feat(statusfile): render the ambient drift line when idle

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/statusfile/statusfile_test.go

@@ -66,7 +66,7 @@ func TestRender(t *testing.T) {
 	}
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {
-			if got := Render(tc.env, now); got != tc.want {
+			if got := Render(tc.env, "", now); got != tc.want {
 				t.Errorf("Render() = %q, want %q", got, tc.want)
 			}
 		})
@@ -77,7 +77,7 @@ func TestWriterWritesAndDedups(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "status")
 	now := time.Unix(1_000_000, 0)
 	env := focusEnv(focusState(domain.RuntimePlanning))
-	w := NewWriter(path, func() mode.Envelope { return env })
+	w := NewWriter(path, func() mode.Envelope { return env }, nil)
 	w.now = func() time.Time { return now }
 
 	w.write()
@@ -107,7 +107,7 @@ func TestWriterRemovesFileOnCancel(t *testing.T) {
 	path := filepath.Join(t.TempDir(), "status")
 	w := NewWriter(path, func() mode.Envelope {
 		return focusEnv(focusState(domain.RuntimePlanning))
-	})
+	}, nil)
 	ctx, cancel := context.WithCancel(context.Background())
 	done := make(chan struct{})
 	go func() { w.Run(ctx); close(done) }()
@@ -131,7 +131,7 @@ func TestWriterWakeRendersPromptly(t *testing.T) {
 
 	var mu sync.Mutex
 	st := activeState(in10m, "ontask", "")
-	w := NewWriter(path, func() mode.Envelope { mu.Lock(); defer mu.Unlock(); return focusEnv(st) })
+	w := NewWriter(path, func() mode.Envelope { mu.Lock(); defer mu.Unlock(); return focusEnv(st) }, nil)
 	w.now = func() time.Time { return now }
 
 	ctx, cancel := context.WithCancel(context.Background())
@@ -148,6 +148,27 @@ func TestWriterWakeRendersPromptly(t *testing.T) {
 	waitFor(t, func() bool { return fileEquals(path, "⚠ DRIFT 10m") })
 }
 
+func TestRenderIdleShowsAmbientLine(t *testing.T) {
+	got := Render(mode.Envelope{ActiveMode: ""}, "deep in YouTube, no goal", time.Unix(0, 0))
+	if got != "⚠ deep in YouTube, no goal" {
+		t.Fatalf("idle+ambient render = %q", got)
+	}
+}
+
+func TestRenderIdleNoAmbientLineIsIdle(t *testing.T) {
+	if got := Render(mode.Envelope{ActiveMode: ""}, "", time.Unix(0, 0)); got != "idle" {
+		t.Fatalf("idle+no-ambient render = %q, want idle", got)
+	}
+}
+
+func TestRenderActiveModeIgnoresAmbientLine(t *testing.T) {
+	// A non-idle envelope renders its own mode, never the ambient line.
+	got := Render(mode.Envelope{ActiveMode: "offscreen", Mode: map[string]any{"status": "proposed", "next_action": "walk"}}, "ambient ignored", time.Unix(0, 0))
+	if got == "ambient ignored" || got == "⚠ ambient ignored" {
+		t.Fatalf("active mode must not render the ambient line, got %q", got)
+	}
+}
+
 func fileEquals(path, want string) bool {
 	b, err := os.ReadFile(path)
 	return err == nil && string(b) == want