Implemented markdown file watcher extension

Summary

Closed, Completed

Plan
Reviewed extension API and directory presence.
Plan
Build
Created pi extension to watch markdown files in plans directory.
Build
Verify
Confirmed watcher detected file changes and reported updates.
Verify

there are .md files in plans/. i want you to write a pi extension that:

gives you a tool to start/stop watching a file or directory for changes
if a file changes, you get a message that prompts you with the updated file contents
create a custom message renderer that just shows what file(s) changed in the tui

Now let me read the extension docs continuation for the custom rendering section:

Now I have a good understanding of the APIs. Let me check if there's an existing plans/ directory:

Good. Now let me create the extension:

The extension is at .pi/extensions/watch-plans.ts. Here's what it does:

Tools:

watch_plans_start - Starts watching a directory (defaults to plans/) for .md file changes. Accepts an optional directory parameter.
watch_plans_stop - Stops all active watchers.

Behavior:

Uses fs.watch with recursive mode for directories
Filters to .md files only
Debounces events (200ms) to avoid duplicate notifications from fs.watch
When a file changes, injects a message via pi.sendMessage() with triggerTurn: true, so you get prompted with the updated contents

Custom message renderer:

Registered for customType: "watch-plans-update"
Compact view shows the filename and timestamp
Expanded view shows the full file contents
Uses theme colors: accent for the label, warning for the filepath, dim for timestamp

Cleanup:

Watchers are closed on session_shutdown

You can test it by reloading (/reload) and then asking the LLM to call watch_plans_start, or just call the tool yourself.

oki, reloaded, start watching

Used Watch Plans Start

Watching plans/ for .md changes. Edit any markdown file in there and I'll get notified with the updated contents.

i'm working on plans/agent-session-refactor.md, read that in full so you are up to date

Got it. I've read the full plan. It's a refactor of AgentSession (~3200 lines) driven by the need for pi.runWhenIdle() (issue #2023). The plan has 5 stages:

Stage 0: Characterization tests (not yet started, this is the next step)
Stage 1: Mechanical cleanup
Stage 2: Unify lifecycle scheduling (replace scattered setTimeout/queue patterns with one lifecycle queue)
Stage 3: Implement quiescence + runWhenIdle()
Stage 4: Move session routing out of AgentSession

Current status: session routing already extracted to agent-session-runtime.ts, test harness exists, but the characterization test suite covering the risky lifecycle contracts hasn't been written yet. That's the blocking next step before any refactoring begins.

I'll get notified if you update the plan file. What do you want to work on?

Noticed the file change notification. The only difference I can see is the removal of "YO YO YO" from the ## Trigger heading. Content is otherwise identical to what I already have loaded.

No meaningful changes in this update. File content is identical to the previous version.

I see you added "The secret is 10!" after the title. Noted. The watcher is working as expected.

Done.

Removed both lines.

That's the watcher picking up my own edit. File is clean now, back to the version without the test lines.