Reduce agent timeline focus catch-up

packages/app/src/hooks/use-agent-initialization.test.ts

@@ -24,7 +24,7 @@ afterEach(() => {
 });
 
 describe("useAgentInitialization", () => {
-  it("always requests a canonical tail bootstrap even with an authoritative cursor", () => {
+  it("requests bounded canonical catch-up after the current cursor when authoritative history is loaded", () => {
     const client = makeClient();
     useSessionStore.getState().initializeSession(serverId, client as never);
     useSessionStore
@@ -43,6 +43,27 @@ describe("useAgentInitialization", () => {
       void result.current.ensureAgentIsInitialized(agentId);
     });
 
+    expect(client.fetchAgentTimeline).toHaveBeenCalledWith(agentId, {
+      direction: "after",
+      cursor: { epoch: "epoch-1", seq: 42 },
+      limit: TIMELINE_FETCH_PAGE_SIZE,
+      projection: "canonical",
+    });
+    expect(getInitDeferred(getInitKey(serverId, agentId))?.requestDirection).toBe("after");
+  });
+
+  it("requests a bounded canonical tail when no authoritative cursor is available", () => {
+    const client = makeClient();
+    useSessionStore.getState().initializeSession(serverId, client as never);
+
+    const { result } = renderHook(() =>
+      useAgentInitialization({ serverId, client: client as never }),
+    );
+
+    act(() => {
+      void result.current.ensureAgentIsInitialized(agentId);
+    });
+
     expect(client.fetchAgentTimeline).toHaveBeenCalledWith(agentId, {
       direction: "tail",
       limit: TIMELINE_FETCH_PAGE_SIZE,

packages/app/src/hooks/use-agent-initialization.ts

@@ -42,13 +42,25 @@ export function useAgentInitialization({
         return existing.promise;
       }
 
-      const timelineRequest = {
-        direction: "tail" as const,
-        limit: TIMELINE_FETCH_PAGE_SIZE,
-        projection: "canonical" as const,
-      };
+      const session = useSessionStore.getState().sessions[serverId];
+      const cursor = session?.agentTimelineCursor.get(agentId);
+      const hasAuthoritativeHistory =
+        session?.agentAuthoritativeHistoryApplied.get(agentId) === true;
+      const timelineRequest =
+        hasAuthoritativeHistory && cursor
+          ? {
+              direction: "after" as const,
+              cursor: { epoch: cursor.epoch, seq: cursor.endSeq },
+              limit: TIMELINE_FETCH_PAGE_SIZE,
+              projection: "canonical" as const,
+            }
+          : {
+              direction: "tail" as const,
+              limit: TIMELINE_FETCH_PAGE_SIZE,
+              projection: "canonical" as const,
+            };
 
-      const deferred = createInitDeferred(key, "tail");
+      const deferred = createInitDeferred(key, timelineRequest.direction);
       const timeoutId = setTimeout(() => {
         setAgentInitializing(agentId, false);
         rejectInitDeferred(