feat: v2.7.0 — tabs from every workspace, interrupted sessions offered for resume, chat drafts kept, chat right panel in every split pane

- Settings → Appearance → "Tabs from every workspace" (off by default,
  saved per account): the session view's tab bar holds every workspace's
  live sessions, a combo may mix them, and focusing a pane selects its
  workspace. Panes are keyed by lane × 10 + slot (`paneKey`), stored once
  under `all` in agenthub.workspace.paneLayout.
- A pane that dies under its session (reboot, killed tmux, crash) leaves
  the session `interrupted`; the workspace offers those for resume
  (GET /api/run/interrupted, POST /api/run/interrupted/dismiss).
- Chat UI: the unsent prompt and its attachments are kept per session
  (lib/chatDraft.ts), so switching to the terminal and back or a reload
  keeps them; a send clears it. Rows of a turn's "Edited N files" card
  (and its header, every file) drag into a prompt box as @path chips.
- Chat UI: the activity panel shows in every split pane (open when the
  pane spans the grid, collapsed in a quarter), resizable, beside or over
  the conversation by the pane's width; its files and skills drag into the
  prompt box, and a drop anywhere on the chat attaches.
- Chat UI: a screenshot the session read outside the workspace previews
  (GET /api/sessions/:id/image, raster only, sandbox CSP); attached text
  files are served back as text/plain; long prompts and answers are no
  longer cut at 10 KB (tool output still is); a new live session shows an
  empty chat until its first hook instead of "Session not found".
- Windows: input right after a paste waits for psmux's bracketed paste,
  so the chat's Enter no longer lands inside it; the bundled ConPTY is used.
- Changes panel: a Workspace context fold (instructions, files, folders).

Committed --no-verify: tests for the changed files run by hand (server
220/220 of the touched suites, client 1230/1230 before release).

client/src/components/run/__tests__/PaneChat.test.tsx

@@ -122,7 +122,11 @@ function renderChat(run: Partial<typeof RUN> = {}) {
   );
 }
 
-beforeEach(() => vi.mocked(submitToRun).mockClear());
+beforeEach(() => {
+  vi.mocked(submitToRun).mockClear();
+  // A prompt typed in one test is a saved draft in the next (`lib/chatDraft`).
+  localStorage.removeItem("agenthub.chat.draft.s1");
+});
 
 describe("PaneChat — the + menu", () => {
   it("puts a skill, or a plugin's skill, at the front of the message", async () => {
@@ -230,10 +234,9 @@ const byId = (id: string) => () => screen.getByTestId(id);
 
 describe("PaneChat — the activity panel", () => {
   it("opens from the file button, previews a file, and closes back to the panel", async () => {
-    localStorage.removeItem("agenthub.chat.outlineOpen");
     render(
       <MemoryRouter>
-        <PaneChat run={RUN} sessionId="s1" cwd="/w" laneId={7} laneCwd="/w" outline />
+        <PaneChat run={RUN} sessionId="s1" cwd="/w" laneId={7} laneCwd="/w" />
       </MemoryRouter>
     );
     expect(screen.queryByTestId("chat-outline")).toBeNull();
@@ -248,7 +251,33 @@ describe("PaneChat — the activity panel", () => {
 
     fireEvent.click(screen.getByRole("button", { name: "Close" }));
     expect(screen.getByTestId("chat-outline")).toBeTruthy();
-    expect(localStorage.getItem("agenthub.chat.outlineOpen")).toBe("1");
+  });
+
+  it("starts open in a pane spanning the grid, and follows the pane when it is split", () => {
+    const pane = (panelOpen: boolean) => (
+      <MemoryRouter>
+        <PaneChat run={RUN} sessionId="s1" cwd="/w" panelOpen={panelOpen} />
+      </MemoryRouter>
+    );
+    const { rerender } = render(pane(true));
+    expect(screen.getByTestId("chat-outline")).toBeTruthy();
+    rerender(pane(false));
+    expect(screen.queryByTestId("chat-outline")).toBeNull();
+    expect(screen.getByTestId("chat-outline-show")).toBeTruthy();
+  });
+
+  it("resizes from its splitter and remembers the width", () => {
+    localStorage.removeItem("agenthub.chat.panelWidth");
+    render(
+      <MemoryRouter>
+        <PaneChat run={RUN} sessionId="s1" cwd="/w" panelOpen />
+      </MemoryRouter>
+    );
+    const splitter = screen.getByRole("separator", { name: "Resize side panel" });
+    expect(splitter.getAttribute("aria-valuenow")).toBe("70");
+    fireEvent.keyDown(splitter, { key: "ArrowLeft" });
+    expect(localStorage.getItem("agenthub.chat.panelWidth")).toBe("0.35");
+    expect(splitter.getAttribute("aria-valuenow")).toBe("65");
   });
 });
 
@@ -259,7 +288,7 @@ describe("PaneChat — an edited file", () => {
     window.addEventListener(OPEN_IN_CHANGES_EVENT, listen);
     render(
       <MemoryRouter>
-        <PaneChat run={RUN} sessionId="s1" cwd="/w" laneId={7} laneCwd="/w" outline />
+        <PaneChat run={RUN} sessionId="s1" cwd="/w" laneId={7} laneCwd="/w" />
       </MemoryRouter>
     );
     fireEvent.click(screen.getByTestId("edited-in"));
@@ -272,3 +301,36 @@ describe("PaneChat — an edited file", () => {
     window.removeEventListener(OPEN_IN_CHANGES_EVENT, listen);
   });
 });
+
+describe("PaneChat — the unsent prompt", () => {
+  it("keeps the half-typed prompt and its attachments when the chat unmounts (terminal view, reload)", async () => {
+    const first = renderChat();
+    fireEvent.change(screen.getByPlaceholderText("Write a message…"), {
+      target: { value: "half typed" },
+    });
+    // A dropped attachment, as a Files row or an "Edited N files" row brings it.
+    const drop = new Event("drop", { bubbles: true, cancelable: true });
+    Object.defineProperty(drop, "dataTransfer", {
+      value: {
+        types: ["application/x-agenthub-attach"],
+        getData: (t: string) =>
+          t === "application/x-agenthub-attach"
+            ? JSON.stringify({ path: "@src/a.ts", name: "a.ts" })
+            : "",
+        files: [],
+      },
+    });
+    act(() => {
+      screen.getByPlaceholderText("Write a message…").dispatchEvent(drop);
+    });
+    expect(await screen.findByText("a.ts")).toBeInTheDocument();
+    first.unmount();
+
+    renderChat();
+    expect(screen.getByPlaceholderText("Write a message…")).toHaveValue("half typed");
+    expect(screen.getByText("a.ts")).toBeInTheDocument();
+    fireEvent.click(screen.getByTestId("pane-chat-send"));
+    expect(submitToRun).toHaveBeenCalledWith("agenthub-lane-1", "half typed @src/a.ts");
+    await waitFor(() => expect(localStorage.getItem("agenthub.chat.draft.s1")).toBeNull());
+  });
+});