fix(control-ui): disable refresh during active runs

Disable the Control UI refresh button while chat is disconnected, loading, sending, running, or streaming.

This prevents manual chat-history refresh from racing active run/stream state and adds browser render coverage for the disabled-state matrix.

Closes #65522.

Validation:
- Exact PR head `1511a086614a727fc4200730e7ad9622134bb7d3` reached `CLEAN` merge state.
- GitHub CI for the exact head completed with no failed or pending checks.

ui/src/ui/app-render.helpers.browser.test.ts

@@ -15,6 +15,9 @@ function createState(overrides: Partial<AppViewState> = {}) {
   return {
     connected: true,
     chatLoading: false,
+    chatRunId: null,
+    chatSending: false,
+    chatStream: null,
     onboarding: false,
     sessionKey: "main",
     sessionsHideCron: true,
@@ -49,6 +52,17 @@ function createState(overrides: Partial<AppViewState> = {}) {
   } as unknown as AppViewState;
 }
 
+function renderRefreshButton(overrides: Partial<AppViewState> = {}) {
+  const container = document.createElement("div");
+  render(renderChatControls(createState(overrides)), container);
+
+  const button = container.querySelector<HTMLButtonElement>(
+    `.chat-controls .btn--icon[data-tooltip="${t("chat.refreshTitle")}"]`,
+  );
+  expect(button).not.toBeNull();
+  return button!;
+}
+
 describe("chat header controls (browser)", () => {
   it("renders explicit hover tooltip metadata for the top-right action buttons", async () => {
     const container = document.createElement("div");
@@ -76,6 +90,19 @@ describe("chat header controls (browser)", () => {
     }
   });
 
+  it.each([
+    ["connected and idle", {}, false],
+    ["chat history loading", { chatLoading: true }, true],
+    ["chat send in flight", { chatSending: true }, true],
+    ["active run", { chatRunId: "run-123" }, true],
+    ["active stream", { chatStream: "streaming" }, true],
+    ["disconnected", { connected: false }, true],
+  ] as const)("sets refresh disabled state while %s", (_name, overrides, disabled) => {
+    const button = renderRefreshButton(overrides);
+
+    expect(button.disabled).toBe(disabled);
+  });
+
   it("renders the cron session filter in the mobile dropdown controls", async () => {
     const state = createState({
       sessionsResult: {

ui/src/ui/app-render.helpers.ts

@@ -222,6 +222,12 @@ export function renderChatControls(state: AppViewState) {
       ? t("chat.showCronSessionsHidden", { count: String(hiddenCronCount) })
       : t("chat.showCronSessions")
     : t("chat.hideCronSessions");
+  const refreshDisabled =
+    !state.connected ||
+    state.chatLoading ||
+    state.chatSending ||
+    Boolean(state.chatRunId) ||
+    state.chatStream !== null;
   const toolCallsIcon = html`
     <svg
       width="18"
@@ -275,7 +281,7 @@ export function renderChatControls(state: AppViewState) {
     <div class="chat-controls">
       <button
         class="btn btn--sm btn--icon"
-        ?disabled=${state.chatLoading || !state.connected}
+        ?disabled=${refreshDisabled}
         @click=${async () => {
           const app = state as unknown as ChatRefreshHost;
           app.chatManualRefreshInFlight = true;