feat: v2.6.0 — Chat UI composer (+ menu, project files, activity panel, permission mode, Stop), git on a workspace's extra folders (#70), long paste as a file (#68), S3 server mode (experimental)

Chat UI:
- Each Claude/Codex session keeps its own chat/terminal view; Settings only
  sets how new sessions open.
- Composer + menu: upload, project files and folders (#54, also dragged from
  the Files/Changes tree), context files, recent uploads, skills, plugins.
- Activity side panel (progress, outputs, files read, uploads, memory,
  skills, connectors) with a file preview; edited-file counts per turn.
- Permission-mode chip (Shift+Tab steps, read back from the pane:
  server/lib/pane-mode.js, GET|POST /api/run/:id/permission-mode).
- Stop (Esc) while the main agent works; the status is checked per agent
  (with session_id /api/agents ignores its status filter) and re-read every
  5 s while Stop shows.
- Dropped images shown in the conversation (GET /api/run/drop/:name, the
  requester's own drop dir), full-size viewer.
- A plain-text paste over 5,000 characters is attached as pasted-text.txt,
  so no prompt reaches tmux/argv limits (#68).

Changes panel: every /api/lanes/:id/git* route takes ?source=<lane_sources
id> (sourceFolder; ENOSOURCE otherwise) and a folder picker switches the
whole panel to a workspace's extra folder (#70).

Server mode S3 (one Linux user per account) — experimental, verified with
fake sudo plus a P6 managed-settings spike on a test account:
- member tmux listing runs in the background (cached, 15 s => unknown);
- transcript snapshot copy is async, chunked, temp file + rename;
- Express Layer patch only on Express 4;
- tmux capturePane/sendKey go to the member's own server.

Docs: the multi-user design moved in as docs/plans/server-mode/README.md
(the AgentHub-Server repo is gone); S3-PLAN P6 result; LANES/API/openapi.

client/src/components/__tests__/WorkspaceTree.owners.test.tsx

@@ -0,0 +1,143 @@
+/**
+ * @file WorkspaceTree.owners.test.tsx
+ * @description Server mode, the sidebar workspace list for an analyst: every
+ * user's workspaces, grouped under their owner (yours first, no owner last),
+ * groups folding and remembered; another user's workspace is read only — no
+ * menu, no new session, and a session opens its analysis page, never a pane.
+ * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
+ */
+
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { render, screen, within } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { MemoryRouter, Route, Routes, useLocation } from "react-router-dom";
+import type { Lane, Session } from "../../lib/types";
+
+const ME = { id: 2, username: "ana", role: "analyst" as const };
+
+const lane = (id: number, owner: number | null, name: string | null, title: string) =>
+  ({
+    id,
+    title,
+    cwd: `/w/${id}`,
+    kind: "adopted",
+    tool: "claude",
+    status: "idle",
+    liveness: "idle",
+    pipeline_nodes: [],
+    owner_id: owner,
+    owner_name: name,
+  }) as unknown as Lane;
+
+const lanes = [
+  lane(1, 3, "bob", "Bob app"),
+  lane(2, null, null, "Old"),
+  lane(3, ME.id, "ana", "Mine"),
+  lane(4, 1, "admin", "Admin site"),
+];
+
+vi.mock("../AuthGate", () => ({
+  useAuth: () => ({ state: { mode: "server", user: ME } }),
+  usePermissions: () => ({
+    isAdmin: false,
+    seesAll: true,
+    canEditLane: (l?: { owner_id?: number | null } | null) => l?.owner_id === ME.id,
+  }),
+}));
+vi.mock("../../lib/api", async (importOriginal) => {
+  const actual = await importOriginal<Record<string, unknown>>();
+  return {
+    ...actual,
+    api: {
+      lanes: { list: vi.fn(async () => ({ lanes, counts: {} })) },
+      sessions: {
+        list: vi.fn(async () => ({
+          sessions: [
+            { id: "s-1", name: "Bob's run", status: "completed", started_at: "2026-10-01" },
+          ] as Session[],
+          total: 1,
+          limit: 6,
+          offset: 0,
+        })),
+      },
+      run: { list: vi.fn(async () => ({ items: [] })) },
+      aiTools: { list: vi.fn(async () => ({ tools: [], default: "claude" })), iconUrl: () => "" },
+    },
+  };
+});
+
+import { WorkspaceTree } from "../WorkspaceTree";
+
+function Where() {
+  const loc = useLocation();
+  return <span data-testid="where">{loc.pathname + loc.search}</span>;
+}
+
+function renderTree() {
+  return render(
+    <MemoryRouter>
+      <Routes>
+        <Route
+          path="*"
+          element={
+            <>
+              <WorkspaceTree />
+              <Where />
+            </>
+          }
+        />
+      </Routes>
+    </MemoryRouter>
+  );
+}
+
+beforeEach(() => localStorage.clear());
+
+describe("WorkspaceTree for an analyst", () => {
+  it("groups every workspace under its owner: yours first, no owner last", async () => {
+    renderTree();
+    await screen.findByTestId("workspace-row-1");
+    const order = screen
+      .getAllByTestId(/^workspace-(owner-\w+|row-\d+)$/)
+      .map((el) => el.dataset.testid);
+    expect(order).toEqual([
+      "workspace-owner-2",
+      "workspace-row-3",
+      "workspace-owner-1",
+      "workspace-row-4",
+      "workspace-owner-3",
+      "workspace-row-1",
+      "workspace-owner-none",
+      "workspace-row-2",
+    ]);
+    expect(screen.getByTestId("workspace-owner-2")).toHaveTextContent("ana (you)");
+  });
+
+  it("folds a group and remembers it", async () => {
+    const user = userEvent.setup();
+    renderTree();
+    await user.click(await screen.findByTestId("workspace-owner-3"));
+    expect(screen.queryByTestId("workspace-row-1")).toBeNull();
+    expect(screen.getByTestId("workspace-owner-3")).toHaveAttribute("aria-expanded", "false");
+    expect(JSON.parse(localStorage.getItem("agenthub.sidebar.projects")!).collapsedOwners).toEqual({
+      "3": true,
+    });
+  });
+
+  it("keeps another user's workspace read only", async () => {
+    const user = userEvent.setup();
+    renderTree();
+    await screen.findByTestId("workspace-row-1");
+    // Yours keeps its controls; theirs has none.
+    expect(screen.getByTestId("workspace-menu-3")).toBeInTheDocument();
+    expect(screen.queryByTestId("workspace-menu-1")).toBeNull();
+    expect(screen.queryByTestId("workspace-new-1")).toBeNull();
+    // Picking it unfolds it instead of opening a workspace home.
+    await user.click(screen.getByTestId("workspace-open-1"));
+    expect(screen.getByTestId("where")).toHaveTextContent(/^\/$/);
+    const list = await screen.findByTestId("workspace-sessions-1");
+    expect(within(list).queryByTestId("workspace-session-archive-s-1")).toBeNull();
+    await user.click(within(list).getByTestId("workspace-session-s-1"));
+    expect(screen.getByTestId("where")).toHaveTextContent("/sessions/s-1");
+  });
+});