fix(ui): keep keyboard focus when collapsing standalone questions (#181296)

Preserve keyboard focus on Expand when a standalone question collapses, retaining its answer draft and Chat composer focus behavior.

Reviewed-by: @shakkernerd

ui/src/pages/chat/components/chat-question-panel.tsx

@@ -1,4 +1,12 @@
-import { action, createMemo, createOptimistic, createSignal, Show, untrack } from "solid-js";
+import {
+  action,
+  createMemo,
+  createOptimistic,
+  createSignal,
+  onSettled,
+  Show,
+  untrack,
+} from "solid-js";
 import type { QuestionDraft } from "../../../app/question-prompt.ts";
 import { Icon } from "../../../components/solid/icon.tsx";
 import { registerChatSessionEnglish } from "../../../i18n/locales/en-chat-session.ts";
@@ -35,6 +43,7 @@ function QuestionPanelRequest(props: { panel: QuestionPanelProps }) {
   const [pendingKind, setPendingKind] = createOptimistic<"submit" | "skip" | null>(null);
   let resolving = false;
   let panel: HTMLElement | undefined;
+  let expandButton: HTMLButtonElement | undefined;
   let answerControl: HTMLInputElement | HTMLTextAreaElement | undefined;
   let hostsInput: HTMLInputElement | undefined;
   const options = new Set<HTMLButtonElement>();
@@ -73,6 +82,10 @@ function QuestionPanelRequest(props: { panel: QuestionPanelProps }) {
       props.panel.onCollapsedChange(value);
     } else {
       setUncontrolledCollapsed(value);
+      // Controlled callers own their destination (for example, the chat composer).
+      if (value) {
+        onSettled(() => expandButton?.focus({ preventScroll: true }));
+      }
     }
   };
   const updateDraft = (item: QuestionPanelQuestion, value: QuestionDraft) => {
@@ -316,6 +329,7 @@ function QuestionPanelRequest(props: { panel: QuestionPanelProps }) {
               aria-label={model().title}
             >
               <button
+                ref={(element) => (expandButton = element)}
                 class="chat-question-panel__collapsed-button"
                 type="button"
                 onClick={() => setCollapsed(false)}

ui/src/pages/question/question-page.test.ts

@@ -76,6 +76,28 @@ it.each(["question", "outside"] as const)("restores only question focus (%s)", a
   expect(request).toHaveBeenCalledTimes(1);
 });
 
+it("keeps focus on the collapsed question so it can be reopened", async () => {
+  const { page } = await mount(vi.fn().mockResolvedValue({ question: question() }));
+  await questionPanelIn(page);
+  const input = page.querySelector("textarea")!;
+  input.value = "The design team";
+  input.dispatchEvent(new InputEvent("input", { bubbles: true }));
+  const collapse = page.querySelector<HTMLButtonElement>(".chat-question-panel__collapse")!;
+  collapse.focus();
+  collapse.click();
+  await waitForSolid(() => {
+    const expand = page.querySelector(".chat-question-panel__collapsed-button");
+    expect(expand).not.toBeNull();
+    expect(document.activeElement).toBe(expand);
+  });
+
+  page.querySelector<HTMLButtonElement>(".chat-question-panel__collapsed-button")!.click();
+  await waitForSolid(() => {
+    expect(document.activeElement).toBe(page.querySelector(".chat-question-panel"));
+    expect(page.querySelector("textarea")?.value).toBe("The design team");
+  });
+});
+
 it("recovers a failed reconnect lookup without losing the typed answer", async () => {
   const request = vi
     .fn()