fix: wake pi crewmates after each turn

[kunchenguid]

Intent

Fix firstmate's pi crewmate turn-end hook. fm-spawn's generated pi extension listened on pi's 'agent_end' event, which (per pi 0.79.1 type docs) fires only once when the whole agent run exits - so the turn-end backstop never fired at per-turn boundaries for pi crewmates, leaving firstmate reliant on crewmate status appends alone and blind to an idle crewmate that stopped without writing status. Change the hook to 'turn_end', which fires after each turn the agent finishes, matching how the claude/codex/opencode adapters behave. One-line change to the pi-ext template in bin/fm-spawn.sh plus an explanatory comment; no other behavior change.

What Changed

• Updated the pi harness extension generated by bin/fm-spawn.sh to listen for turn_end instead of agent_end, so firstmate receives a turn-ended signal after each completed pi turn rather than only when the whole agent run exits.
• Added an inline comment explaining why the pi hook must use turn_end for per-turn idle detection.
• Documented the pi adapter requirement in AGENTS.md so future harness changes preserve the same watcher behavior.

Risk Assessment

✅ Low: The branch is a narrow one-line event-name correction plus explanatory generated-code comments, with no broader control-flow or API surface changes.

Testing

Baseline bootstrap could not run due missing local firstmate config state, but the focused end-to-end spawn path was exercised: fm-spawn.sh generated and launched a pi extension using turn_end; live pi execution stopped at the trust prompt, which I did not accept because it would change user-level trust outside the worktree boundary, so I supplemented it with a mocked extension event simulation proving the generated hook would touch the turn-ended sentinel. All focused checks passed and temporary worktree test scaffolding was removed.

Evidence: Generated pi extension evidence

The emitted extension registers pi.on("turn_end", ...) and touches state/pi-hook-e2e.turn-ended; it contains no pi.on("agent_end", ...) registration.

// Firstmate turn-end signal; written by fm-spawn.
// Use "turn_end" (fires after each turn the agent finishes), not "agent_end"
// (fires once, only when the whole run exits): the watcher needs a signal at
// every turn boundary so an idle crewmate is surfaced, not just at shutdown.
import { execFile } from "node:child_process";
export default function (pi: any) {
  pi.on("turn_end", () => execFile("touch", ["/Users/kunchen/.no-mistakes/worktrees/016d88035d58/01KV18PMDX505TN87957JNNXTT/state/pi-hook-e2e.turn-ended"]));
}

Evidence: Pi spawn pane transcript

Shows the real spawn command launching pi -e /Users/kunchen/.no-mistakes/worktrees/016d88035d58/01KV18PMDX505TN87957JNNXTT/state/pi-hook-e2e.pi-ext.ts ... before pi displayed its project trust prompt.

treehouse get
01KV18PMDX505TN87957JNNXTT HEAD
❯ treehouse get
🌳 Setting up worktree...
🌳 Entered worktree at ~/.treehouse/01KV18PMDX505TN87957JNNXTT-b8697d/1/01KV18PMDX505TN87957JNNXTT. Type 'exit' to return.
01KV18PMDX505TN87957JNNXTT HEAD
❯ pi -e /Users/kunchen/.no-mistakes/worktrees/016d88035d58/01KV18PMDX505TN87957JNNXTT/state/pi-hook-e2e.pi-ext.ts "$(cat /Users/kunchen/.no-mistakes/worktrees/016d88035d58/01KV18PMDX505TN87957JNNXTT/data/pi-hook-e2e/brief.md)"
───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

 Trust project folder?
 /Users/kunchen/.treehouse/01KV18PMDX505TN87957JNNXTT-b8697d/1/01KV18PMDX505TN87957JNNXTT

 This allows pi to load .pi settings and resources, install missing project packages, and execute project extensions.

 → Trust
   Trust parent folder (/Users/kunchen/.treehouse/01KV18PMDX505TN87957JNNXTT-b8697d/1)
   Trust (this session only)
   Do not trust
   Do not trust (this session only)

 ↑↓ navigate  enter select  escape/ctrl+c cancel

───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

Evidence: Generated extension event simulation

registered_event=turn_end execFile_command=touch execFile_arg=/Users/kunchen/.no-mistakes/worktrees/016d88035d58/01KV18PMDX505TN87957JNNXTT/state/pi-hook-e2e.turn-ended

registered_event=turn_end
execFile_command=touch
execFile_arg=/Users/kunchen/.no-mistakes/worktrees/016d88035d58/01KV18PMDX505TN87957JNNXTT/state/pi-hook-e2e.turn-ended

Pipeline

Updates from git push no-mistakes

✅ **intent** - passed

✅ No issues found.

✅ **Rebase** - passed

✅ No issues found.

✅ **Review** - passed

✅ No issues found.

✅ **Test** - passed

✅ No issues found.

• bin/fm-bootstrap.sh - attempted baseline bootstrap; it failed because this isolated worktree lacks config/crew-harness parent state, so validation continued without creating persistent config.
• Created temporary data/pi-hook-e2e/brief.md and state/, then ran bin/fm-spawn.sh pi-hook-e2e . pi --scout to exercise the real pi spawn path.
• Captured state/pi-hook-e2e.pi-ext.ts and the tmux pane transcript into /var/folders/5x/4nqprlbx0518k3ybcb1sz6gr0000gn/T/no-mistakes-evidence/01KV18PMDX505TN87957JNNXTT.
• node -e '...' asserted the generated pi extension contains pi.on("turn_end"...) and does not register pi.on("agent_end"...).
• node -e '...' asserted the captured spawn transcript launched pi -e .../state/pi-hook-e2e.pi-ext.ts.
• node <<'NODE' ... NODE loaded the generated extension text with a mocked pi event emitter and verified triggering the registered callback calls touch on state/pi-hook-e2e.turn-ended.
• bin/fm-teardown.sh pi-hook-e2e tore down the spawned scout task; git status --short confirmed no temporary worktree scaffolding remained.

✅ **Document** - passed

✅ No issues found.

✅ **Lint** - passed

✅ No issues found.

✅ **Push** - passed

✅ No issues found.