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/e2e/rewind-menu.ui-contract.spec.ts

@@ -2,6 +2,7 @@ import type { Locator } from "@playwright/test";
 import { expect, test, type Page } from "./fixtures";
 import { openAgentRoute, seedMockAgentWorkspace } from "./helpers/mock-agent";
 import { installDaemonWebSocketGate } from "./helpers/daemon-websocket-gate";
+import { scrollChatAwayFromBottom } from "./helpers/agent-bottom-anchor";
 import {
   composerLocator,
   expectComposerDraft,
@@ -191,6 +192,10 @@ test.describe("Rewind sheet", () => {
       await expect(page.getByText("Cycle 1", { exact: true })).toBeVisible();
       await expectUserMessageCount(page, 2);
 
+      await scrollChatAwayFromBottom(page, {
+        deltaY: -900,
+        minDistanceFromBottom: 300,
+      });
       await userMessage(page, firstPrompt).hover();
       await page.getByTestId("rewind-menu-trigger").first().click();
       const rewindSheet = page.getByTestId("rewind-menu-content");