Add setting to keep app previews running forever (#3273)

rules/adding-settings.md

@@ -7,6 +7,7 @@ When adding a new toggle/setting to the Settings page:
 3. Add a `SETTING_IDS` entry and search index entry in `src/lib/settingsSearchIndex.ts`
 4. Create a switch component (e.g., `src/components/MySwitch.tsx`) - follow `AutoApproveSwitch.tsx` as a template
 5. Import and add the switch to the relevant section in `src/pages/settings.tsx`
+6. Adding a field to `DEFAULT_SETTINGS` breaks the inline snapshots in `src/__tests__/readSettings.test.ts`. After confirming the diff is just your new field, regenerate them with `npm test -- -u`.
 
 For settings whose default can be overridden remotely:
 

src/__tests__/readSettings.test.ts

@@ -77,6 +77,7 @@ describe("readSettings", () => {
           "hasRunBefore": false,
           "isRunning": false,
           "lastKnownPerformance": undefined,
+          "previewIdleTimeoutPolicy": "default",
           "providerSettings": {},
           "releaseChannel": "stable",
           "selectedChatMode": "build",
@@ -469,6 +470,7 @@ describe("readSettings", () => {
           "hasRunBefore": false,
           "isRunning": false,
           "lastKnownPerformance": undefined,
+          "previewIdleTimeoutPolicy": "default",
           "providerSettings": {},
           "releaseChannel": "stable",
           "selectedChatMode": "build",

src/components/KeepPreviewsRunningSwitch.tsx

+import { useSettings } from "@/hooks/useSettings";
+import { Label } from "@/components/ui/label";
+import { Switch } from "@/components/ui/switch";
+
+export function KeepPreviewsRunningSwitch() {
+  const { settings, updateSettings } = useSettings();
+  const isEnabled = settings?.previewIdleTimeoutPolicy === "never";
+
+  return (
+    <div className="flex items-center space-x-2">
+      <Switch
+        id="keep-previews-running"
+        aria-label="Keep app previews running forever"
+        checked={isEnabled}
+        onCheckedChange={(checked) => {
+          updateSettings({
+            previewIdleTimeoutPolicy: checked ? "never" : "default",
+          });
+        }}
+      />
+      <Label htmlFor="keep-previews-running">
+        Keep app previews running forever
+      </Label>
+    </div>
+  );
+}

src/ipc/utils/process_manager.ts

@@ -9,6 +9,7 @@ import {
   stopCloudSandboxFileSync,
   unregisterRunningCloudSandbox,
 } from "./cloud_sandbox_provider";
+import { readSettings } from "../../main/settings";
 
 const logger = log.scope("process_manager");
 
@@ -244,6 +245,10 @@ export function getCurrentlySelectedAppId(): number | null {
  * and are not the currently selected app.
  */
 export async function garbageCollectIdleApps(): Promise<void> {
+  if (readSettings().previewIdleTimeoutPolicy === "never") {
+    return;
+  }
+
   const now = Date.now();
   const appsToStop: number[] = [];
 

src/lib/schemas.ts

@@ -369,6 +369,7 @@ const BaseUserSettingsFields = {
   enableContextCompaction: z.boolean().optional(),
   skipNotificationBanner: z.boolean().optional(),
   enableSelectAppFromHomeChatInput: z.boolean().optional(),
+  previewIdleTimeoutPolicy: z.enum(["default", "never"]).optional(),
 };
 
 /**

src/lib/settingsSearchIndex.ts

@@ -23,6 +23,7 @@ export const SETTING_IDS = {
   autoApprove: "setting-auto-approve",
   autoFix: "setting-auto-fix",
   autoExpandPreview: "setting-auto-expand-preview",
+  keepPreviewsRunning: "setting-keep-previews-running",
   chatEventNotification: "setting-chat-event-notification",
   thinkingBudget: "setting-thinking-budget",
   maxChatTurns: "setting-max-chat-turns",
@@ -145,6 +146,25 @@ export const SETTINGS_SEARCH_INDEX: SearchableSettingItem[] = [
     sectionId: SECTION_IDS.workflow,
     sectionLabel: "Workflow",
   },
+  {
+    id: SETTING_IDS.keepPreviewsRunning,
+    label: "Keep app previews running forever",
+    description:
+      "Prevent idle app previews from being stopped after 10 minutes; uses more memory but enables faster preview loads when switching apps",
+    keywords: [
+      "preview",
+      "idle",
+      "timeout",
+      "gc",
+      "garbage collect",
+      "memory",
+      "forever",
+      "keep",
+      "running",
+    ],
+    sectionId: SECTION_IDS.workflow,
+    sectionLabel: "Workflow",
+  },
   {
     id: SETTING_IDS.chatEventNotification,
     label: "Notifications",

src/main/settings.ts

@@ -48,6 +48,7 @@ const DEFAULT_SETTINGS: UserSettings = {
   enableNativeGit: true,
   autoExpandPreviewPanel: true,
   enableContextCompaction: true,
+  previewIdleTimeoutPolicy: "default",
 };
 
 const SETTINGS_FILE = "user-settings.json";

src/pages/settings.tsx

@@ -22,6 +22,7 @@ import { Switch } from "@/components/ui/switch";
 import { Label } from "@/components/ui/label";
 import { AutoFixProblemsSwitch } from "@/components/AutoFixProblemsSwitch";
 import { AutoExpandPreviewSwitch } from "@/components/AutoExpandPreviewSwitch";
+import { KeepPreviewsRunningSwitch } from "@/components/KeepPreviewsRunningSwitch";
 import { ChatEventNotificationSwitch } from "@/components/ChatEventNotificationSwitch";
 import { AutoUpdateSwitch } from "@/components/AutoUpdateSwitch";
 import { ReleaseChannelSelector } from "@/components/ReleaseChannelSelector";
@@ -425,6 +426,14 @@ export function WorkflowSettings() {
         </div>
       </div>
 
+      <div id={SETTING_IDS.keepPreviewsRunning} className="space-y-1 mt-4">
+        <KeepPreviewsRunningSwitch />
+        <div className="text-sm text-gray-500 dark:text-gray-400">
+          Note: this may take more memory but allows faster preview loads when
+          switching apps.
+        </div>
+      </div>
+
       <div id={SETTING_IDS.chatEventNotification} className="space-y-1 mt-4">
         <ChatEventNotificationSwitch />
         <div className="text-sm text-gray-500 dark:text-gray-400">