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/run/__tests__/RunSetup.test.tsx

@@ -3,7 +3,10 @@
  * @description The run-form pieces that outlived the pane's run form:
  * `PromptEditor`'s `/` and `@` autocomplete (Enter picks while the list is
  * open, `/` only where slash commands apply), Shift/Alt+Enter newlines, a
- * pasted image shown as a thumbnail and sent as its saved path, and `ModelPicker` — a tool's own
+ * pasted image shown as a thumbnail and sent as its saved path (and
+ * remembered as a recent upload), a Files panel row dropped as an `@path`
+ * chip, a composer
+ * (`bare`) box growing with its text up to a cap, and `ModelPicker` — a tool's own
  * list from the server, a fixed list (an AI Proxy's models) when given one,
  * and Custom…, which is a sentinel, never a model id — and `ModelMenu`, the
  * same list as one chip: aliases up front, pinned versions under More models,
@@ -13,17 +16,19 @@
  */
 
 import { useState } from "react";
-import { fireEvent, render, screen } from "@testing-library/react";
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import i18n from "i18next";
 import {
   ModelMenu,
   ModelPicker,
+  PASTE_AS_FILE_CHARS,
   PromptEditor,
   promptWithImages,
   type PromptImage,
 } from "../RunSetup";
 import { api } from "../../../lib/api";
+import { dragProjectPath, recentUploads } from "../../../lib/promptAttach";
 
 vi.mock("../../../lib/api", async (importOriginal) => {
   const actual = await importOriginal<Record<string, unknown>>();
@@ -158,6 +163,34 @@ describe("PromptEditor — / and @ suggestions", () => {
   });
 });
 
+describe("PromptEditor — a composer grows with its text", () => {
+  it("takes the height its text needs, capped by max-h, and only when bare", () => {
+    const tall = vi
+      .spyOn(HTMLTextAreaElement.prototype, "scrollHeight", "get")
+      .mockReturnValue(180);
+    const props = {
+      placeholder: "Ask anything…",
+      slash: false,
+      fileCwd: "/Users/tester",
+      images: [],
+      onImagesChange: () => {},
+      onChange: () => {},
+      onSubmit: () => {},
+    };
+    const view = render(<PromptEditor {...props} value={"a\nb\nc\nd\ne"} bare />);
+    expect(box().style.height).toBe("180px");
+    expect(box().className).toContain("max-h-[40vh]");
+    tall.mockReturnValue(60);
+    view.rerender(<PromptEditor {...props} value="a" bare />);
+    expect(box().style.height).toBe("60px");
+    view.unmount();
+    // The framed editor keeps its fixed rows.
+    render(<PromptEditor {...props} value={"a\nb\nc"} />);
+    expect(box().style.height).toBe("");
+    tall.mockRestore();
+  });
+});
+
 describe("PromptEditor — newlines and images", () => {
   it("Alt+Enter inserts a newline and does not send", () => {
     const spies = renderEditor("ab");
@@ -202,7 +235,8 @@ describe("PromptEditor — newlines and images", () => {
     expect(screen.getByTestId("sent").textContent).toBe("see /tmp/agenthub-drops-1/a.png");
 
     fireEvent.click(thumb);
-    expect(screen.getByRole("dialog", { name: "shot.png" })).toBeTruthy();
+    // On the page, not in the composer's layer: nothing stacked over a pane covers it.
+    expect(screen.getByRole("dialog", { name: "shot.png" }).parentElement).toBe(document.body);
     fireEvent.keyDown(document, { key: "Escape" });
     expect(screen.queryByRole("dialog")).toBeNull();
 
@@ -212,6 +246,38 @@ describe("PromptEditor — newlines and images", () => {
     expect(screen.getByTestId("sent").textContent).toBe("see");
   });
 
+  it("a composer's Upload opens a picker whose files attach like a paste", async () => {
+    const pick: { current: (() => void) | null } = { current: null };
+    function Harness() {
+      const [images, setImages] = useState<PromptImage[]>([]);
+      return (
+        <>
+          <PromptEditor
+            value=""
+            onChange={() => {}}
+            onSubmit={() => {}}
+            placeholder="Ask anything…"
+            slash
+            fileCwd="/Users/tester"
+            images={images}
+            onImagesChange={setImages}
+            pickFiles={pick}
+          />
+          <output data-testid="sent">{promptWithImages("", images)}</output>
+        </>
+      );
+    }
+    render(<Harness />);
+    const input = screen.getByTestId("prompt-file-input") as HTMLInputElement;
+    const clicked = vi.spyOn(input, "click");
+    pick.current?.();
+    expect(clicked).toHaveBeenCalled();
+    const doc = new File(["x"], "spec.pdf", { type: "application/pdf" });
+    fireEvent.change(input, { target: { files: [doc] } });
+    expect(api.run.dropFile).toHaveBeenCalledWith(doc, undefined); // no workspace named
+    expect(await screen.findByText("spec.pdf")).toBeTruthy();
+  });
+
   it("attaches a dropped non-image file as a name chip sent by its path", async () => {
     vi.mocked(api.run.dropFile).mockResolvedValueOnce({ path: "/tmp/agenthub-drops-1/b-spec.pdf" });
     function Harness() {
@@ -237,13 +303,70 @@ describe("PromptEditor — newlines and images", () => {
     fireEvent.drop(box(), { dataTransfer: { files: [pdf] } });
     expect(await screen.findByText("spec.pdf")).toBeTruthy();
     expect(screen.getByTestId("sent").textContent).toBe("read /tmp/agenthub-drops-1/b-spec.pdf");
+    // Remembered for the + menu's Recent uploads.
+    expect(recentUploads()).toContainEqual({
+      path: "/tmp/agenthub-drops-1/b-spec.pdf",
+      name: "spec.pdf",
+    });
+  });
+
+  it("attaches a Files panel row dropped on it as an @path chip, once", () => {
+    function Harness() {
+      const [images, setImages] = useState<PromptImage[]>([]);
+      return (
+        <>
+          <PromptEditor
+            value="read"
+            onChange={() => {}}
+            onSubmit={() => {}}
+            placeholder="Ask anything…"
+            slash
+            fileCwd="/Users/tester"
+            images={images}
+            onImagesChange={setImages}
+          />
+          <output data-testid="sent">{promptWithImages("read", images)}</output>
+        </>
+      );
+    }
+    render(<Harness />);
+    const data: Record<string, string> = {};
+    const dataTransfer = {
+      setData: (k: string, v: string) => (data[k] = v),
+      getData: (k: string) => data[k] ?? "",
+      get types() {
+        return Object.keys(data);
+      },
+      files: [],
+    };
+    // What a Files panel row's onDragStart puts on the drag.
+    dragProjectPath({ dataTransfer } as unknown as React.DragEvent, "src/lib/");
+    fireEvent.drop(box(), { dataTransfer });
+    fireEvent.drop(box(), { dataTransfer });
+    expect(screen.getByText("lib/")).toBeTruthy();
+    expect(api.run.dropFile).not.toHaveBeenCalled();
+    expect(screen.getByTestId("sent").textContent).toBe("read @src/lib/");
   });
 
   it("leaves a text paste to the textarea", () => {
     renderEditor("");
-    fireEvent.paste(box(), { clipboardData: { files: [] } });
+    fireEvent.paste(box(), {
+      clipboardData: { files: [], getData: () => "a short note" },
+    });
     expect(api.run.dropFile).not.toHaveBeenCalled();
   });
+
+  it("attaches a very long text paste as a text file, like a pasted file (#68)", async () => {
+    renderEditor("");
+    const long = "x".repeat(PASTE_AS_FILE_CHARS + 1);
+    fireEvent.paste(box(), { clipboardData: { files: [], getData: () => long } });
+    await waitFor(() => expect(api.run.dropFile).toHaveBeenCalledTimes(1));
+    const file = vi.mocked(api.run.dropFile).mock.calls[0]![0] as File;
+    expect(file.name).toBe("pasted-text.txt");
+    expect(file.type).toBe("text/plain");
+    expect(file.size).toBe(long.length); // the whole paste, nothing cut
+    expect(box()).toHaveValue(""); // not typed into the box
+  });
 });
 
 describe("ModelPicker", () => {