Srihari Sriraman shared in

Public

Fixed visual line counting bug in expand functionalityPublic

Agent

Model

Claude Opus 4.5 (latest)

Started

Jan 24, 2:17 AM

Messages75

Downloads0

Summary

Closed, Completed

Understand
Reviewed GitHub issue and related code files.
Understand
Understand
Identified root cause in line counting due to prepended newline.
Understand
Build
Proposed and implemented fix for visual line counting.
Build
Edit
Committed and pushed fix.
Edit
Verify
Displayed file contents on user request.
Verify

Analyze GitHub issue(s): https://github.com/badlogic/pi-mono/issues/921

For each issue:

Read the issue in full, including all comments and linked issues/PRs.
For bugs:
- Ignore any root cause analysis in the issue (likely wrong)
- Read all related code files in full (no truncation)
- Trace the code path and identify the actual root cause
- Propose a fix
For feature requests:
- Read all related code files in full (no truncation)
- Propose the most concise implementation approach
- List affected files and changes needed

Do NOT implement unless explicitly asked. Analyze and propose only.

Let me search for the relevant code handling the "ctrl+o to expand" functionality:

Let me read the visual-truncate.ts file which calculates the skippedCount:

Now I understand the bug. Let me analyze:

Root Cause Analysis

The bug is in tool-execution.ts in the renderBashContent() method (lines ~300-325).

The Problem

The code prepends a newline (\n) to the output for spacing purposes. This newline gets counted as a visual line during truncation.

Example with 5-line output:

output = "line1\nline2\nline3\nline4\nline5" (5 lines)
textContent = "\nline1\nline2\nline3\nline4\nline5" (leading \n added)
When rendered as visual lines: ["", "line1", "line2", "line3", "line4", "line5"] = 6 visual lines
BASH_PREVIEW_LINES = 5
Since 6 > 5, truncation triggers: skippedCount = 6 - 5 = 1
The "1 earlier lines" message appears, but only the empty spacing line was "hidden", not actual content

The Second Bug

When no truncation occurs (line ~320):

But when truncation occurs (line ~314-316):

The truncated path adds a blank line ("") before the hint, but the non-truncated path doesn't add this spacing. This causes inconsistent visual spacing between collapsed and expanded states.

Proposed Fix

File: packages/coding-agent/src/modes/interactive/components/tool-execution.ts

Change 1 (line ~302): Remove the leading \n from textContent:

Change 2 (line ~320): Add blank line for consistent spacing:

This ensures:

Only actual content lines are counted in truncation (5 lines = 5 visual lines, no false "1 earlier lines")
Consistent spacing between header and output in both truncated and non-truncated cases

terrible analysis

Let me re-read the code more carefully.

Let me trace through more carefully with a concrete example:

With 5 lines of output:

output = "line1\nline2\nline3\nline4\nline5"
textContent = "\nline1\nline2\nline3\nline4\nline5" (line 370 adds leading \n)
truncateToVisualLines renders this and gets 6 visual lines: ["", "line1", "line2", "line3", "line4", "line5"]
BASH_PREVIEW_LINES = 5
6 > 5, so truncation triggers
cachedLines = ["line1", "line2", "line3", "line4", "line5"] (last 5)
skippedCount = 1
Returns ["", hint, ...cachedLines] showing "1 earlier lines" message

The bug: The leading \n on line 370 is a formatting spacer, not content. It gets counted as a "hidden line", causing the off-by-one error.

With 7 lines: 8 visual lines (1 empty + 7 content), skips 3, reports "3 earlier lines" when only 2 actual content lines are hidden.

Fix

File: packages/coding-agent/src/modes/interactive/components/tool-execution.ts

Line 370: Change:

to:

Line 390: Change:

to:

This removes the spacer from the truncation calculation while preserving the visual spacing in both truncated and non-truncated cases.

fix it

Now let me update the changelog:

+371 // Note: Don't include leading \n in truncation - it's just spacing, not content +372 const textContent = styledOutput;

why this assignment? and comment? do we still need this?

You're right, it's pointless. Just use styledOutput directly:

Done.

commit and push

Done. Committed and pushed 3235926e.

do a cat lines.txt

100 lines, line1 through line100.