Keep older chat history and image previews stable (#2490)

* fix(app): keep timeline history and previews stable

Treat persisted timeline replicas as display-only so authoritative pagination always comes from the daemon. Require renewed user intent between older-history pages unless the viewport genuinely remains at the history edge.

Model assistant image acquisition as loading, loaded, or failed so recreating a preview URL cannot be rendered as an error.

* fix(app): keep file image previews current

* fix(app): stabilize history pagination edges

* fix(app): recover transient timeline loads

* fix(app): retain assistant image previews

* Stabilize history pagination lifecycle

* Stabilize history settlement and image previews

* Retry file images after reconnect

* Keep active previews and pagination requests alive

* Replace image hook tests with typed ports

* Integrate timeline hydration with submission authority

* Harden pre-hydration timeline reconciliation

* Make rewind E2E use real scroll intent

* Preserve live timeline state through hydration

* Keep mounted image attachments retained

* Protect preview persistence and lifecycle hydration

* Preserve idless live assistant continuations

* Preserve timeline rows across delayed hydration

* test(app): cover real assistant image files

* Preserve assistant tool ordering during hydration

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

@@ -111,6 +111,47 @@ describe("ensureAgentIsInitialized", () => {
     expect(getInitDeferred(getInitKey(serverId, agentId))?.requestDirection).toBe("tail");
   });
 
+  it("requests a bounded projected tail after restoring painted replica items", () => {
+    const client = new FakeDaemonClient();
+    const runtime = new FakeTimelineRuntime();
+    useSessionStore.getState().restoreSessionReplica(serverId, {
+      agents: new Map(),
+      workspaces: new Map(),
+      emptyProjects: new Map(),
+      timeline: {
+        agentId,
+        items: [
+          {
+            kind: "assistant_message",
+            id: "painted-item",
+            text: "Painted before hydration",
+            timestamp: new Date("2026-07-27T10:00:00.000Z"),
+          },
+        ],
+      },
+    });
+
+    void ensureAgentIsInitialized({
+      serverId,
+      agentId,
+      client: client as never,
+      runtime,
+      setAgentInitializing: bindSetAgentInitializing(),
+    });
+
+    expect(runtime.requests).toEqual([
+      {
+        serverId,
+        agentId,
+        request: {
+          direction: "tail",
+          limit: TIMELINE_FETCH_PAGE_SIZE,
+          projection: "projected",
+        },
+      },
+    ]);
+  });
+
   it("times out initialization after 65 seconds", async () => {
     vi.useFakeTimers();
     const client = new FakeDaemonClient();

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

@@ -1,7 +1,7 @@
 import { useCallback, useMemo } from "react";
 import { useTranslation } from "react-i18next";
 import type { DaemonClient } from "@getpaseo/client/internal/daemon-client";
-import { useSessionStore } from "@/stores/session-store";
+import { selectAgentTimelineState, useSessionStore } from "@/stores/session-store";
 import {
   createInitDeferred,
   getInitDeferred,
@@ -52,8 +52,9 @@ export function ensureAgentIsInitialized(input: EnsureAgentIsInitializedInput):
   }
 
   const session = useSessionStore.getState().sessions[serverId];
-  const cursor = session?.agentTimelineCursor.get(agentId);
-  const hasAuthoritativeHistory = session?.agentAuthoritativeHistoryApplied.get(agentId) === true;
+  const timeline = selectAgentTimelineState(session, agentId);
+  const cursor = timeline.status === "synced" ? (timeline.range ?? undefined) : undefined;
+  const hasAuthoritativeHistory = timeline.status === "synced";
   const timelineRequest = planInitialAgentTimelineSync({ cursor, hasAuthoritativeHistory });
 
   const deferred = createInitDeferred(key, timelineRequest.direction);

packages/app/src/hooks/use-load-older-agent-history.test.ts

@@ -84,7 +84,7 @@ describe("loadOlderAgentHistory", () => {
     const client = createClient();
     const inFlight = createInFlight();
 
-    await loadOlderAgentHistory(agentId, {
+    const started = await loadOlderAgentHistory(agentId, {
       client,
       cursor: undefined,
       hasOlder: true,
@@ -94,13 +94,14 @@ describe("loadOlderAgentHistory", () => {
 
     expect(client.calls).toEqual([]);
     expect(inFlight.values).toEqual([false]);
+    expect(started).toBe(false);
   });
 
   it("no-ops when the daemon says no older history exists", async () => {
     const client = createClient();
     const inFlight = createInFlight();
 
-    await loadOlderAgentHistory(agentId, {
+    const started = await loadOlderAgentHistory(agentId, {
       client,
       cursor: someCursor,
       hasOlder: false,
@@ -110,13 +111,14 @@ describe("loadOlderAgentHistory", () => {
 
     expect(client.calls).toEqual([]);
     expect(inFlight.values).toEqual([false]);
+    expect(started).toBe(false);
   });
 
   it("no-ops when a request is already in flight", async () => {
     const client = createClient();
     const inFlight = createInFlight(true);
 
-    await loadOlderAgentHistory(agentId, {
+    const started = await loadOlderAgentHistory(agentId, {
       client,
       cursor: someCursor,
       hasOlder: true,
@@ -126,13 +128,14 @@ describe("loadOlderAgentHistory", () => {
 
     expect(client.calls).toEqual([]);
     expect(inFlight.values).toEqual([true]);
+    expect(started).toBe(true);
   });
 
   it("requests the page before the current start cursor and clears in-flight on success", async () => {
     const client = createClient();
     const inFlight = createInFlight();
 
-    await loadOlderAgentHistory(agentId, {
+    const started = await loadOlderAgentHistory(agentId, {
       client,
       cursor: someCursor,
       hasOlder: true,
@@ -152,6 +155,7 @@ describe("loadOlderAgentHistory", () => {
       },
     ]);
     expect(inFlight.values).toEqual([false, true, false]);
+    expect(started).toBe(true);
   });
 
   it("shows a panel toast, warns, and clears in-flight on failure", async () => {

packages/app/src/hooks/use-load-older-agent-history.ts

@@ -2,7 +2,11 @@ import { useCallback } from "react";
 import { useTranslation } from "react-i18next";
 import type { ToastApi } from "@/components/toast-host";
 import { i18n } from "@/i18n/i18next";
-import { useSessionStore, type AgentTimelineCursorState } from "@/stores/session-store";
+import {
+  selectAgentTimelineState,
+  useSessionStore,
+  type AgentTimelineCursorState,
+} from "@/stores/session-store";
 import { planTimelineOlderFetch } from "@/timeline/timeline-sync-plan";
 import { getHostRuntimeStore } from "@/runtime/host-runtime";
 
@@ -36,11 +40,14 @@ export interface LoadOlderAgentHistoryDeps {
 export async function loadOlderAgentHistory(
   agentId: string,
   deps: LoadOlderAgentHistoryDeps,
-): Promise<void> {
+): Promise<boolean> {
   const { client, cursor, hasOlder, isLoadingOlder, setInFlight, toast, logger, failedMessage } =
     deps;
-  if (!client || !cursor || !hasOlder || isLoadingOlder) {
-    return;
+  if (isLoadingOlder) {
+    return true;
+  }
+  if (!client || !cursor || !hasOlder) {
+    return false;
   }
 
   setInFlight(true);
@@ -58,6 +65,7 @@ export async function loadOlderAgentHistory(
   } finally {
     setInFlight(false);
   }
+  return true;
 }
 
 export function useLoadOlderAgentHistory({
@@ -70,15 +78,17 @@ export function useLoadOlderAgentHistory({
   toast?: ToastApi | null;
 }) {
   const { t } = useTranslation();
-  const hasOlder =
-    useSessionStore((state) => state.sessions[serverId]?.agentTimelineHasOlder.get(agentId)) ===
-    true;
+  const hasOlder = useSessionStore((state) => {
+    const timeline = selectAgentTimelineState(state.sessions[serverId], agentId);
+    return timeline.status === "synced" && timeline.older === "available";
+  });
   const isLoadingOlder =
     useSessionStore((state) =>
       state.sessions[serverId]?.agentTimelineOlderFetchInFlight.get(agentId),
     ) === true;
   const progressKey = useSessionStore((state) => {
-    const cursor = state.sessions[serverId]?.agentTimelineCursor.get(agentId);
+    const timeline = selectAgentTimelineState(state.sessions[serverId], agentId);
+    const cursor = timeline.status === "synced" ? timeline.range : null;
     return cursor ? `${cursor.epoch}:${cursor.startSeq}` : null;
   });
   const setOlderFetchInFlight = useSessionStore(
@@ -99,17 +109,18 @@ export function useLoadOlderAgentHistory({
     [agentId, serverId, setOlderFetchInFlight],
   );
 
-  const loadOlder = useCallback(() => {
+  const loadOlder = useCallback(async (): Promise<boolean> => {
     const session = useSessionStore.getState().sessions[serverId];
-    void loadOlderAgentHistory(agentId, {
+    const timeline = selectAgentTimelineState(session, agentId);
+    return await loadOlderAgentHistory(agentId, {
       client: session?.client
         ? {
             fetchAgentTimeline: (timelineAgentId, request) =>
               getHostRuntimeStore().fetchAgentTimeline(serverId, timelineAgentId, request),
           }
         : null,
-      cursor: session?.agentTimelineCursor.get(agentId),
-      hasOlder: session?.agentTimelineHasOlder.get(agentId) === true,
+      cursor: timeline.status === "synced" ? (timeline.range ?? undefined) : undefined,
+      hasOlder: timeline.status === "synced" && timeline.older === "available",
       isLoadingOlder: session?.agentTimelineOlderFetchInFlight.get(agentId) === true,
       setInFlight,
       toast,