feat(04-01): integrate notifications and focus mode into daemon

- Notifier + FocusTimer fields in Daemon, initialized in NewDaemon
- processHookEvent notifies on Working -> Needs Input only (D-01)
- Focus mode suppresses notifications when active (D-05)
- FocusArgs in protocol, "focus" handler in daemon
- CLI "vmux focus <minutes>" command
- Tests for all notification transitions and focus handler

daemon_test.go

@@ -432,6 +432,122 @@ func TestDaemonLabelOverSocket(t *testing.T) {
 	}
 }
 
+// spyNotifier records calls to Notify for test assertions.
+type spyNotifier struct {
+	calls []struct{ title, body string }
+}
+
+func (s *spyNotifier) Notify(title, body string) error {
+	s.calls = append(s.calls, struct{ title, body string }{title, body})
+	return nil
+}
+
+func TestNotification_WorkingToNeedsInput(t *testing.T) {
+	d := newTestDaemon(t)
+	spy := &spyNotifier{}
+	d.notifier = spy
+
+	// Seed session as Working
+	d.registry.UpdateFromHook("sess-1", "Working", "", "/tmp/proj")
+
+	// Transition to Needs Input
+	d.processHookEvent(HookEvent{
+		SessionID:     "sess-1",
+		HookEventName: "Stop",
+		Cwd:           "/tmp/proj",
+	})
+
+	if len(spy.calls) != 1 {
+		t.Fatalf("notify calls = %d, want 1", len(spy.calls))
+	}
+	if spy.calls[0].title != "vmux: proj" {
+		t.Errorf("title = %q, want %q", spy.calls[0].title, "vmux: proj")
+	}
+}
+
+func TestNotification_IdleToNeedsInput(t *testing.T) {
+	d := newTestDaemon(t)
+	spy := &spyNotifier{}
+	d.notifier = spy
+
+	// Seed session as Idle (not Working)
+	d.registry.UpdateFromHook("sess-1", "Idle", "", "/tmp/proj")
+
+	// Transition to Needs Input from Idle
+	d.processHookEvent(HookEvent{
+		SessionID:     "sess-1",
+		HookEventName: "Stop",
+		Cwd:           "/tmp/proj",
+	})
+
+	if len(spy.calls) != 0 {
+		t.Errorf("notify calls = %d, want 0 (Idle -> Needs Input should not notify)", len(spy.calls))
+	}
+}
+
+func TestNotification_FocusActive(t *testing.T) {
+	d := newTestDaemon(t)
+	spy := &spyNotifier{}
+	d.notifier = spy
+	d.focus.Set(30 * time.Minute)
+
+	// Seed session as Working
+	d.registry.UpdateFromHook("sess-1", "Working", "", "/tmp/proj")
+
+	// Transition to Needs Input (but focus active)
+	d.processHookEvent(HookEvent{
+		SessionID:     "sess-1",
+		HookEventName: "Stop",
+		Cwd:           "/tmp/proj",
+	})
+
+	if len(spy.calls) != 0 {
+		t.Errorf("notify calls = %d, want 0 (focus active should suppress)", len(spy.calls))
+	}
+}
+
+func TestNotification_FocusExpired(t *testing.T) {
+	d := newTestDaemon(t)
+	spy := &spyNotifier{}
+	d.notifier = spy
+	d.focus.Set(0) // expired immediately
+
+	// Seed session as Working
+	d.registry.UpdateFromHook("sess-1", "Working", "", "/tmp/proj")
+
+	// Transition to Needs Input (focus expired)
+	d.processHookEvent(HookEvent{
+		SessionID:     "sess-1",
+		HookEventName: "Stop",
+		Cwd:           "/tmp/proj",
+	})
+
+	if len(spy.calls) != 1 {
+		t.Fatalf("notify calls = %d, want 1 (focus expired should notify)", len(spy.calls))
+	}
+}
+
+func TestFocusHandler(t *testing.T) {
+	d := newTestDaemon(t)
+
+	if err := d.Start(); err != nil {
+		t.Fatalf("start: %v", err)
+	}
+	defer d.Stop()
+
+	args, _ := json.Marshal(FocusArgs{Minutes: 30})
+	resp := sendRequest(t, d.sockPath, Request{Action: "focus", Args: args})
+	if !resp.OK {
+		t.Fatalf("focus resp.OK = false, error = %q", resp.Error)
+	}
+	if !d.focus.IsActive() {
+		t.Error("focus should be active after handler")
+	}
+	if resp.FocusRemaining <= 0 {
+		t.Errorf("FocusRemaining = %v, want > 0", resp.FocusRemaining)
+	}
+}
+
 func TestDaemonUnknownAction(t *testing.T) {
 	d := newTestDaemon(t)