feat: add image generation tool and WebUI mode

Co-authored-by: Cursor <cursoragent@cursor.com>

webui/src/tests/thread-shell.test.tsx

@@ -250,6 +250,64 @@ describe("ThreadShell", () => {
     expect(onNewChat).not.toHaveBeenCalled();
   });
 
+  it("keeps the first landing message when new chat history is still empty", async () => {
+    const client = makeClient();
+    const onCreateChat = vi.fn().mockResolvedValue("chat-new");
+    vi.stubGlobal(
+      "fetch",
+      vi.fn(async () => ({
+        ok: false,
+        status: 404,
+        json: async () => ({}),
+      })),
+    );
+
+    const { rerender } = render(
+      wrap(
+        client,
+        <ThreadShell
+          session={null}
+          title="nanobot"
+          onToggleSidebar={() => {}}
+          onCreateChat={onCreateChat}
+        />,
+      ),
+    );
+
+    fireEvent.change(screen.getByLabelText("Message input"), {
+      target: { value: "first message should stay" },
+    });
+    fireEvent.click(screen.getByRole("button", { name: "Send message" }));
+
+    await waitFor(() => expect(onCreateChat).toHaveBeenCalledTimes(1));
+
+    await act(async () => {
+      rerender(
+        wrap(
+          client,
+          <ThreadShell
+            session={session("chat-new")}
+            title="Chat chat-new"
+            onToggleSidebar={() => {}}
+            onCreateChat={onCreateChat}
+          />,
+        ),
+      );
+    });
+
+    await waitFor(() =>
+      expect(client.sendMessage).toHaveBeenCalledWith(
+        "chat-new",
+        "first message should stay",
+        undefined,
+      ),
+    );
+    await waitFor(() =>
+      expect(screen.getByText("first message should stay")).toBeInTheDocument(),
+    );
+    expect(screen.queryByText("What can I do for you?")).not.toBeInTheDocument();
+  });
+
   it("sends quick action prompts from the empty thread landing", async () => {
     const client = makeClient();
     const onNewChat = vi.fn().mockResolvedValue("chat-a");
@@ -566,6 +624,30 @@ describe("ThreadShell", () => {
     expect(screen.queryByRole("listbox", { name: "Slash commands" })).not.toBeInTheDocument();
   });
 
+  it("switches welcome quick actions when image mode is enabled", async () => {
+    const client = makeClient();
+    render(
+      wrap(
+        client,
+        <ThreadShell
+          session={null}
+          title="nanobot"
+          onToggleSidebar={() => {}}
+          onNewChat={() => {}}
+        />,
+      ),
+    );
+    await act(async () => {});
+
+    expect(screen.getByText("Write code")).toBeInTheDocument();
+    expect(screen.queryByText("Design an app icon")).not.toBeInTheDocument();
+
+    fireEvent.click(screen.getByRole("button", { name: "Toggle image generation mode" }));
+
+    expect(screen.getByText("Design an app icon")).toBeInTheDocument();
+    expect(screen.queryByText("Write code")).not.toBeInTheDocument();
+  });
+
   it("surfaces a dismissible banner when the stream reports message_too_big", async () => {
     const client = makeClient();
     const onNewChat = vi.fn().mockResolvedValue("chat-a");