feat(settings): warn that keep-awake cannot survive a closed laptop lid

The "Keep awake while agents work" power-save blocker only prevents
idle system sleep; closing a laptop lid forces sleep on macOS and
Windows regardless. Detect a built-in battery (macOS ioreg, Windows
Win32_Battery, Linux /sys/class/power_supply) and append a lid-close
caveat to the setting description on laptops.

Generated-By: PostHog Code
Task-Id: 6b1cbbfe-903b-400d-a76f-45e614c6d0f8

Author: robbie-c

apps/code/src/main/platform-adapters/electron-power-manager.ts

@@ -1,9 +1,16 @@
+import { execFile } from "node:child_process";
+import { readdir } from "node:fs/promises";
+import { promisify } from "node:util";
 import type { IPowerManager } from "@posthog/platform/power-manager";
 import { powerMonitor, powerSaveBlocker } from "electron";
 import { injectable } from "inversify";
 
+const execFileAsync = promisify(execFile);
+
 @injectable()
 export class ElectronPowerManager implements IPowerManager {
+  private hasBuiltInBatteryResult: Promise<boolean> | null = null;
+
   public onResume(handler: () => void): () => void {
     powerMonitor.on("resume", handler);
     return () => powerMonitor.off("resume", handler);
@@ -17,4 +24,38 @@ export class ElectronPowerManager implements IPowerManager {
       }
     };
   }
+
+  public hasBuiltInBattery(): Promise<boolean> {
+    if (!this.hasBuiltInBatteryResult) {
+      this.hasBuiltInBatteryResult = detectBuiltInBattery().catch(() => false);
+    }
+    return this.hasBuiltInBatteryResult;
+  }
+}
+
+async function detectBuiltInBattery(): Promise<boolean> {
+  switch (process.platform) {
+    case "darwin": {
+      const { stdout } = await execFileAsync("ioreg", [
+        "-rc",
+        "AppleSmartBattery",
+      ]);
+      return stdout.includes("AppleSmartBattery");
+    }
+    case "win32": {
+      const { stdout } = await execFileAsync("powershell", [
+        "-NoProfile",
+        "-NonInteractive",
+        "-Command",
+        "[bool](Get-CimInstance -ClassName Win32_Battery)",
+      ]);
+      return stdout.trim().toLowerCase() === "true";
+    }
+    case "linux": {
+      const supplies = await readdir("/sys/class/power_supply");
+      return supplies.some((name) => name.startsWith("BAT"));
+    }
+    default:
+      return false;
+  }
 }

packages/core/src/auth/auth.test.ts

@@ -27,6 +27,7 @@ vi.mock("@posthog/shared", async (importOriginal) => {
 const mockPowerManager = vi.hoisted(() => ({
   onResume: vi.fn(() => () => {}),
   preventSleep: vi.fn(() => () => {}),
+  hasBuiltInBattery: vi.fn(async () => false),
 }));
 
 function createSessionPort(): IAuthSessionStore {

packages/core/src/sleep/sleep.test.ts

@@ -18,6 +18,7 @@ function createDeps(preventSleepInitially = true) {
   const powerManager: IPowerManager = {
     onResume: vi.fn(() => () => {}),
     preventSleep: vi.fn(() => release),
+    hasBuiltInBattery: vi.fn(async () => false),
   };
 
   let stored = preventSleepInitially;

packages/core/src/sleep/sleep.ts

@@ -43,6 +43,10 @@ export class SleepService {
     return this.enabled;
   }
 
+  hasBuiltInBattery(): Promise<boolean> {
+    return this.powerManager.hasBuiltInBattery();
+  }
+
   acquire(activityId: string): void {
     this.activeActivities.add(activityId);
     this.updateBlocker();

packages/host-router/src/routers/sleep.router.ts

@@ -15,4 +15,10 @@ export const sleepRouter = router({
     .mutation(({ ctx, input }) => {
       ctx.container.get<SleepService>(SLEEP_SERVICE).setEnabled(input.enabled);
     }),
+
+  hasBuiltInBattery: publicProcedure
+    .output(z.boolean())
+    .query(({ ctx }) =>
+      ctx.container.get<SleepService>(SLEEP_SERVICE).hasBuiltInBattery(),
+    ),
 });

packages/platform/src/power-manager.ts

@@ -1,6 +1,7 @@
 export interface IPowerManager {
   onResume(handler: () => void): () => void;
   preventSleep(reason: string): () => void;
+  hasBuiltInBattery(): Promise<boolean>;
 }
 
 export const POWER_MANAGER_SERVICE = Symbol.for(

packages/ui/src/features/settings/sections/GeneralSettings.tsx

@@ -40,6 +40,9 @@ export function GeneralSettings() {
   const { data: serverPreventSleep } = useQuery(
     hostTRPC.sleep.getEnabled.queryOptions(),
   );
+  const { data: hasBuiltInBattery } = useQuery(
+    hostTRPC.sleep.hasBuiltInBattery.queryOptions(),
+  );
   const preventSleepMutation = useMutation(
     hostTRPC.sleep.setEnabled.mutationOptions(),
   );
@@ -434,7 +437,11 @@ export function GeneralSettings() {
 
       <SettingRow
         label="Keep awake while agents work"
-        description="Prevent your computer from sleeping while the agent is running a task"
+        description={
+          hasBuiltInBattery
+            ? "Prevent your computer from going to sleep on its own while the agent is running a task. Closing the lid will still put it to sleep."
+            : "Prevent your computer from going to sleep on its own while the agent is running a task"
+        }
         noBorder
       >
         <Switch

packages/workspace-server/src/services/agent/agent.test.ts

@@ -157,6 +157,7 @@ function createMockDependencies() {
     powerManager: {
       onResume: vi.fn(() => () => {}),
       preventSleep: vi.fn(() => () => {}),
+      hasBuiltInBattery: vi.fn(async () => false),
     },
     bundledResources: {
       resolve: vi.fn((rel: string) => `/mock/appPath/${rel}`),