emrg: the older-page cursor has a guard, so a dropped cursor fails the suite

Agent.md

@@ -57,7 +57,7 @@ One line per command: what it answers. The *why* behind each guard is in its doc
 
 - Python: `uv run pytest tests/ -v` — the number is **measured, never stored** (a stored count is a conflict magnet that goes stale silently): `uv run --no-sync python3 scripts/check-doc-count.py --measure`. Import check: `uv run python -c "from emrg.client.app import run_client"`
 GUI: `cd emrg/gui && npm test` (137: 81 daemon_client + 20 conn-manager + 7 integration + 7 nav-policy + 7 gui-state + 6 build-config + 4 boot-contract + 3 preload-api + 2 theme-guard) — syntax: `node --check main.js preload.js daemon_client.js`
-Renderer: `cd emrg/gui/renderer && npm run typecheck && npm test` (537: 5 snapshot-store + 9 utils + 3 ErrorBoundary + 2 App smoke + 11 commands + 4 copywriting + 11 i18n + 13 markdown + 21 transcript + 11 TranscriptView + 18 history + 15 historyReplay + 31 composer + 42 Composer + 6 LinkDialog + 16 sidebar + 17 Sidebar + 9 fileTree + 9 FileTree + 16 resultPanel + 8 ResultPanel + 27 workspaceView + 10 WorkspaceView + 10 dialog + 6 Dialog + 9 ConfirmDialog + 9 RenameDialog + 10 dialogLists + 3 HelpDialog + 9 MemoryDialog + 6 SkillsDialog + 8 openSession + 6 WelcomeDialog + 9 OpenSessionDialog + 7 NewSessionDialog + 7 rewind + 8 RewindDialog + 7 GithubDeviceDialog + 20 daemonBridge + 7 DaemonBridgeProvider + 32 Shell + 15 DialogHost + 20 SettingsPanel + 6 TaskFormDialog + 5 RantDialog + 4 vendorMarkdown)
+Renderer: `cd emrg/gui/renderer && npm run typecheck && npm test` (539: 5 snapshot-store + 9 utils + 3 ErrorBoundary + 2 App smoke + 11 commands + 4 copywriting + 11 i18n + 13 markdown + 21 transcript + 11 TranscriptView + 18 history + 15 historyReplay + 31 composer + 42 Composer + 6 LinkDialog + 16 sidebar + 17 Sidebar + 9 fileTree + 9 FileTree + 16 resultPanel + 8 ResultPanel + 27 workspaceView + 10 WorkspaceView + 10 dialog + 6 Dialog + 9 ConfirmDialog + 9 RenameDialog + 10 dialogLists + 3 HelpDialog + 9 MemoryDialog + 6 SkillsDialog + 8 openSession + 6 WelcomeDialog + 9 OpenSessionDialog + 7 NewSessionDialog + 7 rewind + 8 RewindDialog + 7 GithubDeviceDialog + 20 daemonBridge + 7 DaemonBridgeProvider + 34 Shell + 15 DialogHost + 20 SettingsPanel + 6 TaskFormDialog + 5 RantDialog + 4 vendorMarkdown)
 - CI: pytest on ubuntu **and windows-2025**, the GUI suites, and an actionlint gate over `.github/workflows/`; re-trigger a dropped push with `scripts/re-trigger-ci.sh <branch>`, never an empty commit
 - Merge gates, run before merging — each answers a question no other gate asks: `uv run --no-sync python3 scripts/check-vote-count.py` (approvals still valid) · `scripts/check-pr-base.py` (base reaches master) · `scripts/check-merge-freshness.py` (that green CI is about the landing tree) · `scripts/check-merge-order.py` (what merging dirties) · `scripts/check-merge-landing-diff.py` (what the landing changes) · `scripts/check-merge-pairs.py` / `scripts/check-merge-sequence.py` (two PRs together; every step of an order) · `scripts/check-merge-tree-health.py` (the merged tree passes the guards) · `scripts/check-merge-plan-suite.py` (the plan's final tree passes the suite) — all under `uv run --no-sync python3`
 - Other tools: `uv run --no-sync python3 scripts/check-node-test-count.py --write` (syncs the Node totals above), `scripts/check-patch-files.py` (a rebuilt patch carries every file the previous one did), `scripts/cast-vote.py` (a vote the counter counts), `bump-version.py`, `classify-conflict.py`, `sync-master-from-api.py`, `push-branch-from-api.py`

emrg/gui/renderer/src/components/Shell.test.tsx

@@ -208,6 +208,86 @@ describe("Shell (Batch 5 slice 3 chat wiring)", () => {
     expect(screen.getByText("结论：一切正常。")).toBeInTheDocument();
   });
 
+  /**
+   * 两页记录（更新的一页 + 更早的一页），桥的替身照 `before_index` 回答：带游标 = 更早那一页，
+   * 不带 = 又一份最新页。于是「游标丢了」这个真实退化在断言里可辨，而不只是断言一个参数名。
+   */
+  function mockTwoHistoryPages(m: ReturnType<typeof mockEmrg>) {
+    const newest = [
+      { record_index: 4, kind: "message", role: "user", content: "newest-1" },
+      { record_index: 5, kind: "message", role: "assistant", content: "newest-2" },
+      { record_index: 6, kind: "message", role: "user", content: "newest-3" },
+    ];
+    const older = [
+      { record_index: 1, kind: "message", role: "user", content: "older-1" },
+      { record_index: 2, kind: "message", role: "assistant", content: "older-2" },
+      { record_index: 3, kind: "message", role: "user", content: "older-3" },
+    ];
+    m.listHistory.mockImplementation((p: { beforeIndex?: number } = {}) =>
+      Promise.resolve(
+        p.beforeIndex != null
+          ? { messages: older, hasMore: false }
+          : { messages: newest, hasMore: true },
+      ),
+    );
+    return { newest, older };
+  }
+
+  /** 打开一个会话，等第一页落定，再把滚动位置带到顶部（TranscriptView 的 capture 监听在 scrollTop<=2 时上翻）。 */
+  async function openSessionAndScrollToTop(
+    m: ReturnType<typeof mockEmrg>,
+    container: HTMLElement,
+    firstPageText: string,
+  ) {
+    await waitFor(() => expect(m.onEvent).toHaveBeenCalledTimes(1));
+    m.emit(openSessionsFrame([{ sid: "s1", title: "Alpha" }]));
+    await waitFor(() => expect(m.listHistory).toHaveBeenCalledTimes(1));
+    // 第一页真的渲染出来（此时 hasMore 已落定 → canLoadOlder 为真），再模拟上翻。
+    await waitFor(() => expect(screen.getByText(firstPageText)).toBeInTheDocument());
+    const viewport = container.querySelector<HTMLElement>('[data-testid="transcript-view"]');
+    expect(viewport).not.toBeNull();
+    Object.defineProperty(viewport, "scrollTop", { value: 0, configurable: true, writable: true });
+    Object.defineProperty(viewport, "scrollHeight", { value: 1000, configurable: true });
+    Object.defineProperty(viewport, "clientHeight", { value: 400, configurable: true });
+    act(() => {
+      viewport!.dispatchEvent(new Event("scroll", { bubbles: false }));
+    });
+  }
+
+  it("asks for the records BEFORE the oldest loaded one when scrolled to the top (rant 2026-09-20T18:58:44)", async () => {
+    // 该 rant 的第三条缺陷是「分页会重复、会漏、会让更早内容不可达」，修法是游标改成
+    // 最早已加载记录的绝对 record_index。游标一旦丢失，页 2 会再取一次最新页，而
+    // `loaded` 会把整页滤空 —— 视图永不前进，且套件全绿（issue #1493 的变异臂实测）。
+    const m = mockEmrg();
+    const { older } = mockTwoHistoryPages(m);
+    const { container } = render(wrapper(<Shell />));
+    await openSessionAndScrollToTop(m, container, "newest-1");
+
+    await waitFor(() => expect(m.listHistory).toHaveBeenCalledTimes(2));
+    expect(m.listHistory).toHaveBeenNthCalledWith(
+      2,
+      expect.objectContaining({ sessionId: "s1", includeRecords: true, beforeIndex: 4 }),
+    );
+    // 更早一页确实进了视图，而不是被 `loaded` 去重滤空。
+    await waitFor(() => expect(screen.getByText(older[0].content)).toBeInTheDocument());
+  });
+
+  it("prepends an older page as one block, keeping record order (rant 2026-09-20T18:58:44)", async () => {
+    const m = mockEmrg();
+    const { newest, older } = mockTwoHistoryPages(m);
+    const { container } = render(wrapper(<Shell />));
+    await openSessionAndScrollToTop(m, container, "newest-1");
+    await waitFor(() => expect(screen.getByText(older[2].content)).toBeInTheDocument());
+
+    // 文本在容器里的先后 = DOM 顺序：更早一页整块在当前页之前，且页内仍是记录顺序
+    // （倒序 unshift 会让页内反而颠倒，这一条同时钉住「前插」和「不翻转」）。
+    const text = container.querySelector('[data-testid="transcript-view"]')?.textContent ?? "";
+    const at = (s: string) => text.indexOf(s);
+    expect(at(older[0].content)).toBeGreaterThanOrEqual(0);
+    expect(at(older[2].content)).toBeLessThan(at(newest[0].content));
+    expect(at(older[0].content)).toBeLessThan(at(older[2].content));
+  });
+
   it("shows the connection status + model from the status broadcast", async () => {
     const m = mockEmrg();
     render(wrapper(<Shell />));