fix(app): start a catch-up's follow-up page after rows applied meanwhile

A recovery paged forward from each page's end cursor without looking at
what the chat had applied since. When the latest-tail fallback brought
the chat to the end during a recovery, the recovery kept paging through
history it already held, one round trip per page.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/app/src/timeline/viewed-timeline-sync.test.ts

@@ -497,6 +497,40 @@ test("a chat without coverage that recovers a gap loads the latest tail when his
   world.sync.dispose();
 });
 
+test("a recovery's follow-up page starts after rows another fetch applied meanwhile", async () => {
+  const world = new TimelineWorld();
+  world.sync.setConnected(true);
+  world.sync.replaceVisibleAgentIds("workspace", ["agent-a"]);
+  (await world.nextMembership()).succeed();
+  (await world.nextFetch("agent-a")).respond({ hasNewer: false, seq: 0 });
+  await vi.waitFor(() => expect(world.sync.getAgentTimelineStatus("agent-a")).toBe("ready"));
+
+  world.sync.recoverGap("agent-a", { epoch: "epoch-agent-a", endSeq: 0 });
+  const firstPage = await world.nextFetch("agent-a");
+  world.cursors.set("agent-a", { epoch: "epoch-agent-a", endSeq: 40 });
+  firstPage.respond({ hasNewer: true, seq: 40 });
+  const latestTail = await world.nextFetch("agent-a");
+  expect(latestTail.request.direction).toBe("tail");
+
+  world.sync.recoverGap("agent-a", { epoch: "epoch-agent-a", endSeq: 40 });
+  const recovery = await world.nextFetch("agent-a");
+  world.cursors.set("agent-a", { epoch: "epoch-agent-a", endSeq: 300 });
+  latestTail.respond({ hasNewer: false, seq: 300 });
+  recovery.respond({ hasNewer: true, seq: 80 });
+
+  const followUp = await world.nextFetch("agent-a");
+  expect(followUp.request).toEqual({
+    direction: "after",
+    cursor: { epoch: "epoch-agent-a", seq: 300 },
+    limit: 40,
+    projection: "projected",
+    wholeTurns: true,
+  });
+  followUp.respond({ hasNewer: false, seq: 300 });
+  await vi.waitFor(() => expect(world.sync.getAgentTimelineStatus("agent-a")).toBe("ready"));
+  world.sync.dispose();
+});
+
 test("reports a chat current only once its parked follow-up page completes", async () => {
   const world = new TimelineWorld();
   world.sync.setConnected(true);

packages/app/src/timeline/viewed-timeline-sync.ts

@@ -742,7 +742,10 @@ export function createViewedTimelineSync(ports: ViewedTimelineSyncPorts): Viewed
         await fetchUntilCurrent(
           agentId,
           generation,
-          planTimelineCatchUpAfter(page.endCursor),
+          planTimelineCatchUpPastApplied(
+            planTimelineCatchUpAfter(page.endCursor),
+            ports.readCursor(agentId),
+          ),
           false,
         );
         return;