Brain API HTTP 502: {
  "ok": false,
  "error": "Academy structured output invalid after round-specific canonicalisation: Academy structured output invalid: unexpected fields: acceptance_criteria, project_steps, safe_knowledge_gate, unknown_source_quarantine",
  "retryable": true,
  "infrastructure_failure": true,
  "output_contract": "academy_round_json_v6",
  "exam_round": 3,
  "raw_answer": "{\n  \"project_steps\": [\n    \"Define a rectangular room footprint using explicit meters, origin at the southwest corner