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/agent-stream/view.tsx

@@ -77,6 +77,7 @@ import {
   type BottomAnchorLocalRequest,
   type BottomAnchorRouteRequest,
 } from "./bottom-anchor-controller";
+import { createAssistantImageOccurrenceKey } from "@/assistant-image/acquisition-cache";
 import {
   AssistantFileLinkResolverProvider,
   normalizeInlinePathTarget,
@@ -250,7 +251,7 @@ export interface AgentStreamViewProps {
     hasOlder: boolean;
     isLoadingOlder: boolean;
     progressKey: string | null;
-    onLoadOlder: () => void;
+    onLoadOlder: () => boolean | Promise<boolean>;
   };
 }
 
@@ -694,6 +695,7 @@ const AgentStreamViewComponent = forwardRef<AgentStreamViewHandle, AgentStreamVi
             toast={toast}
           >
             <AssistantMessage
+              occurrenceKey={createAssistantImageOccurrenceKey({ agentId, itemId: item.id })}
               message={item.text}
               timestamp={item.timestamp.getTime()}
               workspaceRoot={workspaceRoot}
@@ -704,7 +706,7 @@ const AgentStreamViewComponent = forwardRef<AgentStreamViewHandle, AgentStreamVi
           </AssistantFileLinkResolverProvider>
         );
       },
-      [client, handleInlinePathPress, resolvedServerId, toast, workspaceRoot],
+      [agentId, client, handleInlinePathPress, resolvedServerId, toast, workspaceRoot],
     );
 
     const renderThoughtItem = useCallback(