diff --git a/apps/electron-backend-e2e/src/electron-unautomated-launch.ts b/apps/electron-backend-e2e/src/electron-unautomated-launch.ts
index ee29ff715..7abb8ad19 100644
--- a/apps/electron-backend-e2e/src/electron-unautomated-launch.ts
+++ b/apps/electron-backend-e2e/src/electron-unautomated-launch.ts
@@ -55,9 +55,18 @@ async function openCdpSocket(url: string): Promise<CdpSocket> {
         );
     });
     socket.addEventListener('message', (event) => {
-        const message = JSON.parse(String(event.data));
-        pending.get(message.id)?.(message);
-        pending.delete(message.id);
+        const message = JSON.parse(String(event.data)) as Record<
+            string,
+            unknown
+        >;
+        // Only replies to our own numbered requests settle a promise; events
+        // and unknown ids are ignored.
+        const id = message['id'];
+        if (typeof id !== 'number') return;
+        const settle = pending.get(id);
+        if (typeof settle !== 'function') return;
+        pending.delete(id);
+        settle(message);
     });
     return {
         send: (method, params = {}) =>
diff --git a/apps/electron-backend-e2e/src/window-visibility.e2e.ts b/apps/electron-backend-e2e/src/window-visibility.e2e.ts
index 5810607c1..ae323c541 100644
--- a/apps/electron-backend-e2e/src/window-visibility.e2e.ts
+++ b/apps/electron-backend-e2e/src/window-visibility.e2e.ts
@@ -1,3 +1,5 @@
+import { join } from 'node:path';
+import { pathToFileURL } from 'node:url';
 import { expect, test } from './electron-test-fixtures';
 import {
     launchUnautomatedElectronApp,
@@ -9,6 +11,10 @@ import {
 const isWindowManagerlessCi =
     process.platform === 'linux' && !!process.env['CI'];
 
+const videoFixtureUrl = pathToFileURL(
+    join(__dirname, '../../web-e2e/src/fixtures/playback/episode.webm')
+).href;
+
 const visibility = (app: UnautomatedElectronApp) =>
     app.evaluateInPage<string>('document.visibilityState');
 
@@ -92,4 +98,50 @@ test.describe('Main window visibility', () => {
             await app.close();
         }
     });
+
+    test('@electron releases the playback display lock while the window is hidden', async ({
+        dataDir,
+    }) => {
+        const app = await launchUnautomatedElectronApp(dataDir);
+        try {
+            await waitUntilShown(app);
+            // Record the display-sleep blockers the keep-awake service holds.
+            await app.evaluateInMain(`
+                const blocker = electron.powerSaveBlocker;
+                const active = (globalThis.__e2eDisplayBlockers = new Set());
+                const start = blocker.start.bind(blocker);
+                const stop = blocker.stop.bind(blocker);
+                blocker.start = (type) => {
+                    const id = start(type);
+                    if (type === 'prevent-display-sleep') active.add(id);
+                    return id;
+                };
+                blocker.stop = (id) => {
+                    active.delete(id);
+                    return stop(id);
+                };
+            `);
+            const heldBlockers = () =>
+                app.evaluateInMain<number>(
+                    'return globalThis.__e2eDisplayBlockers.size;'
+                );
+            await app.evaluateInPage(`(() => {
+                const video = document.createElement('video');
+                video.muted = true;
+                video.loop = true;
+                video.src = ${JSON.stringify(videoFixtureUrl)};
+                document.body.append(video);
+                return video.play().then(() => true);
+            })()`);
+            await expect.poll(heldBlockers, { timeout: 10_000 }).toBe(1);
+
+            await setWindowState(app, 'hide');
+            await expect.poll(heldBlockers, { timeout: 10_000 }).toBe(0);
+
+            await setWindowState(app, 'show');
+            await expect.poll(heldBlockers, { timeout: 10_000 }).toBe(1);
+        } finally {
+            await app.close();
+        }
+    });
 });