Reject unsafe numeric Content-Length values in the OpenAI chat tools E2E client before waiting on the response stream.
Also hardens Docker E2E heartbeat timing coverage after the exact-head release gate exposed a brittle zero-padded heartbeat assertion.
Verification: direct mock gateway repro, docker heartbeat shell proof, autoreview clean, and exact-head CI release gate https://github.com/openclaw/openclaw/actions/runs/27843455246.