPendingBreak()
  }

  for (let chunkIndex = 0; chunkIndex < chunks.length; chunkIndex++) {
    const chunk = chunks[chunkIndex]!
    if (chunk.startSegmentIndex === chunk.endSegmentIndex) {
      emitEmptyChunk(chunk)
      continue
    }

    hasContent = false
    lineW = 0
    lineStartSegmentIndex = chunk.startSegmentIndex
    lineStartGraphemeIndex = 0
    lineEndSegmentIndex = chunk.startSegmentIndex
    lineEndGraphemeIndex = 0
    clearPendingBreak()

    let i = chunk.startSegmentIndex
    while (i < chunk.endSegmentIndex) {
      const kind = kinds[i]!
      const w = kind === 'tab' ? getTabAdvance(lineW, tabStopAdvance) : widths[i]!

      if (kind === 'soft-hyphen') {
        if (hasContent) {
          lineEndSegmentIndex = i + 1
          lineEndGraphemeIndex = 0
          pendingBreakSegmentIndex = i + 1
          pendingBreakFitWidth = lineW + discretionaryHyphenWidth
          pendingBreakPaintWidth = lineW + discretionaryHyphenWidth
          pendingBreakKind = kind
        }
        i++
        continue
      }

      if (!hasContent) {
        if (w > maxWidth && breakableWidths[i] !== null) {
          appendBreakableSegment(i)
        } else {
          startLineAtSegment(i, w)
        }
        updatePendingBreakForWholeSegment(i, w)
        i++
        continue
      }

      const newW = lineW + w
      if (newW > maxWidth + lineFitEpsilon) {
        const currentBreakFitWidth = lineW + (kind === 'tab' ? 0 : lineEndFitAdvances[i]!)
        const currentBreakPaintWidth = lineW + (kind === 'tab' ? w : lineEndPaintAdvances[i]!)

        if (
          pendingBreakKind === 'soft-hyphen' &&
          engineProfile.preferEarlySoftHyphenBreak &&
          pendingBreakFitWidth <= maxWidth + lineFitEpsilon
        ) {
          emitCurrentLine(pendingBreakSegmentIndex, 0, pendingBreakPaintWidth)
          continue
        }

        if (pendingBreakKind === 'soft-hyphen' && continueSoftHyphenBreakableSegment(i)) {
          i++
          continue
        }

        if (canBreakAfter(kind) && currentBreakFitWidth <= maxWidth + lineFitEpsilon) {
          appendWholeSegment(i, w)
          emitCurrentLine(i + 1, 0, currentBreakPaintWidth)
          i++
          continue
        }

        if (pendingBreakSegmentIndex >= 0 && pendingBreakFitWidth <= maxWidth + lineFitEpsilon) {
          if (
            lineEndSegmentIndex > pendingBreakSegmentIndex ||
            (lineEndSegmentIndex === pendingBreakSegmentIndex && lineEndGraphemeIndex > 0)
          ) {
            emitCurrentLine()
            continue
          }
          const nextSegmentIndex = pendingBreakSegmentIndex
          emitCurrentLine(nextSegmentIndex, 0, pendingBreakPaintWidth)
          i = nextSegmentIndex
          continue
        }

        if (w > maxWidth && breakableWidths[i] !== null) {
          emitCurrentLine()
          appendBreakableSegment(i)
          i++
          continue
        }

        emitCurrentLine()
        continue
      }

      appendWholeSegment(i, w)
      updatePendingBreakForWholeSegment(i, w)
      i++
    }

    if (hasContent) {
      const finalPaintWidth =
        pendingBreakSegmentIndex === chunk.consumedEndSegmentIndex
          ? pendingBreakPaintWidth
          : lineW
      emitCurrentLine(chunk.consumedEndSegmentIndex, 0, finalPaintWidth)
    }
  }

  return lineCount
}

export function layoutNextLineRange(
  prepared: PreparedLineBreakData,
  start: LineBreakCursor,
  maxWidth: number,
): InternalLayoutLine | null {
  const normalizedStart = normalizeLineStart(prepared, start)
  if (normalizedStart === null) return null

  if (prepared.simpleLineWalkFastPath) {
    return layoutNextLineRangeSimple(prepared, normalizedStart, maxWidth)
  }

  const chunkIndex = findChunkIndexForStart(prepared, normalizedStart.segmentIndex)
  if (chunkIndex < 0) return null

  const chunk = prepared.chunks[chunkIndex]!
  if (chunk.startSegmentIndex === chunk.endSegmentIndex) {
    return {
      startSegmentIndex: chunk.startSegmentIndex,
      startGraphemeIndex: 0,
      endSegmentIndex: chunk.consumedEndSegmentIndex,
      endGraphemeIndex: 0,
      width: 0,
    }
  }

  const {
    widths,
    lineEndFitAdvances,
    lineEndPaintAdvances,
    kinds,
    breakableWidths,
    breakablePrefixWidths,
    discretionaryHyphenWidth,
    tabStopAdvance,
  } = prepared
  const engineProfile = getEngineProfile()
  const lineFitEpsilon = engineProfile.lineFitEpsilon

  let lineW = 0
  let hasContent = false
  const lineStartSegmentIndex = normalizedStart.segmentIndex
  const lineStartGraphemeIndex = normalizedStart.graphemeIndex
  let lineEndSegmentIndex = lineStartSegmentIndex
  let lineEndGraphemeIndex = lineStartGraphemeIndex
  let pendingBreakSegmentIndex = -1
  let pendingBreakFitWidth = 0
  let pendingBreakPaintWidth = 0
  let pendingBreakKind: SegmentBreakKind | null = null

  function clearPendingBreak(): void {
    pendingBreakSegmentIndex = -1
    pendingBreakFitWidth = 0
    pendingBreakPaintWidth = 0
    pendingBreakKind = null
  }

  function finishLine(
    endSegmentIndex = lineEndSegmentIndex,
    endGraphemeIndex = lineEndGraphemeIndex,
    width = lineW,
  ): InternalLayoutLine | null {
    if (!hasContent) return null

    return {
      startSegmentIndex: lineStartSegmentIndex,
      startGraphemeIndex: lineStartGraphemeIndex,
      endSegmentIndex,
      endGraphemeIndex,
      width,
    }
  }

  function startLineAtSegment(segmentIndex: number, width: number): void {
    hasContent = true
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
    lineW = width
  }

  function startLineAtGrapheme(segmentIndex: number, graphemeIndex: number, width: number): void {
    hasContent = true
    lineEndSegmentIndex = segmentIndex
    lineEndGraphemeIndex = graphemeIndex + 1
    lineW = width
  }

  function appendWholeSegment(segmentIndex: number, width: number): void {
    if (!hasContent) {
      startLineAtSegment(segmentIndex, width)
      return
    }
    lineW += width
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
  }

  function updatePendingBreakForWholeSegment(segmentIndex: number, segmentWidth: number): void {
    if (!canBreakAfter(kinds[segmentIndex]!)) return
    const fitAdvance = kinds[segmentIndex] === 'tab' ? 0 : lineEndFitAdvances[segmentIndex]!
    const paintAdvance = kinds[segmentIndex] === 'tab' ? segmentWidth : lineEndPaintAdvances[segmentIndex]!
    pendingBreakSegmentIndex = segmentIndex + 1
    pendingBreakFitWidth = lineW - segmentWidth + fitAdvance
    pendingBreakPaintWidth = lineW - segmentWidth + paintAdvance
    pendingBreakKind = kinds[segmentIndex]!
  }

  function appendBreakableSegmentFrom(segmentIndex: number, startGraphemeIndex: number): InternalLayoutLine | null {

>sed -n '781,1084p' src/line-break.ts

Command: /bin/zsh -lc "sed -n '781,1084p' src/line-break.ts"
Chunk ID: 76e986
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2375
Output:
    const gWidths = breakableWidths[segmentIndex]!
    const gPrefixWidths = breakablePrefixWidths[segmentIndex] ?? null
    for (let g = startGraphemeIndex; g < gWidths.length; g++) {
      const gw = getBreakableAdvance(
        gWidths,
        gPrefixWidths,
        g,
        engineProfile.preferPrefixWidthsForBreakableRuns,
      )

      if (!hasContent) {
        startLineAtGrapheme(segmentIndex, g, gw)
        continue
      }

      if (lineW + gw > maxWidth + lineFitEpsilon) {
        return finishLine()
      }

      lineW += gw
      lineEndSegmentIndex = segmentIndex
      lineEndGraphemeIndex = g + 1
    }

    if (hasContent && lineEndSegmentIndex === segmentIndex && lineEndGraphemeIndex === gWidths.length) {
      lineEndSegmentIndex = segmentIndex + 1
      lineEndGraphemeIndex = 0
    }
    return null
  }

  function maybeFinishAtSoftHyphen(segmentIndex: number): InternalLayoutLine | null {
    if (pendingBreakKind !== 'soft-hyphen' || pendingBreakSegmentIndex < 0) return null

    const gWidths = breakableWidths[segmentIndex] ?? null
    if (gWidths !== null) {
      const fitWidths = engineProfile.preferPrefixWidthsForBreakableRuns
        ? breakablePrefixWidths[segmentIndex] ?? gWidths
        : gWidths
      const usesPrefixWidths = fitWidths !== gWidths
      const { fitCount, fittedWidth } = fitSoftHyphenBreak(
        fitWidths,
        lineW,
        maxWidth,
        lineFitEpsilon,
        discretionaryHyphenWidth,
        usesPrefixWidths,
      )

      if (fitCount === gWidths.length) {
        lineW = fittedWidth
        lineEndSegmentIndex = segmentIndex + 1
        lineEndGraphemeIndex = 0
        clearPendingBreak()
        return null
      }

      if (fitCount > 0) {
        return finishLine(
          segmentIndex,
          fitCount,
          fittedWidth + discretionaryHyphenWidth,
        )
      }
    }

    if (pendingBreakFitWidth <= maxWidth + lineFitEpsilon) {
      return finishLine(pendingBreakSegmentIndex, 0, pendingBreakPaintWidth)
    }

    return null
  }

  for (let i = normalizedStart.segmentIndex; i < chunk.endSegmentIndex; i++) {
    const kind = kinds[i]!
    const startGraphemeIndex = i === normalizedStart.segmentIndex ? normalizedStart.graphemeIndex : 0
    const w = kind === 'tab' ? getTabAdvance(lineW, tabStopAdvance) : widths[i]!

    if (kind === 'soft-hyphen' && startGraphemeIndex === 0) {
      if (hasContent) {
        lineEndSegmentIndex = i + 1
        lineEndGraphemeIndex = 0
        pendingBreakSegmentIndex = i + 1
        pendingBreakFitWidth = lineW + discretionaryHyphenWidth
        pendingBreakPaintWidth = lineW + discretionaryHyphenWidth
        pendingBreakKind = kind
      }
      continue
    }

    if (!hasContent) {
      if (startGraphemeIndex > 0) {
        const line = appendBreakableSegmentFrom(i, startGraphemeIndex)
        if (line !== null) return line
      } else if (w > maxWidth && breakableWidths[i] !== null) {
        const line = appendBreakableSegmentFrom(i, 0)
        if (line !== null) return line
      } else {
        startLineAtSegment(i, w)
      }
      updatePendingBreakForWholeSegment(i, w)
      continue
    }

    const newW = lineW + w
    if (newW > maxWidth + lineFitEpsilon) {
      const currentBreakFitWidth = lineW + (kind === 'tab' ? 0 : lineEndFitAdvances[i]!)
      const currentBreakPaintWidth = lineW + (kind === 'tab' ? w : lineEndPaintAdvances[i]!)

      if (
        pendingBreakKind === 'soft-hyphen' &&
        engineProfile.preferEarlySoftHyphenBreak &&
        pendingBreakFitWidth <= maxWidth + lineFitEpsilon
      ) {
        return finishLine(pendingBreakSegmentIndex, 0, pendingBreakPaintWidth)
      }

      const softBreakLine = maybeFinishAtSoftHyphen(i)
      if (softBreakLine !== null) return softBreakLine

      if (canBreakAfter(kind) && currentBreakFitWidth <= maxWidth + lineFitEpsilon) {
        appendWholeSegment(i, w)
        return finishLine(i + 1, 0, currentBreakPaintWidth)
      }

      if (pendingBreakSegmentIndex >= 0 && pendingBreakFitWidth <= maxWidth + lineFitEpsilon) {
        if (
          lineEndSegmentIndex > pendingBreakSegmentIndex ||
          (lineEndSegmentIndex === pendingBreakSegmentIndex && lineEndGraphemeIndex > 0)
        ) {
          return finishLine()
        }
        return finishLine(pendingBreakSegmentIndex, 0, pendingBreakPaintWidth)
      }

      if (w > maxWidth && breakableWidths[i] !== null) {
        const currentLine = finishLine()
        if (currentLine !== null) return currentLine
        const line = appendBreakableSegmentFrom(i, 0)
        if (line !== null) return line
      }

      return finishLine()
    }

    appendWholeSegment(i, w)
    updatePendingBreakForWholeSegment(i, w)
  }

  if (pendingBreakSegmentIndex === chunk.consumedEndSegmentIndex && lineEndGraphemeIndex === 0) {
    return finishLine(chunk.consumedEndSegmentIndex, 0, pendingBreakPaintWidth)
  }

  return finishLine(chunk.consumedEndSegmentIndex, 0, lineW)
}

function layoutNextLineRangeSimple(
  prepared: PreparedLineBreakData,
  normalizedStart: LineBreakCursor,
  maxWidth: number,
): InternalLayoutLine | null {
  const { widths, kinds, breakableWidths, breakablePrefixWidths } = prepared
  const engineProfile = getEngineProfile()
  const lineFitEpsilon = engineProfile.lineFitEpsilon

  let lineW = 0
  let hasContent = false
  const lineStartSegmentIndex = normalizedStart.segmentIndex
  const lineStartGraphemeIndex = normalizedStart.graphemeIndex
  let lineEndSegmentIndex = lineStartSegmentIndex
  let lineEndGraphemeIndex = lineStartGraphemeIndex
  let pendingBreakSegmentIndex = -1
  let pendingBreakPaintWidth = 0

  function finishLine(
    endSegmentIndex = lineEndSegmentIndex,
    endGraphemeIndex = lineEndGraphemeIndex,
    width = lineW,
  ): InternalLayoutLine | null {
    if (!hasContent) return null

    return {
      startSegmentIndex: lineStartSegmentIndex,
      startGraphemeIndex: lineStartGraphemeIndex,
      endSegmentIndex,
      endGraphemeIndex,
      width,
    }
  }

  function startLineAtSegment(segmentIndex: number, width: number): void {
    hasContent = true
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
    lineW = width
  }

  function startLineAtGrapheme(segmentIndex: number, graphemeIndex: number, width: number): void {
    hasContent = true
    lineEndSegmentIndex = segmentIndex
    lineEndGraphemeIndex = graphemeIndex + 1
    lineW = width
  }

  function appendWholeSegment(segmentIndex: number, width: number): void {
    if (!hasContent) {
      startLineAtSegment(segmentIndex, width)
      return
    }
    lineW += width
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
  }

  function updatePendingBreak(segmentIndex: number, segmentWidth: number): void {
    if (!canBreakAfter(kinds[segmentIndex]!)) return
    pendingBreakSegmentIndex = segmentIndex + 1
    pendingBreakPaintWidth = lineW - segmentWidth
  }

  function appendBreakableSegmentFrom(segmentIndex: number, startGraphemeIndex: number): InternalLayoutLine | null {
    const gWidths = breakableWidths[segmentIndex]!
    const gPrefixWidths = breakablePrefixWidths[segmentIndex] ?? null
    for (let g = startGraphemeIndex; g < gWidths.length; g++) {
      const gw = getBreakableAdvance(
        gWidths,
        gPrefixWidths,
        g,
        engineProfile.preferPrefixWidthsForBreakableRuns,
      )

      if (!hasContent) {
        startLineAtGrapheme(segmentIndex, g, gw)
        continue
      }

      if (lineW + gw > maxWidth + lineFitEpsilon) {
        return finishLine()
      }

      lineW += gw
      lineEndSegmentIndex = segmentIndex
      lineEndGraphemeIndex = g + 1
    }

    if (hasContent && lineEndSegmentIndex === segmentIndex && lineEndGraphemeIndex === gWidths.length) {
      lineEndSegmentIndex = segmentIndex + 1
      lineEndGraphemeIndex = 0
    }
    return null
  }

  for (let i = normalizedStart.segmentIndex; i < widths.length; i++) {
    const w = widths[i]!
    const kind = kinds[i]!
    const startGraphemeIndex = i === normalizedStart.segmentIndex ? normalizedStart.graphemeIndex : 0

    if (!hasContent) {
      if (startGraphemeIndex > 0) {
        const line = appendBreakableSegmentFrom(i, startGraphemeIndex)
        if (line !== null) return line
      } else if (w > maxWidth && breakableWidths[i] !== null) {
        const line = appendBreakableSegmentFrom(i, 0)
        if (line !== null) return line
      } else {
        startLineAtSegment(i, w)
      }
      updatePendingBreak(i, w)
      continue
    }

    const newW = lineW + w
    if (newW > maxWidth + lineFitEpsilon) {
      if (canBreakAfter(kind)) {
        appendWholeSegment(i, w)
        return finishLine(i + 1, 0, lineW - w)
      }

      if (pendingBreakSegmentIndex >= 0) {
        if (
          lineEndSegmentIndex > pendingBreakSegmentIndex ||
          (lineEndSegmentIndex === pendingBreakSegmentIndex && lineEndGraphemeIndex > 0)
        ) {
          return finishLine()
        }
        return finishLine(pendingBreakSegmentIndex, 0, pendingBreakPaintWidth)
      }

      if (w > maxWidth && breakableWidths[i] !== null) {
        const currentLine = finishLine()
        if (currentLine !== null) return currentLine
        const line = appendBreakableSegmentFrom(i, 0)
        if (line !== null) return line
      }

      return finishLine()
    }

    appendWholeSegment(i, w)
    updatePendingBreak(i, w)
  }

  return finishLine()
}

>sed -n '1,260p' src/analysis.ts

Command: /bin/zsh -lc "sed -n '1,260p' src/analysis.ts"
Chunk ID: dbd9cd
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1481
Output:
export type WhiteSpaceMode = 'normal' | 'pre-wrap'

export type SegmentBreakKind =
  | 'text'
  | 'space'
  | 'preserved-space'
  | 'tab'
  | 'glue'
  | 'zero-width-break'
  | 'soft-hyphen'
  | 'hard-break'

type SegmentationPiece = {
  text: string
  isWordLike: boolean
  kind: SegmentBreakKind
  start: number
}

export type MergedSegmentation = {
  len: number
  texts: string[]
  isWordLike: boolean[]
  kinds: SegmentBreakKind[]
  starts: number[]
}

export type AnalysisChunk = {
  startSegmentIndex: number
  endSegmentIndex: number
  consumedEndSegmentIndex: number
}

export type TextAnalysis = { normalized: string, chunks: AnalysisChunk[] } & MergedSegmentation

export type AnalysisProfile = {
  carryCJKAfterClosingQuote: boolean
}

const collapsibleWhitespaceRunRe = /[ \t\n\r\f]+/g
const needsWhitespaceNormalizationRe = /[\t\n\r\f]| {2,}|^ | $/

type WhiteSpaceProfile = {
  mode: WhiteSpaceMode
  preserveOrdinarySpaces: boolean
  preserveHardBreaks: boolean
}

function getWhiteSpaceProfile(whiteSpace?: WhiteSpaceMode): WhiteSpaceProfile {
  const mode = whiteSpace ?? 'normal'
  return mode === 'pre-wrap'
    ? { mode, preserveOrdinarySpaces: true, preserveHardBreaks: true }
    : { mode, preserveOrdinarySpaces: false, preserveHardBreaks: false }
}

export function normalizeWhitespaceNormal(text: string): string {
  if (!needsWhitespaceNormalizationRe.test(text)) return text

  let normalized = text.replace(collapsibleWhitespaceRunRe, ' ')
  if (normalized.charCodeAt(0) === 0x20) {
    normalized = normalized.slice(1)
  }
  if (normalized.length > 0 && normalized.charCodeAt(normalized.length - 1) === 0x20) {
    normalized = normalized.slice(0, -1)
  }
  return normalized
}

function normalizeWhitespacePreWrap(text: string): string {
  if (!/[\r\f]/.test(text)) return text.replace(/\r\n/g, '\n')
  return text
    .replace(/\r\n/g, '\n')
    .replace(/[\r\f]/g, '\n')
}

let sharedWordSegmenter: Intl.Segmenter | null = null
let segmenterLocale: string | undefined

function getSharedWordSegmenter(): Intl.Segmenter {
  if (sharedWordSegmenter === null) {
    sharedWordSegmenter = new Intl.Segmenter(segmenterLocale, { granularity: 'word' })
  }
  return sharedWordSegmenter
}

export function clearAnalysisCaches(): void {
  sharedWordSegmenter = null
}

export function setAnalysisLocale(locale?: string): void {
  const nextLocale = locale && locale.length > 0 ? locale : undefined
  if (segmenterLocale === nextLocale) return
  segmenterLocale = nextLocale
  sharedWordSegmenter = null
}

const arabicScriptRe = /\p{Script=Arabic}/u
const combiningMarkRe = /\p{M}/u
const decimalDigitRe = /\p{Nd}/u

function containsArabicScript(text: string): boolean {
  return arabicScriptRe.test(text)
}

export function isCJK(s: string): boolean {
  for (const ch of s) {
    const c = ch.codePointAt(0)!
    if ((c >= 0x4E00 && c <= 0x9FFF) ||
        (c >= 0x3400 && c <= 0x4DBF) ||
        (c >= 0x20000 && c <= 0x2A6DF) ||
        (c >= 0x2A700 && c <= 0x2B73F) ||
        (c >= 0x2B740 && c <= 0x2B81F) ||
        (c >= 0x2B820 && c <= 0x2CEAF) ||
        (c >= 0x2CEB0 && c <= 0x2EBEF) ||
        (c >= 0x30000 && c <= 0x3134F) ||
        (c >= 0xF900 && c <= 0xFAFF) ||
        (c >= 0x2F800 && c <= 0x2FA1F) ||
        (c >= 0x3000 && c <= 0x303F) ||
        (c >= 0x3040 && c <= 0x309F) ||
        (c >= 0x30A0 && c <= 0x30FF) ||
        (c >= 0xAC00 && c <= 0xD7AF) ||
        (c >= 0xFF00 && c <= 0xFFEF)) {
      return true
    }
  }
  return false
}

export const kinsokuStart = new Set([
  '\uFF0C',
  '\uFF0E',
  '\uFF01',
  '\uFF1A',
  '\uFF1B',
  '\uFF1F',
  '\u3001',
  '\u3002',
  '\u30FB',
  '\uFF09',
  '\u3015',
  '\u3009',
  '\u300B',
  '\u300D',
  '\u300F',
  '\u3011',
  '\u3017',
  '\u3019',
  '\u301B',
  '\u30FC',
  '\u3005',
  '\u303B',
  '\u309D',
  '\u309E',
  '\u30FD',
  '\u30FE',
])

export const kinsokuEnd = new Set([
  '"',
  '(', '[', '{',
  '“', '‘', '«', '‹',
  '\uFF08',
  '\u3014',
  '\u3008',
  '\u300A',
  '\u300C',
  '\u300E',
  '\u3010',
  '\u3016',
  '\u3018',
  '\u301A',
])

const forwardStickyGlue = new Set([
  "'", '’',
])

export const leftStickyPunctuation = new Set([
  '.', ',', '!', '?', ':', ';',
  '\u060C',
  '\u061B',
  '\u061F',
  '\u0964',
  '\u0965',
  '\u104A',
  '\u104B',
  '\u104C',
  '\u104D',
  '\u104F',
  ')', ']', '}',
  '%',
  '"',
  '”', '’', '»', '›',
  '…',
])

const arabicNoSpaceTrailingPunctuation = new Set([
  ':',
  '.',
  '\u060C',
  '\u061B',
])

const myanmarMedialGlue = new Set([
  '\u104F',
])

const closingQuoteChars = new Set([
  '”', '’', '»', '›',
  '\u300D',
  '\u300F',
  '\u3011',
  '\u300B',
  '\u3009',
  '\u3015',
  '\uFF09',
])

function isLeftStickyPunctuationSegment(segment: string): boolean {
  if (isEscapedQuoteClusterSegment(segment)) return true
  let sawPunctuation = false
  for (const ch of segment) {
    if (leftStickyPunctuation.has(ch)) {
      sawPunctuation = true
      continue
    }
    if (sawPunctuation && combiningMarkRe.test(ch)) continue
    return false
  }
  return sawPunctuation
}

function isCJKLineStartProhibitedSegment(segment: string): boolean {
  for (const ch of segment) {
    if (!kinsokuStart.has(ch) && !leftStickyPunctuation.has(ch)) return false
  }
  return segment.length > 0
}

function isForwardStickyClusterSegment(segment: string): boolean {
  if (isEscapedQuoteClusterSegment(segment)) return true
  for (const ch of segment) {
    if (!kinsokuEnd.has(ch) && !forwardStickyGlue.has(ch) && !combiningMarkRe.test(ch)) return false
  }
  return segment.length > 0
}

function isEscapedQuoteClusterSegment(segment: string): boolean {
  let sawQuote = false
  for (const ch of segment) {
    if (ch === '\\' || combiningMarkRe.test(ch)) continue
    if (kinsokuEnd.has(ch) || leftStickyPunctuation.has(ch) || forwardStickyGlue.has(ch)) {
      sawQuote = true
      continue
    }
    return false
  }
  return sawQuote
}

>sed -n '261,520p' src/analysis.ts

Command: /bin/zsh -lc "sed -n '261,520p' src/analysis.ts"
Chunk ID: f7a014
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1746
Output:
function splitTrailingForwardStickyCluster(text: string): { head: string, tail: string } | null {
  const chars = Array.from(text)
  let splitIndex = chars.length

  while (splitIndex > 0) {
    const ch = chars[splitIndex - 1]!
    if (combiningMarkRe.test(ch)) {
      splitIndex--
      continue
    }
    if (kinsokuEnd.has(ch) || forwardStickyGlue.has(ch)) {
      splitIndex--
      continue
    }
    break
  }

  if (splitIndex <= 0 || splitIndex === chars.length) return null
  return {
    head: chars.slice(0, splitIndex).join(''),
    tail: chars.slice(splitIndex).join(''),
  }
}

function isRepeatedSingleCharRun(segment: string, ch: string): boolean {
  if (segment.length === 0) return false
  for (const part of segment) {
    if (part !== ch) return false
  }
  return true
}

function endsWithArabicNoSpacePunctuation(segment: string): boolean {
  if (!containsArabicScript(segment) || segment.length === 0) return false
  return arabicNoSpaceTrailingPunctuation.has(segment[segment.length - 1]!)
}

function endsWithMyanmarMedialGlue(segment: string): boolean {
  if (segment.length === 0) return false
  return myanmarMedialGlue.has(segment[segment.length - 1]!)
}

function splitLeadingSpaceAndMarks(segment: string): { space: string, marks: string } | null {
  if (segment.length < 2 || segment[0] !== ' ') return null
  const marks = segment.slice(1)
  if (/^\p{M}+$/u.test(marks)) {
    return { space: ' ', marks }
  }
  return null
}

export function endsWithClosingQuote(text: string): boolean {
  for (let i = text.length - 1; i >= 0; i--) {
    const ch = text[i]!
    if (closingQuoteChars.has(ch)) return true
    if (!leftStickyPunctuation.has(ch)) return false
  }
  return false
}

function classifySegmentBreakChar(ch: string, whiteSpaceProfile: WhiteSpaceProfile): SegmentBreakKind {
  if (whiteSpaceProfile.preserveOrdinarySpaces || whiteSpaceProfile.preserveHardBreaks) {
    if (ch === ' ') return 'preserved-space'
    if (ch === '\t') return 'tab'
    if (whiteSpaceProfile.preserveHardBreaks && ch === '\n') return 'hard-break'
  }
  if (ch === ' ') return 'space'
  if (ch === '\u00A0' || ch === '\u202F' || ch === '\u2060' || ch === '\uFEFF') {
    return 'glue'
  }
  if (ch === '\u200B') return 'zero-width-break'
  if (ch === '\u00AD') return 'soft-hyphen'
  return 'text'
}

function splitSegmentByBreakKind(
  segment: string,
  isWordLike: boolean,
  start: number,
  whiteSpaceProfile: WhiteSpaceProfile,
): SegmentationPiece[] {
  const pieces: SegmentationPiece[] = []
  let currentKind: SegmentBreakKind | null = null
  let currentText = ''
  let currentStart = start
  let currentWordLike = false
  let offset = 0

  for (const ch of segment) {
    const kind = classifySegmentBreakChar(ch, whiteSpaceProfile)
    const wordLike = kind === 'text' && isWordLike

    if (currentKind !== null && kind === currentKind && wordLike === currentWordLike) {
      currentText += ch
      offset += ch.length
      continue
    }

    if (currentKind !== null) {
      pieces.push({
        text: currentText,
        isWordLike: currentWordLike,
        kind: currentKind,
        start: currentStart,
      })
    }

    currentKind = kind
    currentText = ch
    currentStart = start + offset
    currentWordLike = wordLike
    offset += ch.length
  }

  if (currentKind !== null) {
    pieces.push({
      text: currentText,
      isWordLike: currentWordLike,
      kind: currentKind,
      start: currentStart,
    })
  }

  return pieces
}

function isTextRunBoundary(kind: SegmentBreakKind): boolean {
  return (
    kind === 'space' ||
    kind === 'preserved-space' ||
    kind === 'zero-width-break' ||
    kind === 'hard-break'
  )
}

const urlSchemeSegmentRe = /^[A-Za-z][A-Za-z0-9+.-]*:$/

function isUrlLikeRunStart(segmentation: MergedSegmentation, index: number): boolean {
  const text = segmentation.texts[index]!
  if (text.startsWith('www.')) return true
  return (
    urlSchemeSegmentRe.test(text) &&
    index + 1 < segmentation.len &&
    segmentation.kinds[index + 1] === 'text' &&
    segmentation.texts[index + 1] === '//'
  )
}

function isUrlQueryBoundarySegment(text: string): boolean {
  return text.includes('?') && (text.includes('://') || text.startsWith('www.'))
}

function mergeUrlLikeRuns(segmentation: MergedSegmentation): MergedSegmentation {
  const texts = segmentation.texts.slice()
  const isWordLike = segmentation.isWordLike.slice()
  const kinds = segmentation.kinds.slice()
  const starts = segmentation.starts.slice()

  for (let i = 0; i < segmentation.len; i++) {
    if (kinds[i] !== 'text' || !isUrlLikeRunStart(segmentation, i)) continue

    let j = i + 1
    while (j < segmentation.len && !isTextRunBoundary(kinds[j]!)) {
      texts[i] += texts[j]!
      isWordLike[i] = true
      const endsQueryPrefix = texts[j]!.includes('?')
      kinds[j] = 'text'
      texts[j] = ''
      j++
      if (endsQueryPrefix) break
    }
  }

  let compactLen = 0
  for (let read = 0; read < texts.length; read++) {
    const text = texts[read]!
    if (text.length === 0) continue
    if (compactLen !== read) {
      texts[compactLen] = text
      isWordLike[compactLen] = isWordLike[read]!
      kinds[compactLen] = kinds[read]!
      starts[compactLen] = starts[read]!
    }
    compactLen++
  }

  texts.length = compactLen
  isWordLike.length = compactLen
  kinds.length = compactLen
  starts.length = compactLen

  return {
    len: compactLen,
    texts,
    isWordLike,
    kinds,
    starts,
  }
}

function mergeUrlQueryRuns(segmentation: MergedSegmentation): MergedSegmentation {
  const texts: string[] = []
  const isWordLike: boolean[] = []
  const kinds: SegmentBreakKind[] = []
  const starts: number[] = []

  for (let i = 0; i < segmentation.len; i++) {
    const text = segmentation.texts[i]!
    texts.push(text)
    isWordLike.push(segmentation.isWordLike[i]!)
    kinds.push(segmentation.kinds[i]!)
    starts.push(segmentation.starts[i]!)

    if (!isUrlQueryBoundarySegment(text)) continue

    const nextIndex = i + 1
    if (
      nextIndex >= segmentation.len ||
      isTextRunBoundary(segmentation.kinds[nextIndex]!)
    ) {
      continue
    }

    let queryText = ''
    const queryStart = segmentation.starts[nextIndex]!
    let j = nextIndex
    while (j < segmentation.len && !isTextRunBoundary(segmentation.kinds[j]!)) {
      queryText += segmentation.texts[j]!
      j++
    }

    if (queryText.length > 0) {
      texts.push(queryText)
      isWordLike.push(true)
      kinds.push('text')
      starts.push(queryStart)
      i = j - 1
    }
  }

  return {
    len: texts.length,
    texts,
    isWordLike,
    kinds,
    starts,
  }
}

const numericJoinerChars = new Set([
  ':', '-', '/', '×', ',', '.', '+',
  '\u2013',
  '\u2014',
])

const asciiPunctuationChainSegmentRe = /^[A-Za-z0-9_]+[,:;]*$/
const asciiPunctuationChainTrailingJoinersRe = /[,:;]+$/

function segmentContainsDecimalDigit(text: string): boolean {
  for (const ch of text) {

>sed -n '521,780p' src/analysis.ts

Command: /bin/zsh -lc "sed -n '521,780p' src/analysis.ts"
Chunk ID: ee2603
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1686
Output:
    if (decimalDigitRe.test(ch)) return true
  }
  return false
}

function isNumericRunSegment(text: string): boolean {
  if (text.length === 0) return false
  for (const ch of text) {
    if (decimalDigitRe.test(ch) || numericJoinerChars.has(ch)) continue
    return false
  }
  return true
}

function mergeNumericRuns(segmentation: MergedSegmentation): MergedSegmentation {
  const texts: string[] = []
  const isWordLike: boolean[] = []
  const kinds: SegmentBreakKind[] = []
  const starts: number[] = []

  for (let i = 0; i < segmentation.len; i++) {
    const text = segmentation.texts[i]!
    const kind = segmentation.kinds[i]!

    if (kind === 'text' && isNumericRunSegment(text) && segmentContainsDecimalDigit(text)) {
      let mergedText = text
      let j = i + 1
      while (
        j < segmentation.len &&
        segmentation.kinds[j] === 'text' &&
        isNumericRunSegment(segmentation.texts[j]!)
      ) {
        mergedText += segmentation.texts[j]!
        j++
      }

      texts.push(mergedText)
      isWordLike.push(true)
      kinds.push('text')
      starts.push(segmentation.starts[i]!)
      i = j - 1
      continue
    }

    texts.push(text)
    isWordLike.push(segmentation.isWordLike[i]!)
    kinds.push(kind)
    starts.push(segmentation.starts[i]!)
  }

  return {
    len: texts.length,
    texts,
    isWordLike,
    kinds,
    starts,
  }
}

function mergeAsciiPunctuationChains(segmentation: MergedSegmentation): MergedSegmentation {
  const texts: string[] = []
  const isWordLike: boolean[] = []
  const kinds: SegmentBreakKind[] = []
  const starts: number[] = []

  for (let i = 0; i < segmentation.len; i++) {
    const text = segmentation.texts[i]!
    const kind = segmentation.kinds[i]!
    const wordLike = segmentation.isWordLike[i]!

    if (kind === 'text' && wordLike && asciiPunctuationChainSegmentRe.test(text)) {
      let mergedText = text
      let j = i + 1

      while (
        asciiPunctuationChainTrailingJoinersRe.test(mergedText) &&
        j < segmentation.len &&
        segmentation.kinds[j] === 'text' &&
        segmentation.isWordLike[j] &&
        asciiPunctuationChainSegmentRe.test(segmentation.texts[j]!)
      ) {
        mergedText += segmentation.texts[j]!
        j++
      }

      texts.push(mergedText)
      isWordLike.push(true)
      kinds.push('text')
      starts.push(segmentation.starts[i]!)
      i = j - 1
      continue
    }

    texts.push(text)
    isWordLike.push(wordLike)
    kinds.push(kind)
    starts.push(segmentation.starts[i]!)
  }

  return {
    len: texts.length,
    texts,
    isWordLike,
    kinds,
    starts,
  }
}

function splitHyphenatedNumericRuns(segmentation: MergedSegmentation): MergedSegmentation {
  const texts: string[] = []
  const isWordLike: boolean[] = []
  const kinds: SegmentBreakKind[] = []
  const starts: number[] = []

  for (let i = 0; i < segmentation.len; i++) {
    const text = segmentation.texts[i]!
    if (segmentation.kinds[i] === 'text' && text.includes('-')) {
      const parts = text.split('-')
      let shouldSplit = parts.length > 1
      for (let j = 0; j < parts.length; j++) {
        const part = parts[j]!
        if (!shouldSplit) break
        if (
          part.length === 0 ||
          !segmentContainsDecimalDigit(part) ||
          !isNumericRunSegment(part)
        ) {
          shouldSplit = false
        }
      }

      if (shouldSplit) {
        let offset = 0
        for (let j = 0; j < parts.length; j++) {
          const part = parts[j]!
          const splitText = j < parts.length - 1 ? `${part}-` : part
          texts.push(splitText)
          isWordLike.push(true)
          kinds.push('text')
          starts.push(segmentation.starts[i]! + offset)
          offset += splitText.length
        }
        continue
      }
    }

    texts.push(text)
    isWordLike.push(segmentation.isWordLike[i]!)
    kinds.push(segmentation.kinds[i]!)
    starts.push(segmentation.starts[i]!)
  }

  return {
    len: texts.length,
    texts,
    isWordLike,
    kinds,
    starts,
  }
}

function mergeGlueConnectedTextRuns(segmentation: MergedSegmentation): MergedSegmentation {
  const texts: string[] = []
  const isWordLike: boolean[] = []
  const kinds: SegmentBreakKind[] = []
  const starts: number[] = []

  let read = 0
  while (read < segmentation.len) {
    let text = segmentation.texts[read]!
    let wordLike = segmentation.isWordLike[read]!
    let kind = segmentation.kinds[read]!
    let start = segmentation.starts[read]!

    if (kind === 'glue') {
      let glueText = text
      const glueStart = start
      read++
      while (read < segmentation.len && segmentation.kinds[read] === 'glue') {
        glueText += segmentation.texts[read]!
        read++
      }

      if (read < segmentation.len && segmentation.kinds[read] === 'text') {
        text = glueText + segmentation.texts[read]!
        wordLike = segmentation.isWordLike[read]!
        kind = 'text'
        start = glueStart
        read++
      } else {
        texts.push(glueText)
        isWordLike.push(false)
        kinds.push('glue')
        starts.push(glueStart)
        continue
      }
    } else {
      read++
    }

    if (kind === 'text') {
      while (read < segmentation.len && segmentation.kinds[read] === 'glue') {
        let glueText = ''
        while (read < segmentation.len && segmentation.kinds[read] === 'glue') {
          glueText += segmentation.texts[read]!
          read++
        }

        if (read < segmentation.len && segmentation.kinds[read] === 'text') {
          text += glueText + segmentation.texts[read]!
          wordLike = wordLike || segmentation.isWordLike[read]!
          read++
          continue
        }

        text += glueText
      }
    }

    texts.push(text)
    isWordLike.push(wordLike)
    kinds.push(kind)
    starts.push(start)
  }

  return {
    len: texts.length,
    texts,
    isWordLike,
    kinds,
    starts,
  }
}

function carryTrailingForwardStickyAcrossCJKBoundary(segmentation: MergedSegmentation): MergedSegmentation {
  const texts = segmentation.texts.slice()
  const isWordLike = segmentation.isWordLike.slice()
  const kinds = segmentation.kinds.slice()
  const starts = segmentation.starts.slice()

  for (let i = 0; i < texts.length - 1; i++) {
    if (kinds[i] !== 'text' || kinds[i + 1] !== 'text') continue
    if (!isCJK(texts[i]!) || !isCJK(texts[i + 1]!)) continue

    const split = splitTrailingForwardStickyCluster(texts[i]!)
    if (split === null) continue

    texts[i] = split.head
    texts[i + 1] = split.tail + texts[i + 1]!
    starts[i + 1] = starts[i]! + split.head.length
  }

  return {
    len: texts.length,
    texts,
    isWordLike,
    kinds,
    starts,
  }
}

>sed -n '781,1040p' src/analysis.ts

Command: /bin/zsh -lc "sed -n '781,1040p' src/analysis.ts"
Chunk ID: 3623ef
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1781
Output:


function buildMergedSegmentation(
  normalized: string,
  profile: AnalysisProfile,
  whiteSpaceProfile: WhiteSpaceProfile,
): MergedSegmentation {
  const wordSegmenter = getSharedWordSegmenter()
  let mergedLen = 0
  const mergedTexts: string[] = []
  const mergedWordLike: boolean[] = []
  const mergedKinds: SegmentBreakKind[] = []
  const mergedStarts: number[] = []

  for (const s of wordSegmenter.segment(normalized)) {
    for (const piece of splitSegmentByBreakKind(s.segment, s.isWordLike ?? false, s.index, whiteSpaceProfile)) {
      const isText = piece.kind === 'text'

      if (
        profile.carryCJKAfterClosingQuote &&
        isText &&
        mergedLen > 0 &&
        mergedKinds[mergedLen - 1] === 'text' &&
        isCJK(piece.text) &&
        isCJK(mergedTexts[mergedLen - 1]!) &&
        endsWithClosingQuote(mergedTexts[mergedLen - 1]!)
      ) {
        mergedTexts[mergedLen - 1] += piece.text
        mergedWordLike[mergedLen - 1] = mergedWordLike[mergedLen - 1]! || piece.isWordLike
      } else if (
        isText &&
        mergedLen > 0 &&
        mergedKinds[mergedLen - 1] === 'text' &&
        isCJKLineStartProhibitedSegment(piece.text) &&
        isCJK(mergedTexts[mergedLen - 1]!)
      ) {
        mergedTexts[mergedLen - 1] += piece.text
        mergedWordLike[mergedLen - 1] = mergedWordLike[mergedLen - 1]! || piece.isWordLike
      } else if (
        isText &&
        mergedLen > 0 &&
        mergedKinds[mergedLen - 1] === 'text' &&
        endsWithMyanmarMedialGlue(mergedTexts[mergedLen - 1]!)
      ) {
        mergedTexts[mergedLen - 1] += piece.text
        mergedWordLike[mergedLen - 1] = mergedWordLike[mergedLen - 1]! || piece.isWordLike
      } else if (
        isText &&
        mergedLen > 0 &&
        mergedKinds[mergedLen - 1] === 'text' &&
        piece.isWordLike &&
        containsArabicScript(piece.text) &&
        endsWithArabicNoSpacePunctuation(mergedTexts[mergedLen - 1]!)
      ) {
        mergedTexts[mergedLen - 1] += piece.text
        mergedWordLike[mergedLen - 1] = true
      } else if (
        isText &&
        !piece.isWordLike &&
        mergedLen > 0 &&
        mergedKinds[mergedLen - 1] === 'text' &&
        piece.text.length === 1 &&
        piece.text !== '-' &&
        piece.text !== '—' &&
        isRepeatedSingleCharRun(mergedTexts[mergedLen - 1]!, piece.text)
      ) {
        mergedTexts[mergedLen - 1] += piece.text
      } else if (
        isText &&
        !piece.isWordLike &&
        mergedLen > 0 &&
        mergedKinds[mergedLen - 1] === 'text' &&
        (
          isLeftStickyPunctuationSegment(piece.text) ||
          (piece.text === '-' && mergedWordLike[mergedLen - 1]!)
        )
      ) {
        mergedTexts[mergedLen - 1] += piece.text
      } else {
        mergedTexts[mergedLen] = piece.text
        mergedWordLike[mergedLen] = piece.isWordLike
        mergedKinds[mergedLen] = piece.kind
        mergedStarts[mergedLen] = piece.start
        mergedLen++
      }
    }
  }

  for (let i = 1; i < mergedLen; i++) {
    if (
      mergedKinds[i] === 'text' &&
      !mergedWordLike[i]! &&
      isEscapedQuoteClusterSegment(mergedTexts[i]!) &&
      mergedKinds[i - 1] === 'text'
    ) {
      mergedTexts[i - 1] += mergedTexts[i]!
      mergedWordLike[i - 1] = mergedWordLike[i - 1]! || mergedWordLike[i]!
      mergedTexts[i] = ''
    }
  }

  for (let i = mergedLen - 2; i >= 0; i--) {
    if (mergedKinds[i] === 'text' && !mergedWordLike[i]! && isForwardStickyClusterSegment(mergedTexts[i]!)) {
      let j = i + 1
      while (j < mergedLen && mergedTexts[j] === '') j++
      if (j < mergedLen && mergedKinds[j] === 'text') {
        mergedTexts[j] = mergedTexts[i]! + mergedTexts[j]!
        mergedStarts[j] = mergedStarts[i]!
        mergedTexts[i] = ''
      }
    }
  }

  let compactLen = 0
  for (let read = 0; read < mergedLen; read++) {
    const text = mergedTexts[read]!
    if (text.length === 0) continue
    if (compactLen !== read) {
      mergedTexts[compactLen] = text
      mergedWordLike[compactLen] = mergedWordLike[read]!
      mergedKinds[compactLen] = mergedKinds[read]!
      mergedStarts[compactLen] = mergedStarts[read]!
    }
    compactLen++
  }

  mergedTexts.length = compactLen
  mergedWordLike.length = compactLen
  mergedKinds.length = compactLen
  mergedStarts.length = compactLen

  const compacted = mergeGlueConnectedTextRuns({
    len: compactLen,
    texts: mergedTexts,
    isWordLike: mergedWordLike,
    kinds: mergedKinds,
    starts: mergedStarts,
  })
  const withMergedUrls = carryTrailingForwardStickyAcrossCJKBoundary(
    mergeAsciiPunctuationChains(
      splitHyphenatedNumericRuns(mergeNumericRuns(mergeUrlQueryRuns(mergeUrlLikeRuns(compacted)))),
    ),
  )

  for (let i = 0; i < withMergedUrls.len - 1; i++) {
    const split = splitLeadingSpaceAndMarks(withMergedUrls.texts[i]!)
    if (split === null) continue
    if (
      (withMergedUrls.kinds[i] !== 'space' && withMergedUrls.kinds[i] !== 'preserved-space') ||
      withMergedUrls.kinds[i + 1] !== 'text' ||
      !containsArabicScript(withMergedUrls.texts[i + 1]!)
    ) {
      continue
    }

    withMergedUrls.texts[i] = split.space
    withMergedUrls.isWordLike[i] = false
    withMergedUrls.kinds[i] = withMergedUrls.kinds[i] === 'preserved-space' ? 'preserved-space' : 'space'
    withMergedUrls.texts[i + 1] = split.marks + withMergedUrls.texts[i + 1]!
    withMergedUrls.starts[i + 1] = withMergedUrls.starts[i]! + split.space.length
  }

  return withMergedUrls
}

function compileAnalysisChunks(segmentation: MergedSegmentation, whiteSpaceProfile: WhiteSpaceProfile): AnalysisChunk[] {
  if (segmentation.len === 0) return []
  if (!whiteSpaceProfile.preserveHardBreaks) {
    return [{
      startSegmentIndex: 0,
      endSegmentIndex: segmentation.len,
      consumedEndSegmentIndex: segmentation.len,
    }]
  }

  const chunks: AnalysisChunk[] = []
  let startSegmentIndex = 0

  for (let i = 0; i < segmentation.len; i++) {
    if (segmentation.kinds[i] !== 'hard-break') continue

    chunks.push({
      startSegmentIndex,
      endSegmentIndex: i,
      consumedEndSegmentIndex: i + 1,
    })
    startSegmentIndex = i + 1
  }

  if (startSegmentIndex < segmentation.len) {
    chunks.push({
      startSegmentIndex,
      endSegmentIndex: segmentation.len,
      consumedEndSegmentIndex: segmentation.len,
    })
  }

  return chunks
}

export function analyzeText(
  text: string,
  profile: AnalysisProfile,
  whiteSpace: WhiteSpaceMode = 'normal',
): TextAnalysis {
  const whiteSpaceProfile = getWhiteSpaceProfile(whiteSpace)
  const normalized = whiteSpaceProfile.mode === 'pre-wrap'
    ? normalizeWhitespacePreWrap(text)
    : normalizeWhitespaceNormal(text)
  if (normalized.length === 0) {
    return {
      normalized,
      chunks: [],
      len: 0,
      texts: [],
      isWordLike: [],
      kinds: [],
      starts: [],
    }
  }
  const segmentation = buildMergedSegmentation(normalized, profile, whiteSpaceProfile)
  return {
    normalized,
    chunks: compileAnalysisChunks(segmentation, whiteSpaceProfile),
    ...segmentation,
  }
}

>sed -n '1,260p' src/layout.test.ts

Command: /bin/zsh -lc "sed -n '1,260p' src/layout.test.ts"
Chunk ID: 137b2e
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2168
Output:
import { beforeAll, beforeEach, describe, expect, test } from 'bun:test'

// Keep the permanent suite small and durable. These tests exercise the shipped
// prepare/layout exports with a deterministic fake canvas backend. For narrow
// browser-specific investigations, prefer throwaway probes and browser checkers
// over mirroring the full implementation here.

const FONT = '16px Test Sans'
const LINE_HEIGHT = 19

type LayoutModule = typeof import('./layout.ts')
type LineBreakModule = typeof import('./line-break.ts')

let prepare: LayoutModule['prepare']
let prepareWithSegments: LayoutModule['prepareWithSegments']
let layout: LayoutModule['layout']
let layoutWithLines: LayoutModule['layoutWithLines']
let layoutNextLine: LayoutModule['layoutNextLine']
let walkLineRanges: LayoutModule['walkLineRanges']
let clearCache: LayoutModule['clearCache']
let setLocale: LayoutModule['setLocale']
let countPreparedLines: LineBreakModule['countPreparedLines']
let walkPreparedLines: LineBreakModule['walkPreparedLines']

const emojiPresentationRe = /\p{Emoji_Presentation}/u
const punctuationRe = /[.,!?;:%)\]}'"”’»›…—-]/u
const graphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })

type TestLayoutCursor = {
  segmentIndex: number
  graphemeIndex: number
}

type TestPreparedTextWithSegments = {
  segments: string[]
}

type TestLayoutLine = {
  start: TestLayoutCursor
  end: TestLayoutCursor
}

function parseFontSize(font: string): number {
  const match = font.match(/(\d+(?:\.\d+)?)\s*px/)
  return match ? Number.parseFloat(match[1]!) : 16
}

function isWideCharacter(ch: string): boolean {
  const code = ch.codePointAt(0)!
  return (
    (code >= 0x4E00 && code <= 0x9FFF) ||
    (code >= 0x3400 && code <= 0x4DBF) ||
    (code >= 0xF900 && code <= 0xFAFF) ||
    (code >= 0x2F800 && code <= 0x2FA1F) ||
    (code >= 0x20000 && code <= 0x2A6DF) ||
    (code >= 0x2A700 && code <= 0x2B73F) ||
    (code >= 0x2B740 && code <= 0x2B81F) ||
    (code >= 0x2B820 && code <= 0x2CEAF) ||
    (code >= 0x2CEB0 && code <= 0x2EBEF) ||
    (code >= 0x30000 && code <= 0x3134F) ||
    (code >= 0x3000 && code <= 0x303F) ||
    (code >= 0x3040 && code <= 0x309F) ||
    (code >= 0x30A0 && code <= 0x30FF) ||
    (code >= 0xAC00 && code <= 0xD7AF) ||
    (code >= 0xFF00 && code <= 0xFFEF)
  )
}

function measureWidth(text: string, font: string): number {
  const fontSize = parseFontSize(font)
  let width = 0

  for (const ch of text) {
    if (ch === ' ') {
      width += fontSize * 0.33
    } else if (ch === '\t') {
      width += fontSize * 1.32
    } else if (emojiPresentationRe.test(ch) || ch === '\uFE0F') {
      width += fontSize
    } else if (isWideCharacter(ch)) {
      width += fontSize
    } else if (punctuationRe.test(ch)) {
      width += fontSize * 0.4
    } else {
      width += fontSize * 0.6
    }
  }

  return width
}

function nextTabAdvance(lineWidth: number, spaceWidth: number, tabSize = 8): number {
  const tabStopAdvance = spaceWidth * tabSize
  const remainder = lineWidth % tabStopAdvance
  return remainder === 0 ? tabStopAdvance : tabStopAdvance - remainder
}

function getSegmentGraphemes(text: string): string[] {
  return Array.from(graphemeSegmenter.segment(text), segment => segment.segment)
}

function slicePreparedText(
  prepared: TestPreparedTextWithSegments,
  start: TestLayoutCursor,
  end: TestLayoutCursor,
): string {
  if (start.segmentIndex === end.segmentIndex) {
    const segment = prepared.segments[start.segmentIndex]
    if (segment === undefined) return ''
    return getSegmentGraphemes(segment).slice(start.graphemeIndex, end.graphemeIndex).join('')
  }

  let result = ''
  for (let segmentIndex = start.segmentIndex; segmentIndex < end.segmentIndex; segmentIndex++) {
    const segment = prepared.segments[segmentIndex]
    if (segment === undefined) break
    if (segmentIndex === start.segmentIndex && start.graphemeIndex > 0) {
      result += getSegmentGraphemes(segment).slice(start.graphemeIndex).join('')
    } else {
      result += segment
    }
  }

  if (end.graphemeIndex > 0) {
    const segment = prepared.segments[end.segmentIndex]
    if (segment !== undefined) {
      result += getSegmentGraphemes(segment).slice(0, end.graphemeIndex).join('')
    }
  }

  return result
}

function reconstructFromLineBoundaries(
  prepared: TestPreparedTextWithSegments,
  lines: TestLayoutLine[],
): string {
  return lines.map(line => slicePreparedText(prepared, line.start, line.end)).join('')
}

function collectStreamedLines(
  prepared: TestPreparedTextWithSegments,
  width: number,
): TestLayoutLine[] {
  const lines: TestLayoutLine[] = []
  let cursor = { segmentIndex: 0, graphemeIndex: 0 }

  while (true) {
    const line = layoutNextLine(prepared as Parameters<typeof layoutNextLine>[0], cursor, width)
    if (line === null) break
    lines.push(line)
    cursor = line.end
  }

  return lines
}

function reconstructFromWalkedRanges(
  prepared: TestPreparedTextWithSegments,
  width: number,
): string {
  const slices: string[] = []
  walkLineRanges(prepared as Parameters<typeof walkLineRanges>[0], width, line => {
    slices.push(slicePreparedText(prepared, line.start, line.end))
  })
  return slices.join('')
}

class TestCanvasRenderingContext2D {
  font = ''

  measureText(text: string): { width: number } {
    return { width: measureWidth(text, this.font) }
  }
}

class TestOffscreenCanvas {
  constructor(_width: number, _height: number) {}

  getContext(_kind: string): TestCanvasRenderingContext2D {
    return new TestCanvasRenderingContext2D()
  }
}

beforeAll(async () => {
  Reflect.set(globalThis, 'OffscreenCanvas', TestOffscreenCanvas)
  const mod = await import('./layout.ts')
  const lineBreakMod = await import('./line-break.ts')
  ;({
    prepare,
    prepareWithSegments,
    layout,
    layoutWithLines,
    layoutNextLine,
    walkLineRanges,
    clearCache,
    setLocale,
  } = mod)
  ;({ countPreparedLines, walkPreparedLines } = lineBreakMod)
})

beforeEach(() => {
  setLocale(undefined)
  clearCache()
})

describe('prepare invariants', () => {
  test('whitespace-only input stays empty', () => {
    const prepared = prepare('  \t\n  ', FONT)
    expect(layout(prepared, 200, LINE_HEIGHT)).toEqual({ lineCount: 0, height: 0 })
  })

  test('collapses ordinary whitespace runs and trims the edges', () => {
    const prepared = prepareWithSegments('  Hello\t \n  World  ', FONT)
    expect(prepared.segments).toEqual(['Hello', ' ', 'World'])
  })

  test('pre-wrap mode keeps ordinary spaces instead of collapsing them', () => {
    const prepared = prepareWithSegments('  Hello   World  ', FONT, { whiteSpace: 'pre-wrap' })
    expect(prepared.segments).toEqual(['  ', 'Hello', '   ', 'World', '  '])
    expect(prepared.kinds).toEqual(['preserved-space', 'text', 'preserved-space', 'text', 'preserved-space'])
  })

  test('pre-wrap mode keeps hard breaks as explicit segments', () => {
    const prepared = prepareWithSegments('Hello\nWorld', FONT, { whiteSpace: 'pre-wrap' })
    expect(prepared.segments).toEqual(['Hello', '\n', 'World'])
    expect(prepared.kinds).toEqual(['text', 'hard-break', 'text'])
  })

  test('pre-wrap mode normalizes CRLF into a single hard break', () => {
    const prepared = prepareWithSegments('Hello\r\nWorld', FONT, { whiteSpace: 'pre-wrap' })
    expect(prepared.segments).toEqual(['Hello', '\n', 'World'])
    expect(prepared.kinds).toEqual(['text', 'hard-break', 'text'])
  })

  test('pre-wrap mode keeps tabs as explicit segments', () => {
    const prepared = prepareWithSegments('Hello\tWorld', FONT, { whiteSpace: 'pre-wrap' })
    expect(prepared.segments).toEqual(['Hello', '\t', 'World'])
    expect(prepared.kinds).toEqual(['text', 'tab', 'text'])
  })

  test('keeps non-breaking spaces as glue instead of collapsing them away', () => {
    const prepared = prepareWithSegments('Hello\u00A0world', FONT)
    expect(prepared.segments).toEqual(['Hello\u00A0world'])
    expect(prepared.kinds).toEqual(['text'])
  })

  test('keeps standalone non-breaking spaces as visible glue content', () => {
    const prepared = prepareWithSegments('\u00A0', FONT)
    expect(prepared.segments).toEqual(['\u00A0'])
    expect(layout(prepared, 200, LINE_HEIGHT)).toEqual({ lineCount: 1, height: LINE_HEIGHT })
  })

  test('pre-wrap mode keeps whitespace-only input visible', () => {
    const prepared = prepare('   ', FONT, { whiteSpace: 'pre-wrap' })
    expect(layout(prepared, 200, LINE_HEIGHT)).toEqual({ lineCount: 1, height: LINE_HEIGHT })
  })

  test('keeps narrow no-break spaces as glue content', () => {
    const prepared = prepareWithSegments('10\u202F000', FONT)

>sed -n '261,520p' src/layout.test.ts

Command: /bin/zsh -lc "sed -n '261,520p' src/layout.test.ts"
Chunk ID: 06fed2
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2883
Output:
    expect(prepared.segments).toEqual(['10\u202F000'])
    expect(prepared.kinds).toEqual(['text'])
  })

  test('keeps word joiners as glue content', () => {
    const prepared = prepareWithSegments('foo\u2060bar', FONT)
    expect(prepared.segments).toEqual(['foo\u2060bar'])
    expect(prepared.kinds).toEqual(['text'])
  })

  test('treats zero-width spaces as explicit break opportunities', () => {
    const prepared = prepareWithSegments('alpha\u200Bbeta', FONT)
    expect(prepared.segments).toEqual(['alpha', '\u200B', 'beta'])
    expect(prepared.kinds).toEqual(['text', 'zero-width-break', 'text'])

    const alphaWidth = prepared.widths[0]!
    expect(layout(prepared, alphaWidth + 0.1, LINE_HEIGHT).lineCount).toBe(2)
  })

  test('treats soft hyphens as discretionary break points', () => {
    const prepared = prepareWithSegments('trans\u00ADatlantic', FONT)
    expect(prepared.segments).toEqual(['trans', '\u00AD', 'atlantic'])
    expect(prepared.kinds).toEqual(['text', 'soft-hyphen', 'text'])

    const wide = layoutWithLines(prepared, 200, LINE_HEIGHT)
    expect(wide.lineCount).toBe(1)
    expect(wide.lines.map(line => line.text)).toEqual(['transatlantic'])

    const prefixed = prepareWithSegments('foo trans\u00ADatlantic', FONT)
    const softBreakWidth = Math.max(
      prefixed.widths[0]! + prefixed.widths[1]! + prefixed.widths[2]! + prefixed.discretionaryHyphenWidth,
      prefixed.widths[4]!,
    ) + 0.1
    const narrow = layoutWithLines(prefixed, softBreakWidth, LINE_HEIGHT)
    expect(narrow.lineCount).toBe(2)
    expect(narrow.lines.map(line => line.text)).toEqual(['foo trans-', 'atlantic'])
    expect(layout(prefixed, softBreakWidth, LINE_HEIGHT).lineCount).toBe(narrow.lineCount)

    const continuedSoftBreakWidth =
      prefixed.widths[0]! +
      prefixed.widths[1]! +
      prefixed.widths[2]! +
      prefixed.breakableWidths[4]![0]! +
      prefixed.discretionaryHyphenWidth +
      0.1
    const continued = layoutWithLines(prefixed, continuedSoftBreakWidth, LINE_HEIGHT)
    expect(continued.lines.map(line => line.text)).toEqual(['foo trans-a', 'tlantic'])
    expect(layout(prefixed, continuedSoftBreakWidth, LINE_HEIGHT).lineCount).toBe(continued.lineCount)
  })

  test('keeps closing punctuation attached to the preceding word', () => {
    const prepared = prepareWithSegments('hello.', FONT)
    expect(prepared.segments).toEqual(['hello.'])
  })

  test('keeps arabic punctuation attached to the preceding word', () => {
    const prepared = prepareWithSegments('مرحبا، عالم؟', FONT)
    expect(prepared.segments).toEqual(['مرحبا،', ' ', 'عالم؟'])
  })

  test('keeps arabic punctuation-plus-mark clusters attached to the preceding word', () => {
    const prepared = prepareWithSegments('وحوارى بكشء،ٍ من قولهم', FONT)
    expect(prepared.segments).toEqual(['وحوارى', ' ', 'بكشء،ٍ', ' ', 'من', ' ', 'قولهم'])
  })

  test('keeps arabic no-space punctuation clusters together', () => {
    const prepared = prepareWithSegments('فيقول:وعليك السلام', FONT)
    expect(prepared.segments).toEqual(['فيقول:وعليك', ' ', 'السلام'])
  })

  test('keeps arabic comma-followed text together without a space', () => {
    const prepared = prepareWithSegments('همزةٌ،ما كان', FONT)
    expect(prepared.segments).toEqual(['همزةٌ،ما', ' ', 'كان'])
  })

  test('keeps leading arabic combining marks with the following word', () => {
    const prepared = prepareWithSegments('كل ِّواحدةٍ', FONT)
    expect(prepared.segments).toEqual(['كل', ' ', 'ِّواحدةٍ'])
  })

  test('keeps devanagari danda punctuation attached to the preceding word', () => {
    const prepared = prepareWithSegments('नमस्ते। दुनिया॥', FONT)
    expect(prepared.segments).toEqual(['नमस्ते।', ' ', 'दुनिया॥'])
  })

  test('keeps myanmar punctuation attached to the preceding word', () => {
    const prepared = prepareWithSegments('ဖြစ်သည်။ နောက်တစ်ခု၊ ကိုက်ချီ၍ ယုံကြည်မိကြ၏။', FONT)
    expect(prepared.segments.slice(0, 7)).toEqual(['ဖြစ်သည်။', ' ', 'နောက်တစ်ခု၊', ' ', 'ကိုက်', 'ချီ၍', ' '])
    expect(prepared.segments.at(-1)).toBe('ကြ၏။')
  })

  test('keeps myanmar possessive marker attached to the following word', () => {
    const prepared = prepareWithSegments('ကျွန်ုပ်၏လက်မဖြင့်', FONT)
    expect(prepared.segments).toEqual(['ကျွန်ုပ်၏လက်မ', 'ဖြင့်'])
  })

  test('keeps opening quotes attached to the following word', () => {
    const prepared = prepareWithSegments('“Whenever', FONT)
    expect(prepared.segments).toEqual(['“Whenever'])
  })

  test('keeps apostrophe-led elisions attached to the following word', () => {
    const prepared = prepareWithSegments('“Take ’em downstairs', FONT)
    expect(prepared.segments).toEqual(['“Take', ' ', '’em', ' ', 'downstairs'])
  })

  test('keeps stacked opening quotes attached to the following word', () => {
    const prepared = prepareWithSegments('invented, “‘George B. Wilson', FONT)
    expect(prepared.segments).toEqual(['invented,', ' ', '“‘George', ' ', 'B.', ' ', 'Wilson'])
  })

  test('treats ascii quotes as opening and closing glue by context', () => {
    const prepared = prepareWithSegments('said "hello" there', FONT)
    expect(prepared.segments).toEqual(['said', ' ', '"hello"', ' ', 'there'])
  })

  test('treats escaped ascii quote clusters as opening and closing glue by context', () => {
    const text = String.raw`say \"hello\" there`
    const prepared = prepareWithSegments(text, FONT)
    expect(prepared.segments).toEqual(['say', ' ', String.raw`\"hello\"`, ' ', 'there'])
  })

  test('keeps URL-like runs together as one breakable segment', () => {
    const prepared = prepareWithSegments('see https://example.com/reports/q3?lang=ar&mode=full now', FONT)
    expect(prepared.segments).toEqual([
      'see',
      ' ',
      'https://example.com/reports/q3?',
      'lang=ar&mode=full',
      ' ',
      'now',
    ])
  })

  test('keeps no-space ascii punctuation chains together as one breakable segment', () => {
    const prepared = prepareWithSegments('foo;bar foo:bar foo,bar as;lkdfjals;k', FONT)
    expect(prepared.segments).toEqual([
      'foo;bar',
      ' ',
      'foo:bar',
      ' ',
      'foo,bar',
      ' ',
      'as;lkdfjals;k',
    ])
  })

  test('keeps numeric time ranges together', () => {
    const prepared = prepareWithSegments('window 7:00-9:00 only', FONT)
    expect(prepared.segments).toEqual(['window', ' ', '7:00-', '9:00', ' ', 'only'])
  })

  test('splits hyphenated numeric identifiers at preferred boundaries', () => {
    const prepared = prepareWithSegments('SSN 420-69-8008 filed', FONT)
    expect(prepared.segments).toEqual(['SSN', ' ', '420-', '69-', '8008', ' ', 'filed'])
  })

  test('keeps unicode-digit numeric expressions together', () => {
    const prepared = prepareWithSegments('यह २४×७ सपोर्ट है', FONT)
    expect(prepared.segments).toEqual(['यह', ' ', '२४×७', ' ', 'सपोर्ट', ' ', 'है'])
  })

  test('does not attach opening punctuation to following whitespace', () => {
    const prepared = prepareWithSegments('“ hello', FONT)
    expect(prepared.segments).toEqual(['“', ' ', 'hello'])
  })

  test('keeps japanese iteration marks attached to the preceding kana', () => {
    const prepared = prepareWithSegments('棄てゝ行く', FONT)
    expect(prepared.segments).toEqual(['棄', 'てゝ', '行', 'く'])
  })

  test('carries trailing cjk opening punctuation forward across segment boundaries', () => {
    const prepared = prepareWithSegments('作者はさつき、「下人', FONT)
    expect(prepared.segments).toEqual(['作', '者', 'は', 'さ', 'つ', 'き、', '「下', '人'])
  })

  test('keeps em dashes breakable', () => {
    const prepared = prepareWithSegments('universe—so', FONT)
    expect(prepared.segments).toEqual(['universe', '—', 'so'])
  })

  test('coalesces repeated punctuation runs into a single segment', () => {
    const prepared = prepareWithSegments('=== heading ===', FONT)
    expect(prepared.segments).toEqual(['===', ' ', 'heading', ' ', '==='])
  })

  test('applies CJK and Hangul punctuation attachment rules', () => {
    expect(prepareWithSegments('中文，测试。', FONT).segments).toEqual(['中', '文，', '测', '试。'])
    expect(prepareWithSegments('테스트입니다.', FONT).segments.at(-1)).toBe('다.')
  })

  test('adjacent CJK text units stay breakable after visible text, not only after spaces', () => {
    const prepared = prepareWithSegments('foo 世界 bar', FONT)
    expect(prepared.segments).toEqual(['foo', ' ', '世', '界', ' ', 'bar'])

    const width = prepared.widths[0]! + prepared.widths[1]! + prepared.widths[2]! + 0.1
    const batched = layoutWithLines(prepared, width, LINE_HEIGHT)
    expect(batched.lines.map(line => line.text)).toEqual(['foo 世', '界 bar'])

    const streamed = []
    let cursor = { segmentIndex: 0, graphemeIndex: 0 }
    while (true) {
      const line = layoutNextLine(prepared, cursor, width)
      if (line === null) break
      streamed.push(line.text)
      cursor = line.end
    }
    expect(streamed).toEqual(['foo 世', '界 bar'])
    expect(layout(prepared, width, LINE_HEIGHT)).toEqual({ lineCount: 2, height: LINE_HEIGHT * 2 })
  })

  test('treats astral CJK ideographs as CJK break units', () => {
    expect(prepareWithSegments('𠀀𠀁', FONT).segments).toEqual(['𠀀', '𠀁'])
    expect(prepareWithSegments('𠀀。', FONT).segments).toEqual(['𠀀。'])
  })

  test('prepare and prepareWithSegments agree on layout behavior', () => {
    const plain = prepare('Alpha beta gamma', FONT)
    const rich = prepareWithSegments('Alpha beta gamma', FONT)
    for (const width of [40, 80, 200]) {
      expect(layout(plain, width, LINE_HEIGHT)).toEqual(layout(rich, width, LINE_HEIGHT))
    }
  })

  test('locale can be reset without disturbing later prepares', () => {
    setLocale('th')
    const thai = prepare('ภาษาไทยภาษาไทย', FONT)
    expect(layout(thai, 80, LINE_HEIGHT).lineCount).toBeGreaterThan(0)

    setLocale(undefined)
    const latin = prepare('hello world', FONT)
    expect(layout(latin, 200, LINE_HEIGHT)).toEqual({ lineCount: 1, height: LINE_HEIGHT })
  })
})

describe('layout invariants', () => {
  test('line count grows monotonically as width shrinks', () => {
    const prepared = prepare('The quick brown fox jumps over the lazy dog', FONT)
    let previous = 0

    for (const width of [320, 200, 140, 90]) {
      const { lineCount } = layout(prepared, width, LINE_HEIGHT)
      expect(lineCount).toBeGreaterThanOrEqual(previous)
      previous = lineCount
    }
  })

  test('trailing whitespace hangs past the line edge', () => {
    const prepared = prepareWithSegments('Hello ', FONT)
    const widthOfHello = prepared.widths[0]!

    expect(layout(prepared, widthOfHello, LINE_HEIGHT).lineCount).toBe(1)

    const withLines = layoutWithLines(prepared, widthOfHello, LINE_HEIGHT)
    expect(withLines.lineCount).toBe(1)
    expect(withLines.lines).toEqual([{
      text: 'Hello',
      width: widthOfHello,
      start: { segmentIndex: 0, graphemeIndex: 0 },

>sed -n '521,780p' src/layout.test.ts

Command: /bin/zsh -lc "sed -n '521,780p' src/layout.test.ts"
Chunk ID: b677fb
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2883
Output:
      end: { segmentIndex: 1, graphemeIndex: 0 },
    }])
  })

  test('breaks long words at grapheme boundaries and keeps both layout APIs aligned', () => {
    const prepared = prepareWithSegments('Superlongword', FONT)
    const graphemeWidths = prepared.breakableWidths[0]!
    const maxWidth = graphemeWidths[0]! + graphemeWidths[1]! + graphemeWidths[2]! + 0.1

    const plain = layout(prepared, maxWidth, LINE_HEIGHT)
    const rich = layoutWithLines(prepared, maxWidth, LINE_HEIGHT)

    expect(plain.lineCount).toBeGreaterThan(1)
    expect(rich.lineCount).toBe(plain.lineCount)
    expect(rich.height).toBe(plain.height)
    expect(rich.lines.map(line => line.text).join('')).toBe('Superlongword')
    expect(rich.lines[0]!.start).toEqual({ segmentIndex: 0, graphemeIndex: 0 })
    expect(rich.lines.at(-1)!.end).toEqual({ segmentIndex: 1, graphemeIndex: 0 })
  })

  test('mixed-direction text is a stable smoke test', () => {
    const prepared = prepareWithSegments('According to محمد الأحمد, the results improved.', FONT)
    const result = layoutWithLines(prepared, 120, LINE_HEIGHT)

    expect(result.lineCount).toBeGreaterThanOrEqual(1)
    expect(result.height).toBe(result.lineCount * LINE_HEIGHT)
    expect(result.lines.map(line => line.text).join('')).toBe('According to محمد الأحمد, the results improved.')
  })

  test('layoutNextLine reproduces layoutWithLines exactly', () => {
    const prepared = prepareWithSegments('foo trans\u00ADatlantic said "hello" to 世界 and waved.', FONT)
    const width = prepared.widths[0]! + prepared.widths[1]! + prepared.widths[2]! + prepared.breakableWidths[4]![0]! + prepared.discretionaryHyphenWidth + 0.1
    const expected = layoutWithLines(prepared, width, LINE_HEIGHT)

    const actual = []
    let cursor = { segmentIndex: 0, graphemeIndex: 0 }
    while (true) {
      const line = layoutNextLine(prepared, cursor, width)
      if (line === null) break
      actual.push(line)
      cursor = line.end
    }

    expect(actual).toEqual(expected.lines)
  })

  test('rich line boundary cursors reconstruct normalized source text exactly', () => {
    const cases = [
      'a b c',
      '  Hello\t \n  World  ',
      'foo trans\u00ADatlantic said "hello" to 世界 and waved.',
      'According to محمد الأحمد, the results improved.',
      'see https://example.com/reports/q3?lang=ar&mode=full now',
      'alpha\u200Bbeta gamma',
    ]
    const widths = [40, 80, 120, 200]

    for (const text of cases) {
      const prepared = prepareWithSegments(text, FONT)
      const expected = prepared.segments.join('')

      for (const width of widths) {
        const batched = layoutWithLines(prepared, width, LINE_HEIGHT)
        const streamed = collectStreamedLines(prepared, width)

        expect(reconstructFromLineBoundaries(prepared, batched.lines)).toBe(expected)
        expect(reconstructFromLineBoundaries(prepared, streamed)).toBe(expected)
        expect(reconstructFromWalkedRanges(prepared, width)).toBe(expected)
      }
    }
  })

  test('soft-hyphen round-trip uses source slices instead of rendered line text', () => {
    const prepared = prepareWithSegments('foo trans\u00ADatlantic', FONT)
    const width =
      prepared.widths[0]! +
      prepared.widths[1]! +
      prepared.widths[2]! +
      prepared.breakableWidths[4]![0]! +
      prepared.discretionaryHyphenWidth +
      0.1
    const result = layoutWithLines(prepared, width, LINE_HEIGHT)

    expect(result.lines.map(line => line.text).join('')).toBe('foo trans-atlantic')
    expect(reconstructFromLineBoundaries(prepared, result.lines)).toBe('foo trans\u00ADatlantic')
  })

  test('pre-wrap mode keeps hanging spaces visible at line end', () => {
    const prepared = prepareWithSegments('foo   bar', FONT, { whiteSpace: 'pre-wrap' })
    const width = measureWidth('foo', FONT) + 0.1
    const lines = layoutWithLines(prepared, width, LINE_HEIGHT)
    expect(lines.lineCount).toBe(2)
    expect(lines.lines.map(line => line.text)).toEqual(['foo   ', 'bar'])
    expect(layout(prepared, width, LINE_HEIGHT).lineCount).toBe(2)
  })

  test('pre-wrap mode treats hard breaks as forced line boundaries', () => {
    const prepared = prepareWithSegments('a\nb', FONT, { whiteSpace: 'pre-wrap' })
    const lines = layoutWithLines(prepared, 200, LINE_HEIGHT)
    expect(lines.lines.map(line => line.text)).toEqual(['a', 'b'])
    expect(layout(prepared, 200, LINE_HEIGHT).lineCount).toBe(2)
  })

  test('pre-wrap mode treats tabs as hanging whitespace aligned to tab stops', () => {
    const prepared = prepareWithSegments('a\tb', FONT, { whiteSpace: 'pre-wrap' })
    const spaceWidth = measureWidth(' ', FONT)
    const prefixWidth = measureWidth('a', FONT)
    const tabAdvance = nextTabAdvance(prefixWidth, spaceWidth, 8)
    const textWidth = prefixWidth + tabAdvance + measureWidth('b', FONT)
    const width = textWidth - 0.1

    const lines = layoutWithLines(prepared, width, LINE_HEIGHT)
    expect(lines.lines.map(line => line.text)).toEqual(['a\t', 'b'])
    expect(layout(prepared, width, LINE_HEIGHT).lineCount).toBe(2)
  })

  test('pre-wrap mode treats consecutive tabs as distinct tab stops', () => {
    const prepared = prepareWithSegments('a\t\tb', FONT, { whiteSpace: 'pre-wrap' })
    const spaceWidth = measureWidth(' ', FONT)
    const prefixWidth = measureWidth('a', FONT)
    const firstTabAdvance = nextTabAdvance(prefixWidth, spaceWidth, 8)
    const afterFirstTab = prefixWidth + firstTabAdvance
    const secondTabAdvance = nextTabAdvance(afterFirstTab, spaceWidth, 8)
    const width = prefixWidth + firstTabAdvance + secondTabAdvance - 0.1

    const lines = layoutWithLines(prepared, width, LINE_HEIGHT)
    expect(lines.lines.map(line => line.text)).toEqual(['a\t\t', 'b'])
    expect(layout(prepared, width, LINE_HEIGHT).lineCount).toBe(2)
  })

  test('pre-wrap mode keeps whitespace-only middle lines visible', () => {
    const prepared = prepareWithSegments('foo\n  \nbar', FONT, { whiteSpace: 'pre-wrap' })
    const lines = layoutWithLines(prepared, 200, LINE_HEIGHT)
    expect(lines.lines.map(line => line.text)).toEqual(['foo', '  ', 'bar'])
    expect(layout(prepared, 200, LINE_HEIGHT)).toEqual({ lineCount: 3, height: LINE_HEIGHT * 3 })
  })

  test('pre-wrap mode keeps trailing spaces before a hard break on the current line', () => {
    const prepared = prepareWithSegments('foo  \nbar', FONT, { whiteSpace: 'pre-wrap' })
    const lines = layoutWithLines(prepared, 200, LINE_HEIGHT)
    expect(lines.lines.map(line => line.text)).toEqual(['foo  ', 'bar'])
    expect(layout(prepared, 200, LINE_HEIGHT)).toEqual({ lineCount: 2, height: LINE_HEIGHT * 2 })
  })

  test('pre-wrap mode keeps trailing tabs before a hard break on the current line', () => {
    const prepared = prepareWithSegments('foo\t\nbar', FONT, { whiteSpace: 'pre-wrap' })
    const lines = layoutWithLines(prepared, 200, LINE_HEIGHT)
    expect(lines.lines.map(line => line.text)).toEqual(['foo\t', 'bar'])
    expect(layout(prepared, 200, LINE_HEIGHT)).toEqual({ lineCount: 2, height: LINE_HEIGHT * 2 })
  })

  test('pre-wrap mode restarts tab stops after a hard break', () => {
    const prepared = prepareWithSegments('foo\n\tbar', FONT, { whiteSpace: 'pre-wrap' })
    const lines = layoutWithLines(prepared, 200, LINE_HEIGHT)
    const spaceWidth = measureWidth(' ', FONT)
    const expectedSecondLineWidth = nextTabAdvance(0, spaceWidth, 8) + measureWidth('bar', FONT)

    expect(lines.lines.map(line => line.text)).toEqual(['foo', '\tbar'])
    expect(lines.lines[1]!.width).toBeCloseTo(expectedSecondLineWidth, 5)
  })

  test('layoutNextLine stays aligned with layoutWithLines in pre-wrap mode', () => {
    const prepared = prepareWithSegments('foo\n  bar baz\nquux', FONT, { whiteSpace: 'pre-wrap' })
    const width = measureWidth('  bar', FONT) + 0.1
    const expected = layoutWithLines(prepared, width, LINE_HEIGHT)

    const actual = []
    let cursor = { segmentIndex: 0, graphemeIndex: 0 }
    while (true) {
      const line = layoutNextLine(prepared, cursor, width)
      if (line === null) break
      actual.push(line)
      cursor = line.end
    }

    expect(actual).toEqual(expected.lines)
  })

  test('pre-wrap mode keeps empty lines from consecutive hard breaks', () => {
    const prepared = prepareWithSegments('\n\n', FONT, { whiteSpace: 'pre-wrap' })
    const lines = layoutWithLines(prepared, 200, LINE_HEIGHT)
    expect(lines.lines.map(line => line.text)).toEqual(['', ''])
    expect(layout(prepared, 200, LINE_HEIGHT)).toEqual({ lineCount: 2, height: LINE_HEIGHT * 2 })
  })

  test('pre-wrap mode does not invent an extra trailing empty line', () => {
    const prepared = prepareWithSegments('a\n', FONT, { whiteSpace: 'pre-wrap' })
    const lines = layoutWithLines(prepared, 200, LINE_HEIGHT)
    expect(lines.lines.map(line => line.text)).toEqual(['a'])
    expect(layout(prepared, 200, LINE_HEIGHT)).toEqual({ lineCount: 1, height: LINE_HEIGHT })
  })

  test('overlong breakable segments wrap onto a fresh line when the current line already has content', () => {
    const prepared = prepareWithSegments('foo abcdefghijk', FONT)
    const prefixWidth = prepared.widths[0]! + prepared.widths[1]!
    const wordBreaks = prepared.breakableWidths[2]!
    const width = prefixWidth + wordBreaks[0]! + wordBreaks[1]! + 0.1

    const batched = layoutWithLines(prepared, width, LINE_HEIGHT)
    expect(batched.lines[0]?.text).toBe('foo ')
    expect(batched.lines[1]?.text.startsWith('ab')).toBe(true)

    const streamed = layoutNextLine(prepared, { segmentIndex: 0, graphemeIndex: 0 }, width)
    expect(streamed?.text).toBe('foo ')
    expect(layout(prepared, width, LINE_HEIGHT).lineCount).toBe(batched.lineCount)
  })

  test('walkLineRanges reproduces layoutWithLines geometry without materializing text', () => {
    const prepared = prepareWithSegments('foo trans\u00ADatlantic said "hello" to 世界 and waved.', FONT)
    const width = prepared.widths[0]! + prepared.widths[1]! + prepared.widths[2]! + prepared.breakableWidths[4]![0]! + prepared.discretionaryHyphenWidth + 0.1
    const expected = layoutWithLines(prepared, width, LINE_HEIGHT)
    const actual: Array<{
      width: number
      start: { segmentIndex: number, graphemeIndex: number }
      end: { segmentIndex: number, graphemeIndex: number }
    }> = []

    const lineCount = walkLineRanges(prepared, width, line => {
      actual.push({
        width: line.width,
        start: { ...line.start },
        end: { ...line.end },
      })
    })

    expect(lineCount).toBe(expected.lineCount)
    expect(actual).toEqual(expected.lines.map(line => ({
      width: line.width,
      start: line.start,
      end: line.end,
    })))
  })

  test('countPreparedLines stays aligned with the walked line counter', () => {
    const texts = [
      'The quick brown fox jumps over the lazy dog.',
      'said "hello" to 世界 and waved.',
      'مرحبا، عالم؟',
      'author 7:00-9:00 only',
      'alpha\u200Bbeta gamma',
    ]
    const widths = [40, 80, 120, 200]

    for (let textIndex = 0; textIndex < texts.length; textIndex++) {
      const prepared = prepareWithSegments(texts[textIndex]!, FONT)
      for (let widthIndex = 0; widthIndex < widths.length; widthIndex++) {
        const width = widths[widthIndex]!
        const counted = countPreparedLines(prepared, width)
        const walked = walkPreparedLines(prepared, width)
        expect(counted).toBe(walked)
      }
    }
  })
})

>sed -n '781,980p' src/layout.test.ts

Command: /bin/zsh -lc "sed -n '781,980p' src/layout.test.ts"
Chunk ID: d13340
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 0
Output:

>sed -n '1,220p' STATUS.md

Command: /bin/zsh -lc "sed -n '1,220p' STATUS.md"
Chunk ID: 7c09ea
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 721
Output:
# Current Status

Machine-readable current snapshot data for the main browser sweep and benchmark numbers lives in JSON.

Use this file for "where do I look right now?".
Use [RESEARCH.md](/Users/chenglou/github/pretext/RESEARCH.md) for why the numbers changed and what was tried.
Use [corpora/STATUS.md](/Users/chenglou/github/pretext/corpora/STATUS.md) for the long-form corpus canaries.

## Browser Accuracy

Machine-readable dashboard:
- [status/dashboard.json](/Users/chenglou/github/pretext/status/dashboard.json)

Raw snapshots:
- [accuracy/chrome.json](/Users/chenglou/github/pretext/accuracy/chrome.json)
- [accuracy/safari.json](/Users/chenglou/github/pretext/accuracy/safari.json)
- [accuracy/firefox.json](/Users/chenglou/github/pretext/accuracy/firefox.json)

Notes:
- This is the 4-font × 8-size × 8-width × 30-text browser corpus.
- The public accuracy page is effectively a regression gate now, not the main steering metric.

## Benchmark Snapshot

Machine-readable dashboard:
- [status/dashboard.json](/Users/chenglou/github/pretext/status/dashboard.json)

Raw snapshots:
- [benchmarks/chrome.json](/Users/chenglou/github/pretext/benchmarks/chrome.json)
- [benchmarks/safari.json](/Users/chenglou/github/pretext/benchmarks/safari.json)

Notes:
- Chrome remains the main maintained performance baseline. Safari snapshots are still useful, but they are noisier and warm up less predictably.
- The checked-in JSON snapshots are cold checker runs. Ad hoc page-driven numbers, especially in Safari, can differ after warmup.
- Refresh the benchmark JSON snapshots when a diff changes benchmark methodology or the text engine's hot path (`src/analysis.ts`, `src/measurement.ts`, `src/line-break.ts`, `src/layout.ts`, `src/bidi.ts`, or `pages/benchmark.ts`).
- `layout()` remains the resize hot path; `prepare()` is where script-specific cost still lives.
- Long-form corpus benchmark rows split `prepare()` into analysis and measurement phases, which helps separate segmentation/glue cost from raw width-measurement cost.

## Pointers

- Main dashboard summary: [status/dashboard.json](/Users/chenglou/github/pretext/status/dashboard.json)
- Accuracy snapshots: [accuracy/chrome.json](/Users/chenglou/github/pretext/accuracy/chrome.json), [accuracy/safari.json](/Users/chenglou/github/pretext/accuracy/safari.json), [accuracy/firefox.json](/Users/chenglou/github/pretext/accuracy/firefox.json)
- Benchmark snapshots: [benchmarks/chrome.json](/Users/chenglou/github/pretext/benchmarks/chrome.json), [benchmarks/safari.json](/Users/chenglou/github/pretext/benchmarks/safari.json)
- Corpus dashboard: [corpora/dashboard.json](/Users/chenglou/github/pretext/corpora/dashboard.json)
- Corpus anchor rows: [corpora/representative.json](/Users/chenglou/github/pretext/corpora/representative.json)
- Full exploration log: [RESEARCH.md](/Users/chenglou/github/pretext/RESEARCH.md)

>sed -n '1,220p' TODO.md

Command: /bin/zsh -lc "sed -n '1,220p' TODO.md"
Chunk ID: 0a53b0
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 695
Output:
Current priorities:

1. Keep the canaries honest

- Mixed app text still has the extractor-sensitive `710px` soft-hyphen miss.
- Chinese is still the clearest active CJK canary: Safari anchors are clean, while Chrome keeps a broader narrow-width positive field with real font sensitivity.
- Myanmar and Urdu remain useful shaping/context canaries, but they are not the active tuning target right now.

2. Next engine work

- Use the split `analyze()` / `measure()` benchmark rows to steer any remaining `prepare()` work instead of reopening generic profiling.
- Expand mixed app text only when it adds a real product-shaped class, e.g. URL/query runs, mixed bidi with numbers, emoji ZWJ runs, or `NBSP` / `ZWSP` / `WJ` behavior.
- Broaden canaries only when the source text is clean.
- If we add another Southeast Asian canary, prefer a clean source text that broadens the class instead of another wrapped/legal/raw-source artifact.
- Expand the sampled font matrix only where a canary still looks genuinely imperfect.
- Treat strongly font-sensitive or shaping-sensitive misses as boundary-finding for the current architecture, not automatic invitations for another local glue rule.
- Keep the hot `layout()` path simple and allocation-light while the rich path absorbs more userland layout needs.

3. Demo work

- Keep the editorial demos as the dogfood path for the rich line APIs.
- Prefer `layoutNextLine()` / `walkLineRanges()` when a demo is really about streaming or obstacle-aware layout.
- Add a new demo only if it exposes something the current editorial demos do not already cover.

Not worth doing right now:

- Do not chase universal exactness as the product claim.
- Do not put measurement back in `layout()`.
- Do not resurrect dirty corpora just to cover another language.
- Do not overfit one-line misses in one browser/corpus without broader evidence.
- Do not let browser-profile shims turn into a grab bag of ad hoc engine knobs.
- Do not explode the public API with cache or engine knobs.

Still-open design questions:

- Whether line-fit tolerance should stay as a browser shim or move toward runtime calibration.
- Whether `{ whiteSpace: 'pre-wrap' }` should grow beyond spaces / tabs / `\n`.
- Whether strong real-world demand for `system-ui` would justify a narrow prepare-time DOM fallback.
- Whether server canvas support should become an explicit supported backend.
- Whether automatic hyphenation beyond manual soft hyphen is in scope.
- Whether intrinsic sizing / logical width APIs are needed beyond fixed-width height prediction.
- Whether bidi rendering concerns like selection and copy/paste belong here or stay out of scope.
- Whether a separate optional slow verify path is worth having as a diagnostic mode, without contaminating `layout()`.

>git log --reverse --date=short --pretty=format:'%h %ad %s'

Command: /bin/zsh -lc "git log --reverse --date=short --pretty=format:'%h %ad %s'"
Chunk ID: 0e1cbf
Wall time: 0.0001 seconds
Process exited with code 0
Original token count: 4272
Output:
f962f72 2026-03-03 Initial project setup
f0f03ba 2026-03-03 Add oxlint config with type-aware linting
1d3941e 2026-03-03 Add accuracy sweep page
dfd40ed 2026-03-03 Add headless test suite with HarfBuzz measurement
d399fc4 2026-03-03 Add word-sum vs full-line accuracy test
0167c1e 2026-03-03 Fix HarfBuzz direction: explicit LTR for consistent measurement
820e8e1 2026-03-03 Add comments documenting motivations throughout
c78b35a 2026-03-03 Write README documenting problem, solution, perf, accuracy, i18n, limitations, how it works, what we tried and rejected, and credits
ead6bd7 2026-03-03 Update CLAUDE.md with test commands, file inventory, rejected approaches
a797983 2026-03-03 Remove serve.ts, use bun's direct HTML serving
61c1e25 2026-03-03 Add RESEARCH.md, consolidate docs, rename serve to start
73783d0 2026-03-03 Add line-break diagnostic, document Safari CSS behavior differences
f54a344 2026-03-03 Revert trailing space experiment — restore Chrome 99.4%
08a1404 2026-03-03 Document Safari CSS line-breaking differences in RESEARCH.md
e0837f6 2026-03-03 Update CLAUDE.md and README for fresh session handoff
91304c0 2026-03-03 Emoji correction, merging fix, overflow handling — Chrome 99.4% → 99.7%
6ce9982 2026-03-03 Kinsoku shori — CJK line-breaking rules, Chrome 99.7% → 99.9%
315658b 2026-03-03 Document cache design decision, slim down CLAUDE.md
e8de24c 2026-03-03 Fix prepare() perf regression: skip emoji grapheme scan for non-emoji text
ae466fa 2026-03-03 Hoist word segmenter to module level, add TODO section
aff5ba7 2026-03-03 Benchmark CJK scaling, cleanup for...of, --no-hmr, NaN guard
fee6750 2026-03-03 Opening bracket forward-merge, CSS config docs, Chrome 3838/3840
22a2f26 2026-03-03 Document word-sum divergence, revert failed fix attempts
e2f1321 2026-03-03 Document char-level experiment, prior art, fix text-layout repo URL
c48295a 2026-03-03 Document hybrid verify experiment (99.9% → 99.8%, reverted)
573b6db 2026-03-04 Fix emoji correction for Safari — compare canvas vs DOM, not fontSize
3fd4f01 2026-03-04 Document lineHeight default mismatch across browsers
71c0e58 2026-03-04 Document Firefox system-ui font mismatch and Thai segmenter divergence
1135318 2026-03-04 Add browser bug links to RESEARCH.md, update emoji correction docs
bad8fbc 2026-03-04 CJK-split all CJK segments, not just word-like — Firefox 99.7% → 99.9%
48116bd 2026-03-04 Add Firefox system-ui bug link to RESEARCH.md
038a812 2026-03-04 Add Chrome system-ui bug link to RESEARCH.md
5f76956 2026-03-04 Add Verdana and Courier New to accuracy sweep — 7677/7680 (99.96%)
b22efa0 2026-03-04 Show 2 decimal places for accuracy percentage
76c2766 2026-03-04 Update all docs for 4-font accuracy, clean up stale comments
7d0a54d 2026-03-04 Remove checked in chromium issue
5ecce72 2026-03-04 Simplify layout code: flatten data, remove dead computation, cut allocations
965a546 2026-03-04 Update RESEARCH.md with Firefox developer's DPR explanation
06cb7d0 2026-03-04 Add bubble shrinkwrap demo page
f99df17 2026-03-06 Remove interleaving demo stub
dbebb7d 2026-03-06 Clean up stale docs and unify test data
fea1fa7 2026-03-06 Split fast and rich layout APIs
0aca7b6 2026-03-06 Link system-ui warnings to RESEARCH.md exploration
7a4f827 2026-03-06 Make lineHeight an explicit layout-time input
9d37c3a 2026-03-07 Trim CLAUDE.md to internal notes
89ed442 2026-03-07 Document public layout data fields
71d5ff4 2026-03-07 Improve benchmark methodology for tiny layout timings
3eabf39 2026-03-07 TODOs and more use-cases
374aece 2026-03-07 Rename project from text-metrics to pretext
bf0741a 2026-03-07 Add unported ancestor ideas to notes
b1c4041 2026-03-07 Move harfbuzzjs from dependencies to devDependencies
81f7bf1 2026-03-07 Clarify break-word docs
31af255 2026-03-07 Clarify CSS config claim and server-side status, add TODOs
a724b7f 2026-03-07 Update benchmark snapshot
d07dd7a 2026-03-07 gatsby test: first pass
5cd5762 2026-03-07 Add Gatsby diagnostics without regressing hot-path layout
9af7f63 2026-03-07 Close the remaining browser accuracy gaps cheaply
8f4ac00 2026-03-07 Harden browser-accuracy diagnostics without slowing layout
3f9cb1e 2026-03-08 Separate prepare analysis from measurement
84cccc8 2026-03-08 Shrink permanent tests to exported invariants
7137f0a 2026-03-08 Add a fast Gatsby width sweep
dfd81ae 2026-03-08 Harden Gatsby sweep browser automation
06e6437 2026-03-08 Keep apostrophe-led elisions with the following word
c852293 2026-03-08 Simplify merged segmentation and CJK measurement
3202f3a 2026-03-08 Add multilingual corpus stress canaries
16c04fe 2026-03-08 Improve Arabic and Hindi corpus wrapping
516e5e6 2026-03-08 Make bun start clear stale port 3000 listeners
bba3624 2026-03-08 Benchmark long-form corpora alongside the shared corpus
cb0a76a 2026-03-08 Harden corpus mismatch diagnostics
7fb726d 2026-03-08 Fingerprint browser test environments and fix Korean quote wraps in Chromium
cdec07c 2026-03-08 Clean Arabic corpus artifacts and harden RTL diagnostics
bc031c3 2026-03-08 Document the rejected Arabic shaping experiments
e7b9cbe 2026-03-08 Expose logical break offsets in corpus diagnostics
52fcf70 2026-03-09 Add a single-snippet browser line-break probe
cd8b642 2026-03-09 Rename CLAUDE.md to AGENTS.md
d91a0af 2026-03-09 Merge Arabic no-space punctuation clusters
9612485 2026-03-09 Refine Arabic preprocessing around punctuation and marks
1495b5c 2026-03-09 Fix multilingual corpus diagnostics and clean Arabic source artifacts
09e6c03 2026-03-09 Clean remaining Arabic corpus punctuation artifacts
8aaf7b8 2026-03-09 Keep Arabic punctuation-plus-mark clusters with their word
49e0f36 2026-03-09 Loosen non-Safari edge tolerance for remaining Arabic fits
dcd410b 2026-03-09 Add Arabic and Hebrew stress corpora
30b1220 2026-03-09 Trim editorial noise from Hebrew stress corpus
9b59710 2026-03-09 Add sampled sweep mode for large corpora
4715123 2026-03-09 Add Thai stress corpus and fix ASCII quote wrapping
3e991df 2026-03-09 Share line breaking between layout APIs
d988bb0 2026-03-09 Keep layout on a specialized fast path
62b258a 2026-03-10 Strengthen break semantics beyond plain spaces
c340d09 2026-03-10 Cache richer segment metrics during prepare
d9f9873 2026-03-10 Model discretionary soft hyphen breaks
7995c72 2026-03-10 Add a mixed app-text canary and glue URL runs
86f741f 2026-03-10 Refine mixed app-text breaking and diagnostics
b7ec1a8 2026-03-10 Add a Khmer stress corpus and benchmark coverage
5e92358 2026-03-10 Make prepare() return an opaque handle
396caff 2026-03-10 Add corpus font-matrix checks and font overrides
ccec343 2026-03-10 Reject the Lao raw-law canary and add a clean Myanmar corpus
c9cbfca 2026-03-10 Tighten Myanmar punctuation glue and probe diagnostics
b6e2104 2026-03-10 Finish the Myanmar phrase-glue canary
b89a7fb 2026-03-10 Make layout imports safe outside the DOM
09a5f8c 2026-03-10 Give shared Safari automation its own window
c94b2ba 2026-03-10 Improve SHY diagnostics and line rendering
78a64be 2026-03-10 Add a second clean Thai stress corpus
115558d 2026-03-10 Document rejected Myanmar break experiments
1b32ece 2026-03-10 Add normalized slice mode to corpus diagnostics
7c37dfb 2026-03-10 Add a second Myanmar stress corpus
a87e756 2026-03-10 Add a compact corpus status snapshot
35d4ff8 2026-03-10 Separate current snapshots from historical notes
d8e7c64 2026-03-10 Refresh current snapshots and benchmark corpus rows
93b10a6 2026-03-10 Keep bidi metadata off the fast prepare path
830d8ad 2026-03-10 Add a Japanese prose canary and fix iteration marks
2c17aec 2026-03-10 Stop browser checkers from polling the active tab
0c30ea1 2026-03-10 Keep benchmark runs foregrounded
e30c04e 2026-03-10 Extract bidi logic from layout
da60460 2026-03-10 Split benchmark prepare timings by phase
c4cf982 2026-03-10 Split prepare internals and add a second Japanese canary
92b1192 2026-03-10 Turn the demo page into a manual line layout lab
f11f7e8 2026-03-10 Add an Urdu Nastaliq canary
a734f17 2026-03-10 Expose discretionary hyphen state to userland renderers
d782b14 2026-03-10 Add explicit locale control for text analysis
bc6174f 2026-03-10 Add a three-column userland reflow demo
614dfab 2026-03-10 Add a line-by-line reflow API and contour demo
4a6a457 2026-03-10 Add a Chinese long-form canary
a5f94ba 2026-03-10 Add a second Chinese prose canary
20134b9 2026-03-10 Serialize browser automation per engine
f06fb75 2026-03-10 Extract the internal line-break core
57964f9 2026-03-11 Add corpus taxonomy tooling
90f1624 2026-03-11 Add an editorial reflow demo and carry CJK opening punctuation
bd0be6f 2026-03-11 Expose the corpus taxonomy runner as a bun script
c9796c5 2026-03-11 Add a synced multi-view reflow demo
81526d3 2026-03-11 Highlight shared anchors across synced reflow panes
4e4f71e 2026-03-11 Dogfood layoutNextLine in the browser demos
3fa02c2 2026-03-11 Center the shared anchor in the sync demo
da88d5c 2026-03-11 Stream columns directly from layoutNextLine
cac7a1b 2026-03-11 Record rejected Chinese punctuation experiments
4526cde 2026-03-11 Add a winding-contour editorial demo
2a11156 2026-03-11 Rebuild Chronicle around an explicit render pass
f43a585 2026-03-11 Add a viewport-warped polygon blob lab
f472d70 2026-03-11 Simplify blob lab to tapered black silhouettes
a9652fd 2026-03-11 Add a batch low-level line geometry API
2be6a3a 2026-03-11 Add draft project notes
b2dc7c8 2026-03-11 Add a two-logo contour layout demo
84c0c96 2026-03-11 Tighten logo column contour spacing
f6fe933 2026-03-11 Refine the logo columns layout
a0bc8be 2026-03-11 Adapt the logo demo copy from Situational Awareness
4d4f561 2026-03-11 test
12daa0e 2026-03-11 Use full reload for the dev page server
a98fc00 2026-03-12 Make logo columns interaction geometry-driven
fd9e9d1 2026-03-12 Project logo columns through a DOM cache
28a24bd 2026-03-12 Tune logo columns for narrower spreads
b0f80c2 2026-03-12 Extract generic wrap geometry from logo columns
597500b 2026-03-12 Polish the logo columns editorial spread
cc6ee94 2026-03-12 Wait for logo hulls before first render
4bdf313 2026-03-12 Route the logo spread title around the logo geometry
87d509c 2026-03-12 Consolidate the editorial demos around dynamic layout
938e96f 2026-03-12 Document break-word behavior and trim dynamic layout overhead
c72a1c7 2026-03-12 Keep dynamic layout work in render
45679aa 2026-03-12 Make emoji correction lazy for plain text
b6ad165 2026-03-12 Quantize dynamic layout headline sizing
9de553c 2026-03-12 Make dynamic layout bootstrap explicit
be96850 2026-03-12 Flatten dynamic layout control loops
035bf7c 2026-03-12 Simplify polygon scanline intersections
20c270a 2026-03-12 Remove stale demos and restore text cursor
cdb56ab 2026-03-12 More public docs
cae482d 2026-03-12 Clarify rich bidi metadata and share diagnostics
4fdb790 2026-03-12 Refresh status docs and tighten stale comments
ee8ddac 2026-03-12 Clean up readmes
b4bdd1c 2026-03-17 Rewritten readme for public consumptions
335c2c7 2026-03-17 check in TODOs
656c910 2026-03-17 Fix stale README glossary and improve use-case 2 examples
bbc5fca 2026-03-17 Update bubbles demo
3e8352e 2026-03-20 Broaden internal CJK coverage
54d0206 2026-03-20 Document text-shaper comparison
40bd19f 2026-03-22 Move demos into pages/demos/, remove demo page
0a84e4b 2026-03-22 Add masonry demo: virtualized text layout with pretext
76f3864 2026-03-22 Masonry: 10k cards with array-based domCache
8b8a027 2026-03-23 Masonry: fix centering, proportional column widths, 10k cards
ffc2a75 2026-03-23 Masonry: add DOCTYPE, remove debug, fix virtualization
d346ba8 2026-03-23 Add LAN demo server script
837f080 2026-03-23 Add iOS Safari scroll crash repro demos
2fbae37 2026-03-23 Remove iOS Safari scroll crash repro demos
a0f7c66 2026-03-23 Clean up masonry demo control flow
06de9d7 2026-03-26 Simplify masonry DOM ownership
2823649 2026-03-26 Refresh benchmark snapshots and simplify rich line API
b11f2b2 2026-03-26 Add raw accuracy and corpus snapshots
bc8e0db 2026-03-26 Refine rich layout internals and docs
0662f0b 2026-03-26 Prepare npm package surface
d2ea9b2 2026-03-26 Fix Safari punctuation-chain wrapping
6b7b0e4 2026-03-26 Let overlong breakable segments fill the current line
7edfa07 2026-03-26 Clarify Safari extractor-sensitive diagnostics
3195cb3 2026-03-26 Tune Safari line breaking and add input-box demo
2aeecec 2026-03-27 Refresh snapshots and add changelog
4d3d184 2026-03-27 Document system-ui measurement conclusion
f787f34 2026-03-27 Replace input demo with accordion demo
2da7da3 2026-03-27 Polish bubbles demo and stabilize dev server
b7323f2 2026-03-27 Release 0.0.1
a7f6bab 2026-03-27 Tighten changelog wording
22d2fac 2026-03-27 Publish demos to GitHub Pages
e0a35de 2026-03-27 Fix Pages build on GitHub Actions
489e4b1 2026-03-27 Enable GitHub Pages from workflow
fc78d69 2026-03-27 Tighten bubbles demo copy
4bb6491 2026-03-27 Refresh bubbles demo conversation
7097a8e 2026-03-27 Add variable typographic ASCII demo
5d631d1 2026-03-27 Add wireframe torus demo
415f0a8 2026-03-27 Remove wireframe torus demo
0748356 2026-03-27 Add calligram engine demo
f144a8c 2026-03-27 Remove calligram engine demo
b01f83d 2026-03-27 Add editorial engine demo
2f2ef13 2026-03-27 Update demos index links and README
8257986 2026-03-27 Simplify bubbles startup and runtime
24ad012 2026-03-27 Fix dynamic layout assets and root demo links
cd04257 2026-03-27 Fix + add max' links
6b8d03a 2026-03-27 Update bubbles bidi example copy
cfdc371 2026-03-27 Add preserve-spaces whitespace mode
a28df8c 2026-03-27 Rewrite whitespace mode around pre-wrap chunks
784ee53 2026-03-27 Add pre-wrap oracle validation
98a1ad5 2026-03-27 Add tab stops to pre-wrap mode
8bd147d 2026-03-27 Broaden pre-wrap oracle coverage
0c3c8ce 2026-03-28 Add somnai attribution to demo pages
2fa99fa 2026-03-28 Simplify pre-wrap tabs and broaden coverage
bdb0f95 2026-03-28 Broaden pre-wrap newline coverage
a1ed28e 2026-03-28 Refresh benchmark snapshots for pre-wrap branch
d18bb75 2026-03-28 Restore simple layout fast path
38c7090 2026-03-28 Split simple rich line walking from pre-wrap path
44dc489 2026-03-28 Add checked-in rich path benchmarks
8e305a7 2026-03-28 Only compute prefix widths when the browser needs them
4c634ca 2026-03-28 Merge branch 'preserve-whitespace'
a06fc7f 2026-03-28 Allow selecting editorial demo text
9793990 2026-03-28 Release 0.0.2
2604c28 2026-03-28 Trim internal docs
9754408 2026-03-28 Remove bad link
ddce81e 2026-03-28 Bump dev deps and allow TypeScript 6
212113e 2026-03-28 Restore masonry text selection
e8b7ace 2026-03-28 Add rich text demo
4eeed18 2026-03-28 Improve dynamic layout mobile mode
9f75eba 2026-03-28 Improve editorial demo mobile mode
d79f0f7 2026-03-28 Remove *dev time* harfbuzz scripts so that X dummies don't think this is a harfbuzz wrapper
0363564 2026-03-28 Disable dynamic layout mobile rubber-banding
51b54f9 2026-03-28 Allow dynamic layout text selection on mobile
15f9db5 2026-03-28 Allow editorial text selection on mobile
1dda66b 2026-03-28 Refine editorial selection interaction state
75a6e48 2026-03-29 Publish built ESM package artifacts
4ec8481 2026-03-29 Merge PR #4 (superseded by final packaging implementation)
d618e84 2026-03-29 Consolidate development command docs
19451bc 2026-03-29 Release 0.0.3
53a065b 2026-03-29 Trim duplicated docs guidance
a8b8bfb 2026-03-29 Refresh TODO priorities
a61a101 2026-03-29 Expand TODO notes
92c51d4 2026-03-29 fix(demo): text deselection in demos by skipping unchanged textContent writes
0d6660e 2026-03-29 Preserve demo text DOM during selection
77dabd5 2026-03-29 Use spans for manual text lines
45e447b 2026-03-29 Inline prepare() vs layout() tip in README
04f7ac0 2026-03-29 Unify Firefox accuracy automation
049244d 2026-03-29 Batch corpus sweeps and simplify report transport
3ca1e6d 2026-03-29 Add posted reports for batched corpus sweeps
1fe1201 2026-03-29 Batch Gatsby sweeps in page
7aaff29 2026-03-29 Document batched sweep automation
25121a3 2026-03-29 Support even sampling in gatsby sweeps
ae99378 2026-03-29 Add phase-aware automation timeout diagnostics
588293c 2026-03-29 Batch corpus taxonomy automation
89cd7f6 2026-03-29 Document corpus taxonomy batching
b042fac 2026-03-30 refactor: split justification-comparison into .html + .ts
2558f05 2026-03-29 Merge pull request #26 from somnai-dreams/demo/justification-comparison-split
16e228d 2026-03-29 Add justification comparison demo to demos
12688f0 2026-03-29 Polish justification comparison demo
d5eac0b 2026-03-30 Refactor justification comparison demo
91d2f78 2026-03-30 Generate corpus status from sweep snapshots
d178a84 2026-03-30 Replace markdown status tables with JSON dashboards
39b38e5 2026-03-31 Add rich line round-trip invariants
325c0af 2026-03-31 Trim Gatsby round-trip diagnostics
b232ac2 2026-03-31 Sanitize masonry demo text artifacts
0f889e6 2026-03-31 Route Gatsby through corpus tooling and fix stale pending breaks
aaed2f7 2026-03-31 Normalize masonry demo dataset offline
a8d1e35 2026-03-31 Keep correctness browser automation in background

>sed -n '1,260p' CHANGELOG.md

Command: /bin/zsh -lc "sed -n '1,260p' CHANGELOG.md"
Chunk ID: 92c790
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 331
Output:
# Changelog

## Unreleased

## 0.0.3 - 2026-03-29

### Changed

- npm now publishes built ESM JavaScript from `dist/` instead of exposing raw TypeScript source as the package entrypoint.
- TypeScript consumers now pick up shipped declaration files automatically from the published package, while plain JavaScript consumers can install and import the package without relying on dependency-side TypeScript transpilation.

## 0.0.2 - 2026-03-28

### Added

- `{ whiteSpace: 'pre-wrap' }` mode for textarea-like text, preserving ordinary spaces, tabs, and hard breaks.

## 0.0.1 - 2026-03-27

### Changed

- Safari line breaking now has a clearer browser-specific policy path for narrow soft-hyphen and breakable-run cases.
- Browser tooling is more stable: fresh per-run page ports, diagnostics derived from the public rich layout API, and a non-watch `bun start` by default.

## 0.0.0 - 2026-03-26

Initial public npm release of `@chenglou/pretext`.

### Added

- `prepare()` and `layout()` as the core fast path for DOM-free multiline text height prediction.
- Rich layout APIs including `prepareWithSegments()`, `layoutWithLines()`, `layoutNextLine()`, and `walkLineRanges()` for custom rendering and manual layout.
- Browser accuracy, benchmark, and corpus tooling with checked-in snapshots and representative canaries.

>git log --date=short --pretty=format:'%ad %h %s' -- src/layout.ts src/analysis.ts src/line-break.ts src/measurement.ts src/bidi.ts | head -n 120

Command: /bin/zsh -lc "git log --date=short --pretty=format:'%ad %h %s' -- src/layout.ts src/analysis.ts src/line-break.ts src/measurement.ts src/bidi.ts | head -n 120"
Chunk ID: 2df792
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1326
Output:
2026-03-31 0f889e6 Route Gatsby through corpus tooling and fix stale pending breaks
2026-03-31 39b38e5 Add rich line round-trip invariants
2026-03-29 75a6e48 Publish built ESM package artifacts
2026-03-28 8e305a7 Only compute prefix widths when the browser needs them
2026-03-28 38c7090 Split simple rich line walking from pre-wrap path
2026-03-28 d18bb75 Restore simple layout fast path
2026-03-28 2fa99fa Simplify pre-wrap tabs and broaden coverage
2026-03-27 98a1ad5 Add tab stops to pre-wrap mode
2026-03-27 a28df8c Rewrite whitespace mode around pre-wrap chunks
2026-03-27 cfdc371 Add preserve-spaces whitespace mode
2026-03-26 3195cb3 Tune Safari line breaking and add input-box demo
2026-03-26 6b7b0e4 Let overlong breakable segments fill the current line
2026-03-26 d2ea9b2 Fix Safari punctuation-chain wrapping
2026-03-26 bc8e0db Refine rich layout internals and docs
2026-03-26 2823649 Refresh benchmark snapshots and simplify rich line API
2026-03-20 3e8352e Broaden internal CJK coverage
2026-03-12 4fdb790 Refresh status docs and tighten stale comments
2026-03-12 cae482d Clarify rich bidi metadata and share diagnostics
2026-03-12 45679aa Make emoji correction lazy for plain text
2026-03-11 a9652fd Add a batch low-level line geometry API
2026-03-11 90f1624 Add an editorial reflow demo and carry CJK opening punctuation
2026-03-11 57964f9 Add corpus taxonomy tooling
2026-03-10 f06fb75 Extract the internal line-break core
2026-03-10 614dfab Add a line-by-line reflow API and contour demo
2026-03-10 d782b14 Add explicit locale control for text analysis
2026-03-10 a734f17 Expose discretionary hyphen state to userland renderers
2026-03-10 c4cf982 Split prepare internals and add a second Japanese canary
2026-03-10 da60460 Split benchmark prepare timings by phase
2026-03-10 e30c04e Extract bidi logic from layout
2026-03-10 830d8ad Add a Japanese prose canary and fix iteration marks
2026-03-10 93b10a6 Keep bidi metadata off the fast prepare path
2026-03-10 c94b2ba Improve SHY diagnostics and line rendering
2026-03-10 b89a7fb Make layout imports safe outside the DOM
2026-03-10 b6e2104 Finish the Myanmar phrase-glue canary
2026-03-10 c9cbfca Tighten Myanmar punctuation glue and probe diagnostics
2026-03-10 5e92358 Make prepare() return an opaque handle
2026-03-10 86f741f Refine mixed app-text breaking and diagnostics
2026-03-10 7995c72 Add a mixed app-text canary and glue URL runs
2026-03-10 d9f9873 Model discretionary soft hyphen breaks
2026-03-10 c340d09 Cache richer segment metrics during prepare
2026-03-10 62b258a Strengthen break semantics beyond plain spaces
2026-03-09 d988bb0 Keep layout on a specialized fast path
2026-03-09 3e991df Share line breaking between layout APIs
2026-03-09 4715123 Add Thai stress corpus and fix ASCII quote wrapping
2026-03-09 49e0f36 Loosen non-Safari edge tolerance for remaining Arabic fits
2026-03-09 8aaf7b8 Keep Arabic punctuation-plus-mark clusters with their word
2026-03-09 9612485 Refine Arabic preprocessing around punctuation and marks
2026-03-09 d91a0af Merge Arabic no-space punctuation clusters
2026-03-08 7fb726d Fingerprint browser test environments and fix Korean quote wraps in Chromium
2026-03-08 16c04fe Improve Arabic and Hindi corpus wrapping
2026-03-08 c852293 Simplify merged segmentation and CJK measurement
2026-03-08 06e6437 Keep apostrophe-led elisions with the following word
2026-03-08 3f9cb1e Separate prepare analysis from measurement
2026-03-07 8f4ac00 Harden browser-accuracy diagnostics without slowing layout
2026-03-07 9af7f63 Close the remaining browser accuracy gaps cheaply
2026-03-07 5cd5762 Add Gatsby diagnostics without regressing hot-path layout
2026-03-07 d07dd7a gatsby test: first pass
2026-03-07 89ed442 Document public layout data fields
2026-03-06 7a4f827 Make lineHeight an explicit layout-time input
2026-03-06 0aca7b6 Link system-ui warnings to RESEARCH.md exploration
2026-03-06 fea1fa7 Split fast and rich layout APIs
2026-03-06 dbebb7d Clean up stale docs and unify test data
2026-03-04 5ecce72 Simplify layout code: flatten data, remove dead computation, cut allocations
2026-03-04 76c2766 Update all docs for 4-font accuracy, clean up stale comments
2026-03-04 bad8fbc CJK-split all CJK segments, not just word-like — Firefox 99.7% → 99.9%
2026-03-04 573b6db Fix emoji correction for Safari — compare canvas vs DOM, not fontSize
2026-03-03 e2f1321 Document char-level experiment, prior art, fix text-layout repo URL
2026-03-03 fee6750 Opening bracket forward-merge, CSS config docs, Chrome 3838/3840
2026-03-03 aff5ba7 Benchmark CJK scaling, cleanup for...of, --no-hmr, NaN guard
2026-03-03 ae466fa Hoist word segmenter to module level, add TODO section
2026-03-03 e8de24c Fix prepare() perf regression: skip emoji grapheme scan for non-emoji text
2026-03-03 315658b Document cache design decision, slim down CLAUDE.md
2026-03-03 6ce9982 Kinsoku shori — CJK line-breaking rules, Chrome 99.7% → 99.9%
2026-03-03 91304c0 Emoji correction, merging fix, overflow handling — Chrome 99.4% → 99.7%
2026-03-03 f54a344 Revert trailing space experiment — restore Chrome 99.4%
2026-03-03 73783d0 Add line-break diagnostic, document Safari CSS behavior differences
2026-03-03 820e8e1 Add comments documenting motivations throughout
2026-03-03 f962f72 Initial project setup

>git shortlog -sne

Command: /bin/zsh -lc 'git shortlog -sne'
Chunk ID: 1afbba
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 0
Output:

>wc -l pages/benchmark.ts pages/accuracy.ts pages/probe.ts pages/diagnostic-utils.ts scripts/browser-automation.ts scripts/accuracy-check.ts scripts/benchmark-check.ts scripts/corpus-check.ts pages/demos/editorial-engine.ts pages/demos/dynamic-layout.ts pages/demos/wrap-geometry.ts pages/demos/masonry/index.ts pages/demos/rich-note.ts pages/demos/justification-comparison.ts

Command: /bin/zsh -lc 'wc -l pages/benchmark.ts pages/accuracy.ts pages/probe.ts pages/diagnostic-utils.ts scripts/browser-automation.ts scripts/accuracy-check.ts scripts/benchmark-check.ts scripts/corpus-check.ts pages/demos/editorial-engine.ts pages/demos/dynamic-layout.ts pages/demos/wrap-geometry.ts pages/demos/masonry/index.ts pages/demos/rich-note.ts pages/demos/justification-comparison.ts'
Chunk ID: 961e4b
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 128
Output:
     672 pages/benchmark.ts
     372 pages/accuracy.ts
     497 pages/probe.ts
      74 pages/diagnostic-utils.ts
     698 scripts/browser-automation.ts
     259 scripts/accuracy-check.ts
     136 scripts/benchmark-check.ts
     338 scripts/corpus-check.ts
     968 pages/demos/editorial-engine.ts
     922 pages/demos/dynamic-layout.ts
     328 pages/demos/wrap-geometry.ts
     161 pages/demos/masonry/index.ts
     424 pages/demos/rich-note.ts
      77 pages/demos/justification-comparison.ts
    5926 total

>sed -n '1,260p' pages/benchmark.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/benchmark.ts"
Chunk ID: 9ba28d
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1977
Output:
import {
  prepare,
  prepareWithSegments,
  layout,
  layoutNextLine,
  layoutWithLines,
  walkLineRanges,
  clearCache,
  profilePrepare,
} from '../src/layout.ts'
import type { PreparedText, PreparedTextWithSegments } from '../src/layout.ts'
import { TEXTS } from '../src/test-data.ts'
import {
  clearNavigationReport,
  publishNavigationPhase,
  publishNavigationReport as publishHashReport,
} from './report-utils.ts'
import arRisalatAlGhufranPart1 from '../corpora/ar-risalat-al-ghufran-part-1.txt' with { type: 'text' }
import hiEidgah from '../corpora/hi-eidgah.txt' with { type: 'text' }
import jaKumoNoIto from '../corpora/ja-kumo-no-ito.txt' with { type: 'text' }
import jaRashomon from '../corpora/ja-rashomon.txt' with { type: 'text' }
import kmPrachumReuangPrengKhmerVolume7Stories1To10 from '../corpora/km-prachum-reuang-preng-khmer-volume-7-stories-1-10.txt' with { type: 'text' }
import myBadDeedsReturnToYouTeacher from '../corpora/my-bad-deeds-return-to-you-teacher.txt' with { type: 'text' }
import myCunningHeronTeacher from '../corpora/my-cunning-heron-teacher.txt' with { type: 'text' }
import koUnsuJohEunNal from '../corpora/ko-unsu-joh-eun-nal.txt' with { type: 'text' }
import thNithanVetalStory1 from '../corpora/th-nithan-vetal-story-1.txt' with { type: 'text' }
import urChughd from '../corpora/ur-chughd.txt' with { type: 'text' }
import zhGuxiang from '../corpora/zh-guxiang.txt' with { type: 'text' }
import zhZhufu from '../corpora/zh-zhufu.txt' with { type: 'text' }

const COUNT = 500
const FONT_FAMILY = '"Helvetica Neue", Helvetica, Arial, sans-serif'
const FONT_SIZE = 16
const FONT = `${FONT_SIZE}px ${FONT_FAMILY}`
const LINE_HEIGHT = Math.round(FONT_SIZE * 1.2)
const WIDTH_BEFORE = 400
const WIDTH_AFTER = 300
const WARMUP = 2
const RUNS = 10
const PREPARE_SAMPLE_REPEATS = 1
const LAYOUT_SAMPLE_REPEATS = 200
const LAYOUT_SAMPLE_WIDTHS = [200, 250, 300, 350, 400] as const
const DOM_BATCH_SAMPLE_REPEATS = 1
const DOM_INTERLEAVED_SAMPLE_REPEATS = 1
const RICH_COUNT = 60
const RICH_LAYOUT_SAMPLE_REPEATS = 40
const RICH_LAYOUT_SAMPLE_WIDTHS = [180, 220, 260] as const
const RICH_LONG_REPEAT = 8
const RICH_LONG_SAMPLE_WIDTHS = [240, 300, 360] as const
const CORPUS_LAYOUT_SAMPLE_REPEATS = 200
const CORPUS_WARMUP = 1
const CORPUS_RUNS = 7

type BenchmarkResult = { label: string, ms: number, desc: string }
type CorpusBenchmarkResult = {
  id: string
  label: string
  font: string
  chars: number
  analysisSegments: number
  segments: number
  breakableSegments: number
  width: number
  lineCount: number
  analysisMs: number
  measureMs: number
  prepareMs: number
  layoutMs: number
}

type BenchmarkReport = {
  status: 'ready' | 'error'
  requestId?: string
  results?: BenchmarkResult[]
  richResults?: BenchmarkResult[]
  richLongResults?: BenchmarkResult[]
  corpusResults?: CorpusBenchmarkResult[]
  message?: string
}

const params = new URLSearchParams(location.search)
const reportMode = params.get('report') === '1'
const requestId = params.get('requestId') ?? undefined

const CORPORA = [
  {
    id: 'ja-kumo-no-ito',
    label: 'Japanese prose (story 2)',
    text: jaKumoNoIto,
    font: '20px "Hiragino Mincho ProN", "Yu Mincho", "Noto Serif CJK JP", serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'ja-rashomon',
    label: 'Japanese prose',
    text: jaRashomon,
    font: '20px "Hiragino Mincho ProN", "Yu Mincho", "Noto Serif CJK JP", serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'ko-unsu-joh-eun-nal',
    label: 'Korean prose',
    text: koUnsuJohEunNal,
    font: '18px "Apple SD Gothic Neo", "Malgun Gothic", "Noto Sans CJK KR", sans-serif',
    lineHeight: 30,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'zh-zhufu',
    label: 'Chinese prose',
    text: zhZhufu,
    font: '20px "Songti SC", "PingFang SC", "Noto Serif CJK SC", serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'zh-guxiang',
    label: 'Chinese prose (story 2)',
    text: zhGuxiang,
    font: '20px "Songti SC", "PingFang SC", "Noto Serif CJK SC", serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'th-nithan-vetal-story-1',
    label: 'Thai prose',
    text: thNithanVetalStory1,
    font: '20px "Thonburi", "Noto Sans Thai", sans-serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'my-cunning-heron-teacher',
    label: 'Myanmar prose',
    text: myCunningHeronTeacher,
    font: '20px "Myanmar MN", "Myanmar Sangam MN", "Noto Sans Myanmar", serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'my-bad-deeds-return-to-you-teacher',
    label: 'Myanmar prose (story 2)',
    text: myBadDeedsReturnToYouTeacher,
    font: '20px "Myanmar MN", "Myanmar Sangam MN", "Noto Sans Myanmar", serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'ur-chughd',
    label: 'Urdu prose',
    text: urChughd,
    font: '20px "Noto Nastaliq Urdu", "DecoType Nastaleeq Urdu UI", "Geeza Pro", serif',
    lineHeight: 38,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'km-prachum-reuang-preng-khmer-volume-7-stories-1-10',
    label: 'Khmer prose',
    text: kmPrachumReuangPrengKhmerVolume7Stories1To10,
    font: '20px "Khmer Sangam MN", "Khmer MN", "Noto Sans Khmer", serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'hi-eidgah',
    label: 'Hindi prose',
    text: hiEidgah,
    font: '20px "Kohinoor Devanagari", "Noto Serif Devanagari", serif',
    lineHeight: 32,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
  {
    id: 'ar-risalat-al-ghufran-part-1',
    label: 'Arabic prose',
    text: arRisalatAlGhufranPart1,
    font: '20px "Geeza Pro", "Noto Naskh Arabic", "Arial", serif',
    lineHeight: 34,
    width: 300,
    sampleWidths: [240, 300, 360] as const,
  },
] as const

// Filter edge cases — not realistic comments
const commentTexts = TEXTS.filter(t => t.text.trim().length > 1)
const texts: string[] = []
for (let i = 0; i < COUNT; i++) {
  texts.push(commentTexts[i % commentTexts.length]!.text)
}

declare global {
  interface Window {
    __BENCHMARK_REPORT__?: BenchmarkReport
  }
}

function median(times: number[]): number {
  const sorted = [...times].sort((a, b) => a - b)
  const mid = Math.floor(sorted.length / 2)
  return sorted.length % 2 === 0 ? (sorted[mid - 1]! + sorted[mid]!) / 2 : sorted[mid]!
}

function bench(
  fn: (repeatIndex: number) => void,
  sampleRepeats = 1,
  warmup = WARMUP,
  runs = RUNS,
): number {
  function runRepeated(): void {
    for (let r = 0; r < sampleRepeats; r++) {
      fn(r)
    }
  }

  for (let i = 0; i < warmup; i++) runRepeated()
  const times: number[] = []
  for (let i = 0; i < runs; i++) {
    const t0 = performance.now()
    runRepeated()
    times.push((performance.now() - t0) / sampleRepeats)
  }
  return median(times)
}

// Yield to let the browser paint status updates
function nextFrame(): Promise<void> {
  return new Promise(resolve => { requestAnimationFrame(() => { resolve() }) })
}

function withRequestId<T extends BenchmarkReport>(report: T): BenchmarkReport {
  return requestId === undefined ? report : { ...report, requestId }
}

function publishNavigationReport(report: BenchmarkReport): void {
  if (!reportMode) return
  publishHashReport(report)
}

function setReport(report: BenchmarkReport): void {
  window.__BENCHMARK_REPORT__ = report
  publishNavigationReport(report)
}

function buildCorpusBenchmarks(): CorpusBenchmarkResult[] {
  const corpusResults: CorpusBenchmarkResult[] = []
  let corpusLayoutSink = 0

  for (const corpus of CORPORA) {

>sed -n '1,260p' pages/accuracy.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/accuracy.ts"
Chunk ID: cf9d46
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1930
Output:
import {
  clearCache,
  layout,
  layoutWithLines,
  prepareWithSegments,
  type PreparedTextWithSegments,
} from '../src/layout.ts'
import { getDiagnosticUnits } from './diagnostic-utils.ts'
import { clearNavigationReport, publishNavigationPhase, publishNavigationReport } from './report-utils.ts'
import { TEXTS, SIZES, WIDTHS } from '../src/test-data.ts'

const FONTS = [
  '"Helvetica Neue", Helvetica, Arial, sans-serif',
  'Georgia, "Times New Roman", serif',
  'Verdana, Geneva, sans-serif',
  '"Courier New", Courier, monospace',
]

type Mismatch = {
  label: string
  font: string
  fontSize: number
  lineHeight: number
  width: number
  actual: number
  predicted: number
  diff: number
  text: string
  diagnosticLines?: string[]
}

type AccuracyRow = {
  label: string
  font: string
  fontSize: number
  lineHeight: number
  width: number
  actual: number
  predicted: number
  diff: number
}

type AccuracyReport = {
  status: 'ready' | 'error'
  requestId?: string
  environment?: EnvironmentFingerprint
  total?: number
  matchCount?: number
  mismatchCount?: number
  mismatches?: Mismatch[]
  rows?: AccuracyRow[]
  message?: string
}

type AccuracyNavigationReport = {
  status: 'ready' | 'error'
  requestId?: string
  total?: number
  matchCount?: number
  mismatchCount?: number
  message?: string
}

type EnvironmentFingerprint = {
  userAgent: string
  devicePixelRatio: number
  viewport: {
    innerWidth: number
    innerHeight: number
    outerWidth: number
    outerHeight: number
    visualViewportScale: number | null
  }
  screen: {
    width: number
    height: number
    availWidth: number
    availHeight: number
    colorDepth: number
    pixelDepth: number
  }
}

declare global {
  interface Window {
    __ACCURACY_REPORT__?: AccuracyReport
  }
}

const params = new URLSearchParams(location.search)
const requestId = params.get('requestId') ?? undefined
const includeFullRows = params.get('full') === '1'
const reportEndpoint = params.get('reportEndpoint')

function withRequestId<T extends AccuracyReport>(report: T): AccuracyReport {
  return requestId === undefined ? report : { ...report, requestId }
}

function getEnvironmentFingerprint(): EnvironmentFingerprint {
  return {
    userAgent: navigator.userAgent,
    devicePixelRatio: window.devicePixelRatio,
    viewport: {
      innerWidth: window.innerWidth,
      innerHeight: window.innerHeight,
      outerWidth: window.outerWidth,
      outerHeight: window.outerHeight,
      visualViewportScale: window.visualViewport?.scale ?? null,
    },
    screen: {
      width: window.screen.width,
      height: window.screen.height,
      availWidth: window.screen.availWidth,
      availHeight: window.screen.availHeight,
      colorDepth: window.screen.colorDepth,
      pixelDepth: window.screen.pixelDepth,
    },
  }
}

function publishReport(report: AccuracyReport): void {
  const reportJson = JSON.stringify(report)
  window.__ACCURACY_REPORT__ = report
  if (reportEndpoint !== null) {
    publishNavigationPhase('posting', requestId)
    void (async () => {
      try {
        await fetch(reportEndpoint, {
          method: 'POST',
          body: reportJson,
        })
        publishNavigationReport(toNavigationReport(report))
      } catch {
        // Best-effort side channel for large reports.
      }
    })()
    return
  }
  publishNavigationReport(toNavigationReport(report))
}

function toNavigationReport(report: AccuracyReport): AccuracyNavigationReport {
  if (report.status === 'error') {
    return {
      status: report.status,
      ...(report.requestId === undefined ? {} : { requestId: report.requestId }),
      ...(report.message === undefined ? {} : { message: report.message }),
    }
  }

  return {
    status: report.status,
    ...(report.requestId === undefined ? {} : { requestId: report.requestId }),
    ...(report.total === undefined ? {} : { total: report.total }),
    ...(report.matchCount === undefined ? {} : { matchCount: report.matchCount }),
    ...(report.mismatchCount === undefined ? {} : { mismatchCount: report.mismatchCount }),
  }
}
function getBrowserLines(
  prepared: PreparedTextWithSegments,
  div: HTMLDivElement,
): string[] {
  const textNode = div.firstChild
  if (!(textNode instanceof Text)) return []

  const units = getDiagnosticUnits(prepared)
  const range = document.createRange()
  const browserLines: string[] = []
  let currentLine = ''
  let lastTop: number | null = null

  for (const unit of units) {
    range.setStart(textNode, unit.start)
    range.setEnd(textNode, unit.end)
    const rects = range.getClientRects()
    const rectTop: number | null = rects.length > 0 ? rects[0]!.top : lastTop

    if (rectTop !== null && lastTop !== null && rectTop > lastTop + 0.5) {
      browserLines.push(currentLine)
      currentLine = unit.text
    } else {
      currentLine += unit.text
    }

    if (rectTop !== null) lastTop = rectTop
  }

  if (currentLine) browserLines.push(currentLine)
  return browserLines
}

function runSweep(): { total: number, mismatches: Mismatch[], rows: AccuracyRow[] } {
  const container = document.createElement('div')
  container.style.cssText = 'position:absolute;top:-9999px;left:-9999px;visibility:hidden'
  document.body.appendChild(container)

  const mismatches: Mismatch[] = []
  const rows: AccuracyRow[] = []
  let total = 0

  for (const fontFamily of FONTS) {
    for (const fontSize of SIZES) {
      const font = `${fontSize}px ${fontFamily}`
      const lineHeight = Math.round(fontSize * 1.2)
      clearCache()

      for (const maxWidth of WIDTHS) {
        const divs: HTMLDivElement[] = []
        const prepared: PreparedTextWithSegments[] = []

        for (const { text } of TEXTS) {
          const div = document.createElement('div')
          div.style.font = font
          div.style.lineHeight = `${lineHeight}px`
          div.style.width = `${maxWidth}px`
          div.style.wordWrap = 'break-word'
          div.style.overflowWrap = 'break-word'
          div.textContent = text
          container.appendChild(div)
          divs.push(div)
          prepared.push(prepareWithSegments(text, font))
        }

        for (let i = 0; i < TEXTS.length; i++) {
          const { label, text } = TEXTS[i]!
          const actual = divs[i]!.getBoundingClientRect().height
          const predicted = layout(prepared[i]!, maxWidth, lineHeight).height
          rows.push({
            label,
            font: fontFamily,
            fontSize,
            lineHeight,
            width: maxWidth,
            actual,
            predicted,
            diff: predicted - actual,
          })
          total++
          if (Math.abs(actual - predicted) >= 1) {
            const browserLines = getBrowserLines(prepared[i]!, divs[i]!)
            const ourLayout = layoutWithLines(prepared[i]!, maxWidth, lineHeight)

            const lineDetails: string[] = []
            const maxLines = Math.max(browserLines.length, ourLayout.lines.length)
            for (let li = 0; li < maxLines; li++) {
              const ours = (ourLayout.lines[li]?.text ?? '').trimEnd()
              const theirs = (browserLines[li] ?? '').trimEnd()
              if (ours !== theirs) {
                lineDetails.push(`L${li+1} ours="${ours.slice(0,40)}" browser="${theirs.slice(0,40)}"`)
              }
            }
            if (lineDetails.length === 0 && browserLines.length !== ourLayout.lines.length) {
              lineDetails.push(`ours=${ourLayout.lines.length}L browser=${browserLines.length}L (same content, different count?)`)
            }

            mismatches.push({
              label,
              font: fontFamily,
              fontSize,
              lineHeight,

>sed -n '1,260p' pages/diagnostic-utils.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/diagnostic-utils.ts"
Chunk ID: b98ae5
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 551
Output:
import type { PreparedTextWithSegments } from '../src/layout.ts'

export type DiagnosticUnit = {
  text: string
  start: number
  end: number
}

const diagnosticGraphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })

export function getDiagnosticUnits(prepared: PreparedTextWithSegments): DiagnosticUnit[] {
  const units: DiagnosticUnit[] = []
  let offset = 0

  for (let i = 0; i < prepared.segments.length; i++) {
    const segment = prepared.segments[i]!
    if (prepared.breakableWidths[i] !== null) {
      let localOffset = 0
      for (const grapheme of diagnosticGraphemeSegmenter.segment(segment)) {
        const start = offset + localOffset
        localOffset += grapheme.segment.length
        units.push({ text: grapheme.segment, start, end: offset + localOffset })
      }
    } else {
      units.push({ text: segment, start: offset, end: offset + segment.length })
    }
    offset += segment.length
  }

  return units
}

export function getLineContent(text: string, end: number): { text: string, end: number } {
  const trimmed = text.trimEnd()
  return {
    text: trimmed,
    end: end - (text.length - trimmed.length),
  }
}

export function formatBreakContext(text: string, breakOffset: number, radius = 32): string {
  const start = Math.max(0, breakOffset - radius)
  const end = Math.min(text.length, breakOffset + radius)
  return `${start > 0 ? '…' : ''}${text.slice(start, breakOffset)}|${text.slice(breakOffset, end)}${end < text.length ? '…' : ''}`
}

export function measureCanvasTextWidth(
  ctx: CanvasRenderingContext2D,
  text: string,
  font: string,
): number {
  ctx.font = font
  return ctx.measureText(text).width
}

export function measureDomTextWidth(
  doc: Document,
  text: string,
  font: string,
  direction: string,
): number {
  const span = doc.createElement('span')
  span.style.position = 'absolute'
  span.style.visibility = 'hidden'
  span.style.whiteSpace = 'pre'
  span.style.font = font
  span.style.direction = direction
  span.style.unicodeBidi = 'plaintext'
  span.textContent = text
  doc.body.appendChild(span)
  const width = span.getBoundingClientRect().width
  doc.body.removeChild(span)
  return width
}

>sed -n '1,260p' scripts/browser-automation.ts

Command: /bin/zsh -lc "sed -n '1,260p' scripts/browser-automation.ts"
Chunk ID: 78bd98
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1682
Output:
import { execFileSync, spawn, type ChildProcess } from 'node:child_process'
import { closeSync, mkdirSync, mkdtempSync, openSync, readFileSync, rmSync, writeFileSync } from 'node:fs'
import { createConnection, createServer as createNetServer } from 'node:net'
import { tmpdir } from 'node:os'
import { join } from 'node:path'
import { readNavigationPhaseState, readNavigationReportText, type NavigationPhase } from '../shared/navigation-state.ts'

export type BrowserKind = 'chrome' | 'safari' | 'firefox'
export type AutomationBrowserKind = BrowserKind

type MaybePromise<T> = T | Promise<T>

export type BrowserSession = {
  navigate: (url: string) => MaybePromise<void>
  readLocationUrl: () => MaybePromise<string>
  close: () => void
}

export type BrowserSessionOptions = {
  foreground?: boolean
}

export type PageServer = {
  baseUrl: string
  process: ChildProcess | null
}

export type BrowserAutomationLock = {
  release: () => void
}

function runAppleScript(lines: string[]): string {
  return execFileSync(
    'osascript',
    lines.flatMap(line => ['-e', line]),
    { encoding: 'utf8' },
  ).trim()
}

function getFrontmostApplicationName(): string | null {
  try {
    return runAppleScript([
      'tell application "System Events"',
      'return name of first application process whose frontmost is true',
      'end tell',
    ])
  } catch {
    return null
  }
}

function restoreFrontmostApplication(name: string | null): void {
  if (name === null || name.length === 0) return
  try {
    runAppleScript([`tell application ${JSON.stringify(name)} to activate`])
  } catch {
    // Best effort restore only.
  }
}

function runBackgroundAppleScript(lines: string[]): string {
  const frontmost = getFrontmostApplicationName()
  try {
    return runAppleScript(lines)
  } finally {
    restoreFrontmostApplication(frontmost)
  }
}

export function sleep(ms: number): Promise<void> {
  return new Promise(resolve => setTimeout(resolve, ms))
}

async function waitForPort(port: number): Promise<void> {
  for (let i = 0; i < 200; i++) {
    const open = await new Promise<boolean>(resolve => {
      const socket = createConnection({ host: '127.0.0.1', port })
      let settled = false

      const finish = (value: boolean): void => {
        if (settled) return
        settled = true
        socket.destroy()
        resolve(value)
      }

      socket.once('connect', () => finish(true))
      socket.once('error', () => finish(false))
    })
    if (open) return
    await sleep(100)
  }
  throw new Error(`Timed out waiting for local port ${port}`)
}

export async function getAvailablePort(requestedPort: number | null = null): Promise<number> {
  if (requestedPort !== null && Number.isFinite(requestedPort) && requestedPort > 0) {
    return requestedPort
  }

  return await new Promise((resolve, reject) => {
    const server = createNetServer()
    server.once('error', reject)
    server.listen(0, '127.0.0.1', () => {
      const address = server.address()
      if (address === null || typeof address === 'string') {
        reject(new Error('Failed to allocate a free port'))
        return
      }

      const { port } = address
      server.close(error => {
        if (error) {
          reject(error)
          return
        }
        resolve(port)
      })
    })
  })
}

const LOCK_DIR = join(process.env['TMPDIR'] ?? '/tmp', 'pretext-browser-automation-locks')

type LockMetadata = {
  pid: number
  startedAt: number
}

function readLockMetadata(lockPath: string): LockMetadata | null {
  try {
    const raw = readFileSync(lockPath, 'utf8')
    const parsed = JSON.parse(raw) as Partial<LockMetadata>
    if (
      typeof parsed.pid !== 'number' ||
      !Number.isInteger(parsed.pid) ||
      parsed.pid <= 0 ||
      typeof parsed.startedAt !== 'number'
    ) {
      return null
    }
    return {
      pid: parsed.pid,
      startedAt: parsed.startedAt,
    }
  } catch {
    return null
  }
}

function isProcessAlive(pid: number): boolean {
  try {
    process.kill(pid, 0)
    return true
  } catch (error) {
    if (
      error instanceof Error &&
      'code' in error &&
      error.code === 'EPERM'
    ) {
      return true
    }
    return false
  }
}

export async function acquireBrowserAutomationLock(
  browser: AutomationBrowserKind,
  timeoutMs = 120_000,
): Promise<BrowserAutomationLock> {
  mkdirSync(LOCK_DIR, { recursive: true })
  const lockPath = join(LOCK_DIR, `${browser}.lock`)
  const start = Date.now()

  while (true) {
    try {
      const fd = openSync(lockPath, 'wx')
      writeFileSync(fd, JSON.stringify({
        pid: process.pid,
        startedAt: Date.now(),
      }))
      let released = false
      return {
        release() {
          if (released) return
          released = true
          try {
            closeSync(fd)
          } catch {
            // Ignore close races during teardown.
          }
          try {
            rmSync(lockPath)
          } catch {
            // Best effort cleanup.
          }
        },
      }
    } catch (error) {
      if (!(error instanceof Error) || !String(error).includes('EEXIST')) throw error
      const metadata = readLockMetadata(lockPath)
      if (metadata !== null && !isProcessAlive(metadata.pid)) {
        try {
          rmSync(lockPath)
          continue
        } catch {
          // Another process may have replaced or removed it. Retry normally.
        }
      }
      if (Date.now() - start >= timeoutMs) {
        throw new Error(`Timed out waiting for ${browser} automation lock`)
      }
      await sleep(250)
    }
  }
}

async function canReachUrl(url: string): Promise<boolean> {
  try {
    const response = await fetch(url)
    return response.ok
  } catch {
    return false
  }
}

const LOOPBACK_BASES = [
  'http://127.0.0.1',
  'http://localhost',
  'http://[::1]',
]

async function resolveBaseUrl(port: number, pathname: string): Promise<string | null> {
  for (const base of LOOPBACK_BASES) {
    const url = `${base}:${port}${pathname}`
    if (await canReachUrl(url)) {
      return `${base}:${port}`
    }
  }
  return null
}

function getTimeoutMessage(
  browser: BrowserKind,
  target: 'report' | 'posted report',
  lastPhase: NavigationPhase | null,
): string {
  if (lastPhase === null) {
    return `Timed out waiting for ${target} from ${browser}`
  }
  return `Timed out waiting for ${target} from ${browser} (last phase: ${lastPhase})`
}

async function readLastNavigationPhase(
  session: BrowserSession,
  expectedRequestId: string,
): Promise<NavigationPhase | null> {
  const currentUrl = await session.readLocationUrl()
  const phaseState = readNavigationPhaseState(currentUrl)
  if (phaseState === null) return null

>sed -n '261,520p' scripts/browser-automation.ts

Command: /bin/zsh -lc "sed -n '261,520p' scripts/browser-automation.ts"
Chunk ID: fd09bc
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1949
Output:
  if (phaseState.requestId !== undefined && phaseState.requestId !== expectedRequestId) {
    return null
  }
  return phaseState.phase
}

type BidiResponse = {
  id: number
  result?: unknown
  error?: string
  message?: string
  type?: string
}

type FirefoxBidiClient = {
  send: (method: string, params?: Record<string, unknown>) => Promise<BidiResponse>
  close: () => void
}

type FirefoxSessionState = {
  bidi: FirefoxBidiClient
  context: string
  firefoxProcess: ChildProcess
  profileDir: string
}

async function connectFirefoxBidi(port: number): Promise<FirefoxBidiClient> {
  const ws = new WebSocket(`ws://127.0.0.1:${port}/session`)
  const pending = new Map<number, (message: BidiResponse) => void>()
  let nextId = 1

  ws.onmessage = event => {
    const message = JSON.parse(String(event.data)) as BidiResponse
    if (message.id === undefined) return
    const resolve = pending.get(message.id)
    if (resolve !== undefined) {
      pending.delete(message.id)
      resolve(message)
    }
  }

  await new Promise<void>((resolve, reject) => {
    ws.onopen = () => resolve()
    ws.onerror = event => reject(new Error(String((event as ErrorEvent).message ?? 'Firefox WebSocket error')))
  })

  return {
    async send(method: string, params: Record<string, unknown> = {}): Promise<BidiResponse> {
      const id = nextId++
      ws.send(JSON.stringify({ id, method, params }))
      return await new Promise<BidiResponse>(resolve => pending.set(id, resolve))
    },
    close() {
      ws.close()
    },
  }
}

function getBidiStringValue(response: BidiResponse): string {
  const remoteResult = response.result as {
    type?: string
    result?: {
      type?: string
      value?: unknown
    }
  } | undefined

  const value = remoteResult?.result?.value
  return typeof value === 'string' ? value : ''
}

function closeFirefoxSessionState(state: FirefoxSessionState): void {
  state.bidi.close()
  try {
    state.firefoxProcess.kill('SIGTERM')
  } catch {
    // Best effort cleanup.
  }
  rmSync(state.profileDir, { recursive: true, force: true })
}

async function initializeFirefoxSession(): Promise<FirefoxSessionState> {
  const bidiPort = await getAvailablePort()
  const profileDir = mkdtempSync(join(tmpdir(), 'pretext-firefox-'))
  const firefoxProcess = spawn('/Applications/Firefox.app/Contents/MacOS/firefox', [
    '--headless',
    '--new-instance',
    '--profile',
    profileDir,
    '--remote-debugging-port',
    String(bidiPort),
    'about:blank',
  ], {
    cwd: process.cwd(),
    stdio: 'ignore',
  })

  let bidi: FirefoxBidiClient | null = null

  try {
    await waitForPort(bidiPort)
    bidi = await connectFirefoxBidi(bidiPort)

    const session = await bidi.send('session.new', { capabilities: { alwaysMatch: {} } })
    if (session.error !== undefined) {
      throw new Error(session.message ?? session.error)
    }

    const tree = await bidi.send('browsingContext.getTree', {})
    if (tree.error !== undefined) {
      throw new Error(tree.message ?? tree.error)
    }

    const contexts = (tree.result as { contexts: Array<{ context: string }> }).contexts
    const context = contexts[0]?.context
    if (context === undefined) {
      throw new Error('Firefox BiDi returned no browsing context')
    }

    return {
      bidi,
      context,
      firefoxProcess,
      profileDir,
    }
  } catch (error) {
    bidi?.close()
    try {
      firefoxProcess.kill('SIGTERM')
    } catch {
      // Best effort cleanup.
    }
    rmSync(profileDir, { recursive: true, force: true })
    throw error
  }
}

function createSafariSession(options: BrowserSessionOptions): BrowserSession {
  const scriptLines = ['tell application "Safari"']

  if (options.foreground === true) {
    scriptLines.unshift('tell application "Safari" to activate')
  }

  scriptLines.push('set targetDocument to make new document with properties {URL:"about:blank"}')
  if (options.foreground === true) {
    scriptLines.push('set targetWindow to front window')
    scriptLines.push('set index of targetWindow to 1')
  }
  scriptLines.push('return id of front window as string')
  scriptLines.push('end tell')

  const windowIdRaw = options.foreground === true ? runAppleScript(scriptLines) : runBackgroundAppleScript(scriptLines)

  const windowId = Number.parseInt(windowIdRaw, 10)
  if (!Number.isFinite(windowId)) {
    throw new Error(`Failed to create Safari automation window: ${windowIdRaw}`)
  }

  return {
    navigate(url) {
      const navigateLines = [
        'tell application "Safari"',
        `set targetWindow to first window whose id is ${windowId}`,
      ]
      if (options.foreground === true) {
        navigateLines.unshift('tell application "Safari" to activate')
        navigateLines.push('set index of targetWindow to 1')
      }
      navigateLines.push(`set URL of current tab of targetWindow to ${JSON.stringify(url)}`)
      navigateLines.push('end tell')
      if (options.foreground === true) {
        runAppleScript(navigateLines)
      } else {
        runBackgroundAppleScript(navigateLines)
      }
    },
    readLocationUrl() {
      try {
        return runAppleScript([
          'tell application "Safari"',
          `return URL of current tab of (first window whose id is ${windowId})`,
          'end tell',
        ])
      } catch {
        return ''
      }
    },
    close() {
      try {
        runAppleScript([
          'tell application "Safari"',
          `close (first window whose id is ${windowId})`,
          'end tell',
        ])
      } catch {
        // Ignore cleanup failures if the user already closed the window.
      }
    },
  }
}

function createChromeSession(options: BrowserSessionOptions): BrowserSession {
  const scriptLines = [
    'tell application "Google Chrome"',
    'if (count of windows) = 0 then make new window',
    'set targetWindow to front window',
    'set targetTab to make new tab at end of tabs of targetWindow with properties {URL:"about:blank"}',
  ]

  if (options.foreground === true) {
    scriptLines.splice(1, 0, 'activate')
    scriptLines.push('set active tab index of targetWindow to (count of tabs of targetWindow)')
  }

  scriptLines.push('return (id of targetWindow as string) & "," & (id of targetTab as string)')
  scriptLines.push('end tell')

  const identifiers = options.foreground === true ? runAppleScript(scriptLines) : runBackgroundAppleScript(scriptLines)

  const [windowIdRaw, tabIdRaw] = identifiers.split(',')
  const windowId = Number.parseInt(windowIdRaw ?? '', 10)
  const tabId = Number.parseInt(tabIdRaw ?? '', 10)
  if (!Number.isFinite(windowId) || !Number.isFinite(tabId)) {
    throw new Error(`Failed to create Chrome automation tab: ${identifiers}`)
  }

  return {
    navigate(url) {
      const navigateLines = [
        'tell application "Google Chrome"',
        `set targetWindow to first window whose id is ${windowId}`,
        `set URL of (first tab of targetWindow whose id is ${tabId}) to ${JSON.stringify(url)}`,
        'end tell',
      ]
      if (options.foreground === true) {
        runAppleScript(navigateLines)
      } else {
        runBackgroundAppleScript(navigateLines)
      }
    },
    readLocationUrl() {
      try {
        return runAppleScript([
          'tell application "Google Chrome"',
          `set targetWindow to first window whose id is ${windowId}`,
          `return URL of (first tab of targetWindow whose id is ${tabId})`,
          'end tell',
        ])
      } catch {
        return ''
      }
    },
    close() {
      try {
        runAppleScript([
          'tell application "Google Chrome"',
          `set targetWindow to first window whose id is ${windowId}`,
          `close (first tab of targetWindow whose id is ${tabId})`,
          'end tell',

>sed -n '1,260p' scripts/corpus-check.ts

Command: /bin/zsh -lc "sed -n '1,260p' scripts/corpus-check.ts"
Chunk ID: 580d14
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2181
Output:
import { type ChildProcess } from 'node:child_process'
import {
  acquireBrowserAutomationLock,
  createBrowserSession,
  ensurePageServer,
  getAvailablePort,
  loadHashReport,
  type BrowserKind,
} from './browser-automation.ts'

type CorpusMeta = {
  id: string
  language: string
  title: string
  min_width?: number
  max_width?: number
  default_width?: number
}

type CorpusOverrideOptions = {
  font: string | null
  lineHeight: number | null
  method: 'span' | 'range' | null
  sliceStart: number | null
  sliceEnd: number | null
}

type CorpusReport = {
  status: 'ready' | 'error'
  requestId?: string
  environment?: {
    userAgent: string
    devicePixelRatio: number
    viewport: {
      innerWidth: number
      innerHeight: number
      outerWidth: number
      outerHeight: number
      visualViewportScale: number | null
    }
    screen: {
      width: number
      height: number
      availWidth: number
      availHeight: number
      colorDepth: number
      pixelDepth: number
    }
  }
  corpusId?: string
  sliceStart?: number | null
  sliceEnd?: number | null
  title?: string
  width?: number
  predictedHeight?: number
  actualHeight?: number
  diffPx?: number
  predictedLineCount?: number
  browserLineCount?: number
  browserLineMethod?: 'span-probe' | 'range'
  alternateBrowserLineMethod?: 'span-probe' | 'range'
  alternateBrowserLineCount?: number
  probeHeight?: number
  normalizedHeight?: number
  mismatchCount?: number
  firstMismatch?: {
    line: number
    ours: string
    browser: string
  } | null
  firstBreakMismatch?: {
    line: number
    oursStart: number
    browserStart: number
    oursEnd: number
    browserEnd: number
    oursText: string
    browserText: string
    oursRenderedText: string
    browserRenderedText: string
    oursContext: string
    browserContext: string
    deltaText: string
    reasonGuess: string
    oursSumWidth: number
    oursDomWidth: number
    oursFullWidth: number
    browserDomWidth: number
    browserFullWidth: number
    oursSegments: Array<{
      text: string
      width: number
      domWidth: number
      isSpace: boolean
    }>
  } | null
  alternateFirstBreakMismatch?: object | null
  extractorSensitivity?: string | null
  maxLineWidthDrift?: number
  maxDriftLine?: {
    line: number
    drift: number
    text: string
    sumWidth: number
    fullWidth: number
    domWidth: number
    pairAdjustedWidth: number
    segments: Array<{
      text: string
      width: number
      domWidth: number
      isSpace: boolean
    }>
  } | null
  message?: string
}

function parseStringFlag(name: string): string | null {
  const prefix = `--${name}=`
  const arg = process.argv.find(value => value.startsWith(prefix))
  return arg === undefined ? null : arg.slice(prefix.length)
}

function parseNumberFlag(name: string, fallback: number): number {
  const raw = parseStringFlag(name)
  if (raw === null) return fallback
  const parsed = Number.parseInt(raw, 10)
  if (!Number.isFinite(parsed)) {
    throw new Error(`Invalid value for --${name}: ${raw}`)
  }
  return parsed
}

function parseBrowser(value: string | null): BrowserKind {
  const browser = (value ?? process.env['CORPUS_CHECK_BROWSER'] ?? 'chrome').toLowerCase()
  if (browser !== 'chrome' && browser !== 'safari') {
    throw new Error(`Unsupported browser ${browser}; expected chrome or safari`)
  }
  return browser
}

function parseOptionalNumberFlag(name: string): number | null {
  const raw = parseStringFlag(name)
  if (raw === null) return null
  const parsed = Number.parseInt(raw, 10)
  if (!Number.isFinite(parsed)) {
    throw new Error(`Invalid value for --${name}: ${raw}`)
  }
  return parsed
}

function hasFlag(name: string): boolean {
  return process.argv.includes(`--${name}`)
}

async function loadSources(): Promise<CorpusMeta[]> {
  return await Bun.file('corpora/sources.json').json()
}

function getTargetWidths(meta: CorpusMeta): number[] {
  const widths = process.argv.slice(2)
    .filter(arg => !arg.startsWith('--'))
    .map(arg => Number.parseInt(arg, 10))
    .filter(width => Number.isFinite(width))

  if (widths.length > 0) return widths

  const min = meta.min_width ?? 300
  const max = meta.max_width ?? 900
  const preferred = [min, Math.max(min, Math.min(max, meta.default_width ?? 600)), max]
  return [...new Set(preferred)]
}

function appendOverrideParams(url: string, overrides: CorpusOverrideOptions): string {
  let nextUrl = url
  if (overrides.font !== null) {
    nextUrl += `&font=${encodeURIComponent(overrides.font)}`
  }
  if (overrides.lineHeight !== null) {
    nextUrl += `&lineHeight=${overrides.lineHeight}`
  }
  if (overrides.method !== null) {
    nextUrl += `&method=${encodeURIComponent(overrides.method)}`
  }
  if (overrides.sliceStart !== null) {
    nextUrl += `&sliceStart=${overrides.sliceStart}`
  }
  if (overrides.sliceEnd !== null) {
    nextUrl += `&sliceEnd=${overrides.sliceEnd}`
  }
  return nextUrl
}

function printReport(report: CorpusReport): void {
  if (report.status === 'error') {
    console.log(`error: ${report.message ?? 'unknown error'}`)
    return
  }

  const width = report.width ?? 0
  const diff = Math.round(report.diffPx ?? 0)
  const predicted = Math.round(report.predictedHeight ?? 0)
  const actual = Math.round(report.actualHeight ?? 0)
  const lines = report.predictedLineCount !== undefined && report.browserLineCount !== undefined
    ? `${report.predictedLineCount}/${report.browserLineCount}`
    : '-'

  console.log(
    `width ${width}: diff ${diff > 0 ? '+' : ''}${diff}px | height ${predicted}/${actual} | lines ${lines}`,
  )
  if (report.sliceStart !== undefined || report.sliceEnd !== undefined) {
    console.log(`  slice: ${report.sliceStart ?? 0}-${report.sliceEnd ?? '-'}`)
  }
  if (report.maxLineWidthDrift !== undefined) {
    console.log(`  max line width drift: ${report.maxLineWidthDrift.toFixed(3)}px`)
  }
  if (report.environment !== undefined) {
    const env = report.environment
    console.log(
      `  env: dpr ${env.devicePixelRatio} | viewport ${env.viewport.innerWidth}x${env.viewport.innerHeight} | outer ${env.viewport.outerWidth}x${env.viewport.outerHeight} | scale ${env.viewport.visualViewportScale ?? '-'} | screen ${env.screen.width}x${env.screen.height}`,
    )
  }
  if (report.probeHeight !== undefined || report.normalizedHeight !== undefined) {
    console.log(
      `  probe heights: probe ${Math.round(report.probeHeight ?? 0)}px | normalized ${Math.round(report.normalizedHeight ?? 0)}px | book ${actual}px | method ${report.browserLineMethod ?? '-'}`,
    )
  }
  if (report.extractorSensitivity !== null && report.extractorSensitivity !== undefined) {
    console.log(`  extractor sensitivity: ${report.extractorSensitivity}`)
  }
  if (
    report.alternateBrowserLineMethod !== undefined &&
    report.alternateBrowserLineCount !== undefined
  ) {
    console.log(
      `  alternate method: ${report.alternateBrowserLineMethod} (${report.predictedLineCount ?? '-'}${report.alternateBrowserLineCount !== undefined ? `/${report.alternateBrowserLineCount}` : ''} lines)` +
      (report.alternateFirstBreakMismatch === null ? ' exact' : ''),
    )
  }
  if (report.maxDriftLine !== null && report.maxDriftLine !== undefined) {
    console.log(
      `  drift sample L${report.maxDriftLine.line}: ${report.maxDriftLine.drift.toFixed(3)}px (${report.maxDriftLine.sumWidth.toFixed(3)} sum vs ${report.maxDriftLine.fullWidth.toFixed(3)} full vs ${report.maxDriftLine.domWidth.toFixed(3)} dom vs ${report.maxDriftLine.pairAdjustedWidth.toFixed(3)} pair)`,
    )
    console.log(`  text: ${JSON.stringify(report.maxDriftLine.text.slice(0, 140))}`)
    if (report.maxDriftLine.segments.length > 0) {
      const summary = report.maxDriftLine.segments
        .map(segment => `${JSON.stringify(segment.text)}@${segment.width.toFixed(2)}/${segment.domWidth.toFixed(2)}${segment.isSpace ? ':space' : ''}`)
        .join(' | ')
      console.log(`  segments: ${summary}`)
    }
  }
  if (report.firstBreakMismatch !== null && report.firstBreakMismatch !== undefined) {
    const mismatch = report.firstBreakMismatch
    console.log(`  break L${mismatch.line}: ${mismatch.reasonGuess}`)
    console.log(`  offsets: ours ${mismatch.oursStart}-${mismatch.oursEnd} | browser ${mismatch.browserStart}-${mismatch.browserEnd}`)
    console.log(`  delta: ${JSON.stringify(mismatch.deltaText)}`)
    console.log(`  ours text:    ${JSON.stringify(mismatch.oursText)}`)
    console.log(`  browser text: ${JSON.stringify(mismatch.browserText)}`)
    console.log(`  ours rendered:    ${JSON.stringify(mismatch.oursRenderedText)}`)
    console.log(`  browser rendered: ${JSON.stringify(mismatch.browserRenderedText)}`)

>sed -n '1,260p' pages/probe.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/probe.ts"
Chunk ID: c73c92
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1924
Output:
import {
  layout,
  layoutWithLines,
  prepareWithSegments,
  type PreparedTextWithSegments,
} from '../src/layout.ts'
import {
  formatBreakContext,
  getDiagnosticUnits,
  getLineContent,
  measureCanvasTextWidth,
  measureDomTextWidth,
} from './diagnostic-utils.ts'
import { clearNavigationReport, publishNavigationPhase, publishNavigationReport } from './report-utils.ts'

type ProbeLine = {
  text: string
  renderedText: string
  contentText: string
  start: number
  end: number
  contentEnd: number
  fullWidth: number
  domWidth: number
  sumWidth?: number
}

type ProbeBreakMismatch = {
  line: number
  oursStart: number
  browserStart: number
  oursEnd: number
  browserEnd: number
  oursText: string
  browserText: string
  oursRenderedText: string
  browserRenderedText: string
  oursContext: string
  browserContext: string
  deltaText: string
  reasonGuess: string
  oursSumWidth: number
  oursDomWidth: number
  oursFullWidth: number
  browserDomWidth: number
  browserFullWidth: number
}

type ProbeLineSummary = {
  line: number
  text: string
  renderedText: string
  start: number
  end: number
}

type ProbeReport = {
  status: 'ready' | 'error'
  requestId?: string
  text?: string
  whiteSpace?: 'normal' | 'pre-wrap'
  width?: number
  contentWidth?: number
  font?: string
  lineHeight?: number
  direction?: string
  browserLineMethod?: 'range' | 'span'
  predictedHeight?: number
  actualHeight?: number
  diffPx?: number
  predictedLineCount?: number
  browserLineCount?: number
  firstBreakMismatch?: ProbeBreakMismatch | null
  alternateBrowserLineMethod?: 'range' | 'span'
  alternateBrowserLineCount?: number
  alternateFirstBreakMismatch?: ProbeBreakMismatch | null
  extractorSensitivity?: string | null
  ourLines?: ProbeLineSummary[]
  browserLines?: ProbeLineSummary[]
  alternateBrowserLines?: ProbeLineSummary[]
  message?: string
}

declare global {
  interface Window {
    __PROBE_REPORT__?: ProbeReport
  }
}

const PADDING = 40
const params = new URLSearchParams(location.search)
const requestId = params.get('requestId') ?? undefined
const text = params.get('text') ?? ''
const width = Math.max(100, Number.parseInt(params.get('width') ?? '600', 10))
const font = params.get('font') ?? '18px serif'
const lineHeight = Math.max(1, Number.parseInt(params.get('lineHeight') ?? '32', 10))
const direction = params.get('dir') === 'rtl' ? 'rtl' : 'ltr'
const lang = params.get('lang') ?? (direction === 'rtl' ? 'ar' : 'en')
const browserLineMethod = params.get('method') === 'span' ? 'span' : 'range'
const verbose = params.get('verbose') === '1'
const whiteSpace = params.get('whiteSpace') === 'pre-wrap' ? 'pre-wrap' : 'normal'
const cssWhiteSpace = whiteSpace === 'pre-wrap' ? 'pre-wrap' : 'normal'

const stats = document.getElementById('stats')!
const book = document.getElementById('book')!

const diagnosticDiv = document.createElement('div')
diagnosticDiv.style.position = 'absolute'
diagnosticDiv.style.top = '-99999px'
diagnosticDiv.style.left = '-99999px'
diagnosticDiv.style.visibility = 'hidden'
diagnosticDiv.style.pointerEvents = 'none'
diagnosticDiv.style.boxSizing = 'border-box'
diagnosticDiv.style.whiteSpace = cssWhiteSpace
diagnosticDiv.style.wordWrap = 'break-word'
diagnosticDiv.style.overflowWrap = 'break-word'
diagnosticDiv.style.padding = `${PADDING}px`
document.body.appendChild(diagnosticDiv)

const diagnosticCanvas = document.createElement('canvas')
const diagnosticCtx = diagnosticCanvas.getContext('2d')!
const graphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })

function withRequestId<T extends ProbeReport>(report: T): ProbeReport {
  return requestId === undefined ? report : { ...report, requestId }
}

function publishReport(report: ProbeReport): void {
  window.__PROBE_REPORT__ = report
  publishNavigationReport(report)
}

function setError(message: string): void {
  stats.textContent = `Error: ${message}`
  publishReport(withRequestId({ status: 'error', message }))
}

function getBrowserLinesFromSpans(prepared: PreparedTextWithSegments, measuredFont: string, dir: string): ProbeLine[] {
  const lines: ProbeLine[] = []
  const units = getDiagnosticUnits(prepared)
  const spans: HTMLSpanElement[] = []
  let currentLine = ''
  let currentStart: number | null = null
  let currentEnd = 0
  let lastTop: number | null = null

  diagnosticDiv.textContent = ''
  for (const unit of units) {
    const span = document.createElement('span')
    span.textContent = unit.text
    diagnosticDiv.appendChild(span)
    spans.push(span)
  }

  function pushLine(): void {
    if (currentStart === null || currentLine.length === 0) return
    const content = getLineContent(currentLine, currentEnd)
    lines.push({
      text: currentLine,
      renderedText: currentLine,
      contentText: content.text,
      start: currentStart,
      end: currentEnd,
      contentEnd: content.end,
      fullWidth: measureCanvasTextWidth(diagnosticCtx, content.text, measuredFont),
      domWidth: measureDomTextWidth(document, content.text, measuredFont, dir),
    })
  }

  for (let i = 0; i < units.length; i++) {
    const unit = units[i]!
    const span = spans[i]!
    const rect = span.getBoundingClientRect()
    const top: number | null = rect.width > 0 || rect.height > 0 ? rect.top : lastTop

    if (top !== null && lastTop !== null && top > lastTop + 0.5) {
      pushLine()
      currentLine = unit.text
      currentStart = unit.start
      currentEnd = unit.end
    } else {
      if (currentStart === null) currentStart = unit.start
      currentLine += unit.text
      currentEnd = unit.end
    }

    if (top !== null) lastTop = top
  }

  pushLine()
  diagnosticDiv.textContent = text
  return lines
}

function getBrowserLines(
  prepared: PreparedTextWithSegments,
  measuredFont: string,
  dir: string,
  method: 'range' | 'span',
): ProbeLine[] {
  return method === 'span'
    ? getBrowserLinesFromSpans(prepared, measuredFont, dir)
    : getBrowserLinesFromRange(prepared, measuredFont, dir)
}

function getBrowserLinesFromRange(prepared: PreparedTextWithSegments, measuredFont: string, dir: string): ProbeLine[] {
  const textNode = diagnosticDiv.firstChild
  const lines: ProbeLine[] = []
  if (!(textNode instanceof Text)) return lines

  const units = getDiagnosticUnits(prepared)
  const range = document.createRange()
  let currentLine = ''
  let currentStart: number | null = null
  let currentEnd = 0
  let lastTop: number | null = null

  function pushLine(): void {
    if (currentStart === null || currentLine.length === 0) return
    const content = getLineContent(currentLine, currentEnd)
    lines.push({
      text: currentLine,
      renderedText: currentLine,
      contentText: content.text,
      start: currentStart,
      end: currentEnd,
      contentEnd: content.end,
      fullWidth: measureCanvasTextWidth(diagnosticCtx, content.text, measuredFont),
      domWidth: measureDomTextWidth(document, content.text, measuredFont, dir),
    })
  }

  for (const unit of units) {
    range.setStart(textNode, unit.start)
    range.setEnd(textNode, unit.end)
    const rects = range.getClientRects()
    const top: number | null = rects.length > 0 ? rects[0]!.top : lastTop

    if (top !== null && lastTop !== null && top > lastTop + 0.5) {
      pushLine()
      currentLine = unit.text
      currentStart = unit.start
      currentEnd = unit.end
    } else {
      if (currentStart === null) currentStart = unit.start
      currentLine += unit.text
      currentEnd = unit.end
    }

    if (top !== null) lastTop = top
  }

  pushLine()
  return lines
}

function measurePreparedSlice(
  prepared: PreparedTextWithSegments,
  start: number,
  end: number,

>rg -n "prepare|layoutWithLines|layoutNextLine|walkLineRanges|prepareWithSegments|walkPreparedLines|wrapGeometry|cursor|virtual|masonry|balance|justify" pages/demos pages/*.ts

Command: /bin/zsh -lc 'rg -n "prepare|layoutWithLines|layoutNextLine|walkLineRanges|prepareWithSegments|walkPreparedLines|wrapGeometry|cursor|virtual|masonry|balance|justify" pages/demos pages/*.ts'
Chunk ID: 595917
Wall time: 0.0001 seconds
Process exited with code 0
Original token count: 69674
Output:
Total output lines: 311

pages/diagnostic-utils.ts:11:export function getDiagnosticUnits(prepared: PreparedTextWithSegments): DiagnosticUnit[] {
pages/diagnostic-utils.ts:15:  for (let i = 0; i < prepared.segments.length; i++) {
pages/diagnostic-utils.ts:16:    const segment = prepared.segments[i]!
pages/diagnostic-utils.ts:17:    if (prepared.breakableWidths[i] !== null) {
pages/gatsby.ts:3:  layoutWithLines,
pages/gatsby.ts:4:  prepareWithSegments,
pages/gatsby.ts:209:const prepared = prepareWithSegments(text, FONT)
pages/gatsby.ts:210:const segmentSpans = buildSegmentSpans(prepared)
pages/gatsby.ts:303:function buildSegmentSpans(preparedText: PreparedTextWithSegments): SegmentSpan[] {
pages/gatsby.ts:307:  for (let i = 0; i < preparedText.segments.length; i++) {
pages/gatsby.ts:308:    const segText = preparedText.segments[i]!
pages/gatsby.ts:316:      width: preparedText.widths[i]!,
pages/gatsby.ts:317:      isSpace: preparedText.kinds[i] === 'space',
pages/gatsby.ts:318:      breakable: preparedText.breakableWidths[i] !== null,
pages/gatsby.ts:424:  preparedText: PreparedTextWithSegments,
pages/gatsby.ts:431:  const units = getDiagnosticUnits(preparedText)
pages/gatsby.ts:485:  preparedText: PreparedTextWithSegments,
pages/gatsby.ts:488:  const layoutLines = layoutWithLines(preparedText, maxWidth, LINE_HEIGHT).lines
pages/gatsby.ts:615:  const ourLines = getOurLines(prepared, contentWidth)
pages/gatsby.ts:616:  const browserLines = getBrowserLines(prepared, diagnosticDiv)
pages/gatsby.ts:659:  const predicted = layout(prepared, contentWidth, LINE_HEIGHT)
pages/benchmark.ts:2:  prepare,
pages/benchmark.ts:3:  prepareWithSegments,
pages/benchmark.ts:5:  layoutNextLine,
pages/benchmark.ts:6:  layoutWithLines,
pages/benchmark.ts:7:  walkLineRanges,
pages/benchmark.ts:67:  prepareMs: number
pages/benchmark.ts:263:    const prepareSamples: number[] = []
pages/benchmark.ts:271:        prepareSamples.push(profile.totalMs)
pages/benchmark.ts:277:    const prepareMs = median(prepareSamples)
pages/benchmark.ts:282:    const prepared = prepareWithSegments(corpus.text, corpus.font)
pages/benchmark.ts:283:    const lineCount = layout(prepared, corpus.width, corpus.lineHeight).lineCount
pages/benchmark.ts:287:      const result = layout(prepared, width, corpus.lineHeight)
pages/benchmark.ts:297:      segments: prepared.widths.length,
pages/benchmark.ts:298:      breakableSegments: prepared.breakableWidths.filter(widths => widths !== null).length,
pages/benchmark.ts:303:      prepareMs,
pages/benchmark.ts:313:  prepared: PreparedTextWithSegments[],
pages/benchmark.ts:321:  const layoutWithLinesMs = bench(repeatIndex => {
pages/benchmark.ts:324:    for (let i = 0; i < prepared.length; i++) {
pages/benchmark.ts:325:      const result = layoutWithLines(prepared[i]!, width, lineHeight)
pages/benchmark.ts:331:  const walkLineRangesMs = bench(repeatIndex => {
pages/benchmark.ts:334:    for (let i = 0; i < prepared.length; i++) {
pages/benchmark.ts:335:      sum += walkLineRanges(prepared[i]!, width, line => {
pages/benchmark.ts:342:  const layoutNextLineMs = bench(repeatIndex => {
pages/benchmark.ts:345:    for (let i = 0; i < prepared.length; i++) {
pages/benchmark.ts:346:      let cursor = { segmentIndex: 0, graphemeIndex: 0 }
pages/benchmark.ts:348:        const line = layoutNextLine(prepared[i]!, cursor, width)
pages/benchmark.ts:351:        cursor = line.end
pages/benchmark.ts:361:      label: 'Our library: layoutWithLines()',
pages/benchmark.ts:362:      ms: layoutWithLinesMs,
pages/benchmark.ts:366:      label: 'Our library: walkLineRanges()',
pages/benchmark.ts:367:      ms: walkLineRangesMs,
pages/benchmark.ts:371:      label: 'Our library: layoutNextLine()',
pages/benchmark.ts:372:      ms: layoutNextLineMs,
pages/benchmark.ts:431:  // Pre-prepare for layout benchmark
pages/benchmark.ts:432:  const prepared: PreparedText[] = []
pages/benchmark.ts:434:    prepared.push(prepare(texts[i]!, FONT))
pages/benchmark.ts:441:  // --- 1. prepare() ---
pages/benchmark.ts:442:  root.innerHTML = '<p>Benchmarking prepare()...</p>'
pages/benchmark.ts:447:      prepare(texts[i]!, FONT)
pages/benchmark.ts:450:  results.push({ label: 'Our library: prepare()', ms: tPrepare, desc: `One cold ${COUNT}-text measurement batch` })
pages/benchmark.ts:459:      const result = layout(prepared[i]!, maxWidth, LINE_HEIGHT)
pages/benchmark.ts:504:  const richPrepared = richTexts.map(text => prepareWithSegments(text, FONT))
pages/benchmark.ts:518:    prepareWithSegments(
pages/benchmark.ts:537:  // Relative speed only for resize approaches (layout vs DOM). prepare() is
pages/benchmark.ts:556:    <p class="note">${RICH_COUNT} shared-corpus texts prepared with segments. Median ms per batch across widths ${RICH_LAYOUT_SAMPLE_WIDTHS.join('/')}px. This tracks the richer APIs used by shrinkwrap, custom layout, and manual reflow.</p>
pages/benchmark.ts:561:    <p class="note">${RICH_LONG_REPEAT} copies of the Arabic long-form corpus prepared with segments. Median ms per batch across widths ${RICH_LONG_SAMPLE_WIDTHS.join('/')}px. This is the richer-path worst-case canary.</p>
pages/benchmark.ts:586:    // prepare (cold)
pages/benchmark.ts:589:      clearCache(); let t0 = performance.now(); prepare(cjk, FONT); pTimes.cjk.push(performance.now() - t0)
pages/benchmark.ts:590:      clearCache(); t0 = performance.now(); prepare(lat, FONT); pTimes.lat.push(performance.now() - t0)
pages/benchmark.ts:595:    const pc = prepareWithSegments(cjk, FONT)
pages/benchmark.ts:596:    const pl = prepareWithSegments(lat, FONT)
pages/benchmark.ts:629:      <tr><th>Chars</th><th>CJK segs</th><th>Latin segs</th><th>CJK prepare (ms)</th><th>Latin prepare (ms)</th><th>CJK layout/1k (ms)</th><th>Latin layout/1k (ms)</th></tr>
pages/benchmark.ts:644:          <td>${result.prepareMs.toFixed(2)}</td>
pages/benchmark.ts:650:    <p class="note">Long-form rows split cold prepare into text analysis and measurement phases for one full corpus text, then report one hot layout pass over the prepared result. They are intended to catch script-specific prepare regressions that the short shared corpus can hide.</p>
pages/probe.ts:3:  layoutWithLines,
pages/probe.ts:4:  prepareWithSegments,
pages/probe.ts:138:function getBrowserLinesFromSpans(prepared: PreparedTextWithSegments, measuredFont: string, dir: string): ProbeLine[] {
pages/probe.ts:140:  const units = getDiagnosticUnits(prepared)
pages/probe.ts:196:  prepared: PreparedTextWithSegments,
pages/probe.ts:202:    ? getBrowserLinesFromSpans(prepared, measuredFont, dir)
pages/probe.ts:203:    : getBrowserLinesFromRange(prepared, measuredFont, dir)
pages/probe.ts:206:function getBrowserLinesFromRange(prepared: PreparedTextWithSegments, measuredFont: string, dir: string): ProbeLine[] {
pages/probe.ts:211:  const units = getDiagnosticUnits(prepared)
pages/probe.ts:258:  prepared: PreparedTextWithSegments,
pages/probe.ts:266:  for (let i = 0; i < prepared.segments.length; i++) {
pages/probe.ts:267:    const segment = prepared.segments[i]!
pages/probe.ts:285:      total += prepared.widths[i]!
pages/probe.ts:297:  prepared: PreparedTextWithSegments,
pages/probe.ts:303:  return layoutWithLines(prepared, contentWidth, lineHeight).lines.map(line => {
pages/probe.ts:306:      : computeOffsetFromCursor(prepared, line.start)
pages/probe.ts:307:    const end = computeOffsetFromCursor(prepared, line.end)
pages/probe.ts:321:      sumWidth: measurePreparedSlice(prepared, start, contentEnd, measuredFont),
pages/probe.ts:336:function computeOffsetFromCursor(prepared: PreparedTextWithSegments, cursor: { segmentIndex: number, graphemeIndex: number }): number {
pages/probe.ts:338:  for (let i = 0; i < cursor.segmentIndex; i++) offset += prepared.segments[i]!.length
pages/probe.ts:339:  if (cursor.graphemeIndex === 0 || cursor.segmentIndex >= prepared.segments.length) return offset
pages/probe.ts:342:  for (const grapheme of graphemeSegmenter.segment(prepared.segments[cursor.segmentIndex]!)) {
pages/probe.ts:343:    if (graphemeIndex >= cursor.graphemeIndex) break
pages/probe.ts:439:    const prepared = prepareWithSegments(text, font, { whiteSpace })
pages/probe.ts:440:    const normalizedText = prepared.segments.join('')
pages/probe.ts:442:    const predicted = layout(prepared, contentWidth, lineHeight)
pages/probe.ts:444:    const ourLines = getPublicLines(prepared, normalizedText, contentWidth, lineHeight, font)
pages/probe.ts:446:    const browserLines = getBrowserLines(prepared, font, direction, browserLineMethod)
pages/probe.ts:447:    const alternateBrowserLines = getBrowserLines(prepared, font, direction, alternateBrowserLineMethod)
pages/accuracy.ts:4:  layoutWithLines,
pages/accuracy.ts:5:  prepareWithSegments,
pages/accuracy.ts:160:  prepared: PreparedTextWithSegments,
pages/accuracy.ts:166:  const units = getDiagnosticUnits(prepared)
pages/accuracy.ts:209:        const prepared: PreparedTextWithSegments[] = []
pages/accuracy.ts:221:          prepared.push(prepareWithSegments(text, font))
pages/accuracy.ts:227:          const predicted = layout(prepared[i]!, maxWidth, lineHeight).height
pages/accuracy.ts:240:            const browserLines = getBrowserLines(prepared[i]!, divs[i]!)
pages/accuracy.ts:241:            const ourLayout = layoutWithLines(prepared[i]!, maxWidth, lineHeight)
pages/corpus.ts:3:  layoutWithLines,
pages/corpus.ts:4:  prepareWithSegments,
pages/corpus.ts:200:      layoutWithLines: (width: number) => ReturnType<typeof layoutWithLines>
pages/corpus.ts:361:  prepared: PreparedTextWithSegments,
pages/corpus.ts:366:  const units = getDiagnosticUnits(prepared)
pages/corpus.ts:409:  prepared: PreparedTextWithSegments,
pages/corpus.ts:420:  const units = getDiagnosticUnits(prepared)
pages/corpus.ts:451:function getCursorOffset(prepared: PreparedTextWithSegments, segmentIndex: number, graphemeIndex: number): number {
pages/corpus.ts:454:    offset += prepared.segments[i]!.length
pages/corpus.ts:456:  if (graphemeIndex === 0 || segmentIndex >= prepared.segments.length) {
pages/corpus.ts:462:  for (const grapheme of diagnosticGraphemeSegmenter.segment(prepared.segments[segmentIndex]!)) {
pages/corpus.ts:471:  prepared: PreparedTextWithSegments,
pages/corpus.ts:477:  return layoutWithLines(prepared, maxWidth, lineHeight).lines.map(line => {
pages/corpus.ts:478:    const start = getCursorOffset(prepared, line.start.segmentIndex, line.start.graphemeIndex)
pages/corpus.ts:479:    const end = getCursorOffset(prepared, line.end.segmentIndex, line.end.graphemeIndex)
pages/corpus.ts:498:  prepared: PreparedTextWithSegments,
pages/corpus.ts:506:  for (let i = 0; i < prepared.segments.length; i++) {
pages/corpus.ts:507:    const text = prepared.segments[i]!
pages/corpus.ts:512:        width: prepared.widths[i]!,
pages/corpus.ts:514:        isSpace: prepared.kinds[i] === 'space',
pages/corpus.ts:567:  prepared: PreparedTextWithSegments,
pages/corpus.ts:604:        oursSegments: ours ? getLineSegments(prepared, ours.start, ours.end, font, direction) : [],
pages/corpus.ts:709:  prepared: PreparedTextWithSegments,
pages/corpus.ts:720:  const ourLines = getOurLines(prepared, normalizedText, contentWidth, lineHeight, font)
pages/corpus.ts:721:  const probeResult = getBrowserLinesFromSpans(prepared, lineProbeDiv, normalizedText, font)
pages/corpus.ts:722:  const rangeResult = getBrowserLinesFromRange(prepared, diagnosticDiv, normalizedText, font)
pages/corpus.ts:774:        const segments = getLineSegments(prepared, ours.start, ours.end, font, direction)
pages/corpus.ts:790:    prepared,
pages/corpus.ts:799:    prepared,
pages/corpus.ts:855:  const prepared = currentPrepared
pages/corpus.ts:856:  const normalizedText = prepared.segments.join('')
pages/corpus.ts:862:  const predicted = layout(prepared, contentWidth, lineHeight)
pages/corpus.ts:882:  report = addDiagnostics(report, prepared, font, lineHeight, contentWidth, normalizedText, direction)
pages/corpus.ts:893:    layoutWithLines: nextWidth => layoutWithLines(prepared, nextWidth - PADDING * 2, lineHeight),
pages/corpus.ts:1060:  const fullPrepared = prepareWithSegments(rawText, font)
pages/corpus.ts:1071:    : prepareWithSegments(currentText, font)
pages/demos/bubbles.html:252:          Uses <code>walkLineRanges()</code> to binary-search the tightest width
pages/demos/bubbles.html:279:        <code>walkLineRanges()</code> does, without DOM text measurement in the
pages/demos/dynamic-layout.html:32:        cursor: default;
pages/demos/dynamic-layout.html:115:        cursor: text;
pages/demos/dynamic-layout.html:127:        cursor: text;
pages/demos/dynamic-layout.html:155:        cursor: text;
pages/demos/variable-typographic-ascii.ts:1:import { prepareWithSegments } from '../../src/layout.ts'
pages/demos/variable-typographic-ascii.ts:90:  const prepared = prepareWithSegments(ch, font)
pages/demos/variable-typographic-ascii.ts:91:  return prepared.widths.length > 0 ? prepared.widths[0]! : 0
pages/demos/rich-note.html:86:      justify-content: center;
pages/demos/rich-note.html:150:        justify-content: center;
pages/demos/rich-note.html:161:        justify-items: stretch;
pages/demos/masonry/index.ts:1:import { prepare, layout, type PreparedText } from '../../../src/layout.ts'
pages/demos/masonry/index.ts:14:  prepared: PreparedText
pages/demos/masonry/index.ts:34:// --- prepare all texts upfront ---
pages/demos/masonry/index.ts:38:    prepared: prepare(text, font),
pages/demos/masonry/index.ts:80:    const { height } = layout(st.cards[i]!.prepared, textWidth, lineHeight)
pages/demos/justification-comparison.model.ts:2:  prepareWithSegments,
pages/demos/justification-comparison.model.ts:3:  layoutNextLine,
pages/demos/justification-comparison.model.ts:116:    basePreparedParagraphs: PARAGRAPHS.map(paragraph => prepareWithSegments(paragraph, FONT)),
pages/demos/justification-comparison.model.ts:117:    hyphenatedPreparedParagraphs: PARAGRAPHS.map(paragraph => prepareWithSegments(hyphenateParagraphText(paragraph), FONT)),
pages/demos/justification-comparison.model.ts:205:  preparedParagraphs: PreparedTextWithSegments[],
pages/demos/justification-comparison.model.ts:210:  for (let index = 0; index < preparedParagraphs.length; index++) {
pages/demos/justification-comparison.model.ts:211:    paragraphs.push(layoutParagraphGreedy(preparedParagraphs[index]!, maxWidth, hyphenWidth))
pages/demos/justification-comparison.model.ts:217:  prepared: PreparedTextWithSegments,
pages/demos/justification-comparison.model.ts:222:  let cursor: LayoutCursor = { segmentIndex: 0, graphemeIndex: 0 }
pages/demos/justification-comparison.model.ts:225:    const line = layoutNextLine(prepared, cursor, maxWidth)
pages/demos/justification-comparison.model.ts:227:    lines.push(buildMeasuredLineFromLayoutResult(prepared, line.start, line.end, maxWidth, hyphenWidth))
pages/demos/justification-comparison.model.ts:228:    cursor = line.end
pages/demos/justification-comparison.model.ts:235:  prepared: PreparedTextWithSegments,
pages/demos/justification-comparison.model.ts:241:  const ending: LineEnding = end.segmentIndex >= prepared.segments.length ? 'paragraph-end' : 'wrap'
pages/demos/justification-comparison.model.ts:246:    const text = prepared.segments[segIndex]!
pages/demos/justification-comparison.model.ts:251:    segments.push(toLineSegment(text, prepared.widths[segIndex]!))
pages/demos/justification-comparison.model.ts:254:  if (trailingMarker === 'none' && end.segmentIndex < prepared.segments.length) {
pages/demos/justification-comparison.model.ts:255:    if (prepared.segments[end.segmentIndex] === SOFT_HYPHEN) trailingMarker = 'soft-hyphen'
pages/demos/justification-comparison.model.ts:267:  preparedParagraphs: PreparedTextWithSegments[],
pages/demos/justification-comparison.model.ts:272:  for (let index = 0; index < preparedParagraphs.length; index++) {
pages/demos/justification-comparison.model.ts:273:    paragraphs.push(layoutParagraphOptimal(preparedParagraphs[index]!, maxWidth, resources))
pages/demos/justification-comparison.model.ts:279:  prepared: PreparedTextWithSegments,
pages/demos/justification-comparison.model.ts:283:  const segments = prepared.segments
pages/demos/justification-comparison.model.ts:284:  const widths = prepared.widths
pages/demos/justification-comparison.model.ts:348:    lines.push(buildMeasuredLineFromCandidateRange(prepared, breakCandidates, fromCandidate, toCandidate, maxWidth, resources.hyphenWidth))
pages/demos/justification-comparison.model.ts:438:  prepared: PreparedTextWithSegments,
pages/demos/justification-comparison.model.ts:454:    const text = prepared.segments[segIndex]!
pages/demos/justification-comparison.model.ts:456:    segments.push(toLineSegment(text, prepared.widths[segIndex]!))
pages/demos/dynamic-layout.ts:8:- The left column consumes text first, and the right column resumes from the same cursor.
pages/demos/dynamic-layout.ts:24:import { layoutNextLine, prepareWithSegments, walkLineRanges, type LayoutCursor, type PreparedTextWithSegments } from '../../src/layout.ts'
pages/demos/dynamic-layout.ts:154:const preparedByKey = new Map<string, PreparedTextWithSegments>()
pages/demos/dynamic-layout.ts:219:const preparedBody = getPrepared(BODY_COPY, BODY_FONT)
pages/demos/dynamic-layout.ts:220:const preparedCredit = getPrepared(CREDIT_TEXT, CREDIT_FONT)
pages/demos/dynamic-layout.ts:221:const creditWidth = Math.ceil(getPreparedSingleLineWidth(preparedCredit))
pages/demos/dynamic-layout.ts:229:  const cached = preparedByKey.get(key)
pages/demos/dynamic-layout.ts:231:  const prepared = prepareWithSegments(text, font)
pages/demos/dynamic-layout.ts:232:  preparedByKey.set(key, prepared)
pages/demos/dynamic-layout.ts:233:  return prepared
pages/demos/dynamic-layout.ts:236:function getPreparedSingleLineWidth(prepared: PreparedTextWithSegments): number {
pages/demos/dynamic-layout.ts:238:  walkLineRanges(prepared, 100_000, line => {
pages/demos/dynamic-layout.ts:244:function headlineBreaksInsideWord(prepared: PreparedTextWithSegments, maxWidth: number): boolean {
pages/demos/dynamic-layout.ts:246:  walkLineRanges(prepared, maxWidth, line => {
pages/demos/dynamic-layout.ts:276:  prepared: PreparedTextWithSegments,
pages/demos/dynamic-layout.ts:282:): { lines: PositionedLine[], cursor: LayoutCursor } {
pages/demos/dynamic-layout.ts:283:  let cursor: LayoutCursor = startCursor
pages/demos/dynamic-layout.ts:326:    const line = layoutNextLine(prepared, cursor, width)
pages/demos/dynamic-layout.ts:336:    cursor = line.end
pages/demos/dynamic-layout.ts:340:  return { lines, cursor }
pages/demos/dynamic-layout.ts:671:  preparedBody: PreparedTextWithSegments,
pages/demos/dynamic-layout.ts:764:      preparedBody,
pages/demos/dynamic-layout.ts:784:    preparedBody,
pages/demos/dynamic-layout.ts:793:    preparedBody,
pages/demos/dynamic-layout.ts:794:    leftResult.cursor,
pages/demos/dynamic-layout.ts:819:  const { headlineLines, creditLeft, creditTop, leftLines, rightLines, contentHeight, hits } = evaluateLayout(layout, lineHeight, preparedBody)
pages/demos/dynamic-layout.ts:847:  document.body.style.cursor = hoveredLogo === null ? '' : 'pointer'
pages/demos/index.html:135:      <a class="card" href="/demos/masonry">
pages/demos/bubbles.ts:5:  prepareBubbleTexts,
pages/demos/bubbles.ts:25:const preparedBubbles = prepareBubbleTexts(shrinkNodes.map(readNodeText))
pages/demos/bubbles.ts:107:  const renderState = computeBubbleRender(preparedBubbles, chatWidth)
pages/demos/accordion.html:81:        cursor: pointer;
pages/demos/accordion.html:98:        justify-self: end;
pages/demos/bubbles-shared.ts:1:import { layout, prepareWithSegments, walkLineRanges, type PreparedTextWithSegments } from '../../src/layout.ts'
pages/demos/bubbles-shared.ts:10:  prepared: PreparedTextWithSegments
pages/demos/bubbles-shared.ts:36:export function prepareBubbleTexts(texts: string[]): PreparedBubble[] {
pages/demos/bubbles-shared.ts:38:    prepared: prepareWithSegments(text, FONT),
pages/demos/bubbles-shared.ts:49:export function collectWrapMetrics(prepared: PreparedTextWithSegments, maxWidth: number): WrapMetrics {
pages/demos/bubbles-shared.ts:51:  const lineCount = walkLineRanges(prepared, maxWidth, line => {
pages/demos/bubbles-shared.ts:61:export function findTightWrapMetrics(prepared: PreparedTextWithSegments, maxWidth: number): WrapMetrics {
pages/demos/bubbles-shared.ts:62:  const initial = collectWrapMetrics(prepared, maxWidth)
pages/demos/bubbles-shared.ts:68:    const midLineCount = layout(prepared, mid, LINE_HEIGHT).lineCount
pages/demos/bubbles-shared.ts:76:  return collectWrapMetrics(prepared, lo)
pages/demos/bubbles-shared.ts:79:export function computeBubbleRender(preparedBubbles: PreparedBubble[], chatWidth: number): BubbleRenderState {
pages/demos/bubbles-shared.ts:85:  for (let index = 0; index < preparedBubbles.length; index++) {
pages/demos/bubbles-shared.ts:86:    const bubble = preparedBubbles[index]!
pages/demos/bubbles-shared.ts:87:    const cssMetrics = collectWrapMetrics(bubble.prepared, contentMaxWidth)
pages/demos/bubbles-shared.ts:88:    const tightMetrics = findTightWrapMetrics(bubble.prepared, contentMaxWidth)
pages/demos/editorial-engine.ts:2:  layoutNextLine,
pages/demos/editorial-engine.ts:3:  layoutWithLines,
pages/demos/editorial-engine.ts:4:  prepareWithSegments,
pages/demos/editorial-engine.ts:5:  walkLineRanges,
pages/demos/editorial-engine.ts:105:  prepared: PreparedTextWithSegments
pages/demos/editorial-engine.ts:190:A messaging application needs to know the exact height of every message bubble before rendering a virtualized list. A masonry layout needs the height of every card to position them without overlap. An editorial page needs text to flow around images, advertisements, and interactive elements. A responsive dashboard needs to resize and reflow text in real time as the user drags a panel divider.
pages/demos/editorial-engine.ts:216:Virtualized text rendering becomes exact rather than estimated. A virtual list needs to know the height of items before they enter the viewport, so it can position them correctly and calculate scroll extent. Without pretext, you must either render items off-screen to measure them (defeating the purpose of virtualization) or estimate heights and accept visual jumping when items enter the viewport with different heights than predicted. Pretext computes exact heights without creating any DOM elements, enabling perfect virtualization with zero visual artifacts.
pages/demos/editorial-engine.ts:218:Multi-column text flow with cursor handoff is perhaps the most striking capability. The left column consumes text until it reaches the bottom, then hands its cursor to the right column. The right column picks up exactly where the left column stopped, with no duplication, no gap, and perfect line breaking at the column boundary. This is how newspapers and magazines work on paper, but it has never been achievable on the web without extreme hacks involving multiple elements, hidden overflow, and JavaScript-managed content splitting.
pages/demos/editorial-engine.ts:220:Pretext makes it trivial. Call layoutNextLine in a loop for the first column, using the column width. When the column is full, take the returned cursor and start a new loop for the second column. The cursor carries the exact position in the prepared text — which segment, which grapheme within that segment. The second column continues seamlessly from the first.
pages/demos/editorial-engine.ts:275:const preparedBody = prepareWithSegments(BODY_TEXT, BODY_FONT)
pages/demos/editorial-engine.ts:278:const preparedPullquotes = PULLQUOTE_TEXTS.map(text => prepareWithSegments(text, PQ_FONT))
pages/demos/editorial-engine.ts:280:  { prepared: preparedPullquotes[0]!, placement: { colIdx: 0, yFrac: 0.48, wFrac: 0.52, side: 'right' } },
pages/demos/editorial-engine.ts:281:  { prepared: preparedPullquotes[1]!, placement: { colIdx: 1, yFrac: 0.32, wFrac: 0.5, side: 'left' } },
pages/demos/editorial-engine.ts:286:const preparedDropCap = prepareWithSegments(DROP_…57674 tokens truncated…LI5: How did we get to the point where laptops and smartphones are in the same price range?","ELI5: Stock Market Megathread","ELI5: So how does the the human brain ignore the second the?","ELI5: Why can people walk many miles without discomfort, but when they stand for more than 15 minutes or so, they get uncomfortable?","ELI5: There are infinite numbers between 0 and 1. There are also infinite numbers between 0 and 2. There would more numbers between 0 and 2. How can a set of infinite numbers be bigger than another infinite set?","ELI5 Why is 12 hour time even taught? Wouldn’t it just be easier to remember 13:00 instead of 1:00pm?","ELI5: Military officers swear to protect and defend the Constitution of the United States, not the President","ELI5 remembers u/bossgalaga","ELI5 why do humans need to eat many different kind of foods to get their vitamins etc but large animals like cows only need grass to survive?","ELI5 If diamonds and other gemstones can be lab created, and indistinguishable from their naturally mined counterparts, why are we still paying so much for these jewelry stones?","ELI5: How come you can be falling asleep watching TV, then wide awake when you go to bed five minutes later?","ELI5: How did Germany stop being Nazis after the end of WWII? Did everyone just \"snap out of it\" after Hitler's death?","ELI5: The Panama Papers","ELI5: Addressing Concerns Regarding Reddit","ELI5:Do donated organs age according to the donor´s age or do they adapt to the age of the new body?","ELI5: If there is no cellphone signal, how does the \"emergency calls only\" mode works?","ELI5: Why is it, that you can eat a 2,000 calorie meal, and in theory, you shouldn't need calories again until the next day, but you can be hungry again 6-8 hours after you finish eating? Is your body just not capable of actually processing that many calories?","ELI5: what is the reason that almost every video game today has removed the ability for split screen, including ones that got famous and popular from having split screen?","ELI5: How does your body burn 2000 calories a day, but you have to run a mile to burn 100 extra?","ELI5: Went on vacation. Fridge died while I was gone. Came back to a freezer full of maggots. How do maggots get into a place like a freezer that's sealed air tight?","Eli5: If ants love sugar, and bees make honey, why aren’t bee hives constantly attacked by ants?","ELI5: Why do traditional cars lack any decent ability to warn the driver that the battery is low or about to die?","ELI5: Why aren't power lines in the US burried underground so that everyone doesn't lose power during hurricanes and other natural disasters?","ELI5: How can large chains (Target, Walmart, etc) produce store brand versions of nearly every product imaginable while industry manufacturers only really produce a single type of item?","ELI5: Why does \"Hoo\" produce cold air but \"Haa\" produces hot air ?","ELI5: Why is it that Mandarin and Cantonese are considered dialects of Chinese but Spanish, Portuguese, Italian, and French are considered separate languages and not dialects of Latin?","ELI5: If bacteria die from (for example, boiled water) where do their corpses go?","ELI5: if fruit is sweet to encourage animals to eat it and carry the seeds away from the parent tree, how do lemons and limes fit into this mix?","ELI5: Why does making a 3 degree difference in your homes thermostat feel like a huge change in temperature, but outdoors it feels like nothing?","ELI5: Why do you need a Master's Degree to become a librarian, especially when the median salary is barely above $50,000?","ELI5: Why do blockbuster movies like Avatar and End Game have there success measured in terms of money made instead of tickets sold, wouldn’t that make it easier to compare to older movies without accounting for today’s dollar vs a dollar 30 years ago?","ELI5: How come all those atomic bomb tests were conducted during 60s in deserts in Nevada without any serious consequences to environment and humans?","ELI5: NASA Engineers just communicated with Voyager 1 which is 21 BILLION kilometers away (and out of our solar system) and it communicated back. How is this possible?","ELI5: Why do \"bad smells\" like smoke and rotting food linger longer and are harder to neutralize than \"good smells\" like flowers or perfume?","ELI5: What did Edward Snowden actually reveal abot the U.S Government?","ELI5: Why after a good long cry can't we take a big deep breath without that huh-huh-huh tracheal contraction?","ELI5: How can nothing be faster than light when speed is only relative?","ELI5: Why is W called \"double U\" when it is clearly \"double V\"?","ELI5: How, at 93 million miles away, does the sun feel so warm, yet when a simple cloud passes over it the warmth is incredibly dampened?","ELI5: When toddlers talk ‘gibberish’ are they just making random noises or are they attempting to speak an English sentence that just comes out muddled up?","ELI5: Why do some animals (like spiders or lizards) spend so much time just doing nothing? What is happening and why?","ELI5: Why is it that you can keep a house phone on it's charging dock for years and it doesn't destroy the battery where as a cellphone will eventually wither over just a couple years if you charge it for too long everyday?","ELI5: Why do some letters have a completely different character when written in uppercase (A/a, R/r, E/e, etc), whereas others simply have a larger version of themselves (S/s, P/p, W/w, etc)?","ELI5: Why does hearing yourself speak with a few seconds of delay, completely crash your brain?","ELI5: Why were ridiculously fast planes like the SR-71 built, and why hasn't it speed record been broken for 50 years?","Eli5: Caffeine has almost no calories, but seems to give us a burst of energy on its own. Where does the body get this energy from? Is caffeine forcing the body to use stored fat?","ELI5: Why does your body feel physically ill after experiencing emotional trauma?","ELI5 What is it about grapefruit specifically that messes with pretty much every prescription in existence?","ELI5: What does it mean when scientists say “an eagle can see a rabbit in a field from a mile away”. Is their vision automatically more zoomed in? Do they have better than 20/20 vision? Is their vision just clearer?","ELI5: If I enter a password wrong thrice, the system locks me out. How are hackers able to attempt millions of combinations of passwords without the system locking them out?","ELI5: If the amazon echo doesn’t start processing audio until you say “Alexa”, how does it know when you say it?","ELI5: Why do alcoholics die when they stop drinking?","ELI5: Why is it healthy to strain your heart through exercise, but unhealthy to strain it through stress, caffeine, nicotine etc? What is the difference between these kinds of cardiac strain?","ELi5: When a baby is born, how are their lungs instantly able to breathe air if they haven't been breathing air for 9 months?","ELI5: Why is it children’s shampoo is “tear free” while regular shampoo burns like all hell in the eyes?","ELI5: Why is finding \"patient zero\" in an epidemic so important?","ELI5: You're not supposed to defrost meats in warm water due to harmful bacteria growth, you're not supposed to leave food at room temperature for long without being refrigerated because of harmful growth but, when you go to a buffet, food can sit out for hours under heat lamps and be fine?","ELI5: how can our brains remember that we forgot something, but it can't remember what we forgot?","ELI5: Why is it that when we watch footage from the 70s a lot of times it looks better than footage of the 90s?","ELI5 the difference between 4 Wheel Drive and All Wheel Drive.","ELI5: Why do older emulated games still occasionally slow down when rendering too many sprites, even though it's running on hardware thousands of times faster than what it was programmed on originally?","ELI5: Why do ships have circular windows instead of square ones?","ELI5: How do ships anchor themselves in very deep waters? For example, if they anchored in 10K foot deep oceans, do they actually have 10K feet of anchor chains?","ELI5: what is a hedge-fund?","ELI5: Why can't bots check 'I am not a robot' checkboxes?","eli5 Why does down syndrome cause an almost identical face structure no matter the parents genes?","ELI5: Why does a candle not create smoke when burning but lots of smoke when you blow it out?","ELI5: why can't we have supplements or pills for dopamine, oxytocin, serotonin or endorphins just like we have melatonin or contraceptive pills?","ELI5 : how are we sure that we all see the same colors ?","ELI5: Why is it that it takes few seconds for our body to decide that it's had enough water not to be thirsty, but several minutes to recognize that no more food is needed cuz it's not hungry?","ELI5 Why do people seem to age so incredibly fast after a traumatic experience?","ELI5: What actually happens when we unintentionally start to drift off to sleep but our body suddenly \"shocks\" us awake?","ELI5: When you restart a PC, does it completely \"shut down\"? If it does, what tells it to power up again? If it doesn't, why does it behave like it has been shut down?","ELI5: Whem pouring liquid from one container to another (bowl, cup), why is it that sometimes it pours gloriously without any spills but sometimes the liquid decides to fucking run down the side of the container im pouring from and make a mess all around the surface?","ELI5: Queen Victoria ruled over one of the most powerful empires in history for almost a century. So why did it take until 1918 for women to be considered politically intelligent and allowed to vote?","ELI5: How can the same side of the moon always face earth? Doesn't it rotate?","ELI5: How is peach flavoring so easily captured in gummies, water, etc, when so many other flavors taste obviously fake?","ELI5: What is 'gaslighting' and some examples?","ELI5: Why do most hard candies just shrink down as you suck on them but peppermints get all porous and full of holes?","ELI5: Suicide is listed as a side effect of over 200 common medications. How, specifically, do these medications increase the risk of suicide?","ELI5: Why are so many electrical plugs designed in such a way that they cover adjacent sockets?","ELI5: If the internet is primarily dependent on cables that run through oceans connecting different countries and continents. During a war, anyone can cut off a country's access to the internet. Are there any backup or mitigant in place to avoid this? What happens if you cut the cable?","ELI5: How did the U.S. rise to a global superpower in only 250 years but counties that have been around for 1000s of years are still under-developed?","ELI5: Why does it seem so challenging now to send a manned crew to the moon, when we were able to accomplish this over 50 years ago?","ELI5: What makes a beer belly how it is, round and hard? What makes it different from a normal stomach or a soft(fat) stomach?","ELI5: What is the \"sharp\" in sharp cheddar? How are there various levels of \"sharp\"?","ELI5: Do birds fly for days while over the ocean? How do they sleep?","ELI5: Why is armpit sweat much more pungent than sweat from other areas of the body, such as back sweat?","ELI5:Why do our brains choose short term convenience and long term inconvenience over short term inconvenience and long term convenience? Example included.","ELI5: Why are password managers considered good security practice when they provide a single entry for an attacker to get all of your credentials?","ELI5 : Why does travelling make you feel so tired when you've just sat there for hours doing nothing?","eli5: How comes when you buy vitamins separately, they all come in these large capsules/tablets, but when you buy multivitamins, they can squeeze every vitamin in a tiny tablet?","ELI5: How do recycling factories deal with the problem of people putting things in the wrong bins?","ELI5: If the whole purpose of a fruit/vegetable is to spread seeds by being eaten and what out, why are chilly peppers doing there best to prevent this?","ELI5: Why are modern artists able to draw hyper-realistic art using just a pen/pencil, but artists from 100+ years ago weren’t able to?","ELI5: I’m told skin-to-skin contact leads to healthier babies, stronger romantic relationshipd, etc. but how does our skin know it’s touching someone else’s skin (as opposed to, say, leather)?","ELI5: How does a brain anus rhythm instantly kill you","ELI5 why are there stenographers in courtrooms, can't we just record what is being said?","ELI5: What happens to insects that accidentally travel long distances in cars?","ELI5 Why doesnt Chatgpt and other LLM just say they don't know the answer to a question?","ELI5: Why are poor people warned to avoid loans whereas rich people seem to operate constantly through them?","ELI5: Why is black worn in hot climates to keep cool?","ELi5: why do girls go into puberty so young when pregnancy for them would be unsafe and lead to poor outcomes?","ELI5 why you’re not supposed to sit on the toilet for a long time","ELI5: Why is \"C\" the default Hard Drive letter & not \"A\"","ELI5: The last B-2 bomber was manufactured in 2000. How is it that no other country managed to produce something comparable?","ELI5: When ChatGPT came out, why did so many companies suddenly release their own large language AIs?","ELI5 How does instagram/ social media know what exactly i am discussing with friends if it doesn't record my audio, looking for keywords all the time?","ELI5 Why do waiters leave with your payment card?","ELI5 If you were on a spaceship going 99.9999999999% the speed of light and you started walking, why wouldn’t you be moving faster than the speed of light?","ELI5: How can Paramount announce a hostile takeover bid for WB when the bidding was done and Netflix won?","ELI5: Why is squatting (in someone's house) a thing? And how come it becomes a problem for the owner? Can't they claim trespassing to the cops instead of saying the person is squatting?","ELI5: How did the explorers from hundreds of years ago provide drinking water to their crew for months on end?","ELI5: why don’t planes board back to front, surely that would be faster?","ELI5: When we get sick and get congested, where does the seemingly never ending flow of mucus/snot come from?","ELI5: Why do broken jaws not happen all the time in professional boxing?","ELI5: What is cloudflare EXACTLY and why does it going down take down like 80 percent of the internet","ELI5:  Why do prostate cancer checks still need a finger in the butt?","ELI5: Why are the screens in even luxury cars often so laggy? What prevents them from just investing a couple hundred more $ to install a faster chip?","ELI5 : If em dashes (—) aren’t quite common on the Internet and in social media, then how do LLMs like ChatGPT use a lot of them?","ELI5: Why aren’t viruses “alive”","ELI5 - What makes an ADHD brain process the world so differently","ELI5 Why did Radio Shack go out of business?","ELI5: Why is it good for your cardiovascular health to increase heart rate via exercise, but harmful to increase heart rate via stimulants?","ELI5 how Einstein figured out that time slows down the faster you travel","ELI5: If water makes you urinate more, which causes kidneys to do more work, does that mean high water consumption damages kidneys long-term? If not, why not?","ELI5: Why do car dealers say buying the car when the lease ends would be worse than buying new?","ELI5: why aren't most wounds between your buttocks fatal?","ELI5: How does the US have such amazing diplomacy with Japan when we dropped two nuclear bombs on them? How did we build it back so quickly?","ELI5: How is blackjack \"rigged\" for the casino?","ELI5: How does a bomber plane not get caught in the explosion after dropping a nuclear bomb?","ELI5: Why do reporters in the same city as the studio respond several seconds later, while people on Zoom across the world respond almost instantly?","ELI5: Why can humans run 5km a day but racehorses only run 1-2km every couple weeks?","ELI5: How does a US police officer issuing a ticket by the side of the road instantly have a court date and time for the suspect?","ELI5: Why do Africa and Asia have an abundance of large animals/predators but the Americas and Europe really don’t?","ELI5: If unboiled water going into your nose is risky, then shouldn’t we not swim in a lake or river?","ELI5: If Fentanyl is so deadly how do the clandestine labs manufacture it, smugglers transport it and dealers handle it without killing everyone involved?","ELI5: Why isn’t all the data from the black box on airplanes get uploaded via satellite internet in real time to an airline server negating the need to find the black box if there’s an accident?","ELI5 Why does rabies have a near 100% fatality rate?","ELI5: Why does our body seem to know almost instantly when we’ve had enough water, but takes way longer to realize we’ve eaten enough food and aren’t hungry anymore?","ELI5: If you think about it, why do teeth need so much care? It feels like they kind of go against natural selection, especially when you compare them to how well the rest of our body maintains itself.","ELI5: Why can other carnivores eat raw meat but humans are so prone to infections?","ELI5 why places like nightclubs, tattooists, bar etc won’t accept IDs that are out of date? I’m not going to suddenly get any younger.","ELI5: Why can't we drop a wire with a camera and an LED light to the bottom of the ocean?","ELI5: How do babies breathe inside the womb when its lungs are entirely filled with fluids?","ELI5: What is deli turkey?","ELI5: why do property investors prefer houses standing empty and earning them no money to lowering rent so that people can afford to move in there?","ELI5: If the B2 looks like a small bird on radar, doesn’t it look like a small bird flying at 600mph?","ELI5: How was Vietnam able to defeat the US in the Vietnam War?","ELI5 Is all power generation really just making a turbine spin?","ELI5 how is masking for autistic people different from impulse control?","ELI5: Why has rabies not entirely decimated the world?","ELI5: Fentanyl and related drugs can sometimes cause the user to fold over while standing…why don’t they just sit down? Am I missing something?","Eli5, file compression, how can 5gb file can be compressed to 50mb and decompresses back to normal?","ELI5 : What happens if someone needs an emergency colonoscopy during an ER visit or other acute situation. They obviously aren't \"prepped\" with an empty colon. Can they clean out a bowel instantly if needed?","ELI5: Why can our bodies handle walking for miles, but standing still for a short while feels tiring and uncomfortable?","ELI5 why a second is defined as 197 billion oscillations of a cesium atom?","ELI5: Why does armpit sweat smell so much stronger than sweat from other parts of the body, like your back?","ELI5: Why can't we digest our own blood?","ELI5: H-bombs can reach 300 million Kelvin during detonation; the sun’s surface is 5772 Kelvin. Why can’t we get anywhere near the sun, but a H-bomb wouldn’t burn up the earth?","ELI5: How do they keep managing to make computers faster every year without hitting a wall? For example, why did we not have RTX 5090 level GPUs 10 years ago? What do we have now that we did not have back then, and why did we not have it back then, and why do we have it now?","ELI5 How the heck can the US bunker buster bomb go 200’ underground before it explodes?","ELI5: Can beer hydrate you indefinitely?","ELI5: Why have so many animals evolved to have exactly 2 eyes?","ELI5: Why are the seatbelts in airplane like the way they are (waist to waist) and not the way we have in cars (diagonally shoulder to waist)?","Eli5: how did 350 degrees become such a standard in all thing baking and roasting etc…?","ELI5 How protective are those padded bomb squad suits really?","ELI5: Why do animals all seem to like getting their chins/necks scratched?","ELI5: What actually happens when someone dies in their sleep?","ELI5: If dogs have such great sense of smell, why do they have to get their noses right up against another dog's butt?","ELI5: Why do Stars take so long to burn all their fuel, i know its a lot of fuel, but why doesnt it all burn about the same time? Like when im throwing something in a firepit","ELI5 why men go bald but women typically don't. Can evolution explain things that occur after an organism leaves its reproductive age?","ELI5: How do people die from gunshot or stab wounds days later?","ELI5 'The Panama Papers' and why it fizzled out so quickly?","ELI5: How do our organs sit inside our body if not soaked in blood?","ELI5: Why is it comfortable to sit in positions that are bad for you? Why do we frequently have bad posture?","ELI5 Why do some trees have fruits with a rewarding taste like saying \"come back again :)\" and some others have fruits with a punishing taste and even protection around the fruit like \"don't u even dare eat my fruits! >:/\"","ELI5: Why do so many websites care that you're using a VPN?","ELI5: Why does ice cream seem soft the first time you open it but it gets really hard the next time you take it out of the freezer?","ELI5: I learned that cpr is not, as usually assumed, for bringing people back to life, but for keeping the blood flowing until the medics arrive for reanimating. But now I realized I saw a lot of videos where especially animals where revived by cpr? So what is the chance of reviving someone with cpr","ELI5: Do we need to clean our ears?","ELI5: Why is a grenade more dangerous underwater than on land?","ELI5: Why can’t you buy a car directly from the company that makes it?","ELI5 Why does our stomach growl when we’re hungry?","ELI5: Why can't / don't LLMs say \"I don't know\" or ask back clarifying questions, instead of hallucinating?","eli5: Why do elderly people have a distinct odor?","ELI5: How do “buy now pay later” companies make money if there’s no interest","ELI5 Why do we throw up when we are extremely exhausted eg from a marathon?","ELI5: why do some books have pages that read: “this page has intentionally been left blank”","ELI5: Why do phones and EVs say to keep the battery around 20–80%? What’s physically happening at the extremes that wears batteries faster?","ELI5: why did we use mothball in 90s, but we don't use them now?","ELI5: Why do we do root canals instead of just pulling a tooth?","ELI5: Why dont MRIs rip the iron out of your body? Especially when iron deposits are present.","ELI5: Humans have lived on Earth for millions of years, so why haven’t we adapted to the harmful rays of the sun?","ELI5: What exactly is \"time blindness\" and how is it an actual thing?"]
pages/demos/accordion.ts:1:import { layout, prepare, type PreparedText } from '../../src/layout.ts'
pages/demos/accordion.ts:49:      'We learned the hard way that a giant native scroll range can dominate everything else. The bug looked like DOM churn, then like pooling, then like rendering pressure, until the repros were stripped down enough to show the real limit. That changed the fix completely: simplify the DOM, keep virtualization honest, and stop hiding the worst-case path behind caches that only make the common frame look cheaper.',
pages/demos/accordion.ts:68:const preparedCache = {
pages/demos/accordion.ts:137:  if (preparedCache.font === font) return
pages/demos/accordion.ts:138:  preparedCache.font = font
pages/demos/accordion.ts:139:  preparedCache.items = items.map(item => prepare(item.text, font))
pages/demos/accordion.ts:207:    const metrics = layout(preparedCache.items[index]!, contentWidth, lineHeight)
pages/demos/variable-typographic-ascii.html:19:    .comparison { display: flex; gap: 28px; flex-wrap: wrap; justify-content: center; }

>sed -n '1,240p' pages/demos/masonry/index.ts

Command: /bin/zsh -lc "sed -n '1,240p' pages/demos/masonry/index.ts"
Chunk ID: 732281
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1159
Output:
import { prepare, layout, type PreparedText } from '../../../src/layout.ts'
import rawThoughts from './shower-thoughts.json'

// --- config ---
const font = '15px "Helvetica Neue", Helvetica, Arial, sans-serif'
const lineHeight = 22
const cardPadding = 16
const gap = 12
const maxColWidth = 400
const singleColumnMaxViewportWidth = 520

type Card = {
  text: string
  prepared: PreparedText
}

type PositionedCard = {
  cardIndex: number
  x: number
  y: number
  h: number
}

type LayoutState = {
  colWidth: number
  contentHeight: number
  positionedCards: PositionedCard[]
}

type State = {
  cards: Card[]
}

// --- prepare all texts upfront ---
const st: State = {
  cards: rawThoughts.map(text => ({
    text,
    prepared: prepare(text, font),
  })),
}

type DomCache = {
  container: HTMLDivElement // cache lifetime: same as app
  cards: Array<HTMLDivElement | undefined> // cache lifetime: on visibility changes
}

const domCache: DomCache = {
  container: document.createElement('div'),
  cards: [],
}

domCache.container.style.position = 'relative'
document.body.appendChild(domCache.container)

function computeLayout(windowWidth: number): LayoutState {
  let colCount: number
  let colWidth: number
  if (windowWidth <= singleColumnMaxViewportWidth) {
    colCount = 1
    colWidth = Math.min(maxColWidth, windowWidth - gap * 2)
  } else {
    const minColWidth = 100 + windowWidth * 0.1
    colCount = Math.max(2, Math.floor((windowWidth + gap) / (minColWidth + gap)))
    colWidth = Math.min(maxColWidth, (windowWidth - (colCount + 1) * gap) / colCount)
  }
  const textWidth = colWidth - cardPadding * 2
  const contentWidth = colCount * colWidth + (colCount - 1) * gap
  const offsetLeft = (windowWidth - contentWidth) / 2

  const colHeights = new Float64Array(colCount)
  for (let c = 0; c < colCount; c++) colHeights[c] = gap

  const positionedCards: PositionedCard[] = []
  for (let i = 0; i < st.cards.length; i++) {
    let shortest = 0
    for (let c = 1; c < colCount; c++) {
      if (colHeights[c]! < colHeights[shortest]!) shortest = c
    }

    const { height } = layout(st.cards[i]!.prepared, textWidth, lineHeight)
    const totalH = height + cardPadding * 2

    positionedCards.push({
      cardIndex: i,
      x: offsetLeft + shortest * (colWidth + gap),
      y: colHeights[shortest]!,
      h: totalH,
    })

    colHeights[shortest]! += totalH + gap
  }

  let contentHeight = 0
  for (let c = 0; c < colCount; c++) {
    if (colHeights[c]! > contentHeight) contentHeight = colHeights[c]!
  }

  return { colWidth, contentHeight, positionedCards }
}

function getOrCreateCardNode(cardIndex: number): HTMLDivElement {
  const existingNode = domCache.cards[cardIndex]
  if (existingNode) return existingNode

  const node = document.createElement('div')
  node.className = 'card'
  node.textContent = st.cards[cardIndex]!.text
  domCache.container.appendChild(node)
  domCache.cards[cardIndex] = node
  return node
}

// --- events ---
window.addEventListener('resize', () => scheduleRender())
window.addEventListener('scroll', () => scheduleRender(), true)

let scheduledRaf: number | null = null
function scheduleRender() {
  if (scheduledRaf != null) return
  scheduledRaf = requestAnimationFrame(function renderAndMaybeScheduleAnotherRender() {
    scheduledRaf = null
    render()
  })
}

function render() {
  // --- DOM reads ---
  const windowWidth = document.documentElement.clientWidth
  const windowHeight = document.documentElement.clientHeight
  const scrollTop = window.scrollY

  const layoutState = computeLayout(windowWidth)
  domCache.container.style.height = `${layoutState.contentHeight}px`

  // --- visibility + DOM writes (single pass) ---
  const viewTop = scrollTop - 200
  const viewBottom = scrollTop + windowHeight + 200
  const visibleFlags = new Uint8Array(st.cards.length)

  for (let i = 0; i < layoutState.positionedCards.length; i++) {
    const positionedCard = layoutState.positionedCards[i]!
    if (positionedCard.y > viewBottom || positionedCard.y + positionedCard.h < viewTop) continue

    visibleFlags[positionedCard.cardIndex] = 1
    const node = getOrCreateCardNode(positionedCard.cardIndex)
    node.style.left = `${positionedCard.x}px`
    node.style.top = `${positionedCard.y}px`
    node.style.width = `${layoutState.colWidth}px`
    node.style.height = `${positionedCard.h}px`
  }

  for (let cardIndex = 0; cardIndex < domCache.cards.length; cardIndex++) {
    const node = domCache.cards[cardIndex]
    if (node && visibleFlags[cardIndex] === 0) {
      node.remove()
      domCache.cards[cardIndex] = undefined
    }
  }
}

scheduleRender()

>sed -n '1,260p' pages/demos/wrap-geometry.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/demos/wrap-geometry.ts"
Chunk ID: 6d727a
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1982
Output:
export type Rect = {
  x: number
  y: number
  width: number
  height: number
}

export type Interval = {
  left: number
  right: number
}

export type Point = {
  x: number
  y: number
}

export type WrapHullMode = 'mean' | 'envelope'

export type WrapHullOptions = {
  smoothRadius: number
  mode: WrapHullMode
  convexify?: boolean
}

const wrapHullByKey = new Map<string, Promise<Point[]>>()

export function getWrapHull(src: string, options: WrapHullOptions): Promise<Point[]> {
  const key = `${src}::${options.mode}::${options.smoothRadius}::${options.convexify ? 'convex' : 'raw'}`
  const cached = wrapHullByKey.get(key)
  if (cached !== undefined) return cached
  const promise = makeWrapHull(src, options)
  wrapHullByKey.set(key, promise)
  return promise
}

export function transformWrapPoints(points: Point[], rect: Rect, angle: number): Point[] {
  if (angle === 0) {
    return points.map(point => ({
        x: rect.x + point.x * rect.width,
        y: rect.y + point.y * rect.height,
    }))
  }

  const centerX = rect.x + rect.width / 2
  const centerY = rect.y + rect.height / 2
  const cos = Math.cos(angle)
  const sin = Math.sin(angle)

  return points.map(point => {
    const localX = (point.x - 0.5) * rect.width
    const localY = (point.y - 0.5) * rect.height
    return {
      x: centerX + localX * cos - localY * sin,
      y: centerY + localX * sin + localY * cos,
    }
  })
}

export function isPointInPolygon(points: Point[], x: number, y: number): boolean {
  let inside = false
  for (let index = 0, prev = points.length - 1; index < points.length; prev = index++) {
    const a = points[index]!
    const b = points[prev]!
    const intersects =
      ((a.y > y) !== (b.y > y)) &&
      (x < ((b.x - a.x) * (y - a.y)) / (b.y - a.y) + a.x)
    if (intersects) inside = !inside
  }
  return inside
}

export function getPolygonIntervalForBand(
  points: Point[],
  bandTop: number,
  bandBottom: number,
  horizontalPadding: number,
  verticalPadding: number,
): Interval | null {
  const sampleTop = bandTop - verticalPadding
  const sampleBottom = bandBottom + verticalPadding
  const startY = Math.floor(sampleTop)
  const endY = Math.ceil(sampleBottom)

  let left = Infinity
  let right = -Infinity

  for (let y = startY; y <= endY; y++) {
    const xs = getPolygonXsAtY(points, y + 0.5)
    for (let index = 0; index + 1 < xs.length; index += 2) {
      const runLeft = xs[index]!
      const runRight = xs[index + 1]!
      if (runLeft < left) left = runLeft
      if (runRight > right) right = runRight
    }
  }

  if (!Number.isFinite(left) || !Number.isFinite(right)) return null
  return { left: left - horizontalPadding, right: right + horizontalPadding }
}

export function getRectIntervalsForBand(
  rects: Rect[],
  bandTop: number,
  bandBottom: number,
  horizontalPadding: number,
  verticalPadding: number,
): Interval[] {
  const intervals: Interval[] = []
  for (let index = 0; index < rects.length; index++) {
    const rect = rects[index]!
    if (bandBottom <= rect.y - verticalPadding || bandTop >= rect.y + rect.height + verticalPadding) continue
    intervals.push({
      left: rect.x - horizontalPadding,
      right: rect.x + rect.width + horizontalPadding,
    })
  }
  return intervals
}

// Given one allowed horizontal interval and a set of blocked intervals,
// carve out the remaining usable text slots for one text line band.
//
// Example:
// - base:    80..420
// - blocked: 200..310
// - result:  80..200, 310..420
//
// On the dynamic-layout page, the base interval is one full column row,
// the blocked intervals come from the title/logo shapes at that band,
// and the returned intervals are the candidate text slots for that row.
//
// This helper is intentionally page-oriented, not pure geometry:
// it also discards absurdly narrow leftover slivers that we would never
// want to hand to text layout.
export function carveTextLineSlots(base: Interval, blocked: Interval[]): Interval[] {
  let slots: Interval[] = [base]

  for (let blockedIndex = 0; blockedIndex < blocked.length; blockedIndex++) {
    const interval = blocked[blockedIndex]!
    const next: Interval[] = []
    for (let slotIndex = 0; slotIndex < slots.length; slotIndex++) {
      const slot = slots[slotIndex]!
      if (interval.right <= slot.left || interval.left >= slot.right) {
        next.push(slot)
        continue
      }
      if (interval.left > slot.left) next.push({ left: slot.left, right: interval.left })
      if (interval.right < slot.right) next.push({ left: interval.right, right: slot.right })
    }
    slots = next
  }

  return slots.filter(slot => slot.right - slot.left >= 24)
}

async function makeWrapHull(src: string, options: WrapHullOptions): Promise<Point[]> {
  const image = new Image()
  image.src = src
  await image.decode()

  const maxDimension = 320
  const aspect = image.naturalWidth / image.naturalHeight
  const width = aspect >= 1
    ? maxDimension
    : Math.max(64, Math.round(maxDimension * aspect))
  const height = aspect >= 1
    ? Math.max(64, Math.round(maxDimension / aspect))
    : maxDimension

  const canvas = new OffscreenCanvas(width, height)
  const ctx = canvas.getContext('2d')
  if (ctx === null) throw new Error('2d context unavailable')

  ctx.clearRect(0, 0, width, height)
  ctx.drawImage(image, 0, 0, width, height)

  const { data } = ctx.getImageData(0, 0, width, height)
  const lefts: Array<number | null> = new Array(height).fill(null)
  const rights: Array<number | null> = new Array(height).fill(null)
  const alphaThreshold = 12

  for (let y = 0; y < height; y++) {
    let left = -1
    let right = -1
    for (let x = 0; x < width; x++) {
      const alpha = data[(y * width + x) * 4 + 3]!
      if (alpha < alphaThreshold) continue
      if (left === -1) left = x
      right = x
    }
    if (left !== -1 && right !== -1) {
      lefts[y] = left
      rights[y] = right + 1
    }
  }

  const validRows: number[] = []
  for (let y = 0; y < height; y++) {
    if (lefts[y] !== null && rights[y] !== null) validRows.push(y)
  }
  if (validRows.length === 0) throw new Error(`No opaque pixels found in ${src}`)

  let boundLeft = Infinity
  let boundRight = -Infinity
  const boundTop = validRows[0]!
  const boundBottom = validRows[validRows.length - 1]!
  for (let index = 0; index < validRows.length; index++) {
    const y = validRows[index]!
    const left = lefts[y]!
    const right = rights[y]!
    if (left < boundLeft) boundLeft = left
    if (right > boundRight) boundRight = right
  }
  const boundWidth = Math.max(1, boundRight - boundLeft)
  const boundHeight = Math.max(1, boundBottom - boundTop)

  const smoothedLefts: number[] = new Array(height).fill(0)
  const smoothedRights: number[] = new Array(height).fill(0)

  for (let index = 0; index < validRows.length; index++) {
    const y = validRows[index]!
    let leftSum = 0
    let rightSum = 0
    let count = 0
    let leftEdge = Infinity
    let rightEdge = -Infinity
    for (let offset = -options.smoothRadius; offset <= options.smoothRadius; offset++) {
      const sampleIndex = y + offset
      if (sampleIndex < 0 || sampleIndex >= height) continue
      const left = lefts[sampleIndex]
      const right = rights[sampleIndex]
      if (left == null || right == null) continue
      leftSum += left
      rightSum += right
      if (left < leftEdge) leftEdge = left
      if (right > rightEdge) rightEdge = right
      count++
    }

    if (count === 0) {
      smoothedLefts[y] = 0
      smoothedRights[y] = width
      continue
    }

    switch (options.mode) {
      case 'envelope':
        smoothedLefts[y] = leftEdge
        smoothedRights[y] = rightEdge
        break
      case 'mean':
        smoothedLefts[y] = leftSum / count
        smoothedRights[y] = rightSum / count
        break
    }
  }

  const step = Math.max(1, Math.floor(validRows.length / 52))
  const sampledRows: number[] = []

>sed -n '1,260p' pages/demos/rich-note.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/demos/rich-note.ts"
Chunk ID: d20ce6
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1984
Output:
import {
  layoutNextLine,
  prepareWithSegments,
  walkLineRanges,
  type LayoutCursor,
  type PreparedTextWithSegments,
} from '../../src/layout.ts'

type TextStyleName = 'body' | 'link' | 'code'
type ChipTone = 'mention' | 'status' | 'priority' | 'time' | 'count'

type RichInlineSpec =
  | { kind: 'text'; text: string; style: TextStyleName }
  | { kind: 'chip'; label: string; tone: ChipTone }

type TextStyleModel = {
  className: string
  chromeWidth: number
  font: string
}

type TextInlineItem = {
  kind: 'text'
  className: string
  chromeWidth: number
  endCursor: LayoutCursor
  fullText: string
  fullWidth: number
  leadingGap: number
  prepared: PreparedTextWithSegments
}

type ChipInlineItem = {
  kind: 'chip'
  className: string
  leadingGap: number
  text: string
  width: number
}

type InlineItem = TextInlineItem | ChipInlineItem

type LineFragment = {
  className: string
  leadingGap: number
  text: string
}

type RichLine = {
  fragments: LineFragment[]
}

type State = {
  events: {
    sliderValue: number | null
  }
  requestedWidth: number
}

const BODY_FONT = '500 17px "Helvetica Neue", Helvetica, Arial, sans-serif'
const LINK_FONT = '600 17px "Helvetica Neue", Helvetica, Arial, sans-serif'
const CODE_FONT = '600 14px "SF Mono", ui-monospace, Menlo, Monaco, monospace'
const CHIP_FONT = '700 12px "Helvetica Neue", Helvetica, Arial, sans-serif'

const TEXT_STYLES = {
  body: {
    className: 'frag frag--body',
    chromeWidth: 0,
    font: BODY_FONT,
  },
  code: {
    className: 'frag frag--code',
    chromeWidth: 14,
    font: CODE_FONT,
  },
  link: {
    className: 'frag frag--link',
    chromeWidth: 0,
    font: LINK_FONT,
  },
} satisfies Record<TextStyleName, TextStyleModel>

const CHIP_CLASS_NAMES = {
  count: 'frag chip chip--count',
  mention: 'frag chip chip--mention',
  priority: 'frag chip chip--priority',
  status: 'frag chip chip--status',
  time: 'frag chip chip--time',
} satisfies Record<ChipTone, string>

const LINE_START_CURSOR: LayoutCursor = { segmentIndex: 0, graphemeIndex: 0 }

const LINE_HEIGHT = 34
const LAST_LINE_BLOCK_HEIGHT = 24
const NOTE_SHELL_CHROME_X = 40
const BODY_MIN_WIDTH = 260
const BODY_DEFAULT_WIDTH = 516
const BODY_MAX_WIDTH = 760
const PAGE_MARGIN = 28
const CHIP_CHROME_WIDTH = 22
const UNBOUNDED_WIDTH = 100_000

const collapsedSpaceWidthCache = new Map<string, number>()
const INLINE_BOUNDARY_GAP = measureCollapsedSpaceWidth(BODY_FONT)

const INLINE_SPECS: RichInlineSpec[] = [
  { kind: 'text', text: 'Ship ', style: 'body' },
  { kind: 'chip', label: '@maya', tone: 'mention' },
  { kind: 'text', text: "'s ", style: 'body' },
  { kind: 'text', text: 'rich-note', style: 'code' },
  { kind: 'text', text: ' card once ', style: 'body' },
  { kind: 'text', text: 'pre-wrap', style: 'code' },
  { kind: 'text', text: ' lands. Status ', style: 'body' },
  { kind: 'chip', label: 'blocked', tone: 'status' },
  { kind: 'text', text: ' by ', style: 'body' },
  { kind: 'text', text: 'vertical text', style: 'link' },
  { kind: 'text', text: ' research, but 北京 copy and Arabic QA are both green ✅. Keep ', style: 'body' },
  { kind: 'chip', label: 'جاهز', tone: 'status' },
  { kind: 'text', text: ' for ', style: 'body' },
  { kind: 'text', text: 'Cmd+K', style: 'code' },
  { kind: 'text', text: ' docs; the review bundle now includes 中文 labels, عربي fallback, and one more launch pass 🚀 for ', style: 'body' },
  { kind: 'chip', label: 'Fri 2:30 PM', tone: 'time' },
  { kind: 'text', text: '. Keep ', style: 'body' },
  { kind: 'text', text: 'layoutNextLine()', style: 'code' },
  { kind: 'text', text: ' public, tag this ', style: 'body' },
  { kind: 'chip', label: 'P1', tone: 'priority' },
  { kind: 'text', text: ', keep ', style: 'body' },
  { kind: 'chip', label: '3 reviewers', tone: 'count' },
  { kind: 'text', text: ', and route feedback to ', style: 'body' },
  { kind: 'text', text: 'design sync', style: 'link' },
  { kind: 'text', text: '.', style: 'body' },
]

const domCache = {
  root: document.documentElement, // cache lifetime: page
  noteBody: getRequiredDiv('note-body'), // cache lifetime: page
  widthSlider: getRequiredInput('width-slider'), // cache lifetime: page
  widthValue: getRequiredSpan('width-value'), // cache lifetime: page
}

const items = prepareInlineItems(INLINE_SPECS)

const st: State = {
  events: {
    sliderValue: null,
  },
  requestedWidth: BODY_DEFAULT_WIDTH,
}

let scheduledRaf: number | null = null

domCache.widthSlider.addEventListener('input', () => {
  st.events.sliderValue = Number.parseInt(domCache.widthSlider.value, 10)
  scheduleRender()
})

window.addEventListener('resize', () => scheduleRender())

scheduleRender()

function getRequiredDiv(id: string): HTMLDivElement {
  const element = document.getElementById(id)
  if (!(element instanceof HTMLDivElement)) throw new Error(`#${id} not found`)
  return element
}

function getRequiredInput(id: string): HTMLInputElement {
  const element = document.getElementById(id)
  if (!(element instanceof HTMLInputElement)) throw new Error(`#${id} not found`)
  return element
}

function getRequiredSpan(id: string): HTMLSpanElement {
  const element = document.getElementById(id)
  if (!(element instanceof HTMLSpanElement)) throw new Error(`#${id} not found`)
  return element
}

function scheduleRender(): void {
  if (scheduledRaf !== null) return
  scheduledRaf = requestAnimationFrame(function renderRichNoteDemo() {
    scheduledRaf = null
    render()
  })
}

function measureSingleLineWidth(prepared: PreparedTextWithSegments): number {
  let maxWidth = 0
  walkLineRanges(prepared, UNBOUNDED_WIDTH, line => {
    if (line.width > maxWidth) maxWidth = line.width
  })
  return maxWidth
}

function measureCollapsedSpaceWidth(font: string): number {
  const cached = collapsedSpaceWidthCache.get(font)
  if (cached !== undefined) return cached

  const joinedWidth = measureSingleLineWidth(prepareWithSegments('A A', font))
  const compactWidth = measureSingleLineWidth(prepareWithSegments('AA', font))
  const collapsedWidth = Math.max(0, joinedWidth - compactWidth)
  collapsedSpaceWidthCache.set(font, collapsedWidth)
  return collapsedWidth
}

function prepareInlineItems(specs: RichInlineSpec[]): InlineItem[] {
  const items: InlineItem[] = []
  let pendingGap = 0

  for (let index = 0; index < specs.length; index++) {
    const spec = specs[index]!

    switch (spec.kind) {
      case 'chip': {
        const prepared = prepareWithSegments(spec.label, CHIP_FONT)
        items.push({
          kind: 'chip',
          className: CHIP_CLASS_NAMES[spec.tone],
          leadingGap: pendingGap,
          text: spec.label,
          width: Math.ceil(measureSingleLineWidth(prepared)) + CHIP_CHROME_WIDTH,
        })
        pendingGap = 0
        break
      }

      case 'text': {
        const carryGap = pendingGap
        const hasLeadingWhitespace = /^\s/.test(spec.text)
        const hasTrailingWhitespace = /\s$/.test(spec.text)
        const trimmedText = spec.text.trim()
        pendingGap = hasTrailingWhitespace ? INLINE_BOUNDARY_GAP : 0
        if (trimmedText.length === 0) break

        const style = TEXT_STYLES[spec.style]
        const prepared = prepareWithSegments(trimmedText, style.font)
        const wholeLine = layoutNextLine(prepared, LINE_START_CURSOR, UNBOUNDED_WIDTH)
        if (wholeLine === null) break

        items.push({
          kind: 'text',
          className: style.className,
          chromeWidth: style.chromeWidth,
          endCursor: wholeLine.end,
          fullText: wholeLine.text,
          fullWidth: wholeLine.width,
          leadingGap: carryGap > 0 || hasLeadingWhitespace ? INLINE_BOUNDARY_GAP : 0,
          prepared,
        })
        break
      }
    }
  }

  return items
}

function cursorsMatch(a: LayoutCursor, b: LayoutCursor): boolean {
  return a.segmentIndex === b.segmentIndex && a.graphemeIndex === b.graphemeIndex
}

>sed -n '1,260p' pages/demos/editorial-engine.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/demos/editorial-engine.ts"
Chunk ID: 05364a
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 4447
Output:
import {
  layoutNextLine,
  layoutWithLines,
  prepareWithSegments,
  walkLineRanges,
  type LayoutCursor,
  type PreparedTextWithSegments,
} from '../../src/layout.ts'

const BODY_FONT = '18px "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Palatino, serif'
const BODY_LINE_HEIGHT = 30
const HEADLINE_FONT_FAMILY = '"Iowan Old Style", "Palatino Linotype", "Book Antiqua", Palatino, serif'
const HEADLINE_TEXT = 'THE FUTURE OF TEXT LAYOUT IS NOT CSS'
const GUTTER = 48
const COL_GAP = 40
const BOTTOM_GAP = 20
const DROP_CAP_LINES = 3
const MIN_SLOT_WIDTH = 50
const NARROW_BREAKPOINT = 760
const NARROW_GUTTER = 20
const NARROW_COL_GAP = 20
const NARROW_BOTTOM_GAP = 16
const NARROW_ORB_SCALE = 0.58
const NARROW_ACTIVE_ORBS = 3

type Interval = {
  left: number
  right: number
}

type PositionedLine = {
  x: number
  y: number
  width: number
  text: string
}

type TextProjection = {
  headlineLeft: number
  headlineTop: number
  headlineFont: string
  headlineLineHeight: number
  headlineLines: PositionedLine[]
  bodyFont: string
  bodyLineHeight: number
  bodyLines: PositionedLine[]
  pullquoteFont: string
  pullquoteLineHeight: number
  pullquoteLines: PositionedLine[]
}

type CircleObstacle = {
  cx: number
  cy: number
  r: number
  hPad: number
  vPad: number
}

type RectObstacle = {
  x: number
  y: number
  w: number
  h: number
}

type PullquotePlacement = {
  colIdx: number
  yFrac: number
  wFrac: number
  side: 'left' | 'right'
}

type PullquoteRect = RectObstacle & {
  lines: PositionedLine[]
  colIdx: number
}

type OrbColor = [number, number, number]

type OrbDefinition = {
  fx: number
  fy: number
  r: number
  vx: number
  vy: number
  color: OrbColor
}

type Orb = {
  x: number
  y: number
  r: number
  vx: number
  vy: number
  paused: boolean
}

type HeadlineFit = {
  fontSize: number
  lines: PositionedLine[]
}

type PullquoteSpec = {
  prepared: PreparedTextWithSegments
  placement: PullquotePlacement
}

type PointerSample = {
  x: number
  y: number
}

type PointerState = {
  x: number
  y: number
}

type DragState = {
  orbIndex: number
  startPointerX: number
  startPointerY: number
  startOrbX: number
  startOrbY: number
}

type InteractionMode = 'idle' | 'text-select'

type AppState = {
  orbs: Orb[]
  pointer: PointerState
  drag: DragState | null
  interactionMode: InteractionMode
  selectionActive: boolean
  events: {
    pointerDown: PointerSample | null
    pointerMove: PointerSample | null
    pointerUp: PointerSample | null
  }
  lastFrameTime: number | null
}

function getRequiredDiv(id: string): HTMLDivElement {
  const element = document.getElementById(id)
  if (!(element instanceof HTMLDivElement)) throw new Error(`#${id} not found`)
  return element
}

function carveTextLineSlots(base: Interval, blocked: Interval[]): Interval[] {
  let slots = [base]
  for (let blockedIndex = 0; blockedIndex < blocked.length; blockedIndex++) {
    const interval = blocked[blockedIndex]!
    const next: Interval[] = []
    for (let slotIndex = 0; slotIndex < slots.length; slotIndex++) {
      const slot = slots[slotIndex]!
      if (interval.right <= slot.left || interval.left >= slot.right) {
        next.push(slot)
        continue
      }
      if (interval.left > slot.left) next.push({ left: slot.left, right: interval.left })
      if (interval.right < slot.right) next.push({ left: interval.right, right: slot.right })
    }
    slots = next
  }
  return slots.filter(slot => slot.right - slot.left >= MIN_SLOT_WIDTH)
}

function circleIntervalForBand(
  cx: number,
  cy: number,
  r: number,
  bandTop: number,
  bandBottom: number,
  hPad: number,
  vPad: number,
): Interval | null {
  const top = bandTop - vPad
  const bottom = bandBottom + vPad
  if (top >= cy + r || bottom <= cy - r) return null
  const minDy = cy >= top && cy <= bottom ? 0 : cy < top ? top - cy : cy - bottom
  if (minDy >= r) return null
  const maxDx = Math.sqrt(r * r - minDy * minDy)
  return { left: cx - maxDx - hPad, right: cx + maxDx + hPad }
}

const BODY_TEXT = `The web renders text through a pipeline that was designed thirty years ago for static documents. A browser loads a font, shapes the text into glyphs, measures their combined width, determines where lines break, and positions each line vertically. Every step depends on the previous one. Every step requires the rendering engine to consult its internal layout tree — a structure so expensive to maintain that browsers guard access to it behind synchronous reflow barriers that can freeze the main thread for tens of milliseconds at a time.

For a paragraph in a blog post, this pipeline is invisible. The browser loads, lays out, and paints before the reader’s eye has traveled from the address bar to the first word. But the web is no longer a collection of static documents. It is a platform for applications, and those applications need to know about text in ways the original pipeline never anticipated.

A messaging application needs to know the exact height of every message bubble before rendering a virtualized list. A masonry layout needs the height of every card to position them without overlap. An editorial page needs text to flow around images, advertisements, and interactive elements. A responsive dashboard needs to resize and reflow text in real time as the user drags a panel divider.

Every one of these operations requires text measurement. And every text measurement on the web today requires a synchronous layout reflow. The cost is devastating. Measuring the height of a single text block forces the browser to recalculate the position of every element on the page. When you measure five hundred text blocks in sequence, you trigger five hundred full layout passes. This pattern, known as layout thrashing, is the single largest source of jank on the modern web.

Chrome DevTools will flag it with angry red bars. Lighthouse will dock your performance score. But the developer has no alternative — CSS provides no API for computing text height without rendering it. The information is locked behind the DOM, and the DOM makes you pay for every answer.

Developers have invented increasingly desperate workarounds. Estimated heights replace real measurements with guesses, causing content to visibly jump when the guess is wrong. ResizeObserver watches elements for size changes, but it fires asynchronously and always at least one frame too late. IntersectionObserver tracks visibility but says nothing about dimensions. Content-visibility allows the browser to skip rendering off-screen elements, but it breaks scroll position and accessibility. Each workaround addresses one symptom while introducing new problems.

The CSS Shapes specification, finalized in 2014, was supposed to bring magazine-style text wrap to the web. It allows text to flow around a defined shape — a circle, an ellipse, a polygon, even an image alpha channel. On paper, it was the answer. In practice, it is remarkably limited. CSS Shapes only works with floated elements. Text can only wrap on one side of the shape. The shape must be defined statically in CSS — you cannot animate it or change it dynamically without triggering a full layout reflow. And because it operates within the browser’s layout engine, you have no access to the resulting line geometry. You cannot determine where each line of text starts and ends, how many lines were generated, or what the total height of the shaped text block is.

The editorial layouts we see in print magazines — text flowing around photographs, pull quotes interrupting the column, multiple columns with seamless text handoff — have remained out of reach for the web. Not because they are conceptually difficult, but because the performance cost of implementing them with DOM measurement makes them impractical. A two-column editorial layout that reflows text around three obstacle shapes requires measuring and positioning hundreds of text lines. At thirty milliseconds per measurement, this would take seconds — an eternity for a render frame.

What if text measurement did not require the DOM at all? What if you could compute exactly where every line of text would break, exactly how wide each line would be, and exactly how tall the entire text block would be, using nothing but arithmetic?

This is the core insight of pretext. The browser’s canvas API includes a measureText method that returns the width of any string in any font without triggering a layout reflow. Canvas measurement uses the same font engine as DOM rendering — the results are identical. But because it operates outside the layout tree, it carries no reflow penalty.

Pretext exploits this asymmetry. When text first appears, pretext measures every word once via canvas and caches the widths. After this preparation phase, layout is pure arithmetic: walk the cached widths, track the running line width, insert line breaks when the width exceeds the maximum, and sum the line heights. No DOM. No reflow. No layout tree access.

The performance improvement is not incremental. Measuring five hundred text blocks with DOM methods costs fifteen to thirty milliseconds and triggers five hundred layout reflows. With pretext, the same operation costs 0.05 milliseconds and triggers zero reflows. This is a three hundred to six hundred times improvement. But even that number understates the impact, because pretext’s cost does not scale with page complexity — it is independent of how many other elements exist on the page.

With DOM-free text measurement, an entire class of previously impractical interfaces becomes trivial. Text can flow around arbitrary shapes, not because the browser’s layout engine supports it, but because you control the line widths directly. For each line of text, you compute which horizontal intervals are blocked by obstacles, subtract them from the available width, and pass the remaining width to the layout engine. The engine returns the text that fits, and you position the line at the correct offset.

This is exactly what CSS Shapes tried to accomplish, but with none of its limitations. Obstacles can be any shape — rectangles, circles, arbitrary polygons, even the alpha channel of an image. Text wraps on both sides simultaneously. Obstacles can move, animate, or be dragged by the user, and the text reflows instantly because the layout computation takes less than a millisecond.

Shrinkwrap is another capability that CSS cannot express. Given a block of multiline text, what is the narrowest width that preserves the current line count? CSS offers fit-content, which works for single lines but always leaves dead space for multiline text. Pretext solves this with a binary search over widths: narrow until the line count increases, then back off. The result is the tightest possible bounding box — perfect for chat message bubbles, image captions, and tooltip text.

Virtualized text rendering becomes exact rather than estimated. A virtual list needs to know the height of items before they enter the viewport, so it can position them correctly and calculate scroll extent. Without pretext, you must either render items off-screen to measure them (defeating the purpose of virtualization) or estimate heights and accept visual jumping when items enter the viewport with different heights than predicted. Pretext computes exact heights without creating any DOM elements, enabling perfect virtualization with zero visual artifacts.

Multi-column text flow with cursor handoff is perhaps the most striking capability. The left column consumes text until it reaches the bottom, then hands its cursor to the right column. The right column picks up exactly where the left column stopped, with no duplication, no gap, and perfect line breaking at the column boundary. This is how newspapers and magazines work on paper, but it has never been achievable on the web without extreme hacks involving multiple elements, hidden overflow, and JavaScript-managed content splitting.

Pretext makes it trivial. Call layoutNextLine in a loop for the first column, using the column width. When the column is full, take the returned cursor and start a new loop for the second column. The cursor carries the exact position in the prepared text — which segment, which grapheme within that segment. The second column continues seamlessly from the first.

Adaptive headline sizing is a detail that separates professional typography from amateur layout. The headline should be as large as possible without breaking any word across lines. This requires a binary search: try a font size, measure the text, check if any line breaks occur within a word, and adjust. With DOM measurement, each iteration costs a reflow. With pretext, each iteration is a microsecond of arithmetic.

Real-time text reflow around animated obstacles is the ultimate stress test. The demonstration you are reading right now renders text that flows around multiple moving objects simultaneously, every frame, at sixty frames per second. Each frame, the layout engine computes obstacle intersections for every line of text, determines the available horizontal slots, lays out each line at the correct width and position, and updates the DOM with the results. The total computation time is typically under half a millisecond.

The glowing orbs drifting across this page are not decorative — they are the demonstration. Each orb is a circular obstacle. For every line of text, the engine checks whether the line’s vertical band intersects each orb. If it does, it computes the blocked horizontal interval and subtracts it from the available width. The remaining width might be split into two or more segments — and the engine fills every viable slot, flowing text on both sides of the obstacle simultaneously. This is something CSS Shapes cannot do at all.

All of this runs without a single DOM measurement. The line positions, widths, and text contents are computed entirely in JavaScript using cached font metrics. The only DOM writes are setting the left, top, and textContent of each line element — the absolute minimum required to show text on screen. The browser never needs to compute layout because all positioning is explicit.

This performance characteristic has profound implications for the web platform. For thirty years, the browser has been the gatekeeper of text information. If you wanted to know anything about how text would render — its width, its height, where its lines break — you had to ask the browser, and the browser made you pay for the answer with a layout reflow. This created an artificial scarcity of text information that constrained what interfaces could do.

Pretext removes that constraint. Text information becomes abundant and cheap. You can ask how text would look at a thousand different widths in the time it used to take to ask about one. You can recompute text layout every frame, every drag event, every pixel of window resize, without any performance concern.

The implications extend beyond layout into composition. When you have instant text measurement, you can build compositing engines that combine text with graphics, animation, and interaction in ways that were previously reserved for game engines and native applications. Text becomes a first-class participant in the visual composition, not a static block that the rest of the interface must work around.

Imagine a data visualization where labels reflow around chart elements as the user zooms and pans. Imagine a collaborative document editor where text flows around embedded widgets, images, and annotations placed by other users, updating live as they move things around. Imagine a map application where place names wrap intelligently around geographic features rather than overlapping them. These are not hypothetical — they are engineering problems that become solvable when text measurement costs a microsecond instead of thirty milliseconds.

The open web deserves typography that matches its ambition. We build applications that rival native software in every dimension except text. Our animations are smooth, our interactions are responsive, our graphics are stunning — but our text sits in rigid boxes, unable to flow around obstacles, unable to adapt to dynamic layouts, unable to participate in the fluid compositions that define modern interface design.

This is what changes when text measurement becomes free. Not slightly better — categorically different. The interfaces that were too expensive to build become trivial. The layouts that existed only in print become interactive. The text that sat in boxes begins to flow.

The web has been waiting thirty years for this. A fifteen kilobyte library with zero dependencies delivers it. No browser API changes needed. No specification process. No multi-year standardization timeline. Just math, cached measurements, and the audacity to ask: what if we simply stopped asking the DOM?

Fifteen kilobytes. Zero dependencies. Zero DOM reads. And the text flows.`

const PULLQUOTE_TEXTS = [
  '“The performance improvement is not incremental — it is categorical. 0.05ms versus 30ms. Zero reflows versus five hundred.”',
  '“Text becomes a first-class participant in the visual composition — not a static block, but a fluid material that adapts in real time.”',
]

const stage = getRequiredDiv('stage')

const orbDefs: OrbDefinition[] = [
  { fx: 0.52, fy: 0.22, r: 110, vx: 24, vy: 16, color: [196, 163, 90] },
  { fx: 0.18, fy: 0.48, r: 85, vx: -19, vy: 26, color: [100, 140, 255] },
  { fx: 0.74, fy: 0.58, r: 95, vx: 16, vy: -21, color: [232, 100, 130] },
  { fx: 0.38, fy: 0.72, r: 75, vx: -26, vy: -14, color: [80, 200, 140] },
  { fx: 0.86, fy: 0.18, r: 65, vx: -13, vy: 19, color: [150, 100, 220] },
]

>sed -n '260,520p' pages/demos/editorial-engine.ts

Command: /bin/zsh -lc "sed -n '260,520p' pages/demos/editorial-engine.ts"
Chunk ID: f55f76
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2140
Output:

function createOrbEl(color: OrbColor): HTMLDivElement {
  const element = document.createElement('div')
  element.className = 'orb'
  element.style.background = `radial-gradient(circle at 35% 35%, rgba(${color[0]},${color[1]},${color[2]},0.35), rgba(${color[0]},${color[1]},${color[2]},0.12) 55%, transparent 72%)`
  element.style.boxShadow = `0 0 60px 15px rgba(${color[0]},${color[1]},${color[2]},0.18), 0 0 120px 40px rgba(${color[0]},${color[1]},${color[2]},0.07)`
  stage.appendChild(element)
  return element
}

const W0 = window.innerWidth
const H0 = window.innerHeight

await document.fonts.ready

const preparedBody = prepareWithSegments(BODY_TEXT, BODY_FONT)
const PQ_FONT = `italic 19px ${HEADLINE_FONT_FAMILY}`
const PQ_LINE_HEIGHT = 27
const preparedPullquotes = PULLQUOTE_TEXTS.map(text => prepareWithSegments(text, PQ_FONT))
const pullquoteSpecs: PullquoteSpec[] = [
  { prepared: preparedPullquotes[0]!, placement: { colIdx: 0, yFrac: 0.48, wFrac: 0.52, side: 'right' } },
  { prepared: preparedPullquotes[1]!, placement: { colIdx: 1, yFrac: 0.32, wFrac: 0.5, side: 'left' } },
]
const DROP_CAP_SIZE = BODY_LINE_HEIGHT * DROP_CAP_LINES - 4
const DROP_CAP_FONT = `700 ${DROP_CAP_SIZE}px ${HEADLINE_FONT_FAMILY}`
const DROP_CAP_TEXT = BODY_TEXT[0]!
const preparedDropCap = prepareWithSegments(DROP_CAP_TEXT, DROP_CAP_FONT)

let dropCapWidth = 0
walkLineRanges(preparedDropCap, 9999, line => {
  dropCapWidth = line.width
})
const DROP_CAP_TOTAL_W = Math.ceil(dropCapWidth) + 10

const dropCapEl = document.createElement('div')
dropCapEl.className = 'drop-cap'
dropCapEl.textContent = DROP_CAP_TEXT
dropCapEl.style.font = DROP_CAP_FONT
dropCapEl.style.lineHeight = `${DROP_CAP_SIZE}px`
stage.appendChild(dropCapEl)

const linePool: HTMLSpanElement[] = []
const headlinePool: HTMLSpanElement[] = []
const pullquoteLinePool: HTMLSpanElement[] = []
const pullquoteBoxPool: HTMLDivElement[] = []
const domCache = {
  stage, // cache lifetime: same as page
  dropCap: dropCapEl, // cache lifetime: same as page
  bodyLines: linePool, // cache lifetime: on body line-count changes
  headlineLines: headlinePool, // cache lifetime: on headline line-count changes
  pullquoteLines: pullquoteLinePool, // cache lifetime: on pullquote line-count changes
  pullquoteBoxes: pullquoteBoxPool, // cache lifetime: on pullquote-count changes
  orbs: orbDefs.map(definition => createOrbEl(definition.color)), // cache lifetime: same as orb defs
}

const st: AppState = {
  orbs: orbDefs.map(definition => ({
    x: definition.fx * W0,
    y: definition.fy * H0,
    r: definition.r,
    vx: definition.vx,
    vy: definition.vy,
    paused: false,
  })),
  pointer: { x: -9999, y: -9999 },
  drag: null,
  interactionMode: 'idle',
  selectionActive: false,
  events: {
    pointerDown: null,
    pointerMove: null,
    pointerUp: null,
  },
  lastFrameTime: null,
}

let committedTextProjection: TextProjection | null = null

function syncPool<T extends HTMLElement>(pool: T[], count: number, create: () => T): void {
  while (pool.length < count) {
    const element = create()
    stage.appendChild(element)
    pool.push(element)
  }
  for (let index = 0; index < pool.length; index++) {
    pool[index]!.style.display = index < count ? '' : 'none'
  }
}

let cachedHeadlineWidth = -1
let cachedHeadlineHeight = -1
let cachedHeadlineMaxSize = -1
let cachedHeadlineFontSize = 24
let cachedHeadlineLines: PositionedLine[] = []

function fitHeadline(maxWidth: number, maxHeight: number, maxSize: number = 92): HeadlineFit {
  if (maxWidth === cachedHeadlineWidth && maxHeight === cachedHeadlineHeight && maxSize === cachedHeadlineMaxSize) {
    return { fontSize: cachedHeadlineFontSize, lines: cachedHeadlineLines }
  }

  cachedHeadlineWidth = maxWidth
  cachedHeadlineHeight = maxHeight
  cachedHeadlineMaxSize = maxSize
  let lo = 20
  let hi = maxSize
  let best = lo
  let bestLines: PositionedLine[] = []

  while (lo <= hi) {
    const size = Math.floor((lo + hi) / 2)
    const font = `700 ${size}px ${HEADLINE_FONT_FAMILY}`
    const lineHeight = Math.round(size * 0.93)
    const prepared = prepareWithSegments(HEADLINE_TEXT, font)
    let breaksWord = false
    let lineCount = 0

    walkLineRanges(prepared, maxWidth, line => {
      lineCount++
      if (line.end.graphemeIndex !== 0) breaksWord = true
    })

    const totalHeight = lineCount * lineHeight
    if (!breaksWord && totalHeight <= maxHeight) {
      best = size
      const result = layoutWithLines(prepared, maxWidth, lineHeight)
      bestLines = result.lines.map((line, index) => ({
        x: 0,
        y: index * lineHeight,
        text: line.text,
        width: line.width,
      }))
      lo = size + 1
    } else {
      hi = size - 1
    }
  }

  cachedHeadlineFontSize = best
  cachedHeadlineLines = bestLines
  return { fontSize: best, lines: bestLines }
}

function layoutColumn(
  prepared: PreparedTextWithSegments,
  startCursor: LayoutCursor,
  regionX: number,
  regionY: number,
  regionW: number,
  regionH: number,
  lineHeight: number,
  circleObstacles: CircleObstacle[],
  rectObstacles: RectObstacle[],
  singleSlotOnly: boolean = false,
): { lines: PositionedLine[], cursor: LayoutCursor } {
  let cursor: LayoutCursor = startCursor
  let lineTop = regionY
  const lines: PositionedLine[] = []
  let textExhausted = false

  while (lineTop + lineHeight <= regionY + regionH && !textExhausted) {
    const bandTop = lineTop
    const bandBottom = lineTop + lineHeight
    const blocked: Interval[] = []

    for (let obstacleIndex = 0; obstacleIndex < circleObstacles.length; obstacleIndex++) {
      const obstacle = circleObstacles[obstacleIndex]!
      const interval = circleIntervalForBand(
        obstacle.cx,
        obstacle.cy,
        obstacle.r,
        bandTop,
        bandBottom,
        obstacle.hPad,
        obstacle.vPad,
      )
      if (interval !== null) blocked.push(interval)
    }

    for (let rectIndex = 0; rectIndex < rectObstacles.length; rectIndex++) {
      const rect = rectObstacles[rectIndex]!
      if (bandBottom <= rect.y || bandTop >= rect.y + rect.h) continue
      blocked.push({ left: rect.x, right: rect.x + rect.w })
    }

    const slots = carveTextLineSlots({ left: regionX, right: regionX + regionW }, blocked)
    if (slots.length === 0) {
      lineTop += lineHeight
      continue
    }

    const orderedSlots = singleSlotOnly
      ? [slots.reduce((best, slot) => {
          const bestWidth = best.right - best.left
          const slotWidth = slot.right - slot.left
          if (slotWidth > bestWidth) return slot
          if (slotWidth < bestWidth) return best
          return slot.left < best.left ? slot : best
        })]
      : [...slots].sort((a, b) => a.left - b.left)

    for (let slotIndex = 0; slotIndex < orderedSlots.length; slotIndex++) {
      const slot = orderedSlots[slotIndex]!
      const slotWidth = slot.right - slot.left
      const line = layoutNextLine(prepared, cursor, slotWidth)
      if (line === null) {
        textExhausted = true
        break
      }
      lines.push({
        x: Math.round(slot.left),
        y: Math.round(lineTop),
        text: line.text,
        width: line.width,
      })
      cursor = line.end
    }

    lineTop += lineHeight
  }

  return { lines, cursor }
}

function hitTestOrbs(orbs: Orb[], px: number, py: number, activeCount: number, radiusScale: number): number {
  for (let index = activeCount - 1; index >= 0; index--) {
    const orb = orbs[index]!
    const radius = orb.r * radiusScale
    const dx = px - orb.x
    const dy = py - orb.y
    if (dx * dx + dy * dy <= radius * radius) return index
  }
  return -1
}

function pointerSampleFromEvent(event: PointerEvent): PointerSample {
  return { x: event.clientX, y: event.clientY }
}

function isSelectableTextTarget(target: EventTarget | null): boolean {
  return target instanceof Element && target.closest('.line, .headline-line, .pullquote-line') !== null
}

function hasActiveTextSelection(): boolean {
  const selection = window.getSelection()
  return selection !== null && !selection.isCollapsed && selection.rangeCount > 0
}

function clearQueuedPointerEvents(): void {
  st.events.pointerDown = null
  st.events.pointerMove = null
  st.events.pointerUp = null
}

function positionedLinesEqual(a: PositionedLine[], b: PositionedLine[]): boolean {
  if (a.length !== b.length) return false
  for (let index = 0; index < a.length; index++) {
    const left = a[index]!
    const right = b[index]!
    if (
      left.x !== right.x ||
      left.y !== right.y ||

>sed -n '1,260p' pages/demos/dynamic-layout.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/demos/dynamic-layout.ts"
Chunk ID: b556bc
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2109
Output:
/*
This page's made to show off our layout APIs:
- Title lines are measured and placed by our own layout engine, not inferred from DOM flow.
- Title font size is fit using repeated API calls so whole words survive.
- The title itself now participates in obstacle routing against the OpenAI logo.
- The author line is placed from the measured title result, and it also respects the OpenAI geometry.
- The body is one continuous text stream, not two unrelated excerpts.
- The left column consumes text first, and the right column resumes from the same cursor.
- The right column routes around:
  - the actual title geometry
  - the Anthropic/Claude logo hull
  - the OpenAI logo when it intrudes
- The left column routes around the OpenAI logo hull.
- The logo contours are derived once from rasterized SVG alpha, cached, then transformed per render.
- Hover/click hit testing uses transformed logo hulls too.
- Clicking a logo rotates it, and the text reflows live around the rotated geometry.
- Obstacle exclusion is based on the full line band, not a single y sample.
- The page is a fixed-height viewport-bound spread:
  - vertical resize changes reflow
  - overflow after the second column truncates
- The first visible render now waits for both fonts and hull preload, so it uses the real geometry from the start.
- There is no DOM text measurement loop feeding layout.
*/
import { layoutNextLine, prepareWithSegments, walkLineRanges, type LayoutCursor, type PreparedTextWithSegments } from '../../src/layout.ts'
import { BODY_COPY } from './dynamic-layout-text.ts'
import openaiLogoUrl from '../assets/openai-symbol.svg'
import claudeLogoUrl from '../assets/claude-symbol.svg'
import {
  carveTextLineSlots,
  getPolygonIntervalForBand,
  getRectIntervalsForBand,
  getWrapHull,
  isPointInPolygon,
  transformWrapPoints,
  type Interval,
  type Point,
  type Rect,
} from './wrap-geometry.ts'

const BODY_FONT = '20px "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Palatino, serif'
const BODY_LINE_HEIGHT = 32
const CREDIT_TEXT = 'Leopold Aschenbrenner'
const CREDIT_FONT = '12px "Helvetica Neue", Helvetica, Arial, sans-serif'
const CREDIT_LINE_HEIGHT = 16
const HEADLINE_TEXT = 'SITUATIONAL AWARENESS: THE DECADE AHEAD'
const HEADLINE_FONT_FAMILY = '"Iowan Old Style", "Palatino Linotype", "Book Antiqua", Palatino, serif'
const HINT_PILL_SAFE_TOP = 72
const NARROW_BREAKPOINT = 760
const NARROW_COLUMN_MAX_WIDTH = 430

function resolveImportedAssetUrl(assetUrl: string): string {
  if (/^(?:[a-z]+:)?\/\//i.test(assetUrl) || assetUrl.startsWith('data:') || assetUrl.startsWith('blob:')) {
    return assetUrl
  }
  if (assetUrl.startsWith('/')) {
    return new URL(assetUrl, window.location.origin).href
  }
  return new URL(assetUrl, import.meta.url).href
}

const OPENAI_LOGO_SRC = resolveImportedAssetUrl(openaiLogoUrl)
const CLAUDE_LOGO_SRC = resolveImportedAssetUrl(claudeLogoUrl)

type LogoKind = 'openai' | 'claude'
type SpinState = {
  from: number
  to: number
  start: number
  duration: number
}
type LogoAnimationState = {
  angle: number
  spin: SpinState | null
}

type PositionedLine = {
  x: number
  y: number
  width: number
  text: string
}

type ProjectedBodyLine = PositionedLine & {
  className: string
}

type TextProjection = {
  pageWidth: number
  pageHeight: number
  headlineFont: string
  headlineLineHeight: number
  headlineLines: PositionedLine[]
  creditLeft: number
  creditTop: number
  bodyFont: string
  bodyLineHeight: number
  bodyLines: ProjectedBodyLine[]
}

type BandObstacle =
  | {
      kind: 'polygon'
      points: Point[]
      horizontalPadding: number
      verticalPadding: number
    }
  | {
      kind: 'rects'
      rects: Rect[]
      horizontalPadding: number
      verticalPadding: number
    }

type PageLayout = {
  isNarrow: boolean
  gutter: number
  pageWidth: number
  pageHeight: number
  centerGap: number
  columnWidth: number
  headlineRegion: Rect
  headlineFont: string
  headlineLineHeight: number
  creditGap: number
  copyGap: number
  openaiRect: Rect
  claudeRect: Rect
}

type LogoHits = { openai: Point[]; claude: Point[] }
type WrapHulls = {
  openaiLayout: Point[]
  claudeLayout: Point[]
  openaiHit: Point[]
  claudeHit: Point[]
}

const stageNode = document.getElementById('stage')
if (!(stageNode instanceof HTMLDivElement)) throw new Error('#stage not found')
const stage = stageNode
const pageNode = document.querySelector('.page')
if (!(pageNode instanceof HTMLElement)) throw new Error('.page not found')

type DomCache = {
  page: HTMLElement // cache lifetime: page
  headline: HTMLHeadingElement // cache lifetime: page
  credit: HTMLParagraphElement // cache lifetime: page
  openaiLogo: HTMLImageElement // cache lifetime: page
  claudeLogo: HTMLImageElement // cache lifetime: page
  headlineLines: HTMLSpanElement[] // cache lifetime: headline line count
  bodyLines: HTMLSpanElement[] // cache lifetime: visible line count
}

const preparedByKey = new Map<string, PreparedTextWithSegments>()
const scheduled = { value: false }
const events: { mousemove: MouseEvent | null; click: MouseEvent | null; blur: boolean } = {
  mousemove: null,
  click: null,
  blur: false,
}
const pointer = { x: -Infinity, y: -Infinity }
let currentLogoHits!: LogoHits
let hoveredLogo: LogoKind | null = null
let committedTextProjection: TextProjection | null = null
const logoAnimations: { openai: LogoAnimationState; claude: LogoAnimationState } = {
  openai: { angle: 0, spin: null },
  claude: { angle: 0, spin: null },
}

const domCache: DomCache = {
  page: pageNode,
  headline: createHeadline(),
  credit: createCredit(),
  openaiLogo: createLogo('logo logo--openai', 'OpenAI symbol', OPENAI_LOGO_SRC),
  claudeLogo: createLogo('logo logo--claude', 'Claude symbol', CLAUDE_LOGO_SRC),
  headlineLines: [],
  bodyLines: [],
}

function createHeadline(): HTMLHeadingElement {
  const element = document.createElement('h1')
  element.className = 'headline'
  return element
}

function createCredit(): HTMLParagraphElement {
  const element = document.createElement('p')
  element.className = 'credit'
  element.textContent = CREDIT_TEXT
  return element
}

function createLogo(className: string, alt: string, src: string): HTMLImageElement {
  const element = document.createElement('img')
  element.className = className
  element.alt = alt
  element.src = src
  element.draggable = false
  return element
}

function mountStaticNodes(): void {
  stage.append(
    domCache.headline,
    domCache.credit,
    domCache.openaiLogo,
    domCache.claudeLogo,
  )
}

const [, openaiLayout, claudeLayout, openaiHit, claudeHit] = await Promise.all([
  document.fonts.ready,
  getWrapHull(OPENAI_LOGO_SRC, { smoothRadius: 6, mode: 'mean' }),
  getWrapHull(CLAUDE_LOGO_SRC, { smoothRadius: 6, mode: 'mean' }),
  getWrapHull(OPENAI_LOGO_SRC, { smoothRadius: 3, mode: 'mean' }),
  getWrapHull(CLAUDE_LOGO_SRC, { smoothRadius: 5, mode: 'mean' }),
])
const wrapHulls: WrapHulls = { openaiLayout, claudeLayout, openaiHit, claudeHit }
const preparedBody = getPrepared(BODY_COPY, BODY_FONT)
const preparedCredit = getPrepared(CREDIT_TEXT, CREDIT_FONT)
const creditWidth = Math.ceil(getPreparedSingleLineWidth(preparedCredit))

function getTypography(): { font: string, lineHeight: number } {
  return { font: BODY_FONT, lineHeight: BODY_LINE_HEIGHT }
}

function getPrepared(text: string, font: string): PreparedTextWithSegments {
  const key = `${font}::${text}`
  const cached = preparedByKey.get(key)
  if (cached !== undefined) return cached
  const prepared = prepareWithSegments(text, font)
  preparedByKey.set(key, prepared)
  return prepared
}

function getPreparedSingleLineWidth(prepared: PreparedTextWithSegments): number {
  let width = 0
  walkLineRanges(prepared, 100_000, line => {
    width = line.width
  })
  return width
}

function headlineBreaksInsideWord(prepared: PreparedTextWithSegments, maxWidth: number): boolean {
  let breaksInsideWord = false
  walkLineRanges(prepared, maxWidth, line => {
    if (line.end.graphemeIndex !== 0) breaksInsideWord = true
  })
  return breaksInsideWord
}

function getObstacleIntervals(obstacle: BandObstacle, bandTop: number, bandBottom: number): Interval[] {
  switch (obstacle.kind) {
    case 'polygon': {
      const interval = getPolygonIntervalForBand(
        obstacle.points,
        bandTop,
        bandBottom,
        obstacle.horizontalPadding,
        obstacle.verticalPadding,

>sed -n '261,520p' pages/demos/dynamic-layout.ts

Command: /bin/zsh -lc "sed -n '261,520p' pages/demos/dynamic-layout.ts"
Chunk ID: 2dc162
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2075
Output:
      )
      return interval === null ? [] : [interval]
    }
    case 'rects':
      return getRectIntervalsForBand(
        obstacle.rects,
        bandTop,
        bandBottom,
        obstacle.horizontalPadding,
        obstacle.verticalPadding,
      )
  }
}

function layoutColumn(
  prepared: PreparedTextWithSegments,
  startCursor: LayoutCursor,
  region: Rect,
  lineHeight: number,
  obstacles: BandObstacle[],
  side: 'left' | 'right',
): { lines: PositionedLine[], cursor: LayoutCursor } {
  let cursor: LayoutCursor = startCursor
  let lineTop = region.y
  const lines: PositionedLine[] = []
  while (true) {
    if (lineTop + lineHeight > region.y + region.height) break

    const bandTop = lineTop
    const bandBottom = lineTop + lineHeight
    const blocked: Interval[] = []
    for (let obstacleIndex = 0; obstacleIndex < obstacles.length; obstacleIndex++) {
      const obstacle = obstacles[obstacleIndex]!
      const intervals = getObstacleIntervals(obstacle, bandTop, bandBottom)
      for (let intervalIndex = 0; intervalIndex < intervals.length; intervalIndex++) {
        blocked.push(intervals[intervalIndex]!)
      }
    }

    const slots = carveTextLineSlots(
      { left: region.x, right: region.x + region.width },
      blocked,
    )
    if (slots.length === 0) {
      lineTop += lineHeight
      continue
    }

    let slot = slots[0]!
    for (let slotIndex = 1; slotIndex < slots.length; slotIndex++) {
      const candidate = slots[slotIndex]!
      const bestWidth = slot.right - slot.left
      const candidateWidth = candidate.right - candidate.left
      if (candidateWidth > bestWidth) {
        slot = candidate
        continue
      }
      if (candidateWidth < bestWidth) continue
      if (side === 'left') {
        if (candidate.left > slot.left) slot = candidate
        continue
      }
      if (candidate.left < slot.left) slot = candidate
    }
    const width = slot.right - slot.left
    const line = layoutNextLine(prepared, cursor, width)
    if (line === null) break

    lines.push({
      x: Math.round(slot.left),
      y: Math.round(lineTop),
      width: line.width,
      text: line.text,
    })

    cursor = line.end
    lineTop += lineHeight
  }

  return { lines, cursor }
}

function syncPool<T extends HTMLElement>(pool: T[], length: number, create: () => T, parent: HTMLElement = stage): void {
  while (pool.length < length) {
    const element = create()
    pool.push(element)
    parent.appendChild(element)
  }
  while (pool.length > length) {
    const element = pool.pop()!
    element.remove()
  }
}

function projectHeadlineLines(lines: PositionedLine[], font: string, lineHeight: number): void {
  syncPool(domCache.headlineLines, lines.length, () => {
    const element = document.createElement('span')
    element.className = 'headline-line'
    return element
  }, domCache.headline)

  for (let index = 0; index < lines.length; index++) {
    const line = lines[index]!
    const element = domCache.headlineLines[index]!
    element.textContent = line.text
    element.style.left = `${line.x}px`
    element.style.top = `${line.y}px`
    element.style.font = font
    element.style.lineHeight = `${lineHeight}px`
  }
}

function projectChromeLayout(layout: PageLayout, contentHeight: number): void {
  domCache.page.className = layout.isNarrow ? 'page page--mobile' : 'page'
  stage.style.height = `${contentHeight}px`

  domCache.openaiLogo.style.left = `${layout.openaiRect.x}px`
  domCache.openaiLogo.style.top = `${layout.openaiRect.y}px`
  domCache.openaiLogo.style.width = `${layout.openaiRect.width}px`
  domCache.openaiLogo.style.height = `${layout.openaiRect.height}px`
  domCache.openaiLogo.style.transform = `rotate(${logoAnimations.openai.angle}rad)`

  domCache.claudeLogo.style.left = `${layout.claudeRect.x}px`
  domCache.claudeLogo.style.top = `${layout.claudeRect.y}px`
  domCache.claudeLogo.style.width = `${layout.claudeRect.width}px`
  domCache.claudeLogo.style.height = `${layout.claudeRect.height}px`
  domCache.claudeLogo.style.transform = `rotate(${logoAnimations.claude.angle}rad)`
}

function positionedLinesEqual(a: PositionedLine[], b: PositionedLine[]): boolean {
  if (a.length !== b.length) return false
  for (let index = 0; index < a.length; index++) {
    const left = a[index]!
    const right = b[index]!
    if (
      left.x !== right.x ||
      left.y !== right.y ||
      left.width !== right.width ||
      left.text !== right.text
    ) {
      return false
    }
  }
  return true
}

function projectedBodyLinesEqual(a: ProjectedBodyLine[], b: ProjectedBodyLine[]): boolean {
  if (a.length !== b.length) return false
  for (let index = 0; index < a.length; index++) {
    const left = a[index]!
    const right = b[index]!
    if (
      left.className !== right.className ||
      left.x !== right.x ||
      left.y !== right.y ||
      left.width !== right.width ||
      left.text !== right.text
    ) {
      return false
    }
  }
  return true
}

function textProjectionEqual(a: TextProjection | null, b: TextProjection): boolean {
  return a !== null &&
    a.pageWidth === b.pageWidth &&
    a.pageHeight === b.pageHeight &&
    a.headlineFont === b.headlineFont &&
    a.headlineLineHeight === b.headlineLineHeight &&
    a.creditLeft === b.creditLeft &&
    a.creditTop === b.creditTop &&
    a.bodyFont === b.bodyFont &&
    a.bodyLineHeight === b.bodyLineHeight &&
    positionedLinesEqual(a.headlineLines, b.headlineLines) &&
    projectedBodyLinesEqual(a.bodyLines, b.bodyLines)
}

function projectTextProjection(projection: TextProjection): void {
  domCache.headline.style.left = '0px'
  domCache.headline.style.top = '0px'
  domCache.headline.style.width = `${projection.pageWidth}px`
  domCache.headline.style.height = `${projection.pageHeight}px`
  domCache.headline.style.font = projection.headlineFont
  domCache.headline.style.lineHeight = `${projection.headlineLineHeight}px`
  domCache.headline.style.letterSpacing = '0px'

  projectHeadlineLines(projection.headlineLines, projection.headlineFont, projection.headlineLineHeight)

  domCache.credit.style.left = `${projection.creditLeft}px`
  domCache.credit.style.top = `${projection.creditTop}px`
  domCache.credit.style.width = 'auto'
  domCache.credit.style.font = CREDIT_FONT
  domCache.credit.style.lineHeight = `${CREDIT_LINE_HEIGHT}px`

  syncPool(domCache.bodyLines, projection.bodyLines.length, () => {
    const element = document.createElement('span')
    element.className = 'line'
    return element
  })
  for (let index = 0; index < projection.bodyLines.length; index++) {
    const line = projection.bodyLines[index]!
    const element = domCache.bodyLines[index]!
    element.className = line.className
    element.textContent = line.text
    element.style.left = `${line.x}px`
    element.style.top = `${line.y}px`
    element.style.font = projection.bodyFont
    element.style.lineHeight = `${projection.bodyLineHeight}px`
  }
}

function fitHeadlineFontSize(headlineWidth: number, pageWidth: number): number {
  let low = Math.ceil(Math.max(22, pageWidth * 0.026))
  let high = Math.floor(Math.min(94.4, Math.max(55.2, pageWidth * 0.055)))
  let best = low

  while (low <= high) {
    const size = Math.floor((low + high) / 2)
    const font = `700 ${size}px ${HEADLINE_FONT_FAMILY}`
    const headlinePrepared = getPrepared(HEADLINE_TEXT, font)
    if (!headlineBreaksInsideWord(headlinePrepared, headlineWidth)) {
      best = size
      low = size + 1
    } else {
      high = size - 1
    }
  }

  return best
}

function easeSpin(t: number): number {
  const oneMinusT = 1 - t
  return 1 - oneMinusT * oneMinusT * oneMinusT
}

function getLogoAnimation(kind: LogoKind): LogoAnimationState {
  switch (kind) {
    case 'openai':
      return logoAnimations.openai
    case 'claude':
      return logoAnimations.claude
  }
}

function updateLogoSpin(logo: LogoAnimationState, now: number): boolean {
  if (logo.spin === null) return false

  const progress = Math.min(1, (now - logo.spin.start) / logo.spin.duration)
  logo.angle = logo.spin.from + (logo.spin.to - logo.spin.from) * easeSpin(progress)
  if (progress >= 1) {
    logo.angle = logo.spin.to
    logo.spin = null
    return false
  }
  return true
}

function updateSpinState(now: number): boolean {

>sed -n '1,260p' pages/demos/justification-comparison.model.ts

Command: /bin/zsh -lc "sed -n '1,260p' pages/demos/justification-comparison.model.ts"
Chunk ID: 461a25
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1891
Output:
import {
  prepareWithSegments,
  layoutNextLine,
  type LayoutCursor,
  type PreparedTextWithSegments,
} from '../../src/layout.ts'
import {
  FONT,
  HYPHEN_EXCEPTIONS,
  LINE_HEIGHT,
  PAD,
  PARA_GAP,
  PARAGRAPHS,
  PREFIXES,
  SUFFIXES,
} from './justification-comparison.data.ts'

const HUGE_BADNESS = 1e8
const SOFT_HYPHEN = '\u00AD'
const SHORT_LINE_RATIO = 0.6
const RIVER_THRESHOLD = 1.5
const INFEASIBLE_SPACE_RATIO = 0.4
const OVERFLOW_SPACE_RATIO = 0.2
const MIN_READABLE_SPACE_RATIO = 0.75
const TIGHT_SPACE_RATIO = 0.65

export type DemoControls = {
  colWidth: number
  showIndicators: boolean
}

export type DemoResources = {
  basePreparedParagraphs: PreparedTextWithSegments[]
  hyphenatedPreparedParagraphs: PreparedTextWithSegments[]
  normalSpaceWidth: number
  hyphenWidth: number
}

type TrailingMarker = 'none' | 'soft-hyphen'
type LineEnding = 'paragraph-end' | 'wrap'
type BreakCandidateKind = 'start' | 'space' | 'soft-hyphen' | 'end'

export type LineSegment =
  | { kind: 'text'; text: string; width: number }
  | { kind: 'space'; width: number }

export type MeasuredLine = {
  segments: LineSegment[]
  wordWidth: number
  spaceCount: number
  naturalWidth: number
  maxWidth: number
  ending: LineEnding
  trailingMarker: TrailingMarker
}

export type LineSpacing =
  | { kind: 'ragged' }
  | { kind: 'overflow' }
  | { kind: 'justified'; width: number; isRiver: boolean }

export type PositionedLine = MeasuredLine & {
  y: number
  spacing: LineSpacing
}

export type QualityMetrics = {
  avgDeviation: number
  maxDeviation: number
  riverCount: number
  lineCount: number
}

export type CanvasColumnFrame = {
  colWidth: number
  totalHeight: number
  paragraphs: PositionedLine[][]
  metrics: QualityMetrics
}

export type DemoFrame = {
  controls: DemoControls
  css: {
    metrics: QualityMetrics
  }
  hyphen: CanvasColumnFrame
  optimal: CanvasColumnFrame
}

export type RiverIndicator = {
  red: number
  green: number
  blue: number
  alpha: number
}

type BreakCandidate = {
  segIndex: number
  kind: BreakCandidateKind
}

type LineStats = {
  wordWidth: number
  spaceCount: number
  naturalWidth: number
  trailingMarker: TrailingMarker
}

export function createDemoResources(): DemoResources {
  const measureCanvas = document.createElement('canvas')
  const measureCtx = measureCanvas.getContext('2d')
  if (measureCtx === null) throw new Error('2D canvas context is required for the demo')
  measureCtx.font = FONT

  return {
    basePreparedParagraphs: PARAGRAPHS.map(paragraph => prepareWithSegments(paragraph, FONT)),
    hyphenatedPreparedParagraphs: PARAGRAPHS.map(paragraph => prepareWithSegments(hyphenateParagraphText(paragraph), FONT)),
    normalSpaceWidth: measureCtx.measureText(' ').width,
    hyphenWidth: measureCtx.measureText('-').width,
  }
}

export function buildDemoFrame(resources: DemoResources, controls: DemoControls): DemoFrame {
  const innerWidth = controls.colWidth - PAD * 2

  const cssParagraphs = layoutParagraphsGreedy(resources.basePreparedParagraphs, innerWidth, resources.hyphenWidth)
  const hyphenParagraphs = layoutParagraphsGreedy(resources.hyphenatedPreparedParagraphs, innerWidth, resources.hyphenWidth)
  const optimalParagraphs = layoutParagraphsOptimal(resources.hyphenatedPreparedParagraphs, innerWidth, resources)

  return {
    controls,
    css: {
      metrics: computeMetrics(cssParagraphs, resources.normalSpaceWidth),
    },
    hyphen: buildCanvasColumnFrame(controls.colWidth, hyphenParagraphs, resources.normalSpaceWidth),
    optimal: buildCanvasColumnFrame(controls.colWidth, optimalParagraphs, resources.normalSpaceWidth),
  }
}

export function getRiverIndicator(spaceWidth: number, normalSpaceWidth: number): RiverIndicator | null {
  if (spaceWidth <= normalSpaceWidth * RIVER_THRESHOLD) return null

  const intensity = Math.min(1, (spaceWidth / normalSpaceWidth - RIVER_THRESHOLD) / RIVER_THRESHOLD)
  return {
    red: Math.round(220 + intensity * 35),
    green: Math.round(180 - intensity * 80),
    blue: Math.round(180 - intensity * 80),
    alpha: 0.25 + intensity * 0.35,
  }
}

function hyphenateParagraphText(paragraph: string): string {
  const words = paragraph.split(/(\s+)/)
  let hyphenated = ''
  for (let index = 0; index < words.length; index++) {
    const token = words[index]!
    if (/^\s+$/.test(token)) {
      hyphenated += token
      continue
    }
    const parts = hyphenateWord(token)
    hyphenated += parts.length <= 1 ? token : parts.join(SOFT_HYPHEN)
  }
  return hyphenated
}

function hyphenateWord(word: string): string[] {
  const lower = word.toLowerCase().replace(/[.,;:!?"'—–-]/g, '')
  if (lower.length < 5) return [word]

  const exactMatch = HYPHEN_EXCEPTIONS[lower]
  if (exactMatch !== undefined) {
    const parts: string[] = []
    let position = 0
    for (let index = 0; index < exactMatch.length; index++) {
      const part = exactMatch[index]!
      parts.push(word.slice(position, position + part.length))
      position += part.length
    }
    if (position < word.length) {
      parts[parts.length - 1] += word.slice(position)
    }
    return parts
  }

  for (let index = 0; index < PREFIXES.length; index++) {
    const prefix = PREFIXES[index]!
    if (lower.startsWith(prefix) && lower.length - prefix.length >= 3) {
      return [word.slice(0, prefix.length), word.slice(prefix.length)]
    }
  }

  for (let index = 0; index < SUFFIXES.length; index++) {
    const suffix = SUFFIXES[index]!
    if (lower.endsWith(suffix) && lower.length - suffix.length >= 3) {
      const cut = word.length - suffix.length
      return [word.slice(0, cut), word.slice(cut)]
    }
  }

  return [word]
}

function layoutParagraphsGreedy(
  preparedParagraphs: PreparedTextWithSegments[],
  maxWidth: number,
  hyphenWidth: number,
): MeasuredLine[][] {
  const paragraphs: MeasuredLine[][] = []
  for (let index = 0; index < preparedParagraphs.length; index++) {
    paragraphs.push(layoutParagraphGreedy(preparedParagraphs[index]!, maxWidth, hyphenWidth))
  }
  return paragraphs
}

function layoutParagraphGreedy(
  prepared: PreparedTextWithSegments,
  maxWidth: number,
  hyphenWidth: number,
): MeasuredLine[] {
  const lines: MeasuredLine[] = []
  let cursor: LayoutCursor = { segmentIndex: 0, graphemeIndex: 0 }

  while (true) {
    const line = layoutNextLine(prepared, cursor, maxWidth)
    if (line === null) break
    lines.push(buildMeasuredLineFromLayoutResult(prepared, line.start, line.end, maxWidth, hyphenWidth))
    cursor = line.end
  }

  return lines
}

function buildMeasuredLineFromLayoutResult(
  prepared: PreparedTextWithSegments,
  start: LayoutCursor,
  end: LayoutCursor,
  maxWidth: number,
  hyphenWidth: number,
): MeasuredLine {
  const ending: LineEnding = end.segmentIndex >= prepared.segments.length ? 'paragraph-end' : 'wrap'
  let trailingMarker: TrailingMarker = 'none'
  const segments: LineSegment[] = []

  for (let segIndex = start.segmentIndex; segIndex < end.segmentIndex; segIndex++) {
    const text = prepared.segments[segIndex]!
    if (text === SOFT_HYPHEN) {
      if (segIndex === end.segmentIndex - 1) trailingMarker = 'soft-hyphen'
      continue
    }
    segments.push(toLineSegment(text, prepared.widths[segIndex]!))
  }

  if (trailingMarker === 'none' && end.segmentIndex < prepared.segments.length) {
    if (prepared.segments[end.segmentIndex] === SOFT_HYPHEN) trailingMarker = 'soft-hyphen'
  }

  if (trailingMarker === 'soft-hyphen' && ending === 'wrap') {
    segments.push({ kind: 'text', text: '-', width: hyphenWidth })
  }

>sed -n '261,520p' pages/demos/justification-comparison.model.ts

Command: /bin/zsh -lc "sed -n '261,520p' pages/demos/justification-comparison.model.ts"
Chunk ID: 9fe571
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1920
Output:

  trimTrailingSpaces(segments)
  return finalizeMeasuredLine(segments, maxWidth, ending, trailingMarker)
}

function layoutParagraphsOptimal(
  preparedParagraphs: PreparedTextWithSegments[],
  maxWidth: number,
  resources: DemoResources,
): MeasuredLine[][] {
  const paragraphs: MeasuredLine[][] = []
  for (let index = 0; index < preparedParagraphs.length; index++) {
    paragraphs.push(layoutParagraphOptimal(preparedParagraphs[index]!, maxWidth, resources))
  }
  return paragraphs
}

function layoutParagraphOptimal(
  prepared: PreparedTextWithSegments,
  maxWidth: number,
  resources: DemoResources,
): MeasuredLine[] {
  const segments = prepared.segments
  const widths = prepared.widths
  const segmentCount = segments.length

  if (segmentCount === 0) return []

  const breakCandidates: BreakCandidate[] = [{ segIndex: 0, kind: 'start' }]
  for (let segIndex = 0; segIndex < segmentCount; segIndex++) {
    const text = segments[segIndex]!
    if (text === SOFT_HYPHEN) {
      if (segIndex + 1 < segmentCount) breakCandidates.push({ segIndex: segIndex + 1, kind: 'soft-hyphen' })
      continue
    }
    if (isSpaceText(text) && segIndex + 1 < segmentCount) {
      breakCandidates.push({ segIndex: segIndex + 1, kind: 'space' })
    }
  }
  breakCandidates.push({ segIndex: segmentCount, kind: 'end' })

  const candidateCount = breakCandidates.length
  const dp: number[] = new Array(candidateCount).fill(Infinity)
  const previous: number[] = new Array(candidateCount).fill(-1)
  dp[0] = 0

  for (let toCandidate = 1; toCandidate < candidateCount; toCandidate++) {
    const isLastLine = breakCandidates[toCandidate]!.kind === 'end'

    for (let fromCandidate = toCandidate - 1; fromCandidate >= 0; fromCandidate--) {
      if (dp[fromCandidate] === Infinity) continue
      const lineStats = getLineStatsFromBreakCandidates(
        segments,
        widths,
        breakCandidates,
        fromCandidate,
        toCandidate,
        resources.hyphenWidth,
        resources.normalSpaceWidth,
      )

      if (lineStats.naturalWidth > maxWidth * 2) break

      const totalBadness = dp[fromCandidate]! + lineBadness(lineStats, maxWidth, resources.normalSpaceWidth, isLastLine)
      if (totalBadness < dp[toCandidate]!) {
        dp[toCandidate] = totalBadness
        previous[toCandidate] = fromCandidate
      }
    }
  }

  const breakIndices: number[] = []
  let current = candidateCount - 1
  while (current > 0) {
    if (previous[current] === -1) {
      current--
      continue
    }
    breakIndices.push(current)
    current = previous[current]!
  }
  breakIndices.reverse()

  const lines: MeasuredLine[] = []
  let fromCandidate = 0
  for (let index = 0; index < breakIndices.length; index++) {
    const toCandidate = breakIndices[index]!
    lines.push(buildMeasuredLineFromCandidateRange(prepared, breakCandidates, fromCandidate, toCandidate, maxWidth, resources.hyphenWidth))
    fromCandidate = toCandidate
  }

  return lines
}

function getLineStatsFromBreakCandidates(
  segments: readonly string[],
  widths: readonly number[],
  breakCandidates: readonly BreakCandidate[],
  fromCandidate: number,
  toCandidate: number,
  hyphenWidth: number,
  normalSpaceWidth: number,
): LineStats {
  const from = breakCandidates[fromCandidate]!.segIndex
  const to = breakCandidates[toCandidate]!.segIndex
  const trailingMarker: TrailingMarker = breakCandidates[toCandidate]!.kind === 'soft-hyphen'
    ? 'soft-hyphen'
    : 'none'

  let wordWidth = 0
  let spaceCount = 0
  for (let segIndex = from; segIndex < to; segIndex++) {
    const text = segments[segIndex]!
    if (text === SOFT_HYPHEN) continue
    if (isSpaceText(text)) {
      spaceCount++
      continue
    }
    wordWidth += widths[segIndex]!
  }

  if (to > from && isSpaceText(segments[to - 1]!)) {
    spaceCount--
  }

  if (trailingMarker === 'soft-hyphen') {
    wordWidth += hyphenWidth
  }

  return {
    wordWidth,
    spaceCount,
    naturalWidth: wordWidth + spaceCount * normalSpaceWidth,
    trailingMarker,
  }
}

function lineBadness(
  lineStats: LineStats,
  maxWidth: number,
  normalSpaceWidth: number,
  isLastLine: boolean,
): number {
  if (isLastLine) {
    if (lineStats.wordWidth > maxWidth) return HUGE_BADNESS
    return 0
  }

  if (lineStats.spaceCount <= 0) {
    const slack = maxWidth - lineStats.wordWidth
    if (slack < 0) return HUGE_BADNESS
    return slack * slack * 10
  }

  const justifiedSpace = (maxWidth - lineStats.wordWidth) / lineStats.spaceCount
  if (justifiedSpace < 0) return HUGE_BADNESS
  if (justifiedSpace < normalSpaceWidth * INFEASIBLE_SPACE_RATIO) return HUGE_BADNESS

  const ratio = (justifiedSpace - normalSpaceWidth) / normalSpaceWidth
  const absRatio = Math.abs(ratio)
  const badness = absRatio * absRatio * absRatio * 1000

  const riverExcess = justifiedSpace / normalSpaceWidth - RIVER_THRESHOLD
  const riverPenalty = riverExcess > 0
    ? 5000 + riverExcess * riverExcess * 10000
    : 0

  const tightThreshold = normalSpaceWidth * TIGHT_SPACE_RATIO
  const tightPenalty = justifiedSpace < tightThreshold
    ? 3000 + (tightThreshold - justifiedSpace) * (tightThreshold - justifiedSpace) * 10000
    : 0

  const hyphenPenalty = lineStats.trailingMarker === 'soft-hyphen' ? 50 : 0
  return badness + riverPenalty + tightPenalty + hyphenPenalty
}

function buildMeasuredLineFromCandidateRange(
  prepared: PreparedTextWithSegments,
  breakCandidates: readonly BreakCandidate[],
  fromCandidate: number,
  toCandidate: number,
  maxWidth: number,
  hyphenWidth: number,
): MeasuredLine {
  const from = breakCandidates[fromCandidate]!.segIndex
  const to = breakCandidates[toCandidate]!.segIndex
  const ending: LineEnding = breakCandidates[toCandidate]!.kind === 'end' ? 'paragraph-end' : 'wrap'
  const trailingMarker: TrailingMarker = breakCandidates[toCandidate]!.kind === 'soft-hyphen'
    ? 'soft-hyphen'
    : 'none'

  const segments: LineSegment[] = []
  for (let segIndex = from; segIndex < to; segIndex++) {
    const text = prepared.segments[segIndex]!
    if (text === SOFT_HYPHEN) continue
    segments.push(toLineSegment(text, prepared.widths[segIndex]!))
  }

  if (trailingMarker === 'soft-hyphen' && ending === 'wrap') {
    segments.push({ kind: 'text', text: '-', width: hyphenWidth })
  }

  trimTrailingSpaces(segments)
  return finalizeMeasuredLine(segments, maxWidth, ending, trailingMarker)
}

function toLineSegment(text: string, width: number): LineSegment {
  if (isSpaceText(text)) return { kind: 'space', width }
  return { kind: 'text', text, width }
}

function trimTrailingSpaces(segments: LineSegment[]): void {
  while (segments.length > 0 && segments[segments.length - 1]!.kind === 'space') {
    segments.pop()
  }
}

function finalizeMeasuredLine(
  segments: LineSegment[],
  maxWidth: number,
  ending: LineEnding,
  trailingMarker: TrailingMarker,
): MeasuredLine {
  let wordWidth = 0
  let spaceCount = 0
  let naturalWidth = 0

  for (let index = 0; index < segments.length; index++) {
    const segment = segments[index]!
    naturalWidth += segment.width
    if (segment.kind === 'space') {
      spaceCount++
      continue
    }
    wordWidth += segment.width
  }

  return {
    segments,
    wordWidth,
    spaceCount,
    naturalWidth,
    maxWidth,
    ending,
    trailingMarker,
  }
}

function computeMetrics(
  paragraphs: MeasuredLine[][],
  normalSpaceWidth: number,
): QualityMetrics {
  let totalDeviation = 0
  let maxDeviation = 0
  let deviationCount = 0
  let riverCount = 0
  let lineCount = 0

  for (let paragraphIndex = 0; paragraphIndex < paragraphs.length; paragraphIndex++) {
    const paragraph = paragraphs[paragraphIndex]!

>sed -n '1,220p' pages/demos/bubbles-shared.ts

Command: /bin/zsh -lc "sed -n '1,220p' pages/demos/bubbles-shared.ts"
Chunk ID: 0e94f4
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 847
Output:
import { layout, prepareWithSegments, walkLineRanges, type PreparedTextWithSegments } from '../../src/layout.ts'

export type WrapMetrics = {
  lineCount: number
  height: number
  maxLineWidth: number
}

export type PreparedBubble = {
  prepared: PreparedTextWithSegments
}

export type BubbleRenderWidths = {
  cssWidth: number
  tightWidth: number
}

export type BubbleRenderState = {
  chatWidth: number
  bubbleMaxWidth: number
  totalWastedPixels: number
  widths: BubbleRenderWidths[]
}

export const FONT = '15px "Helvetica Neue", Helvetica, Arial, sans-serif'
export const LINE_HEIGHT = 20
export const PADDING_H = 12
export const PADDING_V = 8
export const BUBBLE_MAX_RATIO = 0.8
export const PAGE_MAX_WIDTH = 1080
export const DESKTOP_PAGE_MARGIN = 32
export const MOBILE_PAGE_MARGIN = 20
export const GRID_GAP = 16
export const PANEL_PADDING_X = 36

export function prepareBubbleTexts(texts: string[]): PreparedBubble[] {
  return texts.map(text => ({
    prepared: prepareWithSegments(text, FONT),
  }))
}

export function getMaxChatWidth(minWidth: number, viewportWidth: number): number {
  const pageWidth = Math.min(PAGE_MAX_WIDTH, viewportWidth - (viewportWidth <= 760 ? MOBILE_PAGE_MARGIN : DESKTOP_PAGE_MARGIN))
  const columnWidth = viewportWidth <= 760 ? pageWidth : (pageWidth - GRID_GAP) / 2
  const panelContentWidth = Math.max(1, Math.floor(columnWidth - PANEL_PADDING_X))
  return Math.max(minWidth, panelContentWidth)
}

export function collectWrapMetrics(prepared: PreparedTextWithSegments, maxWidth: number): WrapMetrics {
  let maxLineWidth = 0
  const lineCount = walkLineRanges(prepared, maxWidth, line => {
    if (line.width > maxLineWidth) maxLineWidth = line.width
  })
  return {
    lineCount,
    height: lineCount * LINE_HEIGHT,
    maxLineWidth,
  }
}

export function findTightWrapMetrics(prepared: PreparedTextWithSegments, maxWidth: number): WrapMetrics {
  const initial = collectWrapMetrics(prepared, maxWidth)
  let lo = 1
  let hi = Math.max(1, Math.ceil(maxWidth))

  while (lo < hi) {
    const mid = Math.floor((lo + hi) / 2)
    const midLineCount = layout(prepared, mid, LINE_HEIGHT).lineCount
    if (midLineCount <= initial.lineCount) {
      hi = mid
    } else {
      lo = mid + 1
    }
  }

  return collectWrapMetrics(prepared, lo)
}

export function computeBubbleRender(preparedBubbles: PreparedBubble[], chatWidth: number): BubbleRenderState {
  const bubbleMaxWidth = Math.floor(chatWidth * BUBBLE_MAX_RATIO)
  const contentMaxWidth = bubbleMaxWidth - PADDING_H * 2
  let totalWastedPixels = 0
  const widths: BubbleRenderWidths[] = []

  for (let index = 0; index < preparedBubbles.length; index++) {
    const bubble = preparedBubbles[index]!
    const cssMetrics = collectWrapMetrics(bubble.prepared, contentMaxWidth)
    const tightMetrics = findTightWrapMetrics(bubble.prepared, contentMaxWidth)

    const cssWidth = Math.ceil(cssMetrics.maxLineWidth) + PADDING_H * 2
    const tightWidth = Math.ceil(tightMetrics.maxLineWidth) + PADDING_H * 2
    const cssHeight = cssMetrics.height + PADDING_V * 2
    totalWastedPixels += Math.max(0, cssWidth - tightWidth) * cssHeight
    widths.push({ cssWidth, tightWidth })
  }

  return {
    chatWidth,
    bubbleMaxWidth,
    totalWastedPixels,
    widths,
  }
}

export function formatPixelCount(value: number): string {
  return `${Math.round(value).toLocaleString()}`
}

>sed -n '1,220p' pages/demos/variable-typographic-ascii.ts

Command: /bin/zsh -lc "sed -n '1,220p' pages/demos/variable-typographic-ascii.ts"
Chunk ID: cf7fb9
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1803
Output:
import { prepareWithSegments } from '../../src/layout.ts'

const COLS = 50
const ROWS = 28
const FONT_SIZE = 14
const LINE_HEIGHT = 16
const TARGET_ROW_W = 440
const PROP_FAMILY = 'Georgia, Palatino, "Times New Roman", serif'
const FIELD_OVERSAMPLE = 2
const FIELD_COLS = COLS * FIELD_OVERSAMPLE
const FIELD_ROWS = ROWS * FIELD_OVERSAMPLE
const CANVAS_W = 220
const CANVAS_H = Math.round(CANVAS_W * ((ROWS * LINE_HEIGHT) / TARGET_ROW_W))
const FIELD_SCALE_X = FIELD_COLS / CANVAS_W
const FIELD_SCALE_Y = FIELD_ROWS / CANVAS_H
const PARTICLE_N = 120
const SPRITE_R = 14
const ATTRACTOR_R = 12
const LARGE_ATTRACTOR_R = 30
const ATTRACTOR_FORCE_1 = 0.22
const ATTRACTOR_FORCE_2 = 0.05
const FIELD_DECAY = 0.82
const CHARSET = ' .,:;!+-=*#@%&abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789'
const WEIGHTS = [300, 500, 800] as const
const STYLES = ['normal', 'italic'] as const

type FontStyleVariant = typeof STYLES[number]

type PaletteEntry = {
  char: string
  weight: number
  style: FontStyleVariant
  font: string
  width: number
  brightness: number
}

type BrightnessEntry = {
  monoChar: string
  propHtml: string
}

type Particle = {
  x: number
  y: number
  vx: number
  vy: number
}

type FieldStamp = {
  radiusX: number
  radiusY: number
  sizeX: number
  sizeY: number
  values: Float32Array
}

type RowNodes = {
  monoNode: HTMLDivElement
  propNode: HTMLDivElement
}

function getRequiredDiv(id: string): HTMLDivElement {
  const element = document.getElementById(id)
  if (!(element instanceof HTMLDivElement)) throw new Error(`#${id} not found`)
  return element
}

const brightnessCanvas = document.createElement('canvas')
brightnessCanvas.width = 28
brightnessCanvas.height = 28
const brightnessContext = brightnessCanvas.getContext('2d', { willReadFrequently: true })
if (brightnessContext === null) throw new Error('brightness context not available')
const bCtx = brightnessContext

function estimateBrightness(ch: string, font: string): number {
  const size = 28
  bCtx.clearRect(0, 0, size, size)
  bCtx.font = font
  bCtx.fillStyle = '#fff'
  bCtx.textBaseline = 'middle'
  bCtx.fillText(ch, 1, size / 2)
  const data = bCtx.getImageData(0, 0, size, size).data
  let sum = 0
  for (let index = 3; index < data.length; index += 4) sum += data[index]!
  return sum / (255 * size * size)
}

function measureWidth(ch: string, font: string): number {
  const prepared = prepareWithSegments(ch, font)
  return prepared.widths.length > 0 ? prepared.widths[0]! : 0
}

const palette: PaletteEntry[] = []
for (const style of STYLES) {
  for (const weight of WEIGHTS) {
    const font = `${style === 'italic' ? 'italic ' : ''}${weight} ${FONT_SIZE}px ${PROP_FAMILY}`
    for (const ch of CHARSET) {
      if (ch === ' ') continue
      const width = measureWidth(ch, font)
      if (width <= 0) continue
      const brightness = estimateBrightness(ch, font)
      palette.push({ char: ch, weight, style, font, width, brightness })
    }
  }
}

const maxBrightness = Math.max(...palette.map(entry => entry.brightness))
if (maxBrightness > 0) {
  for (let index = 0; index < palette.length; index++) {
    palette[index]!.brightness /= maxBrightness
  }
}
palette.sort((a, b) => a.brightness - b.brightness)
const targetCellW = TARGET_ROW_W / COLS

function findBest(targetBrightness: number): PaletteEntry {
  let lo = 0
  let hi = palette.length - 1
  while (lo < hi) {
    const mid = (lo + hi) >> 1
    if (palette[mid]!.brightness < targetBrightness) lo = mid + 1
    else hi = mid
  }

  let bestScore = Infinity
  let best = palette[lo]!
  const start = Math.max(0, lo - 15)
  const end = Math.min(palette.length, lo + 15)
  for (let index = start; index < end; index++) {
    const entry = palette[index]!
    const brightnessError = Math.abs(entry.brightness - targetBrightness) * 2.5
    const widthError = Math.abs(entry.width - targetCellW) / targetCellW
    const score = brightnessError + widthError
    if (score < bestScore) {
      bestScore = score
      best = entry
    }
  }
  return best
}

const MONO_RAMP = ' .`-_:,;^=+/|)\\!?0oOQ#%@'
const brightnessLookup: BrightnessEntry[] = []
for (let brightnessByte = 0; brightnessByte < 256; brightnessByte++) {
  const brightness = brightnessByte / 255
  const monoChar = MONO_RAMP[Math.min(MONO_RAMP.length - 1, (brightness * MONO_RAMP.length) | 0)]!
  if (brightness < 0.03) {
    brightnessLookup.push({ monoChar, propHtml: ' ' })
    continue
  }

  const match = findBest(brightness)
  const alphaIndex = Math.max(1, Math.min(10, Math.round(brightness * 10)))
  brightnessLookup.push({
    monoChar,
    propHtml: `<span class="${wCls(match.weight, match.style)} a${alphaIndex}">${esc(match.char)}</span>`,
  })
}

const particles: Particle[] = []
for (let index = 0; index < PARTICLE_N; index++) {
  const angle = Math.random() * Math.PI * 2
  const radius = Math.random() * 40 + 20
  particles.push({
    x: CANVAS_W / 2 + Math.cos(angle) * radius,
    y: CANVAS_H / 2 + Math.sin(angle) * radius,
    vx: (Math.random() - 0.5) * 0.8,
    vy: (Math.random() - 0.5) * 0.8,
  })
}

const simulationCanvas = document.createElement('canvas')
simulationCanvas.width = CANVAS_W
simulationCanvas.height = CANVAS_H
simulationCanvas.className = 'source-canvas'
const simulationContext = simulationCanvas.getContext('2d', { willReadFrequently: true })
if (simulationContext === null) throw new Error('simulation context not available')
const sCtx = simulationContext
const brightnessField = new Float32Array(FIELD_COLS * FIELD_ROWS)

const spriteCache = new Map<number, HTMLCanvasElement>()

function getSpriteCanvas(radius: number): HTMLCanvasElement {
  const cached = spriteCache.get(radius)
  if (cached !== undefined) return cached

  const canvas = document.createElement('canvas')
  canvas.width = radius * 2
  canvas.height = radius * 2
  const context = canvas.getContext('2d')
  if (context === null) throw new Error('sprite context not available')
  const gradient = context.createRadialGradient(radius, radius, 0, radius, radius, radius)
  gradient.addColorStop(0, 'rgba(255,255,255,0.45)')
  gradient.addColorStop(0.35, 'rgba(255,255,255,0.15)')
  gradient.addColorStop(1, 'rgba(255,255,255,0)')
  context.fillStyle = gradient
  context.fillRect(0, 0, radius * 2, radius * 2)
  spriteCache.set(radius, canvas)
  return canvas
}

function spriteAlphaAt(normalizedDistance: number): number {
  if (normalizedDistance >= 1) return 0
  if (normalizedDistance <= 0.35) return 0.45 + (0.15 - 0.45) * (normalizedDistance / 0.35)
  return 0.15 * (1 - (normalizedDistance - 0.35) / 0.65)
}

function createFieldStamp(radiusPx: number): FieldStamp {
  const fieldRadiusX = radiusPx * FIELD_SCALE_X
  const fieldRadiusY = radiusPx * FIELD_SCALE_Y
  const radiusX = Math.ceil(fieldRadiusX)
  const radiusY = Math.ceil(fieldRadiusY)
  const sizeX = radiusX * 2 + 1
  const sizeY = radiusY * 2 + 1
  const values = new Float32Array(sizeX * sizeY)
  for (let y = -radiusY; y <= radiusY; y++) {
    for (let x = -radiusX; x <= radiusX; x++) {
      const normalizedDistance = Math.sqrt((x / fieldRadiusX) ** 2 + (y / fieldRadiusY) ** 2)
      values[(y + radiusY) * sizeX + x + radiusX] = spriteAlphaAt(normalizedDistance)

>bun test src/layout.test.ts

exec_command failed for `/bin/zsh -lc 'bun test src/layout.test.ts'`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>git show f962f72:src/layout.ts | sed -n '1,260p'

exec_command failed for `/bin/zsh -lc "git show f962f72:src/layout.ts | sed -n '1,260p'"`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>git show 5ecce72:src/layout.ts | sed -n '1,260p'

exec_command failed for `/bin/zsh -lc "git show 5ecce72:src/layout.ts | sed -n '1,260p'"`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>git show fea1fa7:src/layout.ts | sed -n '1,260p'

exec_command failed for `/bin/zsh -lc "git show fea1fa7:src/layout.ts | sed -n '1,260p'"`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>git show f06fb75:src/line-break.ts | sed -n '1,260p'

exec_command failed for `/bin/zsh -lc "git show f06fb75:src/line-break.ts | sed -n '1,260p'"`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>git show --stat --oneline --no-patch f962f72

exec_command failed for `/bin/zsh -lc 'git show --stat --oneline --no-patch f962f72'`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>git ls-tree --name-only -r f962f72 | head -n 40

exec_command failed for `/bin/zsh -lc 'git ls-tree --name-only -r f962f72 | head -n 40'`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>git ls-tree --name-only -r fea1fa7 | head -n 40

exec_command failed for `/bin/zsh -lc 'git ls-tree --name-only -r fea1fa7 | head -n 40'`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>git show --stat --oneline --no-patch fea1fa7

exec_command failed for `/bin/zsh -lc 'git show --stat --oneline --no-patch fea1fa7'`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>ls

exec_command failed for `/bin/zsh -lc ls`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>ls pretext

exec_command failed for `/bin/zsh -lc 'ls pretext'`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>pwd

exec_command failed for `/bin/bash -lc pwd`: CreateProcess { message: "Rejected(\"Failed to create unified exec process: No such file or directory (os error 2)\")" }

>pwd

Command: /bin/zsh -lc pwd
Chunk ID: 7f278e
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 6
Output:
/Users/maxgeorgopoulos

>git show --stat --oneline --no-patch f962f72

Command: /bin/zsh -lc 'git show --stat --oneline --no-patch f962f72'
Chunk ID: dfb768
Wall time: 0.0000 seconds
Process exited with code 128
Original token count: 18
Output:
fatal: not a git repository (or any of the parent directories): .git

>git show f962f72:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "git show f962f72:src/layout.ts | sed -n '1,260p'"
Chunk ID: 98552d
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 18
Output:
fatal: not a git repository (or any of the parent directories): .git

>git show 5ecce72:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "git show 5ecce72:src/layout.ts | sed -n '1,260p'"
Chunk ID: 89d314
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 18
Output:
fatal: not a git repository (or any of the parent directories): .git

>git show fea1fa7:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "git show fea1fa7:src/layout.ts | sed -n '1,260p'"
Chunk ID: 233e87
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 18
Output:
fatal: not a git repository (or any of the parent directories): .git

>cd /Users/maxgeorgopoulos/Documents/blook/experiments/pretext && git show --stat --oneline --no-patch f962f72

Command: /bin/zsh -lc 'cd /Users/maxgeorgopoulos/Documents/blook/experiments/pretext && git show --stat --oneline --no-patch f962f72'
Chunk ID: 1dcdfb
Wall time: 0.0000 seconds
Process exited with code 1
Original token count: 25
Output:
zsh:cd:1: no such file or directory: /Users/maxgeorgopoulos/Documents/blook/experiments/pretext

>cd /Users/maxgeorgopoulos/Documents/blook/experiments/pretext && git show f962f72:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/blook/experiments/pretext && git show f962f72:src/layout.ts | sed -n '1,260p'"
Chunk ID: 92be56
Wall time: 0.0000 seconds
Process exited with code 1
Original token count: 25
Output:
zsh:cd:1: no such file or directory: /Users/maxgeorgopoulos/Documents/blook/experiments/pretext

>cd /Users/maxgeorgopoulos/Documents/blook/experiments/pretext && git show 5ecce72:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/blook/experiments/pretext && git show 5ecce72:src/layout.ts | sed -n '1,260p'"
Chunk ID: 90a616
Wall time: 0.0000 seconds
Process exited with code 1
Original token count: 25
Output:
zsh:cd:1: no such file or directory: /Users/maxgeorgopoulos/Documents/blook/experiments/pretext

>cd /Users/maxgeorgopoulos/Documents/blook/experiments/pretext && git show fea1fa7:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/blook/experiments/pretext && git show fea1fa7:src/layout.ts | sed -n '1,260p'"
Chunk ID: 232b99
Wall time: 0.0000 seconds
Process exited with code 1
Original token count: 25
Output:
zsh:cd:1: no such file or directory: /Users/maxgeorgopoulos/Documents/blook/experiments/pretext

>ls /Users/maxgeorgopoulos

Command: /bin/zsh -lc 'ls /Users/maxgeorgopoulos'
Chunk ID: 05e5ec
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 60
Output:
Applications			Pictures
Calibre Library			Public
Desktop				Screen Studio Projects
Documents			Soulseek Downloads
Downloads			atkinson-hyperlegible-next-mono
Falcon				blender
Library				conductor
Movies				imessage_export
Music

>ls /Users/maxgeorgopoulos/Documents/blook/experiments

Command: /bin/zsh -lc 'ls /Users/maxgeorgopoulos/Documents/blook/experiments'
Chunk ID: 934444
Wall time: 0.0000 seconds
Process exited with code 1
Original token count: 21
Output:
ls: /Users/maxgeorgopoulos/Documents/blook/experiments: No such file or directory

>find /Users/maxgeorgopoulos -maxdepth 4 -type d -name pretext 2>/dev/null | head -n 20

Command: /bin/zsh -lc 'find /Users/maxgeorgopoulos -maxdepth 4 -type d -name pretext 2>/dev/null | head -n 20'
Chunk ID: 35a835
Wall time: 1.0022 seconds
Process running with session ID 75582
Original token count: 0
Output:

Command: /bin/zsh -lc 'find /Users/maxgeorgopoulos -maxdepth 4 -type d -name pretext 2>/dev/null | head -n 20'
Chunk ID: e324ee
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 14
Output:
/Users/maxgeorgopoulos/Documents/experiments/pretext

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show --stat --oneline --no-patch f962f72

Command: /bin/zsh -lc 'cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show --stat --oneline --no-patch f962f72'
Chunk ID: fdc054
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 8
Output:
f962f72 Initial project setup

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show f962f72:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show f962f72:src/layout.ts | sed -n '1,260p'"
Chunk ID: a426e5
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2493
Output:
// Text measurement: Intl.Segmenter + canvas measureText + bidi.
// Two-phase: prepare() once per text, layout() is pure arithmetic on resize.

const canvas = typeof OffscreenCanvas !== 'undefined'
  ? new OffscreenCanvas(1, 1)
  : document.createElement('canvas')
const ctx = canvas.getContext('2d')!

// --- Word width cache: font → Map<segment, width> ---

const wordCaches = new Map<string, Map<string, number>>()

function getWordCache(font: string): Map<string, number> {
  let cache = wordCaches.get(font)
  if (!cache) {
    cache = new Map()
    wordCaches.set(font, cache)
  }
  return cache
}

function measureSegment(seg: string, cache: Map<string, number>): number {
  let w = cache.get(seg)
  if (w === undefined) {
    w = ctx.measureText(seg).width
    cache.set(seg, w)
  }
  return w
}

function parseFontSize(font: string): number {
  const m = font.match(/(\d+(?:\.\d+)?)\s*px/)
  return m ? parseFloat(m[1]!) : 16
}

// --- CJK detection ---

function isCJK(s: string): boolean {
  for (let i = 0; i < s.length; i++) {
    const c = s.charCodeAt(i)
    if ((c >= 0x4E00 && c <= 0x9FFF) ||   // CJK Unified
        (c >= 0x3400 && c <= 0x4DBF) ||   // CJK Extension A
        (c >= 0x3000 && c <= 0x303F) ||   // CJK Punctuation
        (c >= 0x3040 && c <= 0x309F) ||   // Hiragana
        (c >= 0x30A0 && c <= 0x30FF) ||   // Katakana
        (c >= 0xAC00 && c <= 0xD7AF) ||   // Hangul
        (c >= 0xFF00 && c <= 0xFFEF)) {   // Fullwidth
      return true
    }
  }
  return false
}

// --- Bidi character classification (from Unicode/pdf.js) ---

type BidiType = 'L' | 'R' | 'AL' | 'AN' | 'EN' | 'ES' | 'ET' | 'CS' |
                'ON' | 'BN' | 'B' | 'S' | 'WS' | 'NSM'

const baseTypes: BidiType[] = [
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','S','B','S','WS',
  'B','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','BN','B','B','B','S','WS','ON','ON','ET','ET','ET','ON',
  'ON','ON','ON','ON','ON','CS','ON','CS','ON','EN','EN','EN',
  'EN','EN','EN','EN','EN','EN','EN','ON','ON','ON','ON','ON',
  'ON','ON','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','ON','ON',
  'ON','ON','ON','ON','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','ON','ON','ON','ON','BN','BN','BN','BN','BN','BN','B','BN',
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','CS','ON','ET','ET','ET','ET','ON','ON','ON','ON','L','ON',
  'ON','ON','ON','ON','ET','ET','EN','EN','ON','L','ON','ON','ON',
  'EN','L','ON','ON','ON','ON','ON','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','ON','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','ON','L','L','L','L','L','L','L','L'
]

const arabicTypes: BidiType[] = [
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'CS','AL','ON','ON','NSM','NSM','NSM','NSM','NSM','NSM','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','NSM','NSM','NSM','NSM','NSM','NSM','NSM',
  'NSM','NSM','NSM','NSM','NSM','NSM','NSM','AL','AL','AL','AL',
  'AL','AL','AL','AN','AN','AN','AN','AN','AN','AN','AN','AN',
  'AN','ET','AN','AN','AL','AL','AL','NSM','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM',
  'NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','ON','NSM',
  'NSM','NSM','NSM','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL'
]

function classifyChar(charCode: number): BidiType {
  if (charCode <= 0x00ff) return baseTypes[charCode]!
  if (0x0590 <= charCode && charCode <= 0x05f4) return 'R'
  if (0x0600 <= charCode && charCode <= 0x06ff) return arabicTypes[charCode & 0xff]!
  if (0x0700 <= charCode && charCode <= 0x08AC) return 'AL'
  return 'L'
}

function computeBidiLevels(str: string): Int8Array | null {
  const len = str.length
  if (len === 0) return null

  const types: BidiType[] = new Array(len)
  let numBidi = 0

  for (let i = 0; i < len; i++) {
    const t = classifyChar(str.charCodeAt(i))
    if (t === 'R' || t === 'AL' || t === 'AN') numBidi++
    types[i] = t
  }

  if (numBidi === 0) return null

  const startLevel = (len / numBidi) < 0.3 ? 0 : 1
  const levels = new Int8Array(len)
  for (let i = 0; i < len; i++) levels[i] = startLevel

  const e: BidiType = (startLevel & 1) ? 'R' : 'L'
  const sor = e

  // W1-W7
  let lastType: BidiType = sor
  for (let i = 0; i < len; i++) { if (types[i] === 'NSM') types[i] = lastType; else lastType = types[i]! }
  lastType = sor
  for (let i = 0; i < len; i++) { const t = types[i]!; if (t === 'EN') types[i] = lastType === 'AL' ? 'AN' : 'EN'; else if (t === 'R' || t === 'L' || t === 'AL') lastType = t }
  for (let i = 0; i < len; i++) { if (types[i] === 'AL') types[i] = 'R' }
  for (let i = 1; i < len - 1; i++) { if (types[i] === 'ES' && types[i-1] === 'EN' && types[i+1] === 'EN') types[i] = 'EN'; if (types[i] === 'CS' && (types[i-1] === 'EN' || types[i-1] === 'AN') && types[i+1] === types[i-1]) types[i] = types[i-1]! }
  for (let i = 0; i < len; i++) { if (types[i] === 'EN') { let j; for (j = i-1; j >= 0 && types[j] === 'ET'; j--) types[j] = 'EN'; for (j = i+1; j < len && types[j] === 'ET'; j++) types[j] = 'EN' } }
  for (let i = 0; i < len; i++) { const t = types[i]!; if (t === 'WS' || t === 'ES' || t === 'ET' || t === 'CS') types[i] = 'ON' }
  lastType = sor
  for (let i = 0; i < len; i++) { const t = types[i]!; if (t === 'EN') types[i] = lastType === 'L' ? 'L' : 'EN'; else if (t === 'R' || t === 'L') lastType = t }

  // N1-N2
  for (let i = 0; i < len; i++) {
    if (types[i] === 'ON') {
      let end = i + 1
      while (end < len && types[end] === 'ON') end++
      const before: BidiType = i > 0 ? types[i-1]! : sor
      const after: BidiType = end < len ? types[end]! : sor
      const bDir: BidiType = before !== 'L' ? 'R' : 'L'
      const aDir: BidiType = after !== 'L' ? 'R' : 'L'
      if (bDir === aDir) { for (let j = i; j < end; j++) types[j] = bDir }
      i = end - 1
    }
  }
  for (let i = 0; i < len; i++) { if (types[i] === 'ON') types[i] = e }

  // I1-I2
  for (let i = 0; i < len; i++) {
    const t = types[i]!
    if ((levels[i]! & 1) === 0) {
      if (t === 'R') levels[i]!++
      else if (t === 'AN' || t === 'EN') levels[i]! += 2
    } else {
      if (t === 'L' || t === 'AN' || t === 'EN') levels[i]!++
    }
  }

  return levels
}

function reorderLine(segLevels: Int8Array, start: number, end: number): number[] | null {
  let low = 127, high = 0
  for (let i = start; i < end; i++) {
    const lv = segLevels[i]!
    if (lv < low) low = lv
    if (lv > high) high = lv
  }
  if (high <= 0) return null
  if (low % 2 === 0) low++

  const indices = new Array<number>(end - start)
  for (let i = 0; i < indices.length; i++) indices[i] = start + i

  while (high >= low) {
    let i = 0
    while (i < indices.length) {
      while (i < indices.length && segLevels[indices[i]!]! < high) i++
      let j = i
      while (j < indices.length && segLevels[indices[j]!]! >= high) j++
      let a = i, b = j - 1
      while (a < b) { const tmp = indices[a]!; indices[a] = indices[b]!; indices[b] = tmp; a++; b-- }
      i = j
    }
    high--
  }
  return indices
}

// --- Public types ---

type ParaData = {
  widths: number[]
  isWordLike: boolean[]
  isSpace: boolean[]
  segLevels: Int8Array | null
  breakableWidths: (number[] | null)[]
}

export type PreparedText = {
  paraData: ParaData[]
  lineHeight: number
}

export type LayoutResult = {
  lineCount: number
  height: number
}

// --- Public API ---

export function prepare(text: string, font: string, lineHeight?: number): PreparedText {
  ctx.font = font
  const cache = getWordCache(font)

  if (lineHeight === undefined) {
    lineHeight = Math.round(parseFontSize(font) * 1.2)
  }

  const segmenter = new Intl.Segmenter(undefined, { granularity: 'word' })
  const normalized = text.replace(/\n/g, ' ')

  if (normalized.length === 0 || normalized.trim().length === 0) {
    return { paraData: [], lineHeight }
  }

  const graphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })
  const segments = segmenter.segment(normalized)
  const widths: number[] = []
  const isWordLike: boolean[] = []
  const isSpace: boolean[] = []
  const segStarts: number[] = []
  const breakableWidths: (number[] | null)[] = []

  // Merge punctuation into preceding words: "better." as one unit
  const rawSegs = [...segments]
  const merged: { text: string, isWordLike: boolean, isSpace: boolean, start: number }[] = []

  for (let i = 0; i < rawSegs.length; i++) {
    const s = rawSegs[i]!
    const ws = !s.isWordLike && /^\s+$/.test(s.segment)

    if (!s.isWordLike && !ws && merged.length > 0) {
      merged[merged.length - 1]!.text += s.segment
    } else {

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show 5ecce72:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show 5ecce72:src/layout.ts | sed -n '1,260p'"
Chunk ID: d72e62
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2739
Output:
// DOM-free text measurement for browser environments.
//
// Problem: DOM-based text measurement (getBoundingClientRect, offsetHeight)
// forces synchronous layout reflow. When components independently measure text,
// each measurement triggers a reflow of the entire document. This creates
// read/write interleaving that can cost 30ms+ per frame for 500 text blocks.
//
// Solution: two-phase measurement using canvas measureText (no DOM reads).
//   prepare(text, font) — segments text via Intl.Segmenter, measures each word
//     via canvas, caches widths. Call once when text first appears.
//   layout(prepared, maxWidth) — walks cached word widths with pure arithmetic
//     to count lines and compute height. Call on every resize. ~0.0002ms per text.
//
// i18n: Intl.Segmenter handles CJK (per-character breaking), Thai, Arabic, etc.
//   Bidi: Unicode Bidirectional Algorithm for mixed LTR/RTL text.
//   Punctuation merging: "better." measured as one unit (matches CSS behavior).
//   Trailing whitespace: hangs past line edge without triggering breaks (CSS behavior).
//   overflow-wrap: pre-measured grapheme widths enable character-level word breaking.
//
// Emoji correction: Chrome/Firefox canvas measures emoji wider than DOM at font
//   sizes <24px on macOS (Apple Color Emoji). The inflation is constant per emoji
//   grapheme at a given size, font-independent. Auto-detected by comparing canvas
//   vs actual DOM emoji width (one cached DOM read per font). Safari canvas and
//   DOM agree (both wider than fontSize), so correction = 0 there.
//
// Limitations:
//   - system-ui font: canvas resolves to different optical variants than DOM on macOS.
//     Use named fonts (Helvetica, Inter, etc.) for guaranteed accuracy.
//
// Based on Sebastian Markbage's text-layout research (github.com/chenglou/text-layout).

const canvas = typeof OffscreenCanvas !== 'undefined'
  ? new OffscreenCanvas(1, 1)
  : document.createElement('canvas')
const ctx = canvas.getContext('2d')!

// Word width cache: font → Map<segment, width>.
// Persists across prepare() calls. Common words ("the", "a", etc.) are measured
// once and shared across all text blocks. Survives resize since font doesn't change.
// No eviction: grows monotonically per font. Typical single-font feed ≈ few KB.
// Call clearCache() to reclaim if needed (e.g. font change, long session).

const wordCaches = new Map<string, Map<string, number>>()

function getWordCache(font: string): Map<string, number> {
  let cache = wordCaches.get(font)
  if (!cache) {
    cache = new Map()
    wordCaches.set(font, cache)
  }
  return cache
}

function measureSegment(seg: string, cache: Map<string, number>): number {
  let w = cache.get(seg)
  if (w === undefined) {
    w = ctx.measureText(seg).width
    cache.set(seg, w)
  }
  return w
}

function parseFontSize(font: string): number {
  const m = font.match(/(\d+(?:\.\d+)?)\s*px/)
  return m ? parseFloat(m[1]!) : 16
}

// Emoji correction: canvas measureText inflates emoji widths on Chrome/Firefox
// at font sizes <24px on macOS. The inflation is per-emoji-grapheme, constant
// across all emoji types (simple, ZWJ, flags, skin tones, keycaps) and all font
// families. Auto-detected by comparing canvas vs DOM emoji width (one cached
// DOM read per font). Safari canvas and DOM agree, so correction = 0.

const emojiPresentationRe = /\p{Emoji_Presentation}/u
// Shared segmenters: hoisted to module level to avoid per-prepare() construction.
// Intl.Segmenter construction loads ICU data internally — expensive to repeat.
// Captures the default locale at module load time. If locale support is needed
// in the future, expose a function to reinitialize these with a new locale.
const sharedWordSegmenter = new Intl.Segmenter(undefined, { granularity: 'word' })
const sharedGraphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })

function isEmojiGrapheme(g: string): boolean {
  return emojiPresentationRe.test(g) || g.includes('\uFE0F')
}

const emojiCorrectionCache = new Map<string, number>()

function getEmojiCorrection(font: string, fontSize: number): number {
  let correction = emojiCorrectionCache.get(font)
  if (correction !== undefined) return correction

  ctx.font = font
  const canvasW = ctx.measureText('\u{1F600}').width
  correction = 0
  if (canvasW > fontSize + 0.5) {
    const span = document.createElement('span')
    span.style.font = font
    span.style.display = 'inline-block'
    span.style.visibility = 'hidden'
    span.style.position = 'absolute'
    span.textContent = '\u{1F600}'
    document.body.appendChild(span)
    const domW = span.getBoundingClientRect().width
    document.body.removeChild(span)
    if (canvasW - domW > 0.5) {
      correction = canvasW - domW
    }
  }
  emojiCorrectionCache.set(font, correction)
  return correction
}

function countEmojiGraphemes(text: string): number {
  let count = 0
  for (const g of sharedGraphemeSegmenter.segment(text)) {
    if (isEmojiGrapheme(g.segment)) count++
  }
  return count
}

// CJK characters don't use spaces between words. Intl.Segmenter with
// granularity 'word' groups them into multi-character words, but CSS allows
// line breaks between any CJK characters. We detect CJK segments and split
// them into individual graphemes so each character is a valid break point.

function isCJK(s: string): boolean {
  for (let i = 0; i < s.length; i++) {
    const c = s.charCodeAt(i)
    if ((c >= 0x4E00 && c <= 0x9FFF) ||   // CJK Unified
        (c >= 0x3400 && c <= 0x4DBF) ||   // CJK Extension A
        (c >= 0x3000 && c <= 0x303F) ||   // CJK Punctuation
        (c >= 0x3040 && c <= 0x309F) ||   // Hiragana
        (c >= 0x30A0 && c <= 0x30FF) ||   // Katakana
        (c >= 0xAC00 && c <= 0xD7AF) ||   // Hangul
        (c >= 0xFF00 && c <= 0xFFEF)) {   // Fullwidth
      return true
    }
  }
  return false
}

function isWhitespace(s: string): boolean {
  for (let i = 0; i < s.length; i++) {
    const c = s.charCodeAt(i)
    if (c !== 0x20 && c !== 0x09 && c !== 0x0A && c !== 0x0D && c !== 0x0C && c !== 0xA0) {
      return false
    }
  }
  return true
}

// Kinsoku shori (禁則処理): CJK line-breaking rules.
// Line-start prohibition: these characters cannot start a new line.
// To prevent this, they are merged with the preceding grapheme during
// CJK splitting, keeping them together as one unit.
const kinsokuStart = new Set([
  // Fullwidth punctuation
  '\uFF0C', // ，
  '\uFF0E', // ．
  '\uFF01', // ！
  '\uFF1A', // ：
  '\uFF1B', // ；
  '\uFF1F', // ？
  // CJK punctuation
  '\u3001', // 、
  '\u3002', // 。
  '\u30FB', // ・
  // Closing brackets
  '\uFF09', // ）
  '\u3015', // 〕
  '\u3009', // 〉
  '\u300B', // 》
  '\u300D', // 」
  '\u300F', // 』
  '\u3011', // 】
  '\u3017', // 〗
  '\u3019', // 〙
  '\u301B', // 〛
  // Prolonged sound mark, iteration marks
  '\u30FC', // ー
  '\u3005', // 々
  '\u303B', // 〻
])

// Line-end prohibition: these characters cannot end a line (UAX #14 class OP +
// CJK opening brackets). To prevent this, they are merged with the following
// grapheme in CJK splitting, and with the following word in general merging.
const kinsokuEnd = new Set([
  // ASCII/Latin
  '(', '[', '{',
  // CJK fullwidth
  '\uFF08', // （
  '\u3014', // 〔
  '\u3008', // 〈
  '\u300A', // 《
  '\u300C', // 「
  '\u300E', // 『
  '\u3010', // 【
  '\u3016', // 〖
  '\u3018', // 〘
  '\u301A', // 〚
])

// Unicode Bidirectional Algorithm (UAX #9), forked from pdf.js via Sebastian's
// text-layout. Classifies characters into bidi types, computes embedding levels,
// and reorders segments within each line for correct visual display of mixed
// LTR/RTL text. Only needed for paragraphs containing RTL characters; pure LTR
// text fast-paths with null levels (zero overhead).

type BidiType = 'L' | 'R' | 'AL' | 'AN' | 'EN' | 'ES' | 'ET' | 'CS' |
                'ON' | 'BN' | 'B' | 'S' | 'WS' | 'NSM'

const baseTypes: BidiType[] = [
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','S','B','S','WS',
  'B','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','BN','B','B','B','S','WS','ON','ON','ET','ET','ET','ON',
  'ON','ON','ON','ON','ON','CS','ON','CS','ON','EN','EN','EN',
  'EN','EN','EN','EN','EN','EN','EN','ON','ON','ON','ON','ON',
  'ON','ON','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','ON','ON',
  'ON','ON','ON','ON','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','ON','ON','ON','ON','BN','BN','BN','BN','BN','BN','B','BN',
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','CS','ON','ET','ET','ET','ET','ON','ON','ON','ON','L','ON',
  'ON','ON','ON','ON','ET','ET','EN','EN','ON','L','ON','ON','ON',
  'EN','L','ON','ON','ON','ON','ON','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','ON','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','ON','L','L','L','L','L','L','L','L'
]

const arabicTypes: BidiType[] = [
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'CS','AL','ON','ON','NSM','NSM','NSM','NSM','NSM','NSM','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','NSM','NSM','NSM','NSM','NSM','NSM','NSM',
  'NSM','NSM','NSM','NSM','NSM','NSM','NSM','AL','AL','AL','AL',
  'AL','AL','AL','AN','AN','AN','AN','AN','AN','AN','AN','AN',
  'AN','ET','AN','AN','AL','AL','AL','NSM','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM',
  'NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','ON','NSM',
  'NSM','NSM','NSM','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL'
]

function classifyChar(charCode: number): BidiType {

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show fea1fa7:src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show fea1fa7:src/layout.ts | sed -n '1,260p'"
Chunk ID: dd09ff
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2752
Output:
// Text measurement for browser environments using canvas measureText.
//
// Problem: DOM-based text measurement (getBoundingClientRect, offsetHeight)
// forces synchronous layout reflow. When components independently measure text,
// each measurement triggers a reflow of the entire document. This creates
// read/write interleaving that can cost 30ms+ per frame for 500 text blocks.
//
// Solution: two-phase measurement centered around canvas measureText.
//   prepare(text, font) — segments text via Intl.Segmenter, measures each word
//     via canvas, caches widths, and does one cached DOM calibration read per
//     font when emoji correction is needed. Call once when text first appears.
//   layout(prepared, maxWidth) — walks cached word widths with pure arithmetic
//     to count lines and compute height. Call on every resize. ~0.0002ms per text.
//
// i18n: Intl.Segmenter handles CJK (per-character breaking), Thai, Arabic, etc.
//   Bidi: Unicode Bidirectional Algorithm for mixed LTR/RTL text.
//   Punctuation merging: "better." measured as one unit (matches CSS behavior).
//   Trailing whitespace: hangs past line edge without triggering breaks (CSS behavior).
//   overflow-wrap: pre-measured grapheme widths enable character-level word breaking.
//
// Emoji correction: Chrome/Firefox canvas measures emoji wider than DOM at font
//   sizes <24px on macOS (Apple Color Emoji). The inflation is constant per emoji
//   grapheme at a given size, font-independent. Auto-detected by comparing canvas
//   vs actual DOM emoji width (one cached DOM read per font). Safari canvas and
//   DOM agree (both wider than fontSize), so correction = 0 there.
//
// Limitations:
//   - system-ui font: canvas resolves to different optical variants than DOM on macOS.
//     Use named fonts (Helvetica, Inter, etc.) for guaranteed accuracy.
//
// Based on Sebastian Markbage's text-layout research (github.com/chenglou/text-layout).

const canvas = typeof OffscreenCanvas !== 'undefined'
  ? new OffscreenCanvas(1, 1)
  : document.createElement('canvas')
const ctx = canvas.getContext('2d')!

// Word width cache: font → Map<segment, width>.
// Persists across prepare() calls. Common words ("the", "a", etc.) are measured
// once and shared across all text blocks. Survives resize since font doesn't change.
// No eviction: grows monotonically per font. Typical single-font feed ≈ few KB.
// Call clearCache() to reclaim if needed (e.g. font change, long session).

const wordCaches = new Map<string, Map<string, number>>()

function getWordCache(font: string): Map<string, number> {
  let cache = wordCaches.get(font)
  if (!cache) {
    cache = new Map()
    wordCaches.set(font, cache)
  }
  return cache
}

function measureSegment(seg: string, cache: Map<string, number>): number {
  let w = cache.get(seg)
  if (w === undefined) {
    w = ctx.measureText(seg).width
    cache.set(seg, w)
  }
  return w
}

function parseFontSize(font: string): number {
  const m = font.match(/(\d+(?:\.\d+)?)\s*px/)
  return m ? parseFloat(m[1]!) : 16
}

// Emoji correction: canvas measureText inflates emoji widths on Chrome/Firefox
// at font sizes <24px on macOS. The inflation is per-emoji-grapheme, constant
// across all emoji types (simple, ZWJ, flags, skin tones, keycaps) and all font
// families. Auto-detected by comparing canvas vs DOM emoji width (one cached
// DOM read per font). Safari canvas and DOM agree, so correction = 0.

const emojiPresentationRe = /\p{Emoji_Presentation}/u
// Shared segmenters: hoisted to module level to avoid per-prepare() construction.
// Intl.Segmenter construction loads ICU data internally — expensive to repeat.
// Captures the default locale at module load time. If locale support is needed
// in the future, expose a function to reinitialize these with a new locale.
const sharedWordSegmenter = new Intl.Segmenter(undefined, { granularity: 'word' })
const sharedGraphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })

function isEmojiGrapheme(g: string): boolean {
  return emojiPresentationRe.test(g) || g.includes('\uFE0F')
}

const emojiCorrectionCache = new Map<string, number>()

function getEmojiCorrection(font: string, fontSize: number): number {
  let correction = emojiCorrectionCache.get(font)
  if (correction !== undefined) return correction

  ctx.font = font
  const canvasW = ctx.measureText('\u{1F600}').width
  correction = 0
  if (canvasW > fontSize + 0.5) {
    const span = document.createElement('span')
    span.style.font = font
    span.style.display = 'inline-block'
    span.style.visibility = 'hidden'
    span.style.position = 'absolute'
    span.textContent = '\u{1F600}'
    document.body.appendChild(span)
    const domW = span.getBoundingClientRect().width
    document.body.removeChild(span)
    if (canvasW - domW > 0.5) {
      correction = canvasW - domW
    }
  }
  emojiCorrectionCache.set(font, correction)
  return correction
}

function countEmojiGraphemes(text: string): number {
  let count = 0
  for (const g of sharedGraphemeSegmenter.segment(text)) {
    if (isEmojiGrapheme(g.segment)) count++
  }
  return count
}

// CJK characters don't use spaces between words. Intl.Segmenter with
// granularity 'word' groups them into multi-character words, but CSS allows
// line breaks between any CJK characters. We detect CJK segments and split
// them into individual graphemes so each character is a valid break point.

function isCJK(s: string): boolean {
  for (let i = 0; i < s.length; i++) {
    const c = s.charCodeAt(i)
    if ((c >= 0x4E00 && c <= 0x9FFF) ||   // CJK Unified
        (c >= 0x3400 && c <= 0x4DBF) ||   // CJK Extension A
        (c >= 0x3000 && c <= 0x303F) ||   // CJK Punctuation
        (c >= 0x3040 && c <= 0x309F) ||   // Hiragana
        (c >= 0x30A0 && c <= 0x30FF) ||   // Katakana
        (c >= 0xAC00 && c <= 0xD7AF) ||   // Hangul
        (c >= 0xFF00 && c <= 0xFFEF)) {   // Fullwidth
      return true
    }
  }
  return false
}

function isWhitespace(s: string): boolean {
  for (let i = 0; i < s.length; i++) {
    const c = s.charCodeAt(i)
    if (c !== 0x20 && c !== 0x09 && c !== 0x0A && c !== 0x0D && c !== 0x0C && c !== 0xA0) {
      return false
    }
  }
  return true
}

// Kinsoku shori (禁則処理): CJK line-breaking rules.
// Line-start prohibition: these characters cannot start a new line.
// To prevent this, they are merged with the preceding grapheme during
// CJK splitting, keeping them together as one unit.
const kinsokuStart = new Set([
  // Fullwidth punctuation
  '\uFF0C', // ，
  '\uFF0E', // ．
  '\uFF01', // ！
  '\uFF1A', // ：
  '\uFF1B', // ；
  '\uFF1F', // ？
  // CJK punctuation
  '\u3001', // 、
  '\u3002', // 。
  '\u30FB', // ・
  // Closing brackets
  '\uFF09', // ）
  '\u3015', // 〕
  '\u3009', // 〉
  '\u300B', // 》
  '\u300D', // 」
  '\u300F', // 』
  '\u3011', // 】
  '\u3017', // 〗
  '\u3019', // 〙
  '\u301B', // 〛
  // Prolonged sound mark, iteration marks
  '\u30FC', // ー
  '\u3005', // 々
  '\u303B', // 〻
])

// Line-end prohibition: these characters cannot end a line (UAX #14 class OP +
// CJK opening brackets). To prevent this, they are merged with the following
// grapheme in CJK splitting, and with the following word in general merging.
const kinsokuEnd = new Set([
  // ASCII/Latin
  '(', '[', '{',
  // CJK fullwidth
  '\uFF08', // （
  '\u3014', // 〔
  '\u3008', // 〈
  '\u300A', // 《
  '\u300C', // 「
  '\u300E', // 『
  '\u3010', // 【
  '\u3016', // 〖
  '\u3018', // 〘
  '\u301A', // 〚
])

// Unicode Bidirectional Algorithm (UAX #9), forked from pdf.js via Sebastian's
// text-layout. Classifies characters into bidi types, computes embedding levels,
// and reorders segments within each line for correct visual display of mixed
// LTR/RTL text. Only needed for paragraphs containing RTL characters; pure LTR
// text fast-paths with null levels (zero overhead).

type BidiType = 'L' | 'R' | 'AL' | 'AN' | 'EN' | 'ES' | 'ET' | 'CS' |
                'ON' | 'BN' | 'B' | 'S' | 'WS' | 'NSM'

const baseTypes: BidiType[] = [
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','S','B','S','WS',
  'B','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','BN','B','B','B','S','WS','ON','ON','ET','ET','ET','ON',
  'ON','ON','ON','ON','ON','CS','ON','CS','ON','EN','EN','EN',
  'EN','EN','EN','EN','EN','EN','EN','ON','ON','ON','ON','ON',
  'ON','ON','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','ON','ON',
  'ON','ON','ON','ON','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','ON','ON','ON','ON','BN','BN','BN','BN','BN','BN','B','BN',
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN','BN',
  'BN','CS','ON','ET','ET','ET','ET','ON','ON','ON','ON','L','ON',
  'ON','ON','ON','ON','ET','ET','EN','EN','ON','L','ON','ON','ON',
  'EN','L','ON','ON','ON','ON','ON','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','ON','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','L','L','L','L','L','L','L','L','L','L','L','L',
  'L','L','L','ON','L','L','L','L','L','L','L','L'
]

const arabicTypes: BidiType[] = [
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'CS','AL','ON','ON','NSM','NSM','NSM','NSM','NSM','NSM','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','NSM','NSM','NSM','NSM','NSM','NSM','NSM',
  'NSM','NSM','NSM','NSM','NSM','NSM','NSM','AL','AL','AL','AL',
  'AL','AL','AL','AN','AN','AN','AN','AN','AN','AN','AN','AN',
  'AN','ET','AN','AN','AL','AL','AL','NSM','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM',
  'NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','NSM','ON','NSM',
  'NSM','NSM','NSM','AL','AL','AL','AL','AL','AL','AL','AL','AL',
  'AL','AL','AL','AL','AL','AL','AL','AL','AL'
]

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show fea1fa7:src/layout.ts | rg -n "export function|type LayoutLine|type LayoutCursor|function layoutInternal"

Command: /bin/zsh -lc 'cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show fea1fa7:src/layout.ts | rg -n "export function|type LayoutLine|type LayoutCursor|function layoutInternal"'
Chunk ID: fc62b3
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 145
Output:
352:export type LayoutLine = {
357:export type LayoutLinesResult = LayoutResult & {
532:export function prepare(text: string, font: string, lineHeight?: number): PreparedText {
538:export function prepareWithSegments(text: string, font: string, lineHeight?: number): PreparedTextWithSegments {
550:export function layout(prepared: PreparedText, maxWidth: number, lineHeight?: number): LayoutResult {
622:export function layoutWithLines(prepared: PreparedTextWithSegments, maxWidth: number, lineHeight?: number): LayoutLinesResult {
718:export function clearCache(): void {

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show fea1fa7:src/layout.ts | sed -n '520,780p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show fea1fa7:src/layout.ts | sed -n '520,780p'"
Chunk ID: 400795
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1578
Output:
// (e.g. when a comment first appears). The result is width-independent — the
// same PreparedText can be laid out at any maxWidth via layout().
//
// Steps:
//   1. Normalize newlines to spaces (CSS white-space: normal behavior)
//   2. Segment via Intl.Segmenter (handles CJK, Thai, etc.)
//   3. Merge punctuation into preceding word ("better." as one unit)
//   4. Split CJK words into individual graphemes (per-character line breaks)
//   5. Measure each segment via canvas measureText, cache by (segment, font)
//   6. Pre-measure graphemes of long words (for overflow-wrap: break-word)
//   7. Correct emoji canvas inflation (auto-detected per font size)
//   8. Compute bidi embedding levels for mixed-direction text
export function prepare(text: string, font: string, lineHeight?: number): PreparedText {
  return prepareInternal(text, font, lineHeight, false) as PreparedText
}

// Rich variant used by callers that need enough information to render the
// laid-out lines themselves.
export function prepareWithSegments(text: string, font: string, lineHeight?: number): PreparedTextWithSegments {
  return prepareInternal(text, font, lineHeight, true) as PreparedTextWithSegments
}

// Layout prepared text at a given max width. Pure arithmetic on cached widths —
// no canvas calls, no DOM reads, no string operations, no allocations.
// ~0.0002ms per text block. Call on every resize.
//
// Line breaking rules (matching CSS white-space: normal + overflow-wrap: break-word):
//   - Break before any non-space segment that would overflow the line
//   - Trailing whitespace hangs past the line edge (doesn't trigger breaks)
//   - Segments wider than maxWidth are broken at grapheme boundaries
export function layout(prepared: PreparedText, maxWidth: number, lineHeight?: number): LayoutResult {
  if (lineHeight === undefined) lineHeight = prepared.lineHeight
  const { widths, isSpace: isSp, breakableWidths } = prepared
  if (widths.length === 0) return { lineCount: 0, height: 0 }

  let lineCount = 0
  let lineW = 0
  let hasContent = false

  for (let i = 0; i < widths.length; i++) {
    const w = widths[i]!

    if (!hasContent) {
      if (w > maxWidth && breakableWidths[i] !== null) {
        const gWidths = breakableWidths[i]!
        lineW = 0
        for (let g = 0; g < gWidths.length; g++) {
          const gw = gWidths[g]!
          if (lineW > 0 && lineW + gw > maxWidth) {
            lineCount++
            lineW = gw
          } else {
            if (lineW === 0) lineCount++
            lineW += gw
          }
        }
      } else {
        lineW = w
        lineCount++
      }
      hasContent = true
      continue
    }

    const newW = lineW + w

    if (newW > maxWidth) {
      if (isSp[i]) continue // trailing whitespace hangs (CSS behavior)

      if (w > maxWidth && breakableWidths[i] !== null) {
        // Segment wider than line — break at grapheme boundaries
        const gWidths = breakableWidths[i]!
        lineW = 0
        for (let g = 0; g < gWidths.length; g++) {
          const gw = gWidths[g]!
          if (lineW > 0 && lineW + gw > maxWidth) {
            lineCount++
            lineW = gw
          } else {
            if (lineW === 0) lineCount++
            lineW += gw
          }
        }
      } else {
        lineCount++
        lineW = w
      }
    } else {
      lineW = newW
    }
  }

  if (!hasContent) {
    lineCount++
  }

  return { lineCount, height: lineCount * lineHeight }
}

// Rich layout API for callers that want the actual line contents and widths.
// Mirrors layout()'s break decisions, but keeps extra per-line bookkeeping so it
// should stay off the resize hot path.
export function layoutWithLines(prepared: PreparedTextWithSegments, maxWidth: number, lineHeight?: number): LayoutLinesResult {
  if (lineHeight === undefined) lineHeight = prepared.lineHeight
  const { widths, isSpace: isSp, breakableWidths, segments } = prepared
  const lines: LayoutLine[] = []
  if (widths.length === 0) return { lineCount: 0, height: 0, lineHeight, lines }

  let lineCount = 0
  let lineW = 0
  let hasContent = false
  let currentLine = ''

  function pushCurrentLine(): void {
    lines.push({ text: currentLine, width: lineW })
    currentLine = ''
  }

  function layoutBreakableSegment(segIndex: number, closeExistingLine: boolean): void {
    const gWidths = breakableWidths[segIndex]!
    const gTexts: string[] = []
    let gTextCount = 0
    for (const gs of sharedGraphemeSegmenter.segment(segments[segIndex]!)) {
      gTexts[gTextCount] = gs.segment
      gTextCount++
    }

    if (closeExistingLine) pushCurrentLine()

    lineW = 0
    currentLine = ''

    for (let g = 0; g < gWidths.length; g++) {
      const gw = gWidths[g]!
      const gText = gTexts[g]!

      if (lineW > 0 && lineW + gw > maxWidth) {
        pushCurrentLine()
        lineCount++
        lineW = gw
        currentLine = gText
      } else {
        if (lineW === 0) {
          lineCount++
          lineW = gw
          currentLine = gText
        } else {
          lineW += gw
          currentLine += gText
        }
      }
    }
  }

  for (let i = 0; i < widths.length; i++) {
    const w = widths[i]!
    const segText = segments[i]!

    if (!hasContent) {
      if (w > maxWidth && breakableWidths[i] !== null) {
        layoutBreakableSegment(i, false)
      } else {
        lineW = w
        lineCount++
        currentLine = segText
      }
      hasContent = true
      continue
    }

    const newW = lineW + w

    if (newW > maxWidth) {
      if (isSp[i]) continue

      if (w > maxWidth && breakableWidths[i] !== null) {
        layoutBreakableSegment(i, true)
      } else {
        pushCurrentLine()
        lineCount++
        lineW = w
        currentLine = segText
      }
    } else {
      lineW = newW
      currentLine += segText
    }
  }

  if (!hasContent) {
    lineCount++
  } else {
    pushCurrentLine()
  }

  return { lineCount, height: lineCount * lineHeight, lineHeight, lines }
}

export function clearCache(): void {
  wordCaches.clear()
  emojiCorrectionCache.clear()
}

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show f06fb75:src/line-break.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show f06fb75:src/line-break.ts | sed -n '1,260p'"
Chunk ID: 9e2d86
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1837
Output:
import type { SegmentBreakKind } from './analysis.ts'
import { getEngineProfile } from './measurement.ts'

export type LineBreakCursor = {
  segmentIndex: number
  graphemeIndex: number
}

export type PreparedLineBreakData = {
  widths: number[]
  kinds: SegmentBreakKind[]
  breakableWidths: (number[] | null)[]
  discretionaryHyphenWidth: number
}

export type InternalLayoutLine = {
  startSegmentIndex: number
  startGraphemeIndex: number
  endSegmentIndex: number
  endGraphemeIndex: number
  width: number
  discretionaryHyphenBeforeSegmentIndex: number
}

function isCollapsibleSpaceKind(kind: SegmentBreakKind): boolean {
  return kind === 'space'
}

export function normalizeLineStart(
  prepared: PreparedLineBreakData,
  start: LineBreakCursor,
): LineBreakCursor | null {
  let segmentIndex = start.segmentIndex
  const graphemeIndex = start.graphemeIndex

  if (segmentIndex >= prepared.widths.length) return null
  if (graphemeIndex > 0) return start

  while (segmentIndex < prepared.widths.length) {
    const kind = prepared.kinds[segmentIndex]!
    if (kind !== 'space' && kind !== 'zero-width-break' && kind !== 'soft-hyphen') {
      break
    }
    segmentIndex++
  }

  if (segmentIndex >= prepared.widths.length) return null
  return { segmentIndex, graphemeIndex: 0 }
}

export function countPreparedLines(prepared: PreparedLineBreakData, maxWidth: number): number {
  const { widths, kinds, breakableWidths } = prepared
  if (widths.length === 0) return 0
  const lineFitEpsilon = getEngineProfile().lineFitEpsilon
  if (kinds.includes('soft-hyphen')) {
    return walkPreparedLines(prepared, maxWidth)
  }

  let lineCount = 0
  let lineW = 0
  let hasContent = false

  function placeOnFreshLine(segmentIndex: number): void {
    const w = widths[segmentIndex]!
    if (w > maxWidth && breakableWidths[segmentIndex] !== null) {
      const gWidths = breakableWidths[segmentIndex]!
      lineW = 0
      for (let g = 0; g < gWidths.length; g++) {
        const gw = gWidths[g]!
        if (lineW > 0 && lineW + gw > maxWidth + lineFitEpsilon) {
          lineCount++
          lineW = gw
        } else {
          if (lineW === 0) lineCount++
          lineW += gw
        }
      }
    } else {
      lineW = w
      lineCount++
    }
    hasContent = true
  }

  for (let i = 0; i < widths.length; i++) {
    const w = widths[i]!
    const kind = kinds[i]!

    if (!hasContent) {
      placeOnFreshLine(i)
      continue
    }

    const newW = lineW + w

    if (newW > maxWidth + lineFitEpsilon) {
      if (isCollapsibleSpaceKind(kind)) {
        continue
      }
      lineW = 0
      hasContent = false
      placeOnFreshLine(i)
    } else {
      lineW = newW
    }
  }

  if (!hasContent) {
    lineCount++
  }

  return lineCount
}

export function walkPreparedLines(
  prepared: PreparedLineBreakData,
  maxWidth: number,
  onLine?: (line: InternalLayoutLine) => void,
): number {
  const { widths, kinds, breakableWidths, discretionaryHyphenWidth } = prepared
  if (widths.length === 0) return 0
  const lineFitEpsilon = getEngineProfile().lineFitEpsilon

  let lineCount = 0
  let lineW = 0
  let hasContent = false
  let lineStartSegmentIndex = 0
  let lineStartGraphemeIndex = 0
  let lineEndSegmentIndex = 0
  let lineEndGraphemeIndex = 0
  let pendingSoftBreakSegmentIndex = -1
  let pendingSoftBreakWidth = 0

  function clearPendingSoftBreak(): void {
    pendingSoftBreakSegmentIndex = -1
    pendingSoftBreakWidth = 0
  }

  function emitCurrentLine(
    endSegmentIndex = lineEndSegmentIndex,
    endGraphemeIndex = lineEndGraphemeIndex,
    width = lineW,
    discretionaryHyphenBeforeSegmentIndex = -1,
  ): void {
    lineCount++
    onLine?.({
      startSegmentIndex: lineStartSegmentIndex,
      startGraphemeIndex: lineStartGraphemeIndex,
      endSegmentIndex,
      endGraphemeIndex,
      width,
      discretionaryHyphenBeforeSegmentIndex,
    })
    lineW = 0
    hasContent = false
    clearPendingSoftBreak()
  }

  function startLineAtSegment(segmentIndex: number, width: number): void {
    hasContent = true
    lineStartSegmentIndex = segmentIndex
    lineStartGraphemeIndex = 0
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
    lineW = width
  }

  function startLineAtGrapheme(segmentIndex: number, graphemeIndex: number, width: number): void {
    hasContent = true
    lineStartSegmentIndex = segmentIndex
    lineStartGraphemeIndex = graphemeIndex
    lineEndSegmentIndex = segmentIndex
    lineEndGraphemeIndex = graphemeIndex + 1
    lineW = width
  }

  function appendWholeSegment(segmentIndex: number, width: number): void {
    if (!hasContent) {
      startLineAtSegment(segmentIndex, width)
      return
    }
    lineW += width
    lineEndSegmentIndex = segmentIndex + 1
    lineEndGraphemeIndex = 0
  }

  function appendBreakableSegment(segmentIndex: number): void {
    appendBreakableSegmentFrom(segmentIndex, 0)
  }

  function appendBreakableSegmentFrom(segmentIndex: number, startGraphemeIndex: number): void {
    const gWidths = breakableWidths[segmentIndex]!
    for (let g = startGraphemeIndex; g < gWidths.length; g++) {
      const gw = gWidths[g]!

      if (!hasContent) {
        startLineAtGrapheme(segmentIndex, g, gw)
        continue
      }

      if (lineW + gw > maxWidth + lineFitEpsilon) {
        emitCurrentLine()
        startLineAtGrapheme(segmentIndex, g, gw)
      } else {
        lineW += gw
        lineEndSegmentIndex = segmentIndex
        lineEndGraphemeIndex = g + 1
      }
    }

    if (hasContent && lineEndSegmentIndex === segmentIndex && lineEndGraphemeIndex === gWidths.length) {
      lineEndSegmentIndex = segmentIndex + 1
      lineEndGraphemeIndex = 0
    }
  }

  function continueSoftHyphenBreakableSegment(segmentIndex: number): boolean {
    const gWidths = breakableWidths[segmentIndex]!
    if (gWidths === null) return false

    let fitCount = 0
    let fittedWidth = lineW
    while (fitCount < gWidths.length) {
      const nextWidth = fittedWidth + gWidths[fitCount]!
      const nextLineWidth = fitCount + 1 < gWidths.length
        ? nextWidth + discretionaryHyphenWidth
        : nextWidth
      if (nextLineWidth > maxWidth + lineFitEpsilon) break
      fittedWidth = nextWidth
      fitCount++
    }

    if (fitCount === 0) return false

    lineW = fittedWidth
    lineEndSegmentIndex = segmentIndex
    lineEndGraphemeIndex = fitCount
    clearPendingSoftBreak()

    if (fitCount === gWidths.length) {
      lineEndSegmentIndex = segmentIndex + 1
      lineEndGraphemeIndex = 0
      return true
    }

    emitCurrentLine(segmentIndex, fitCount, fittedWidth + discretionaryHyphenWidth, segmentIndex)
    appendBreakableSegmentFrom(segmentIndex, fitCount)
    return true
  }

  for (let i = 0; i < widths.length; i++) {
    const w = widths[i]!
    const kind = kinds[i]!

    if (kind === 'soft-hyphen') {
      if (hasContent) {
        lineEndSegmentIndex = i + 1
        lineEndGraphemeIndex = 0
        pendingSoftBreakSegmentIndex = i + 1
        pendingSoftBreakWidth = lineW + discretionaryHyphenWidth

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show 3e991df:src/layout.ts | rg -n "layoutNextLine|walkLineRanges|layoutWithLines|countPreparedLines|walkPreparedLines"

Command: /bin/zsh -lc 'cd /Users/maxgeorgopoulos/Documents/experiments/pretext && git show 3e991df:src/layout.ts | rg -n "layoutNextLine|walkLineRanges|layoutWithLines|countPreparedLines|walkPreparedLines"'
Chunk ID: 96c110
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 76
Output:
847:function walkPreparedLines(
976:  const lineCount = walkPreparedLines(prepared, maxWidth)
1028:export function layoutWithLines(prepared: PreparedTextWithSegments, maxWidth: number, lineHeight: number): LayoutLinesResult {
1033:  const lineCount = walkPreparedLines(prepared, maxWidth, line => {

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/layout.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/layout.ts | sed -n '1,260p'"
Chunk ID: 9f9d80
Wall time: 0.0001 seconds
Process exited with code 0
Original token count: 2954
Output:
     1	// Text measurement for browser environments using canvas measureText.
     2	//
     3	// Problem: DOM-based text measurement (getBoundingClientRect, offsetHeight)
     4	// forces synchronous layout reflow. When components independently measure text,
     5	// each measurement triggers a reflow of the entire document. This creates
     6	// read/write interleaving that can cost 30ms+ per frame for 500 text blocks.
     7	//
     8	// Solution: two-phase measurement centered around canvas measureText.
     9	//   prepare(text, font) — segments text via Intl.Segmenter, measures each word
    10	//     via canvas, caches widths, and does one cached DOM calibration read per
    11	//     font when emoji correction is needed. Call once when text first appears.
    12	//   layout(prepared, maxWidth, lineHeight) — walks cached word widths with pure
    13	//     arithmetic to count lines and compute height. Call on every resize.
    14	//     ~0.0002ms per text.
    15	//
    16	// i18n: Intl.Segmenter handles CJK (per-character breaking), Thai, Arabic, etc.
    17	//   Bidi: simplified rich-path metadata for mixed LTR/RTL custom rendering.
    18	//   Punctuation merging: "better." measured as one unit (matches CSS behavior).
    19	//   Trailing whitespace: hangs past line edge without triggering breaks (CSS behavior).
    20	//   overflow-wrap: pre-measured grapheme widths enable character-level word breaking.
    21	//
    22	// Emoji correction: Chrome/Firefox canvas measures emoji wider than DOM at font
    23	//   sizes <24px on macOS (Apple Color Emoji). The inflation is constant per emoji
    24	//   grapheme at a given size, font-independent. Auto-detected by comparing canvas
    25	//   vs actual DOM emoji width (one cached DOM read per font). Safari canvas and
    26	//   DOM agree (both wider than fontSize), so correction = 0 there.
    27	//
    28	// Limitations:
    29	//   - system-ui font: canvas resolves to different optical variants than DOM on macOS.
    30	//     Use named fonts (Helvetica, Inter, etc.) for guaranteed accuracy.
    31	//     See RESEARCH.md "Discovery: system-ui font resolution mismatch".
    32	//
    33	// Based on Sebastian Markbage's text-layout research (github.com/chenglou/text-layout).
    34	
    35	import { computeSegmentLevels } from './bidi.js'
    36	import {
    37	  analyzeText,
    38	  clearAnalysisCaches,
    39	  endsWithClosingQuote,
    40	  isCJK,
    41	  kinsokuEnd,
    42	  kinsokuStart,
    43	  leftStickyPunctuation,
    44	  setAnalysisLocale,
    45	  type AnalysisChunk,
    46	  type SegmentBreakKind,
    47	  type TextAnalysis,
    48	  type WhiteSpaceMode,
    49	} from './analysis.js'
    50	import {
    51	  clearMeasurementCaches,
    52	  getCorrectedSegmentWidth,
    53	  getEngineProfile,
    54	  getFontMeasurementState,
    55	  getSegmentGraphemePrefixWidths,
    56	  getSegmentGraphemeWidths,
    57	  getSegmentMetrics,
    58	  textMayContainEmoji,
    59	} from './measurement.js'
    60	import {
    61	  countPreparedLines,
    62	  layoutNextLineRange as stepPreparedLineRange,
    63	  walkPreparedLines,
    64	  type InternalLayoutLine,
    65	} from './line-break.js'
    66	
    67	let sharedGraphemeSegmenter: Intl.Segmenter | null = null
    68	// Rich-path only. Reuses grapheme splits while materializing multiple lines
    69	// from the same prepared handle, without pushing that cache into the API.
    70	let sharedLineTextCaches = new WeakMap<PreparedTextWithSegments, Map<number, string[]>>()
    71	
    72	function getSharedGraphemeSegmenter(): Intl.Segmenter {
    73	  if (sharedGraphemeSegmenter === null) {
    74	    sharedGraphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })
    75	  }
    76	  return sharedGraphemeSegmenter
    77	}
    78	
    79	// --- Public types ---
    80	
    81	declare const preparedTextBrand: unique symbol
    82	
    83	type PreparedCore = {
    84	  widths: number[] // Segment widths, e.g. [42.5, 4.4, 37.2]
    85	  lineEndFitAdvances: number[] // Width contribution when a line ends after this segment
    86	  lineEndPaintAdvances: number[] // Painted width contribution when a line ends after this segment
    87	  kinds: SegmentBreakKind[] // Break behavior per segment, e.g. ['text', 'space', 'text']
    88	  simpleLineWalkFastPath: boolean // Normal text can use the simpler old line walker across all layout APIs
    89	  segLevels: Int8Array | null // Rich-path bidi metadata for custom rendering; layout() never reads it
    90	  breakableWidths: (number[] | null)[] // Grapheme widths for overflow-wrap segments, else null
    91	  breakablePrefixWidths: (number[] | null)[] // Cumulative grapheme prefix widths for narrow browser-policy shims
    92	  discretionaryHyphenWidth: number // Visible width added when a soft hyphen is chosen as the break
    93	  tabStopAdvance: number // Absolute advance between tab stops for pre-wrap tab segments
    94	  chunks: PreparedLineChunk[] // Precompiled hard-break chunks for line walking
    95	}
    96	
    97	// Keep the main prepared handle opaque so the public API does not accidentally
    98	// calcify around the current parallel-array representation.
    99	export type PreparedText = {
   100	  readonly [preparedTextBrand]: true
   101	}
   102	
   103	type InternalPreparedText = PreparedText & PreparedCore
   104	
   105	// Rich/diagnostic variant that still exposes the structural segment data.
   106	// Treat this as the unstable escape hatch for experiments and custom rendering.
   107	export type PreparedTextWithSegments = InternalPreparedText & {
   108	  segments: string[] // Segment text aligned with the parallel arrays, e.g. ['hello', ' ', 'world']
   109	}
   110	
   111	export type LayoutCursor = {
   112	  segmentIndex: number // Segment index in `segments`
   113	  graphemeIndex: number // Grapheme index within that segment; `0` at segment boundaries
   114	}
   115	
   116	export type LayoutResult = {
   117	  lineCount: number // Number of wrapped lines, e.g. 3
   118	  height: number // Total block height, e.g. lineCount * lineHeight = 57
   119	}
   120	
   121	export type LayoutLine = {
   122	  text: string // Full text content of this line, e.g. 'hello world'
   123	  width: number // Measured width of this line, e.g. 87.5
   124	  start: LayoutCursor // Inclusive start cursor in prepared segments/graphemes
   125	  end: LayoutCursor // Exclusive end cursor in prepared segments/graphemes
   126	}
   127	
   128	export type LayoutLineRange = {
   129	  width: number // Measured width of this line, e.g. 87.5
   130	  start: LayoutCursor // Inclusive start cursor in prepared segments/graphemes
   131	  end: LayoutCursor // Exclusive end cursor in prepared segments/graphemes
   132	}
   133	
   134	export type LayoutLinesResult = LayoutResult & {
   135	  lines: LayoutLine[] // Per-line text/width pairs for custom rendering
   136	}
   137	
   138	export type PrepareProfile = {
   139	  analysisMs: number
   140	  measureMs: number
   141	  totalMs: number
   142	  analysisSegments: number
   143	  preparedSegments: number
   144	  breakableSegments: number
   145	}
   146	
   147	export type PrepareOptions = {
   148	  whiteSpace?: WhiteSpaceMode
   149	}
   150	
   151	export type PreparedLineChunk = {
   152	  startSegmentIndex: number
   153	  endSegmentIndex: number
   154	  consumedEndSegmentIndex: number
   155	}
   156	
   157	// --- Public API ---
   158	
   159	function createEmptyPrepared(includeSegments: boolean): InternalPreparedText | PreparedTextWithSegments {
   160	  if (includeSegments) {
   161	    return {
   162	      widths: [],
   163	      lineEndFitAdvances: [],
   164	      lineEndPaintAdvances: [],
   165	      kinds: [],
   166	      simpleLineWalkFastPath: true,
   167	      segLevels: null,
   168	      breakableWidths: [],
   169	      breakablePrefixWidths: [],
   170	      discretionaryHyphenWidth: 0,
   171	      tabStopAdvance: 0,
   172	      chunks: [],
   173	      segments: [],
   174	    } as unknown as PreparedTextWithSegments
   175	  }
   176	  return {
   177	    widths: [],
   178	    lineEndFitAdvances: [],
   179	    lineEndPaintAdvances: [],
   180	    kinds: [],
   181	    simpleLineWalkFastPath: true,
   182	    segLevels: null,
   183	    breakableWidths: [],
   184	    breakablePrefixWidths: [],
   185	    discretionaryHyphenWidth: 0,
   186	    tabStopAdvance: 0,
   187	    chunks: [],
   188	  } as unknown as InternalPreparedText
   189	}
   190	
   191	function measureAnalysis(
   192	  analysis: TextAnalysis,
   193	  font: string,
   194	  includeSegments: boolean,
   195	): InternalPreparedText | PreparedTextWithSegments {
   196	  const graphemeSegmenter = getSharedGraphemeSegmenter()
   197	  const engineProfile = getEngineProfile()
   198	  const { cache, emojiCorrection } = getFontMeasurementState(
   199	    font,
   200	    textMayContainEmoji(analysis.normalized),
   201	  )
   202	  const discretionaryHyphenWidth = getCorrectedSegmentWidth('-', getSegmentMetrics('-', cache), emojiCorrection)
   203	  const spaceWidth = getCorrectedSegmentWidth(' ', getSegmentMetrics(' ', cache), emojiCorrection)
   204	  const tabStopAdvance = spaceWidth * 8
   205	
   206	  if (analysis.len === 0) return createEmptyPrepared(includeSegments)
   207	
   208	  const widths: number[] = []
   209	  const lineEndFitAdvances: number[] = []
   210	  const lineEndPaintAdvances: number[] = []
   211	  const kinds: SegmentBreakKind[] = []
   212	  let simpleLineWalkFastPath = analysis.chunks.length <= 1
   213	  const segStarts = includeSegments ? [] as number[] : null
   214	  const breakableWidths: (number[] | null)[] = []
   215	  const breakablePrefixWidths: (number[] | null)[] = []
   216	  const segments = includeSegments ? [] as string[] : null
   217	  const preparedStartByAnalysisIndex = Array.from<number>({ length: analysis.len })
   218	  const preparedEndByAnalysisIndex = Array.from<number>({ length: analysis.len })
   219	
   220	  function pushMeasuredSegment(
   221	    text: string,
   222	    width: number,
   223	    lineEndFitAdvance: number,
   224	    lineEndPaintAdvance: number,
   225	    kind: SegmentBreakKind,
   226	    start: number,
   227	    breakable: number[] | null,
   228	    breakablePrefix: number[] | null,
   229	  ): void {
   230	    if (kind !== 'text' && kind !== 'space' && kind !== 'zero-width-break') {
   231	      simpleLineWalkFastPath = false
   232	    }
   233	    widths.push(width)
   234	    lineEndFitAdvances.push(lineEndFitAdvance)
   235	    lineEndPaintAdvances.push(lineEndPaintAdvance)
   236	    kinds.push(kind)
   237	    segStarts?.push(start)
   238	    breakableWidths.push(breakable)
   239	    breakablePrefixWidths.push(breakablePrefix)
   240	    if (segments !== null) segments.push(text)
   241	  }
   242	
   243	  for (let mi = 0; mi < analysis.len; mi++) {
   244	    preparedStartByAnalysisIndex[mi] = widths.length
   245	    const segText = analysis.texts[mi]!
   246	    const segWordLike = analysis.isWordLike[mi]!
   247	    const segKind = analysis.kinds[mi]!
   248	    const segStart = analysis.starts[mi]!
   249	
   250	    if (segKind === 'soft-hyphen') {
   251	      pushMeasuredSegment(
   252	        segText,
   253	        0,
   254	        discretionaryHyphenWidth,
   255	        discretionaryHyphenWidth,
   256	        segKind,
   257	        segStart,
   258	        null,
   259	        null,
   260	      )

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/layout.ts | sed -n '260,520p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/layout.ts | sed -n '260,520p'"
Chunk ID: b8a142
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2826
Output:
   260	      )
   261	      preparedEndByAnalysisIndex[mi] = widths.length
   262	      continue
   263	    }
   264	
   265	    if (segKind === 'hard-break') {
   266	      pushMeasuredSegment(segText, 0, 0, 0, segKind, segStart, null, null)
   267	      preparedEndByAnalysisIndex[mi] = widths.length
   268	      continue
   269	    }
   270	
   271	    if (segKind === 'tab') {
   272	      pushMeasuredSegment(segText, 0, 0, 0, segKind, segStart, null, null)
   273	      preparedEndByAnalysisIndex[mi] = widths.length
   274	      continue
   275	    }
   276	
   277	    const segMetrics = getSegmentMetrics(segText, cache)
   278	
   279	    if (segKind === 'text' && segMetrics.containsCJK) {
   280	      let unitText = ''
   281	      let unitStart = 0
   282	
   283	      for (const gs of graphemeSegmenter.segment(segText)) {
   284	        const grapheme = gs.segment
   285	
   286	        if (unitText.length === 0) {
   287	          unitText = grapheme
   288	          unitStart = gs.index
   289	          continue
   290	        }
   291	
   292	        if (
   293	          kinsokuEnd.has(unitText) ||
   294	          kinsokuStart.has(grapheme) ||
   295	          leftStickyPunctuation.has(grapheme) ||
   296	          (engineProfile.carryCJKAfterClosingQuote &&
   297	            isCJK(grapheme) &&
   298	            endsWithClosingQuote(unitText))
   299	        ) {
   300	          unitText += grapheme
   301	          continue
   302	        }
   303	
   304	        const unitMetrics = getSegmentMetrics(unitText, cache)
   305	        const w = getCorrectedSegmentWidth(unitText, unitMetrics, emojiCorrection)
   306	        pushMeasuredSegment(unitText, w, w, w, 'text', segStart + unitStart, null, null)
   307	
   308	        unitText = grapheme
   309	        unitStart = gs.index
   310	      }
   311	
   312	      if (unitText.length > 0) {
   313	        const unitMetrics = getSegmentMetrics(unitText, cache)
   314	        const w = getCorrectedSegmentWidth(unitText, unitMetrics, emojiCorrection)
   315	        pushMeasuredSegment(unitText, w, w, w, 'text', segStart + unitStart, null, null)
   316	      }
   317	      preparedEndByAnalysisIndex[mi] = widths.length
   318	      continue
   319	    }
   320	
   321	    const w = getCorrectedSegmentWidth(segText, segMetrics, emojiCorrection)
   322	    const lineEndFitAdvance =
   323	      segKind === 'space' || segKind === 'preserved-space' || segKind === 'zero-width-break'
   324	        ? 0
   325	        : w
   326	    const lineEndPaintAdvance =
   327	      segKind === 'space' || segKind === 'zero-width-break'
   328	        ? 0
   329	        : w
   330	
   331	    if (segWordLike && segText.length > 1) {
   332	      const graphemeWidths = getSegmentGraphemeWidths(segText, segMetrics, cache, emojiCorrection)
   333	      const graphemePrefixWidths = engineProfile.preferPrefixWidthsForBreakableRuns
   334	        ? getSegmentGraphemePrefixWidths(segText, segMetrics, cache, emojiCorrection)
   335	        : null
   336	      pushMeasuredSegment(
   337	        segText,
   338	        w,
   339	        lineEndFitAdvance,
   340	        lineEndPaintAdvance,
   341	        segKind,
   342	        segStart,
   343	        graphemeWidths,
   344	        graphemePrefixWidths,
   345	      )
   346	    } else {
   347	      pushMeasuredSegment(
   348	        segText,
   349	        w,
   350	        lineEndFitAdvance,
   351	        lineEndPaintAdvance,
   352	        segKind,
   353	        segStart,
   354	        null,
   355	        null,
   356	      )
   357	    }
   358	    preparedEndByAnalysisIndex[mi] = widths.length
   359	  }
   360	
   361	  const chunks = mapAnalysisChunksToPreparedChunks(analysis.chunks, preparedStartByAnalysisIndex, preparedEndByAnalysisIndex)
   362	  const segLevels = segStarts === null ? null : computeSegmentLevels(analysis.normalized, segStarts)
   363	  if (segments !== null) {
   364	    return {
   365	      widths,
   366	      lineEndFitAdvances,
   367	      lineEndPaintAdvances,
   368	      kinds,
   369	      simpleLineWalkFastPath,
   370	      segLevels,
   371	      breakableWidths,
   372	      breakablePrefixWidths,
   373	      discretionaryHyphenWidth,
   374	      tabStopAdvance,
   375	      chunks,
   376	      segments,
   377	    } as unknown as PreparedTextWithSegments
   378	  }
   379	  return {
   380	    widths,
   381	    lineEndFitAdvances,
   382	    lineEndPaintAdvances,
   383	    kinds,
   384	    simpleLineWalkFastPath,
   385	    segLevels,
   386	    breakableWidths,
   387	    breakablePrefixWidths,
   388	    discretionaryHyphenWidth,
   389	    tabStopAdvance,
   390	    chunks,
   391	  } as unknown as InternalPreparedText
   392	}
   393	
   394	function mapAnalysisChunksToPreparedChunks(
   395	  chunks: AnalysisChunk[],
   396	  preparedStartByAnalysisIndex: number[],
   397	  preparedEndByAnalysisIndex: number[],
   398	): PreparedLineChunk[] {
   399	  const preparedChunks: PreparedLineChunk[] = []
   400	  for (let i = 0; i < chunks.length; i++) {
   401	    const chunk = chunks[i]!
   402	    const startSegmentIndex =
   403	      chunk.startSegmentIndex < preparedStartByAnalysisIndex.length
   404	        ? preparedStartByAnalysisIndex[chunk.startSegmentIndex]!
   405	        : preparedEndByAnalysisIndex[preparedEndByAnalysisIndex.length - 1] ?? 0
   406	    const endSegmentIndex =
   407	      chunk.endSegmentIndex < preparedStartByAnalysisIndex.length
   408	        ? preparedStartByAnalysisIndex[chunk.endSegmentIndex]!
   409	        : preparedEndByAnalysisIndex[preparedEndByAnalysisIndex.length - 1] ?? 0
   410	    const consumedEndSegmentIndex =
   411	      chunk.consumedEndSegmentIndex < preparedStartByAnalysisIndex.length
   412	        ? preparedStartByAnalysisIndex[chunk.consumedEndSegmentIndex]!
   413	        : preparedEndByAnalysisIndex[preparedEndByAnalysisIndex.length - 1] ?? 0
   414	
   415	    preparedChunks.push({
   416	      startSegmentIndex,
   417	      endSegmentIndex,
   418	      consumedEndSegmentIndex,
   419	    })
   420	  }
   421	  return preparedChunks
   422	}
   423	
   424	function prepareInternal(
   425	  text: string,
   426	  font: string,
   427	  includeSegments: boolean,
   428	  options?: PrepareOptions,
   429	): InternalPreparedText | PreparedTextWithSegments {
   430	  const analysis = analyzeText(text, getEngineProfile(), options?.whiteSpace)
   431	  return measureAnalysis(analysis, font, includeSegments)
   432	}
   433	
   434	// Diagnostic-only helper used by the browser benchmark harness to separate the
   435	// text-analysis and measurement phases without duplicating the prepare logic.
   436	export function profilePrepare(text: string, font: string, options?: PrepareOptions): PrepareProfile {
   437	  const t0 = performance.now()
   438	  const analysis = analyzeText(text, getEngineProfile(), options?.whiteSpace)
   439	  const t1 = performance.now()
   440	  const prepared = measureAnalysis(analysis, font, false) as InternalPreparedText
   441	  const t2 = performance.now()
   442	
   443	  let breakableSegments = 0
   444	  for (const widths of prepared.breakableWidths) {
   445	    if (widths !== null) breakableSegments++
   446	  }
   447	
   448	  return {
   449	    analysisMs: t1 - t0,
   450	    measureMs: t2 - t1,
   451	    totalMs: t2 - t0,
   452	    analysisSegments: analysis.len,
   453	    preparedSegments: prepared.widths.length,
   454	    breakableSegments,
   455	  }
   456	}
   457	
   458	// Prepare text for layout. Segments the text, measures each segment via canvas,
   459	// and stores the widths for fast relayout at any width. Call once per text block
   460	// (e.g. when a comment first appears). The result is width-independent — the
   461	// same PreparedText can be laid out at any maxWidth and lineHeight via layout().
   462	//
   463	// Steps:
   464	//   1. Normalize collapsible whitespace (CSS white-space: normal behavior)
   465	//   2. Segment via Intl.Segmenter (handles CJK, Thai, etc.)
   466	//   3. Merge punctuation into preceding word ("better." as one unit)
   467	//   4. Split CJK words into individual graphemes (per-character line breaks)
   468	//   5. Measure each segment via canvas measureText, cache by (segment, font)
   469	//   6. Pre-measure graphemes of long words (for overflow-wrap: break-word)
   470	//   7. Correct emoji canvas inflation (auto-detected per font size)
   471	//   8. Optionally compute rich-path bidi metadata for custom renderers
   472	export function prepare(text: string, font: string, options?: PrepareOptions): PreparedText {
   473	  return prepareInternal(text, font, false, options) as PreparedText
   474	}
   475	
   476	// Rich variant used by callers that need enough information to render the
   477	// laid-out lines themselves.
   478	export function prepareWithSegments(text: string, font: string, options?: PrepareOptions): PreparedTextWithSegments {
   479	  return prepareInternal(text, font, true, options) as PreparedTextWithSegments
   480	}
   481	
   482	function getInternalPrepared(prepared: PreparedText): InternalPreparedText {
   483	  return prepared as InternalPreparedText
   484	}
   485	
   486	// Layout prepared text at a given max width and caller-provided lineHeight.
   487	// Pure arithmetic on cached widths — no canvas calls, no DOM reads, no string
   488	// operations, no allocations.
   489	// ~0.0002ms per text block. Call on every resize.
   490	//
   491	// Line breaking rules (matching CSS white-space: normal + overflow-wrap: break-word):
   492	//   - Break before any non-space segment that would overflow the line
   493	//   - Trailing whitespace hangs past the line edge (doesn't trigger breaks)
   494	//   - Segments wider than maxWidth are broken at grapheme boundaries
   495	export function layout(prepared: PreparedText, maxWidth: number, lineHeight: number): LayoutResult {
   496	  // Keep the resize hot path specialized. `layoutWithLines()` shares the same
   497	  // break semantics but also tracks line ranges; the extra bookkeeping is too
   498	  // expensive to pay on every hot-path `layout()` call.
   499	  const lineCount = countPreparedLines(getInternalPrepared(prepared), maxWidth)
   500	  return { lineCount, height: lineCount * lineHeight }
   501	}
   502	
   503	function getSegmentGraphemes(
   504	  segmentIndex: number,
   505	  segments: string[],
   506	  cache: Map<number, string[]>,
   507	): string[] {
   508	  let graphemes = cache.get(segmentIndex)
   509	  if (graphemes !== undefined) return graphemes
   510	
   511	  graphemes = []
   512	  const graphemeSegmenter = getSharedGraphemeSegmenter()
   513	  for (const gs of graphemeSegmenter.segment(segments[segmentIndex]!)) {
   514	    graphemes.push(gs.segment)
   515	  }
   516	  cache.set(segmentIndex, graphemes)
   517	  return graphemes
   518	}
   519	
   520	function getLineTextCache(prepared: PreparedTextWithSegments): Map<number, string[]> {

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/layout.ts | sed -n '520,760p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/layout.ts | sed -n '520,760p'"
Chunk ID: 014465
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1753
Output:
   520	function getLineTextCache(prepared: PreparedTextWithSegments): Map<number, string[]> {
   521	  let cache = sharedLineTextCaches.get(prepared)
   522	  if (cache !== undefined) return cache
   523	
   524	  cache = new Map<number, string[]>()
   525	  sharedLineTextCaches.set(prepared, cache)
   526	  return cache
   527	}
   528	
   529	function lineHasDiscretionaryHyphen(
   530	  kinds: SegmentBreakKind[],
   531	  startSegmentIndex: number,
   532	  startGraphemeIndex: number,
   533	  endSegmentIndex: number,
   534	): boolean {
   535	  return (
   536	    endSegmentIndex > 0 &&
   537	    kinds[endSegmentIndex - 1] === 'soft-hyphen' &&
   538	    !(startSegmentIndex === endSegmentIndex && startGraphemeIndex > 0)
   539	  )
   540	}
   541	
   542	function buildLineTextFromRange(
   543	  segments: string[],
   544	  kinds: SegmentBreakKind[],
   545	  cache: Map<number, string[]>,
   546	  startSegmentIndex: number,
   547	  startGraphemeIndex: number,
   548	  endSegmentIndex: number,
   549	  endGraphemeIndex: number,
   550	): string {
   551	  let text = ''
   552	  const endsWithDiscretionaryHyphen = lineHasDiscretionaryHyphen(
   553	    kinds,
   554	    startSegmentIndex,
   555	    startGraphemeIndex,
   556	    endSegmentIndex,
   557	  )
   558	
   559	  for (let i = startSegmentIndex; i < endSegmentIndex; i++) {
   560	    if (kinds[i] === 'soft-hyphen' || kinds[i] === 'hard-break') continue
   561	    if (i === startSegmentIndex && startGraphemeIndex > 0) {
   562	      text += getSegmentGraphemes(i, segments, cache).slice(startGraphemeIndex).join('')
   563	    } else {
   564	      text += segments[i]!
   565	    }
   566	  }
   567	
   568	  if (endGraphemeIndex > 0) {
   569	    if (endsWithDiscretionaryHyphen) text += '-'
   570	    text += getSegmentGraphemes(endSegmentIndex, segments, cache).slice(
   571	      startSegmentIndex === endSegmentIndex ? startGraphemeIndex : 0,
   572	      endGraphemeIndex,
   573	    ).join('')
   574	  } else if (endsWithDiscretionaryHyphen) {
   575	    text += '-'
   576	  }
   577	
   578	  return text
   579	}
   580	
   581	function createLayoutLine(
   582	  prepared: PreparedTextWithSegments,
   583	  cache: Map<number, string[]>,
   584	  width: number,
   585	  startSegmentIndex: number,
   586	  startGraphemeIndex: number,
   587	  endSegmentIndex: number,
   588	  endGraphemeIndex: number,
   589	): LayoutLine {
   590	  return {
   591	    text: buildLineTextFromRange(
   592	      prepared.segments,
   593	      prepared.kinds,
   594	      cache,
   595	      startSegmentIndex,
   596	      startGraphemeIndex,
   597	      endSegmentIndex,
   598	      endGraphemeIndex,
   599	    ),
   600	    width,
   601	    start: {
   602	      segmentIndex: startSegmentIndex,
   603	      graphemeIndex: startGraphemeIndex,
   604	    },
   605	    end: {
   606	      segmentIndex: endSegmentIndex,
   607	      graphemeIndex: endGraphemeIndex,
   608	    },
   609	  }
   610	}
   611	
   612	function materializeLayoutLine(
   613	  prepared: PreparedTextWithSegments,
   614	  cache: Map<number, string[]>,
   615	  line: InternalLayoutLine,
   616	): LayoutLine {
   617	  return createLayoutLine(
   618	    prepared,
   619	    cache,
   620	    line.width,
   621	    line.startSegmentIndex,
   622	    line.startGraphemeIndex,
   623	    line.endSegmentIndex,
   624	    line.endGraphemeIndex,
   625	  )
   626	}
   627	
   628	function toLayoutLineRange(line: InternalLayoutLine): LayoutLineRange {
   629	  return {
   630	    width: line.width,
   631	    start: {
   632	      segmentIndex: line.startSegmentIndex,
   633	      graphemeIndex: line.startGraphemeIndex,
   634	    },
   635	    end: {
   636	      segmentIndex: line.endSegmentIndex,
   637	      graphemeIndex: line.endGraphemeIndex,
   638	    },
   639	  }
   640	}
   641	
   642	function stepLineRange(
   643	  prepared: PreparedTextWithSegments,
   644	  start: LayoutCursor,
   645	  maxWidth: number,
   646	): LayoutLineRange | null {
   647	  const line = stepPreparedLineRange(prepared, start, maxWidth)
   648	  if (line === null) return null
   649	  return toLayoutLineRange(line)
   650	}
   651	
   652	function materializeLine(
   653	  prepared: PreparedTextWithSegments,
   654	  line: LayoutLineRange,
   655	): LayoutLine {
   656	  return createLayoutLine(
   657	    prepared,
   658	    getLineTextCache(prepared),
   659	    line.width,
   660	    line.start.segmentIndex,
   661	    line.start.graphemeIndex,
   662	    line.end.segmentIndex,
   663	    line.end.graphemeIndex,
   664	  )
   665	}
   666	
   667	// Batch low-level line geometry pass. This is the non-materializing counterpart
   668	// to layoutWithLines(), useful for shrinkwrap and other aggregate geometry work.
   669	export function walkLineRanges(
   670	  prepared: PreparedTextWithSegments,
   671	  maxWidth: number,
   672	  onLine: (line: LayoutLineRange) => void,
   673	): number {
   674	  if (prepared.widths.length === 0) return 0
   675	
   676	  return walkPreparedLines(getInternalPrepared(prepared), maxWidth, line => {
   677	    onLine(toLayoutLineRange(line))
   678	  })
   679	}
   680	
   681	export function layoutNextLine(
   682	  prepared: PreparedTextWithSegments,
   683	  start: LayoutCursor,
   684	  maxWidth: number,
   685	): LayoutLine | null {
   686	  const line = stepLineRange(prepared, start, maxWidth)
   687	  if (line === null) return null
   688	  return materializeLine(prepared, line)
   689	}
   690	
   691	// Rich layout API for callers that want the actual line contents and widths.
   692	// Caller still supplies lineHeight at layout time. Mirrors layout()'s break
   693	// decisions, but keeps extra per-line bookkeeping so it should stay off the
   694	// resize hot path.
   695	export function layoutWithLines(prepared: PreparedTextWithSegments, maxWidth: number, lineHeight: number): LayoutLinesResult {
   696	  const lines: LayoutLine[] = []
   697	  if (prepared.widths.length === 0) return { lineCount: 0, height: 0, lines }
   698	
   699	  const graphemeCache = getLineTextCache(prepared)
   700	  const lineCount = walkPreparedLines(getInternalPrepared(prepared), maxWidth, line => {
   701	    lines.push(materializeLayoutLine(prepared, graphemeCache, line))
   702	  })
   703	
   704	  return { lineCount, height: lineCount * lineHeight, lines }
   705	}
   706	
   707	export function clearCache(): void {
   708	  clearAnalysisCaches()
   709	  sharedGraphemeSegmenter = null
   710	  sharedLineTextCaches = new WeakMap<PreparedTextWithSegments, Map<number, string[]>>()
   711	  clearMeasurementCaches()
   712	}
   713	
   714	export function setLocale(locale?: string): void {
   715	  setAnalysisLocale(locale)
   716	  clearCache()
   717	}

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/measurement.ts | sed -n '1,260p'

Command: /bin/zsh -lc "cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/measurement.ts | sed -n '1,260p'"
Chunk ID: bdee1a
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2257
Output:
     1	import { isCJK } from './analysis.js'
     2	
     3	export type SegmentMetrics = {
     4	  width: number
     5	  containsCJK: boolean
     6	  emojiCount?: number
     7	  graphemeWidths?: number[] | null
     8	  graphemePrefixWidths?: number[] | null
     9	}
    10	
    11	export type EngineProfile = {
    12	  lineFitEpsilon: number
    13	  carryCJKAfterClosingQuote: boolean
    14	  preferPrefixWidthsForBreakableRuns: boolean
    15	  preferEarlySoftHyphenBreak: boolean
    16	}
    17	
    18	let measureContext: CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D | null = null
    19	const segmentMetricCaches = new Map<string, Map<string, SegmentMetrics>>()
    20	let cachedEngineProfile: EngineProfile | null = null
    21	
    22	const emojiPresentationRe = /\p{Emoji_Presentation}/u
    23	const maybeEmojiRe = /[\p{Emoji_Presentation}\p{Extended_Pictographic}\p{Regional_Indicator}\uFE0F\u20E3]/u
    24	let sharedGraphemeSegmenter: Intl.Segmenter | null = null
    25	const emojiCorrectionCache = new Map<string, number>()
    26	
    27	export function getMeasureContext(): CanvasRenderingContext2D | OffscreenCanvasRenderingContext2D {
    28	  if (measureContext !== null) return measureContext
    29	
    30	  if (typeof OffscreenCanvas !== 'undefined') {
    31	    measureContext = new OffscreenCanvas(1, 1).getContext('2d')!
    32	    return measureContext
    33	  }
    34	
    35	  if (typeof document !== 'undefined') {
    36	    measureContext = document.createElement('canvas').getContext('2d')!
    37	    return measureContext
    38	  }
    39	
    40	  throw new Error('Text measurement requires OffscreenCanvas or a DOM canvas context.')
    41	}
    42	
    43	export function getSegmentMetricCache(font: string): Map<string, SegmentMetrics> {
    44	  let cache = segmentMetricCaches.get(font)
    45	  if (!cache) {
    46	    cache = new Map()
    47	    segmentMetricCaches.set(font, cache)
    48	  }
    49	  return cache
    50	}
    51	
    52	export function getSegmentMetrics(seg: string, cache: Map<string, SegmentMetrics>): SegmentMetrics {
    53	  let metrics = cache.get(seg)
    54	  if (metrics === undefined) {
    55	    const ctx = getMeasureContext()
    56	    metrics = {
    57	      width: ctx.measureText(seg).width,
    58	      containsCJK: isCJK(seg),
    59	    }
    60	    cache.set(seg, metrics)
    61	  }
    62	  return metrics
    63	}
    64	
    65	export function getEngineProfile(): EngineProfile {
    66	  if (cachedEngineProfile !== null) return cachedEngineProfile
    67	
    68	  if (typeof navigator === 'undefined') {
    69	    cachedEngineProfile = {
    70	      lineFitEpsilon: 0.005,
    71	      carryCJKAfterClosingQuote: false,
    72	      preferPrefixWidthsForBreakableRuns: false,
    73	      preferEarlySoftHyphenBreak: false,
    74	    }
    75	    return cachedEngineProfile
    76	  }
    77	
    78	  const ua = navigator.userAgent
    79	  const vendor = navigator.vendor
    80	  const isSafari =
    81	    vendor === 'Apple Computer, Inc.' &&
    82	    ua.includes('Safari/') &&
    83	    !ua.includes('Chrome/') &&
    84	    !ua.includes('Chromium/') &&
    85	    !ua.includes('CriOS/') &&
    86	    !ua.includes('FxiOS/') &&
    87	    !ua.includes('EdgiOS/')
    88	  const isChromium =
    89	    ua.includes('Chrome/') ||
    90	    ua.includes('Chromium/') ||
    91	    ua.includes('CriOS/') ||
    92	    ua.includes('Edg/')
    93	
    94	  cachedEngineProfile = {
    95	    lineFitEpsilon: isSafari ? 1 / 64 : 0.005,
    96	    carryCJKAfterClosingQuote: isChromium,
    97	    preferPrefixWidthsForBreakableRuns: isSafari,
    98	    preferEarlySoftHyphenBreak: isSafari,
    99	  }
   100	  return cachedEngineProfile
   101	}
   102	
   103	export function parseFontSize(font: string): number {
   104	  const m = font.match(/(\d+(?:\.\d+)?)\s*px/)
   105	  return m ? parseFloat(m[1]!) : 16
   106	}
   107	
   108	function getSharedGraphemeSegmenter(): Intl.Segmenter {
   109	  if (sharedGraphemeSegmenter === null) {
   110	    sharedGraphemeSegmenter = new Intl.Segmenter(undefined, { granularity: 'grapheme' })
   111	  }
   112	  return sharedGraphemeSegmenter
   113	}
   114	
   115	function isEmojiGrapheme(g: string): boolean {
   116	  return emojiPresentationRe.test(g) || g.includes('\uFE0F')
   117	}
   118	
   119	export function textMayContainEmoji(text: string): boolean {
   120	  return maybeEmojiRe.test(text)
   121	}
   122	
   123	function getEmojiCorrection(font: string, fontSize: number): number {
   124	  let correction = emojiCorrectionCache.get(font)
   125	  if (correction !== undefined) return correction
   126	
   127	  const ctx = getMeasureContext()
   128	  ctx.font = font
   129	  const canvasW = ctx.measureText('\u{1F600}').width
   130	  correction = 0
   131	  if (
   132	    canvasW > fontSize + 0.5 &&
   133	    typeof document !== 'undefined' &&
   134	    document.body !== null
   135	  ) {
   136	    const span = document.createElement('span')
   137	    span.style.font = font
   138	    span.style.display = 'inline-block'
   139	    span.style.visibility = 'hidden'
   140	    span.style.position = 'absolute'
   141	    span.textContent = '\u{1F600}'
   142	    document.body.appendChild(span)
   143	    const domW = span.getBoundingClientRect().width
   144	    document.body.removeChild(span)
   145	    if (canvasW - domW > 0.5) {
   146	      correction = canvasW - domW
   147	    }
   148	  }
   149	  emojiCorrectionCache.set(font, correction)
   150	  return correction
   151	}
   152	
   153	function countEmojiGraphemes(text: string): number {
   154	  let count = 0
   155	  const graphemeSegmenter = getSharedGraphemeSegmenter()
   156	  for (const g of graphemeSegmenter.segment(text)) {
   157	    if (isEmojiGrapheme(g.segment)) count++
   158	  }
   159	  return count
   160	}
   161	
   162	function getEmojiCount(seg: string, metrics: SegmentMetrics): number {
   163	  if (metrics.emojiCount === undefined) {
   164	    metrics.emojiCount = countEmojiGraphemes(seg)
   165	  }
   166	  return metrics.emojiCount
   167	}
   168	
   169	export function getCorrectedSegmentWidth(seg: string, metrics: SegmentMetrics, emojiCorrection: number): number {
   170	  if (emojiCorrection === 0) return metrics.width
   171	  return metrics.width - getEmojiCount(seg, metrics) * emojiCorrection
   172	}
   173	
   174	export function getSegmentGraphemeWidths(
   175	  seg: string,
   176	  metrics: SegmentMetrics,
   177	  cache: Map<string, SegmentMetrics>,
   178	  emojiCorrection: number,
   179	): number[] | null {
   180	  if (metrics.graphemeWidths !== undefined) return metrics.graphemeWidths
   181	
   182	  const widths: number[] = []
   183	  const graphemeSegmenter = getSharedGraphemeSegmenter()
   184	  for (const gs of graphemeSegmenter.segment(seg)) {
   185	    const graphemeMetrics = getSegmentMetrics(gs.segment, cache)
   186	    widths.push(getCorrectedSegmentWidth(gs.segment, graphemeMetrics, emojiCorrection))
   187	  }
   188	
   189	  metrics.graphemeWidths = widths.length > 1 ? widths : null
   190	  return metrics.graphemeWidths
   191	}
   192	
   193	export function getSegmentGraphemePrefixWidths(
   194	  seg: string,
   195	  metrics: SegmentMetrics,
   196	  cache: Map<string, SegmentMetrics>,
   197	  emojiCorrection: number,
   198	): number[] | null {
   199	  if (metrics.graphemePrefixWidths !== undefined) return metrics.graphemePrefixWidths
   200	
   201	  const prefixWidths: number[] = []
   202	  const graphemeSegmenter = getSharedGraphemeSegmenter()
   203	  let prefix = ''
   204	  for (const gs of graphemeSegmenter.segment(seg)) {
   205	    prefix += gs.segment
   206	    const prefixMetrics = getSegmentMetrics(prefix, cache)
   207	    prefixWidths.push(getCorrectedSegmentWidth(prefix, prefixMetrics, emojiCorrection))
   208	  }
   209	
   210	  metrics.graphemePrefixWidths = prefixWidths.length > 1 ? prefixWidths : null
   211	  return metrics.graphemePrefixWidths
   212	}
   213	
   214	export function getFontMeasurementState(font: string, needsEmojiCorrection: boolean): {
   215	  cache: Map<string, SegmentMetrics>
   216	  fontSize: number
   217	  emojiCorrection: number
   218	} {
   219	  const ctx = getMeasureContext()
   220	  ctx.font = font
   221	  const cache = getSegmentMetricCache(font)
   222	  const fontSize = parseFontSize(font)
   223	  const emojiCorrection = needsEmojiCorrection ? getEmojiCorrection(font, fontSize) : 0
   224	  return { cache, fontSize, emojiCorrection }
   225	}
   226	
   227	export function clearMeasurementCaches(): void {
   228	  segmentMetricCaches.clear()
   229	  emojiCorrectionCache.clear()
   230	  sharedGraphemeSegmenter = null
   231	}

>cd /Users/maxgeorgopoulos/Documents/experiments/pretext && nl -ba src/analysis.ts | sed -n '1,260p'