fix: event-loop freezes, plugin-install boot crash, tmux attach/scrollbar, Codex transcripts

- GET /api/workflows: one LEAD() window pass in a read worker (read-pool.js,
  workflow-stats.js); idx_events_session restored, idx_events_tool added
- compat-sqlite gains function/pluck/readonly so a plugin install without a
  better-sqlite3 build boots again; antigravity-usage uses db.js's Database
- install-hooks adds no checkout hooks while the agenthub plugin is enabled
  (events were doubled)
- terminal attach runs the live tmux server's own binary; the pane scrollbar
  gets a visible 2-column style, and claude panes start with
  CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN=1 so tmux keeps history to scroll
- Codex sessions' conversation in GET /api/sessions/:id/transcript
- Codex/Antigravity sessions claimed by their workspace without hooks
- UI-audit follow-ups, docs and OpenAPI

client/src/pages/__tests__/ActivityFeed.agents.test.ts

@@ -0,0 +1,32 @@
+/**
+ * @file ActivityFeed.agents.test.ts
+ * @description The Activity feed asks for agent labels by agent, not by
+ * session: a subagent spawned later in a session already on screen is fetched
+ * too, and an agent already asked about is not asked for again.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+import { describe, it, expect } from "vitest";
+import { agentsToFetch } from "../ActivityFeed";
+
+describe("agentsToFetch", () => {
+  it("asks again for a session once a new agent of it appears", () => {
+    const asked = new Set(["s1-main"]);
+    const events = [
+      { session_id: "s1", agent_id: "s1-main" },
+      { session_id: "s1", agent_id: "s1-sub-late" },
+      { session_id: "s2", agent_id: null },
+    ];
+    expect(agentsToFetch(events, asked)).toEqual({
+      agentIds: ["s1-sub-late"],
+      sessionIds: ["s1"],
+    });
+  });
+
+  it("asks nothing when every agent on screen is known", () => {
+    expect(agentsToFetch([{ session_id: "s1", agent_id: "a" }], new Set(["a"]))).toEqual({
+      agentIds: [],
+      sessionIds: [],
+    });
+  });
+});

client/src/pages/__tests__/CcConfig.dataSafety.test.tsx

@@ -10,7 +10,7 @@
 import { describe, it, expect, vi, afterEach } from "vitest";
 import { render, screen, act, within } from "@testing-library/react";
 import userEvent from "@testing-library/user-event";
-import { MemoryRouter } from "react-router-dom";
+import { MemoryRouter, useLocation, useNavigate } from "react-router-dom";
 import { settleConfirm, subscribeConfirm, type PendingConfirm } from "../../lib/confirm";
 import { eventBus } from "../../lib/eventBus";
 
@@ -119,6 +119,40 @@ describe("CcConfig — settings editor", () => {
     expect(ccConfigMock.patchSettings).toHaveBeenCalledWith({ scope: "user", unset: ["a"] });
   });
 
+  it("a tab change from the URL (a search result) asks before dropping an unsaved edit", async () => {
+    const user = userEvent.setup();
+    function Jump() {
+      const navigate = useNavigate();
+      const loc = useLocation();
+      return (
+        <>
+          <button onClick={() => navigate("/settings/claude?tab=skills")}>jump</button>
+          <span data-testid="url">{loc.search}</span>
+        </>
+      );
+    }
+    render(
+      <MemoryRouter initialEntries={["/settings/claude?tab=settings"]}>
+        <CcConfig />
+        <Jump />
+      </MemoryRouter>
+    );
+    await settle();
+    await user.click(screen.getByRole("button", { name: /^edit$/i }));
+    await user.click(screen.getAllByRole("button", { name: /remove key/i })[0]!);
+    let pending: PendingConfirm | null = null;
+    const off = subscribeConfirm((p) => (pending = p));
+    await user.click(screen.getByRole("button", { name: "jump" }));
+    await settle();
+    expect(pending).not.toBeNull();
+    // Keep editing: the draft stays and the URL goes back to its tab.
+    await act(async () => settleConfirm(false));
+    await settle();
+    off();
+    expect(screen.getByRole("button", { name: /^save$/i })).toBeInTheDocument();
+    expect(screen.getByTestId("url")).toHaveTextContent("?tab=settings");
+  });
+
   it("a renamed key is sent under its new name, not dropped", async () => {
     const user = userEvent.setup();
     render(

client/src/pages/__tests__/SettingsHub.test.tsx

@@ -58,7 +58,7 @@ vi.mock("../../lib/api", async (importOriginal) => {
   };
 });
 
-import { SettingsHub } from "../SettingsHub";
+import { SettingsHub, backDelta } from "../SettingsHub";
 import { __resetAiTools } from "../../hooks/useAiTools";
 import { subscribeToasts, type ToastItem } from "../../lib/toast";
 
@@ -243,6 +243,21 @@ describe("SettingsHub", () => {
     await vi.waitFor(() => expect(row.className).toContain("ring-2"));
   });
 
+  it("a malformed #anchor is ignored instead of crashing the page", async () => {
+    renderAt("/settings/data#%E0%A4");
+    expect(await screen.findByTestId("settings-data")).toBeInTheDocument();
+  });
+
+  it("Back always goes back: one step past the entry, at least one step", () => {
+    // Entered at index 2, now two pages further on: back to index 1.
+    expect(backDelta(4, 2)).toBe(-3);
+    expect(backDelta(2, 2)).toBe(-1);
+    // Browser Back moved below the entry with the hub still mounted: one step,
+    // never history.go(0) (a reload) or a step forward.
+    expect(backDelta(1, 2)).toBe(-1);
+    expect(backDelta(0, 2)).toBe(-1);
+  });
+
   it("toasts when an unknown section falls back to General", async () => {
     let seen: ToastItem[] = [];
     const off = subscribeToasts((i) => (seen = i));