Add durable toasts with an inline action button

src/app/components/Toaster.module.css

@@ -142,6 +142,31 @@
   color: var(--text-secondary);
 }
 
+.actions {
+  margin-top: var(--space-3);
+}
+
+.action {
+  padding: var(--space-1) var(--space-3);
+  font: inherit;
+  font-size: 13px;
+  color: var(--toast-accent);
+  background: transparent;
+  border: var(--border-width) solid var(--toast-accent);
+  border-radius: var(--radius);
+  cursor: pointer;
+  transition: background var(--dur-fast) var(--ease);
+}
+
+.action:hover {
+  background: var(--layer-01);
+}
+
+.action:focus-visible {
+  outline: 2px solid var(--focus);
+  outline-offset: 2px;
+}
+
 .close {
   flex: none;
   display: inline-flex;

src/app/components/Toaster.test.tsx

@@ -171,6 +171,45 @@ describe('Toaster exit animation (two-phase dismiss)', () => {
     vi.useRealTimers();
   });
 
+  test('a durable toast does not auto-dismiss, and its action runs then dismisses it', () => {
+    vi.useFakeTimers();
+    const onClick = vi.fn();
+    let id: string;
+    act(() => {
+      id = useNotificationStore.getState().notify({
+        kind: 'info',
+        title: 'Update available',
+        message: 'A new version is ready.',
+        durable: true,
+        action: { label: 'Reload', onClick },
+      });
+      root.render(<Toaster />);
+    });
+
+    // Well past the auto-dismiss window — still present (durable).
+    act(() => {
+      vi.advanceTimersByTime(60000);
+    });
+    expect(useNotificationStore.getState().notifications.some((n) => n.id === id!)).toBe(true);
+
+    // The action button runs the handler, then the toast exits.
+    const actionBtn = Array.from(container.querySelectorAll('button')).find(
+      (b) => b.textContent === 'Reload',
+    );
+    expect(actionBtn).toBeTruthy();
+    act(() => {
+      actionBtn!.dispatchEvent(new MouseEvent('click', { bubbles: true }));
+    });
+    expect(onClick).toHaveBeenCalledTimes(1);
+
+    act(() => {
+      vi.advanceTimersByTime(TOAST_EXIT_MS);
+    });
+    expect(useNotificationStore.getState().notifications.some((n) => n.id === id!)).toBe(false);
+
+    vi.useRealTimers();
+  });
+
   test('clicking close twice does not reset the exit timer', () => {
     vi.useFakeTimers();
     let id: string;

src/app/components/Toaster.tsx

@@ -70,18 +70,25 @@ function Toast({
   exiting: boolean;
   onStartExit: (id: string) => void;
 }) {
-  const { id, kind, title, message, detail } = notification;
+  const { id, kind, title, message, detail, action, durable } = notification;
 
   // Trigger exit animation; after the animation duration the store removes it.
   const handleDismiss = useCallback(() => onStartExit(id), [id, onStartExit]);
 
-  // Positive/informational toasts clear themselves after a beat. Resets on
+  // Positive/informational toasts clear themselves after a beat — unless marked
-  // re-render only when id/kind changes (stable identity guarantee).
+  // durable (e.g. an update prompt the user must act on). Resets only when
+  // id/kind changes (stable identity guarantee).
   useEffect(() => {
-    if (!AUTO_DISMISS[kind]) return;
+    if (!AUTO_DISMISS[kind] || durable) return;
     const timer = setTimeout(handleDismiss, AUTO_DISMISS_MS);
     return () => clearTimeout(timer);
-  }, [id, kind, handleDismiss]);
+  }, [id, kind, durable, handleDismiss]);
+
+  // Run the action, then dismiss the toast (the handler may navigate/reload).
+  const handleAction = useCallback(() => {
+    action?.onClick();
+    handleDismiss();
+  }, [action, handleDismiss]);
 
   return (
     <div
@@ -100,6 +107,13 @@ function Toast({
             <p className={styles.detailMeta}>Astrolabe v{__APP_VERSION__}</p>
           </details>
         )}
+        {action && (
+          <div className={styles.actions}>
+            <button type="button" className={styles.action} onClick={handleAction}>
+              {action.label}
+            </button>
+          </div>
+        )}
       </div>
       <button
         type="button"

src/app/stores/NotificationStore.ts

@@ -37,6 +37,18 @@ export interface NotifyOptions {
    * notifications — there is nothing for the user to report.
    */
   detail?: string;
+  /**
+   * Optional inline call-to-action rendered as a button in the toast (Carbon
+   * notification action). The toast dismisses after the handler runs. Used for
+   * e.g. the service-worker "Reload to update" prompt (web.dev → council).
+   */
+  action?: { label: string; onClick: () => void };
+  /**
+   * When true, the toast never auto-dismisses — it waits for the user (a Reload
+   * prompt or an offer the user must see). Mirrors how errors/warnings persist;
+   * lets a positive/info kind opt out of the auto-dismiss timer.
+   */
+  durable?: boolean;
 }
 
 export interface Notification extends NotifyOptions {