Cancel pending timers when a child is closed (#6)

Co-authored-by: Harry Bayliss <harry@hjb.dev>
Co-committed-by: Harry Bayliss <harry@hjb.dev>

internal/app/timers_test.go

@@ -411,3 +411,178 @@ func TestTimerRecordsRemovedOnIdleFire(t *testing.T) {
 		t.Fatalf("fired idle timer %s was not removed from registry", resp.ID)
 	}
 }
+
+// TestTimerCloseChildPrunesWatched covers the happy partial-prune
+// case: an idle_any timer watches two children, one is closed, the
+// timer stays pending and the remaining child can still satisfy it.
+func TestTimerCloseChildPrunesWatched(t *testing.T) {
+	sess, mgr, rec := newTestManager(t)
+	owner := fakeChild("p_owner")
+	a := fakeChild("p_a")
+	b := fakeChild("p_b")
+	addChild(sess, owner)
+	addChild(sess, a)
+	addChild(sess, b)
+	working := StateWorking
+	a.idleState.Store(&working)
+	b.idleState.Store(&working)
+
+	resp, err := mgr.TimerFireWhenIdleAny("p_owner", "one done", "", []string{"p_a", "p_b"}, 0)
+	if err != nil {
+		t.Fatalf("TimerFireWhenIdleAny: %v", err)
+	}
+
+	mgr.onChildClosed("p_a")
+
+	mgr.mu.Lock()
+	t1, ok := mgr.timers[resp.ID]
+	if !ok {
+		mgr.mu.Unlock()
+		t.Fatalf("timer was removed but still has live watched")
+	}
+	watched := append([]string(nil), t1.watched...)
+	mgr.mu.Unlock()
+	if len(watched) != 1 || watched[0] != "p_b" {
+		t.Fatalf("watched after close: %v, want [p_b]", watched)
+	}
+	if got := rec.snapshot(); len(got) != 0 {
+		t.Fatalf("close synthesised a fire: %+v", got)
+	}
+
+	// p_b can still satisfy the timer.
+	idle := StateIdle
+	b.idleState.Store(&idle)
+	mgr.onChildStateChanged("p_b", StateIdle)
+	if got := rec.snapshot(); len(got) != 1 || got[0].Body != "one done" {
+		t.Fatalf("post-prune fire: %+v", got)
+	}
+}
+
+// TestTimerCloseLastWatchedCancels is the regression for the
+// reported stale-fire symptom: the only watched child is closed,
+// so the timer must be cancelled — no synthetic fire, and the
+// registry entry must be gone so a trailing classifier tick for the
+// removed child cannot re-deliver later.
+func TestTimerCloseLastWatchedCancels(t *testing.T) {
+	sess, mgr, rec := newTestManager(t)
+	owner := fakeChild("p_owner")
+	a := fakeChild("p_a")
+	addChild(sess, owner)
+	addChild(sess, a)
+	working := StateWorking
+	a.idleState.Store(&working)
+
+	resp, err := mgr.TimerFireWhenIdleAny("p_owner", "stale body", "", []string{"p_a"}, 0)
+	if err != nil {
+		t.Fatalf("TimerFireWhenIdleAny: %v", err)
+	}
+
+	mgr.onChildClosed("p_a")
+
+	mgr.mu.Lock()
+	_, stillThere := mgr.timers[resp.ID]
+	mgr.mu.Unlock()
+	if stillThere {
+		t.Fatalf("timer with no remaining watched should be removed")
+	}
+	if got := rec.snapshot(); len(got) != 0 {
+		t.Fatalf("close synthesised a fire: %+v", got)
+	}
+
+	// Simulate the trailing classifier tick for the now-closed child —
+	// must not fire.
+	mgr.onChildStateChanged("p_a", StateIdle)
+	if got := rec.snapshot(); len(got) != 0 {
+		t.Fatalf("trailing state change re-fired: %+v", got)
+	}
+}
+
+// TestTimerCloseChildIdleAllPartialPrune mirrors the idle_any
+// partial-prune for idle_all: pruning a watched child shrinks the
+// list; the remaining child going idle then satisfies the timer.
+func TestTimerCloseChildIdleAllPartialPrune(t *testing.T) {
+	sess, mgr, rec := newTestManager(t)
+	owner := fakeChild("p_owner")
+	a := fakeChild("p_a")
+	b := fakeChild("p_b")
+	addChild(sess, owner)
+	addChild(sess, a)
+	addChild(sess, b)
+	working := StateWorking
+	a.idleState.Store(&working)
+	b.idleState.Store(&working)
+
+	resp, err := mgr.TimerFireWhenIdleAll("p_owner", "all done", "", []string{"p_a", "p_b"}, 0)
+	if err != nil {
+		t.Fatalf("TimerFireWhenIdleAll: %v", err)
+	}
+	if resp.Status != "pending" {
+		t.Fatalf("status: got %q want pending", resp.Status)
+	}
+
+	mgr.onChildClosed("p_a")
+
+	idle := StateIdle
+	b.idleState.Store(&idle)
+	mgr.onChildStateChanged("p_b", StateIdle)
+	if got := rec.snapshot(); len(got) != 1 || got[0].Body != "all done" {
+		t.Fatalf("idle_all after partial prune: %+v", got)
+	}
+}
+
+// TestTimerCloseOwnerCancelsDelay ensures a delay timer is dropped
+// when its owner is closed: no delivery, registry empty, the
+// underlying time.Timer is stopped.
+func TestTimerCloseOwnerCancelsDelay(t *testing.T) {
+	sess, mgr, rec := newTestManager(t)
+	c := fakeChild("p_owner")
+	addChild(sess, c)
+	id, err := mgr.TimerSet("p_owner", "x", "", 0.1)
+	if err != nil {
+		t.Fatalf("TimerSet: %v", err)
+	}
+
+	mgr.onChildClosed("p_owner")
+
+	mgr.mu.Lock()
+	_, stillThere := mgr.timers[id]
+	mgr.mu.Unlock()
+	if stillThere {
+		t.Fatalf("delay timer was not removed when owner closed")
+	}
+	time.Sleep(200 * time.Millisecond) // past the original firesAt
+	if got := rec.snapshot(); len(got) != 0 {
+		t.Fatalf("delay timer fired after owner close: %+v", got)
+	}
+}
+
+// TestTimerCloseWatchedSubAgent is the exact shape of the reported
+// stale-fire bug: orchestrator registers a watcher on a sub-agent,
+// the sub-agent is closed, and the orchestrator must receive
+// nothing (no stale body delivered after close_process).
+func TestTimerCloseWatchedSubAgent(t *testing.T) {
+	sess, mgr, rec := newTestManager(t)
+	parent := fakeChild("p_owner")
+	sub := fakeChild("p_sub")
+	addChild(sess, parent)
+	addChild(sess, sub)
+	working := StateWorking
+	sub.idleState.Store(&working)
+
+	if _, err := mgr.TimerFireWhenIdleAny(
+		"p_owner",
+		"codex-review-591 finished. Read your own pane …",
+		"", []string{"p_sub"}, 0,
+	); err != nil {
+		t.Fatalf("TimerFireWhenIdleAny: %v", err)
+	}
+
+	mgr.onChildClosed("p_sub")
+
+	// Trailing classifier emission for the closed sub-agent must
+	// not deliver anything to the parent.
+	mgr.onChildStateChanged("p_sub", StateIdle)
+	if got := rec.snapshot(); len(got) != 0 {
+		t.Fatalf("stale fire delivered to parent after sub-agent close: %+v", got)
+	}
+}