fix(webui): route first-run model setup choices

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

@@ -887,6 +887,7 @@ describe("ThreadShell", () => {
     fireEvent.click(screen.getByRole("button", { name: "Close" }));
 
     const input = screen.getByRole("textbox", { name: "Message input" });
+    await waitFor(() => expect(input).toHaveFocus());
     fireEvent.change(input, {
       target: { value: "hello" },
     });
@@ -896,12 +897,37 @@ describe("ThreadShell", () => {
     expect(input).toHaveValue("hello");
     fireEvent.click(screen.getByRole("button", { name: "Use an API key" }));
 
-    expect(onOpenModelSettings).toHaveBeenCalledTimes(1);
+    expect(onOpenModelSettings).toHaveBeenCalledWith("apiKey");
     expect(input).toHaveValue("hello");
-    await waitFor(() => expect(input).toHaveFocus());
+    expect(input).not.toHaveFocus();
     expect(client.sendMessage).not.toHaveBeenCalled();
   });
 
+  it("focuses the composer when returning from model setup", async () => {
+    const client = makeClient();
+    const settings = modelSettings("openai-codex/gpt-5.1-codex", "openai_codex");
+    settings.agent.has_api_key = false;
+    const view = (focusComposerRequest: number) => wrap(
+      client,
+      <ThreadShell
+        session={session("setup-focus")}
+        title="Setup focus"
+        onToggleSidebar={() => {}}
+        settingsSnapshot={settings}
+        focusComposerRequest={focusComposerRequest}
+      />,
+      "openai-codex/gpt-5.1-codex",
+    );
+    const { rerender } = render(view(0));
+    const input = await screen.findByRole("textbox", { name: "Message input" });
+    input.blur();
+    expect(input).not.toHaveFocus();
+
+    rerender(view(1));
+
+    await waitFor(() => expect(input).toHaveFocus());
+  });
+
   it("keeps image generation controls out of the composer", async () => {
     const client = makeClient();
     const disabledSettings = modelSettings("deepseek-v4-pro", "deepseek");