test(news): respect sandboxed preview focus and browser isolation

docs/testing/news-e2e.md

@@ -21,6 +21,8 @@ One Chromium journey exercises the candidate's normal Docker entrypoint and stan
 
 No authentication, application HTTP responses, mutations, database calls or cache calls are mocked. The browser blocks resources outside the local fixture origin, such as external avatars. This does not replace any application response. A local HTTPS edge passes requests to Next and sets trusted forwarding headers, allowing the production Secure-cookie behavior to run normally.
 
+The fresh browser contexts retain normal application service-worker registration. The application worker does not cache article or authentication responses. Playwright's worker-blocking injection is avoided because it throws inside the sandboxed preview; browser errors are still checked without filtering. The preview is closed through its Close button, since keyboard events inside its sandbox do not reach the parent dialog.
+
 ## Isolation and cleanup
 
 - Each run creates a random Docker network and fresh MariaDB, Redis and candidate containers. All mapped ports are allocated dynamically. The HTTPS listener binds only to `127.0.0.1`.