fix(tasks): recover compact history after cancellation and expansion

Co-Authored-By: Paperclip <noreply@paperclip.ing>

tests/e2e/chat-adapters-ui-messaging.spec.ts

@@ -1042,7 +1042,7 @@ test.describe("Board send delivery refresh", () => {
       );
       await page.route(
         new RegExp(
-          `/api/issues/(${issue.id}|${issue.identifier})/comments(?:\\?|$)`,
+          `/api/issues/(${issue.id}|${issue.identifier})/(?:recent-comments|comments)(?:\\?|$)`,
         ),
         async (route) => {
           if (
@@ -1050,9 +1050,7 @@ test.describe("Board send delivery refresh", () => {
             route.request().url().includes(`/issues/${issue.identifier}/`)
           )
             canonicalCommentReadsAfterSend += 1;
-          await fulfill(
+          const comments = sends
-            route,
-            sends
               ? [
                   {
                     id: publicationId,
@@ -1066,8 +1064,10 @@ test.describe("Board send delivery refresh", () => {
                     updatedAt: new Date().toISOString(),
                   },
                 ]
-              : [],
+              : [];
-          );
+          await fulfill(route, route.request().url().includes("/recent-comments")
+            ? { comments, latestCommentId: comments.at(-1)?.id ?? null, hasMore: false }
+            : comments);
         },
       );
       await page.route(

ui/src/components/transcript/useLiveRunTranscripts.test.tsx

@@ -130,6 +130,41 @@ describe("useLiveRunTranscripts", () => {
     }
   });
 
+  it("expands a compact log tail without hiding or duplicating the latest output", async () => {
+    const row = (seq: number, chunk: string) => JSON.stringify({ seq, chunk, ts: `2026-10-24T00:00:0${seq}Z`, stream: "stdout" });
+    const result = (content: string) => ({ runId: "run-1", store: "memory", logRef: "log-1", content, nextOffset: 100_000 });
+    let resolveExpanded!: (value: ReturnType<typeof result>) => void;
+    logMock.mockResolvedValueOnce(result(`${row(2, "Latest answer")}\n`));
+    logMock.mockImplementationOnce(() => new Promise(resolve => { resolveExpanded = resolve; }));
+    function Harness({ limit, bytes = 100_000 }: { limit: number; bytes?: number }) {
+      useLiveRunTranscripts({
+        runs: [{ id: "run-1", status: "succeeded", adapterType: "codex_local", logBytes: bytes }],
+        enableRealtimeUpdates: false,
+        logReadLimitBytes: limit,
+      });
+      return null;
+    }
+    const root = createRoot(document.createElement("div"));
+    const chunks = () => buildTranscriptMock.mock.calls.at(-1)?.[0];
+    try {
+      await act(async () => root.render(<Harness limit={32_000} />));
+      expect(logMock).toHaveBeenLastCalledWith("run-1", 68_000, 32_000, expect.anything());
+      expect(chunks()).toEqual([expect.objectContaining({ chunk: "Latest answer" })]);
+      await act(async () => root.render(<Harness limit={256_000} />));
+      expect(logMock).toHaveBeenLastCalledWith("run-1", 0, 256_000, expect.anything());
+      expect(chunks()).toEqual([expect.objectContaining({ chunk: "Latest answer" })]);
+      await act(async () => resolveExpanded(result(`${row(1, "Earlier activity")}\n${row(2, "Latest answer")}\n`)));
+      expect(chunks()).toEqual([
+        expect.objectContaining({ chunk: "Earlier activity" }),
+        expect.objectContaining({ chunk: "Latest answer" }),
+      ]);
+      await act(async () => root.render(<Harness limit={256_000} bytes={120_000} />));
+      expect(logMock).toHaveBeenLastCalledWith("run-1", 100_000, 256_000, expect.anything());
+    } finally {
+      await act(async () => root.unmount());
+    }
+  });
+
   it("waits for a connecting socket to open before closing it during cleanup", async () => {
     function Harness() {
       useLiveRunTranscripts({

ui/src/components/transcript/useLiveRunTranscripts.ts

@@ -143,6 +143,7 @@ export function useLiveRunTranscripts({
   const trimmedSeqFloorByRunRef = useRef(new Map<string, number>());
   const pendingLogRowsByRunRef = useRef(new Map<string, string>());
   const logOffsetByRunRef = useRef(new Map<string, number>());
+  const logReadLimitByRunRef = useRef(new Map<string, number>());
   const missingTerminalLogRunIdsRef = useRef(new Set<string>());
   // PAP-462 B3: buffered runs that dropped out of the `runs` list, mapped to the
   // wall-clock deadline (ms) after which their buffer may be pruned. A run still
@@ -269,6 +270,7 @@ export function useLiveRunTranscripts({
     for (const runId of logOffsetByRunRef.current.keys()) {
       if (!retainedRunIds.has(runId)) {
         logOffsetByRunRef.current.delete(runId);
+        logReadLimitByRunRef.current.delete(runId);
       }
     }
     for (const runId of trimmedSeqFloorByRunRef.current.keys()) {
@@ -312,6 +314,19 @@ export function useLiveRunTranscripts({
         return;
       }
       inFlightRunIds.add(run.id);
+      const previousReadLimit = logReadLimitByRunRef.current.get(run.id);
+      if (previousReadLimit !== undefined && logReadLimitBytes > previousReadLimit) {
+        // Expanding a compact tail must reread the earlier range. Retain the
+        // visible chunks; merging by sequence deduplicates the overlapping tail.
+        const expandedOffset = resolveInitialLogOffset(run, logReadLimitBytes);
+        const previousOffset = logOffsetByRunRef.current.get(run.id);
+        if (previousOffset !== undefined && expandedOffset < previousOffset) {
+          logOffsetByRunRef.current.set(run.id, expandedOffset);
+          pendingLogRowsByRunRef.current.delete(run.id);
+          pendingLogRowsByRunRef.current.delete(`${run.id}:records`);
+        }
+      }
+      logReadLimitByRunRef.current.set(run.id, logReadLimitBytes);
       const offset = logOffsetByRunRef.current.get(run.id) ?? resolveInitialLogOffset(run, logReadLimitBytes);
       try {
         const result = await readTranscriptRequest(

ui/src/hooks/useIssueHistoryWindow.test.tsx

@@ -34,3 +34,39 @@ it.each([true, false])("retains a burst larger than the preview window (initiall
     expect(new Set(current!.recent.data?.comments.map(c=>c.id)).size).toBe(empty ? 60 : 61);
   } finally { await act(async () => root.unmount()); client.clear(); }
 });
+
+it.each([true, false])("catches up after canceled input and a reply burst (earlier anchor survives: %s)", async (earlierAnchorSurvives) => {
+  const client = new QueryClient({ defaultOptions: { queries: { retry: false } } });
+  const root = createRoot(document.createElement("div"));
+  const comment = (n: number) => ({ id: `comment-${n}`, createdAt: new Date(n * 1000), body: `Message ${n}` } as IssueComment);
+  let current: ReturnType<typeof useIssueHistoryWindow>;
+  function Probe() {
+    current = useIssueHistoryWindow("one", false);
+    return <span>{current.recent.data?.comments.length}</span>;
+  }
+  api.recentComments.mockResolvedValue({ comments: [comment(0), comment(1)], latestCommentId: "comment-1", hasMore: true });
+  api.listComments.mockReset();
+  const wait = () => act(async () => { await new Promise(resolve => setTimeout(resolve, 10)); });
+  try {
+    await act(async () => root.render(<QueryClientProvider client={client}><Probe /></QueryClientProvider>));
+    for (let i = 0; i < 20 && !current!.recent.isSuccess; i++) await wait();
+    expect(current!.recent.isSuccess).toBe(true);
+    api.recentComments.mockResolvedValue({ comments: [58, 59, 60, 61].map(comment), latestCommentId: "comment-61", hasMore: true });
+    api.listComments.mockImplementation(async (_issue, options) => {
+      if (options.after === "comment-1") return []; // Canceled queued input.
+      if (options.after === "comment-0" && !earlierAnchorSurvives) return [];
+      const start = options.after === "comment-51" ? 52 : 2;
+      return Array.from({ length: Math.min(50, 62 - start) }, (_, i) => comment(start + i));
+    });
+    await act(async () => { await client.invalidateQueries({ queryKey: queryKeys.issues.comments("one") }); });
+    for (let i = 0; i < 20 && current!.recent.data?.latestCommentId !== "comment-61"; i++) await wait();
+    expect(current!.recent.error).toBeNull();
+    expect(current!.recent.data?.comments.filter(c => Number(c.id.split("-")[1]) >= 2).map(c => c.id))
+      .toEqual(Array.from({ length: 60 }, (_, i) => `comment-${i + 2}`));
+    expect(current!.recent.data?.latestCommentId).toBe("comment-61");
+    expect(api.listComments).toHaveBeenCalledTimes(earlierAnchorSurvives ? 3 : 4);
+  } finally {
+    await act(async () => root.unmount());
+    client.clear();
+  }
+});

ui/src/hooks/useIssueHistoryWindow.ts

@@ -46,6 +46,13 @@ export function useIssueHistoryWindow(
       // saved cursor instead of dropping messages between two invalidations.
       let cursor = previous.latestCommentId;
       const incoming: IssueComment[] = [];
+      // Canceling queued input deletes its comment, including a saved cursor.
+      // Retry from an earlier observed row, then from the start if that row
+      // was also deleted. Never advance to the preview past unread replies.
+      const recoveryAnchors = [
+        previous.comments.findLast((comment) => comment.id !== cursor)?.id ?? null,
+        null,
+      ];
       while (cursor !== snapshot.latestCommentId) {
         const page = await issuesApi.listComments(issueRef!, {
           order: "asc",
@@ -53,7 +60,13 @@ export function useIssueHistoryWindow(
           limit: 50,
         }, { signal });
         if (signal.aborted) throw new DOMException("Aborted", "AbortError");
-        if (!page.length) break;
+        if (!page.length) {
+          if (cursor && recoveryAnchors.length) {
+            cursor = recoveryAnchors.shift() ?? null;
+            continue;
+          }
+          break;
+        }
         incoming.push(...page);
         const next = page.at(-1)!.id;
         if (next === cursor) break;