feat(app): add chat outline navigation (#2792)

* feat(app): add chat outline navigation

Long agent sessions need prompt navigation without coupling viewport movement to disposable server windows. Keep fetched timeline pages in client state so repeated jumps stay local, and settle prompt jumps against virtualized row measurement changes.

* fix(app): preserve chat outline timeline coverage

* fix(app): reconcile outline window submissions

* fix(app): harden outline timeline navigation

packages/app/e2e/support/helpers/agent-timeline-gate.ts

@@ -27,6 +27,41 @@ export interface DaemonHydrationGate {
   release(): void;
 }
 
+export interface PromptJumpRequestTracker {
+  requests(): Array<{ cursorSeq: number | null; limit: number | null; mergeWindow: boolean }>;
+}
+
+export async function trackPromptJumpRequests(
+  page: Page,
+  agentId: string,
+): Promise<PromptJumpRequestTracker> {
+  const seen: Array<{ cursorSeq: number | null; limit: number | null; mergeWindow: boolean }> = [];
+  await page.routeWebSocket(daemonWsRoutePattern(), (ws) => {
+    const server = ws.connectToServer();
+    ws.onMessage((message) => {
+      const sessionMessage = getSessionMessage(message);
+      if (
+        sessionMessage?.type === "fetch_agent_timeline_request" &&
+        sessionMessage.agentId === agentId &&
+        sessionMessage.direction === "before" &&
+        sessionMessage.mergeWindow === true
+      ) {
+        const cursor = sessionMessage.cursor as { seq?: unknown } | undefined;
+        seen.push({
+          cursorSeq: typeof cursor?.seq === "number" ? cursor.seq : null,
+          limit: typeof sessionMessage.limit === "number" ? sessionMessage.limit : null,
+          mergeWindow: true,
+        });
+      }
+      server.send(message);
+    });
+    server.onMessage((message) => ws.send(message));
+  });
+  return {
+    requests: () => [...seen],
+  };
+}
+
 export interface BootstrapTimelineGate extends AgentTimelineResponseGate {
   releaseCatchUp(): void;
   waitForDelayedCatchUp(): Promise<void>;