fix(desktop): pause background IPC polls when window is hidden (#1079)

src/web-ui/src/features/dispatch/DispatchJobObserver.test.ts

@@ -845,7 +845,7 @@ describe('DispatchJobObserver', () => {
     cleanup();
   });
 
-  it('continues polling while hidden so background notifications can observe changes', async () => {
+  it('pauses polling while hidden to reduce background CPU usage', async () => {
     registerRunningJob();
     mocks.status.mockResolvedValue(status({ state: 'running' }));
     Object.defineProperty(document, 'visibilityState', {
@@ -855,7 +855,7 @@ describe('DispatchJobObserver', () => {
     const cleanup = installDispatchJobObserver(createContext());
 
     await vi.advanceTimersByTimeAsync(0);
-    expect(mocks.status).toHaveBeenCalledTimes(1);
+    expect(mocks.status).not.toHaveBeenCalled();
 
     cleanup();
     Object.defineProperty(document, 'visibilityState', {
@@ -864,6 +864,30 @@ describe('DispatchJobObserver', () => {
     });
   });
 
+  it('resumes polling when the window becomes visible again', async () => {
+    registerRunningJob();
+    mocks.status.mockResolvedValue(status({ state: 'running' }));
+    Object.defineProperty(document, 'visibilityState', {
+      configurable: true,
+      value: 'hidden',
+    });
+    const cleanup = installDispatchJobObserver(createContext());
+
+    await vi.advanceTimersByTimeAsync(0);
+    expect(mocks.status).not.toHaveBeenCalled();
+
+    Object.defineProperty(document, 'visibilityState', {
+      configurable: true,
+      value: 'visible',
+    });
+    document.dispatchEvent(new Event('visibilitychange'));
+
+    await vi.advanceTimersByTimeAsync(0);
+    expect(mocks.status).toHaveBeenCalled();
+
+    cleanup();
+  });
+
   it('does not present target cancellation as a successful completion', async () => {
     registerRunningJob();
     const context = createContext();

src/web-ui/src/features/dispatch/DispatchJobObserver.ts

@@ -998,6 +998,7 @@ export function installDispatchJobObserver(context: FlowChatContext): () => void
 
   async function run(requestedJobId?: string): Promise<void> {
     if (!ownsLease() || isPeerDeviceModeActive()) return;
+    if (typeof document !== 'undefined' && document.visibilityState === 'hidden') return;
     if (inFlight) {
       queuedJobId = requestedJobId;
       return;
@@ -1095,8 +1096,19 @@ export function installDispatchJobObserver(context: FlowChatContext): () => void
     void run();
   }, DISPATCH_JOB_POLL_INTERVAL_MS);
   handleVisibilityChanged = () => {
-    if (typeof document === 'undefined' || document.visibilityState === 'visible') {
+    if (typeof document === 'undefined') return;
+    if (document.visibilityState === 'visible') {
+      if (interval === null) {
+        interval = setInterval(() => {
+          void run();
+        }, DISPATCH_JOB_POLL_INTERVAL_MS);
+      }
       schedule();
+    } else {
+      if (interval !== null) {
+        clearInterval(interval);
+        interval = null;
+      }
     }
   };
   if (typeof document !== 'undefined') {

src/web-ui/src/flow_chat/components/background-command/BackgroundCommandOutputPanel.tsx

@@ -178,6 +178,7 @@ export const BackgroundCommandOutputPanel: React.FC<BackgroundCommandOutputPanel
       if (metadata?.status && metadata.status !== 'running') {
         return;
       }
+      if (typeof document !== 'undefined' && document.visibilityState === 'hidden') return;
       void readOutput(false);
     }, isPeerDeviceModeActive()
       ? PEER_MODE_BACKGROUND_COMMAND_POLL_MS

src/web-ui/src/tools/editor/components/CodeEditor.tsx

@@ -1960,6 +1960,7 @@ const CodeEditor: React.FC<CodeEditorProps> = ({
     }
 
     const tick = () => {
+      if (typeof document !== 'undefined' && document.visibilityState === 'hidden') return;
       void checkFileModification();
     };
     const pollOffsetMs = getPollOffsetMs(filePath);

src/web-ui/src/tools/editor/components/MarkdownEditor.tsx

@@ -414,6 +414,7 @@ const MarkdownEditor: React.FC<MarkdownEditorProps> = ({
       return;
     }
     const tick = () => {
+      if (typeof document !== 'undefined' && document.visibilityState === 'hidden') return;
       void checkMarkdownDisk();
     };
     const pollOffsetMs = getPollOffsetMs(filePath);