Stop TTL flashes from painting a destroyed TUI renderer

Headless tests often tear down the renderer without dispose. A TTL
flash armed before that teardown must not write a freed TextBuffer.

Author: TheGreatAxios

CHANGELOG.md

@@ -11,6 +11,13 @@ matching `## [X.Y.Z]` section (plus install instructions). Do not maintain
 parallel copies under `docs/` or `scripts/notes/`. At cut time: rename
 `## [Unreleased]` to `## [X.Y.Z] - YYYY-MM-DD`, then run the release script.
 
+## [Unreleased]
+
+### Fixed
+
+- One-shot confirmation flashes (copy, mouse toggle, attach results, reasoning effort, stall recovery) now clear themselves after a short TTL. Rate-limit waits no longer park on the bottom notice row; the durable error stays in the transcript. Live stall notice and landing hold still omit a TTL so they stay until replaced.
+- A TTL flash no longer paints chrome after the TUI renderer is destroyed, which crashed parallel TUI tests with `TextBuffer is destroyed`.
+
 ## [0.3.1] - 2026-08-24
 
 ### Fixed

src/tui/copy-wire.test.ts

@@ -34,10 +34,13 @@ function capturingSchedule(lapse: (() => void)[], expectedMs = RUNTIME_FLASH_MS)
   };
 }
 
+/** Do not arm a real timer: bun test runs files in one process. */
+const ignoreExpiry: FlashSchedule = () => () => {};
+
 describe("Alt+C reaches the injected clipboard", () => {
   test("confirming a copy target writes its text", () => {
     const clipboard = createRecordingClipboard();
-    const shell = createAppShell(harness.renderer, { clipboard });
+    const shell = createAppShell(harness.renderer, { clipboard, flashSchedule: ignoreExpiry });
     appendStreamRow(shell, { role: "assistant", text: "copy me" });
     expect(enterCopyMode(shell)).toBe(true);
     expect(confirmCopySelection(shell)).toBe(true);
@@ -47,7 +50,7 @@ describe("Alt+C reaches the injected clipboard", () => {
 
   test("copy all writes every non-system row", () => {
     const clipboard = createRecordingClipboard();
-    const shell = createAppShell(harness.renderer, { clipboard });
+    const shell = createAppShell(harness.renderer, { clipboard, flashSchedule: ignoreExpiry });
     appendStreamRow(shell, { role: "user", text: "one" });
     appendStreamRow(shell, { role: "assistant", text: "two" });
     enterCopyMode(shell);
@@ -92,7 +95,7 @@ describe("Alt+C reaches the injected clipboard", () => {
 describe("drag-select auto-copy", () => {
   test("SELECTION event writes finished text and flashes", () => {
     const clipboard = createRecordingClipboard();
-    const shell = createAppShell(harness.renderer, { clipboard });
+    const shell = createAppShell(harness.renderer, { clipboard, flashSchedule: ignoreExpiry });
     harness.renderer.emit(CliRenderEvents.SELECTION, {
       isDragging: false,
       getSelectedText: () => "dragged snippet",
@@ -123,7 +126,7 @@ describe("drag-select auto-copy", () => {
 
   test("SELECTION while dragging is a no-op", () => {
     const clipboard = createRecordingClipboard();
-    const shell = createAppShell(harness.renderer, { clipboard });
+    const shell = createAppShell(harness.renderer, { clipboard, flashSchedule: ignoreExpiry });
     harness.renderer.emit(CliRenderEvents.SELECTION, {
       isDragging: true,
       getSelectedText: () => "partial",
@@ -135,7 +138,7 @@ describe("drag-select auto-copy", () => {
 
   test("empty SELECTION is a no-op", () => {
     const clipboard = createRecordingClipboard();
-    const shell = createAppShell(harness.renderer, { clipboard });
+    const shell = createAppShell(harness.renderer, { clipboard, flashSchedule: ignoreExpiry });
     harness.renderer.emit(CliRenderEvents.SELECTION, {
       isDragging: false,
       getSelectedText: () => "",
@@ -149,6 +152,7 @@ describe("Alt+M mouse capture", () => {
   test("toggles the host port and reports the new state", () => {
     let enabled = false;
     const shell = createAppShell(harness.renderer, {
+      flashSchedule: ignoreExpiry,
       mouseCapture: {
         get: () => enabled,
         set: (v) => {
@@ -185,7 +189,7 @@ describe("Alt+M mouse capture", () => {
   });
 
   test("reports unavailable when the host exposes no control", () => {
-    const shell = createAppShell(harness.renderer);
+    const shell = createAppShell(harness.renderer, { flashSchedule: ignoreExpiry });
     expect(toggleMouseCapture(shell)).toBeNull();
     expect(shell.statusFlash).toContain("not controllable");
     shell.dispose();

src/tui/prompt-chrome.test.ts

@@ -317,6 +317,28 @@ describe("no permanent hint strip", () => {
     });
   });
 
+  test("a lapsed flash does not paint after the renderer is torn down without dispose", async () => {
+    await withTestRenderer(async (h) => {
+      const lapse: (() => void)[] = [];
+      const shell = createAppShell(h.renderer, {
+        title: "test",
+        cwd: "/src/corbits-code",
+        terminal: { columns: 80, rows: 24 },
+        wireKeys: false,
+        flashSchedule: (fn, ms) => {
+          expect(ms).toBe(RUNTIME_FLASH_MS);
+          lapse.push(fn);
+          return () => {};
+        },
+      });
+      setStatusFlash(shell, "copied 3 lines", { ttlMs: RUNTIME_FLASH_MS });
+      h.destroy();
+      expect(h.renderer.isDestroyed).toBe(true);
+      expect(shell.disposed).toBe(false);
+      expect(() => lapse[0]?.()).not.toThrow();
+    });
+  });
+
   test("the keys strip is gone from the frame entirely", async () => {
     await withShell((shell) => {
       const painted = [

src/tui/shell.ts

@@ -859,6 +859,10 @@ export function setPluginNeedsAttention(shell: AppShell, needs: boolean): void {
 /** Repaint the prompt borders and the transient notice row from live state. */
 export function paintChrome(shell: AppShell): void {
   if (shell.disposed) return;
+  // Headless tests often destroy the renderer without dispose
+  // (`withTestRenderer` cleanup). A TTL flash armed before that teardown
+  // must not write a TextBuffer the harness already freed.
+  if (shell.renderer.isDestroyed || shell.notice.isDestroyed) return;
   syncPending(shell);
   const notice = noticeText(shell);
   shell.notice.content = new StyledText([
@@ -1058,6 +1062,7 @@ export function setStatusFlash(
   paintChrome(shell);
   const ttlMs = options?.ttlMs;
   if (message === null || ttlMs === undefined || ttlMs <= 0) return;
+  if (shell.disposed || shell.renderer.isDestroyed) return;
   const schedule = options?.schedule ?? shellFlashSchedules.get(shell) ?? defaultFlashSchedule;
   flashTimers.set(
     shell,