feat(chat): catch-up strip — the constant agents-TL;DR above the transcript

frontend/src/i18n/locales/en.json

@@ -440,7 +440,18 @@
       "replyFromExpandedThread": "Reply from expanded thread",
       "replyingInThread": "Replying in thread ·"
     },
-    "leadBadge": "Lead"
+    "leadBadge": "Lead",
+    "catchup": {
+      "title": "Catch up",
+      "justNow": "just now",
+      "minutesAgo": "{{count}}m ago",
+      "hoursAgo": "{{count}}h ago",
+      "daysAgo": "{{count}}d ago",
+      "empty": "No summary yet",
+      "summarize": "Summarize",
+      "refresh": "Refresh",
+      "working": "Summarizing…"
+    }
   },
   "landing": {
     "nav": {

frontend/src/i18n/locales/zh-CN.json

@@ -440,7 +440,18 @@
       "replyFromExpandedThread": "在已展开的话题中回复",
       "replyingInThread": "正在话题中回复："
     },
-    "leadBadge": "负责人"
+    "leadBadge": "负责人",
+    "catchup": {
+      "title": "回顾",
+      "justNow": "刚刚",
+      "minutesAgo": "{{count}} 分钟前",
+      "hoursAgo": "{{count}} 小时前",
+      "daysAgo": "{{count}} 天前",
+      "empty": "还没有摘要",
+      "summarize": "生成摘要",
+      "refresh": "刷新",
+      "working": "正在总结…"
+    }
   },
   "landing": {
     "nav": {

frontend/src/v2/__tests__/V2CatchUpStrip.test.tsx

@@ -0,0 +1,63 @@
+// @ts-nocheck
+// The constant agents-TL;DR pinned above the transcript (Sam 2026-09-01).
+// Pinned: reads the existing summaries surface, renders a one-line snippet,
+// offers Summarize when the pod has none, and a refresh replaces the content.
+import React from 'react';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import V2CatchUpStrip from '../components/V2CatchUpStrip';
+
+jest.mock('axios', () => {
+  const mock = {
+    get: jest.fn(),
+    post: jest.fn(),
+    defaults: { baseURL: '', headers: { common: {} } },
+    interceptors: {
+      request: { use: jest.fn(), eject: jest.fn() },
+      response: { use: jest.fn(), eject: jest.fn() },
+    },
+  };
+  return { __esModule: true, default: mock, ...mock };
+});
+
+const axios = jest.requireMock('axios').default;
+
+afterEach(() => jest.clearAllMocks());
+
+describe('V2CatchUpStrip', () => {
+  test('renders the latest summary as a one-line snippet with its age', async () => {
+    axios.get.mockResolvedValueOnce({
+      data: { content: 'Otto verified the token split.\nKai shipped the daemon auth.', createdAt: new Date(Date.now() - 5 * 60000).toISOString() },
+    });
+    render(<V2CatchUpStrip podId="p1" />);
+    await waitFor(() => expect(screen.getByTestId('catchup-strip')).toBeInTheDocument());
+    // Snippet is whitespace-collapsed to one line.
+    expect(screen.getByText('Otto verified the token split. Kai shipped the daemon auth.')).toBeInTheDocument();
+    expect(screen.getByText(/5m ago/)).toBeInTheDocument();
+    expect(axios.get).toHaveBeenCalledWith('/api/summaries/pod/p1');
+  });
+
+  test('expanding shows the full body; no summary shows the Summarize action', async () => {
+    axios.get.mockResolvedValueOnce({ data: { content: 'Line one.\nLine two.', createdAt: new Date().toISOString() } });
+    render(<V2CatchUpStrip podId="p1" />);
+    await waitFor(() => expect(screen.getByTestId('catchup-strip')).toBeInTheDocument());
+    fireEvent.click(screen.getByRole('button', { name: /Catch up/ }));
+    expect(screen.getByTestId('catchup-body')).toHaveTextContent('Line one. Line two.');
+  });
+
+  test('a pod with no summary offers Summarize; refresh swaps in the generated summary', async () => {
+    axios.get.mockResolvedValueOnce({ data: null });
+    axios.post.mockResolvedValueOnce({ data: { summary: { content: 'Fresh digest.', createdAt: new Date().toISOString() } } });
+    render(<V2CatchUpStrip podId="p2" />);
+    await waitFor(() => expect(screen.getByText('No summary yet')).toBeInTheDocument());
+    fireEvent.click(screen.getByRole('button', { name: 'Summarize' }));
+    await waitFor(() => expect(screen.getByTestId('catchup-body')).toHaveTextContent('Fresh digest.'));
+    expect(axios.post).toHaveBeenCalledWith('/api/summaries/pod/p2/refresh', {});
+  });
+
+  test('a failed summary read never blocks the chat — strip still renders', async () => {
+    axios.get.mockRejectedValueOnce(new Error('403'));
+    render(<V2CatchUpStrip podId="p3" />);
+    await waitFor(() => expect(screen.getByTestId('catchup-strip')).toBeInTheDocument());
+    expect(screen.getByText('No summary yet')).toBeInTheDocument();
+  });
+});

frontend/src/v2/components/V2CatchUpStrip.tsx

@@ -0,0 +1,121 @@
+import React, { useCallback, useEffect, useState } from 'react';
+import { useTranslation } from 'react-i18next';
+import axios from 'axios';
+
+// Sam's 2026-09-01 ruling: a constant TL;DR of what the agents are doing,
+// living where the question is actually felt — pinned above the messages of
+// the pod being read (Activity stays the cross-pod view). Backed entirely by
+// the existing summaries surface: GET /api/summaries/pod/:podId (latest,
+// visibility-gated) and POST .../refresh (rate-limited, falls back to a
+// non-agent summary when no summarizer seat is installed).
+
+interface PodSummary {
+  content?: string;
+  createdAt?: string;
+}
+
+interface Props {
+  podId: string;
+}
+
+const relTime = (
+  iso: string | undefined,
+  t: (key: string, opts?: Record<string, unknown>) => string,
+): string => {
+  if (!iso) return '';
+  const ms = Date.now() - new Date(iso).getTime();
+  if (Number.isNaN(ms) || ms < 0) return '';
+  const min = Math.floor(ms / 60000);
+  if (min < 1) return t('podChat.catchup.justNow');
+  if (min < 60) return t('podChat.catchup.minutesAgo', { count: min });
+  const hr = Math.floor(min / 60);
+  if (hr < 24) return t('podChat.catchup.hoursAgo', { count: hr });
+  return t('podChat.catchup.daysAgo', { count: Math.floor(hr / 24) });
+};
+
+const V2CatchUpStrip: React.FC<Props> = ({ podId }) => {
+  const { t } = useTranslation();
+  const [summary, setSummary] = useState<PodSummary | null>(null);
+  const [loaded, setLoaded] = useState(false);
+  const [expanded, setExpanded] = useState(false);
+  const [refreshing, setRefreshing] = useState(false);
+
+  useEffect(() => {
+    let cancelled = false;
+    setSummary(null);
+    setLoaded(false);
+    setExpanded(false);
+    axios.get(`/api/summaries/pod/${podId}`)
+      .then((res) => {
+        if (cancelled) return;
+        setSummary(res.data && res.data.content ? res.data : null);
+        setLoaded(true);
+      })
+      .catch(() => {
+        // Advisory surface: a failed summary read never blocks the chat.
+        if (!cancelled) setLoaded(true);
+      });
+    return () => { cancelled = true; };
+  }, [podId]);
+
+  const handleRefresh = useCallback(async () => {
+    if (refreshing) return;
+    setRefreshing(true);
+    try {
+      const res = await axios.post(`/api/summaries/pod/${podId}/refresh`, {});
+      const next = res.data?.summary;
+      if (next && next.content) {
+        setSummary(next);
+        setExpanded(true);
+      }
+    } catch {
+      // Rate-limited or failed — keep whatever we have.
+    } finally {
+      setRefreshing(false);
+    }
+  }, [podId, refreshing]);
+
+  if (!loaded) return null;
+
+  return (
+    <div className="v2-catchup" data-testid="catchup-strip">
+      <div className="v2-catchup__row">
+        <button
+          type="button"
+          className="v2-catchup__toggle"
+          onClick={() => setExpanded((v) => !v)}
+          aria-expanded={expanded}
+          disabled={!summary}
+        >
+          <span className={`v2-catchup__chevron${expanded ? ' v2-catchup__chevron--open' : ''}`} aria-hidden="true">▸</span>
+          {t('podChat.catchup.title')}
+          {summary?.createdAt && (
+            <span className="v2-catchup__time"> · {relTime(summary.createdAt, t)}</span>
+          )}
+        </button>
+        {!expanded && (
+          <span className="v2-catchup__snippet">
+            {summary?.content
+              ? summary.content.replace(/\s+/g, ' ').trim()
+              : t('podChat.catchup.empty')}
+          </span>
+        )}
+        <button
+          type="button"
+          className="v2-catchup__refresh"
+          onClick={handleRefresh}
+          disabled={refreshing}
+        >
+          {refreshing
+            ? t('podChat.catchup.working')
+            : summary ? t('podChat.catchup.refresh') : t('podChat.catchup.summarize')}
+        </button>
+      </div>
+      {expanded && summary?.content && (
+        <div className="v2-catchup__body" data-testid="catchup-body">{summary.content}</div>
+      )}
+    </div>
+  );
+};
+
+export default V2CatchUpStrip;

frontend/src/v2/components/V2PodChat.tsx

@@ -2,6 +2,7 @@ import React, {
   useCallback, useEffect, useLayoutEffect, useMemo, useRef, useState,
 } from 'react';
 import V2Avatar from './V2Avatar';
+import V2CatchUpStrip from './V2CatchUpStrip';
 import V2MessageBubble from './V2MessageBubble';
 import {
   UseV2PodDetailResult,
@@ -1126,6 +1127,8 @@ const V2PodChat: React.FC<V2PodChatProps> = ({ detail, firstRunVisible = false,
           )}
         </header>
 
+        <V2CatchUpStrip podId={pod._id} />
+
         <div className="v2-chat__messages" ref={messagesContainerRef}>
           {hasMore && (
             <div className="v2-chat__older">

frontend/src/v2/v2.css

@@ -1662,6 +1662,68 @@ body.modern-ui.v2-canvas {
 }
 .v2-chat__older-btn:disabled { opacity: 0.6; cursor: default; }
 
+/* Catch-up strip — the constant agents-TL;DR pinned above the transcript
+   (Sam 2026-09-01). One thin row; the expanded body is bounded so a long
+   summary scrolls inside the strip, never the pane. */
+.v2-catchup {
+  border-bottom: 1px solid var(--v2-border);
+  background: var(--v2-surface);
+  padding: 6px 20px;
+  font-size: 13px;
+}
+.v2-catchup__row {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  min-width: 0;
+}
+.v2-root button.v2-catchup__toggle {
+  background: transparent;
+  border: none;
+  padding: 0;
+  font-size: 13px;
+  font-weight: 650;
+  color: var(--v2-text-secondary);
+  cursor: pointer;
+  white-space: nowrap;
+}
+.v2-root button.v2-catchup__toggle:hover:not(:disabled) { color: var(--v2-text-primary); }
+.v2-root button.v2-catchup__toggle:disabled { cursor: default; }
+.v2-catchup__chevron {
+  display: inline-block;
+  margin-right: 4px;
+  transition: transform 0.08s ease;
+}
+.v2-catchup__chevron--open { transform: rotate(90deg); }
+.v2-catchup__time { font-weight: 400; color: var(--v2-text-tertiary); }
+.v2-catchup__snippet {
+  flex: 1;
+  min-width: 0;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  color: var(--v2-text-tertiary);
+}
+.v2-root button.v2-catchup__refresh {
+  background: transparent;
+  border: none;
+  padding: 0;
+  font-size: 12px;
+  color: var(--v2-accent);
+  cursor: pointer;
+  white-space: nowrap;
+}
+.v2-root button.v2-catchup__refresh:hover:not(:disabled) { text-decoration: underline; }
+.v2-root button.v2-catchup__refresh:disabled { color: var(--v2-text-tertiary); cursor: default; }
+.v2-catchup__body {
+  margin-top: 6px;
+  max-height: 220px;
+  overflow-y: auto;
+  white-space: pre-wrap;
+  color: var(--v2-text-secondary);
+  line-height: 1.5;
+}
+
 .v2-chat__messages {
   flex: 1;
   overflow-y: auto;