diff --git a/AGENTS.md b/AGENTS.md
index ad58f845cc1..61ef6130fa0 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -156,6 +156,7 @@ pi has no permission system - crewmates are always autonomous.
 Keep the brief as ONE positional argument - multiple positional args become separate queued messages (fm-spawn's template does this correctly).
 Project trust dialog can appear on the first pi run in any not-yet-trusted directory (observed even on clean worktrees); accept with Enter - the decision persists per path in `~/.pi/agent/trust.json`, so later spawns in the same worktree slot skip it.
 fm-spawn keeps the turn-end extension in `state/`, outside the worktree, because project-local extension files make the trust gate strictly worse (and pollute the project).
+The extension must listen for pi's `turn_end` event, not `agent_end`, so the watcher wakes after each completed turn instead of only when the whole agent run exits.
 Environment marker for harness detection: pi sets `PI_CODING_AGENT=true` for its children.
 
 ## 5. Recovery (run at every session start, after bootstrap)
diff --git a/bin/fm-spawn.sh b/bin/fm-spawn.sh
index 63cb3967db4..7e08fb0bcc0 100755
--- a/bin/fm-spawn.sh
+++ b/bin/fm-spawn.sh
@@ -135,9 +135,12 @@ EOF
     # elsewhere loads without a dialog. Lives in state/, cleaned by teardown.
     cat > "$FM_ROOT/state/$ID.pi-ext.ts" <<EOF
 // 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("agent_end", () => execFile("touch", ["$TURNEND"]));
+  pi.on("turn_end", () => execFile("touch", ["$TURNEND"]));
 }
 EOF
     ;;