| 400 | invalid_json | Request body contains malformed JSON. |
| 400 | invalid_request_payload | JSON does not match the public endpoint contract. |
| 400 | invalid_idempotency_key | Idempotency-Key is blank, repeated, or exceeds the supported length. |
| 401 | missing_api_key | x-api-key was not provided. |
| 401 | invalid_api_key | Credential is invalid, inactive, or revoked. |
| 403 | quota_access_denied | Customer does not currently have access to the billable operation. |
| 403 | current_usage_access_denied | Current usage is not available for the authenticated customer. |
| 403 | product_not_entitled | Customer is not currently entitled to execute Operational Evidence. |
| 409 | idempotency_conflict | The same idempotency key was already used for a different request. |
| 409 | idempotency_in_progress | The same logical request is currently being processed. |
| 422 | invalid_evidence_report_input | Application input was rejected after HTTP validation. |
| 422 | remote_evidence_image_rejected | A submitted remote image could not be accepted safely. |
| 429 | quota_exceeded | Monthly operation quota is exhausted. |
| 429 | rate_limit_exceeded | The caller exceeded the configured technical request rate. |
| 503 | entitlement_check_unavailable | Product entitlement cannot currently be evaluated safely. |
| 503 | rate_limit_unavailable | Rate-limit evaluation is temporarily unavailable. |
| 503 | remote_evidence_image_unavailable | A remote image cannot currently be retrieved safely. |
| 502 | invalid_generated_report | Generated output could not be represented by the public report contract. |
| 502 | report_generation_failed | Operational report generation failed. |
| 503 | api_key_authentication_unavailable | Authentication cannot currently be completed safely. |
| 503 | quota_check_unavailable | Monthly quota validation is temporarily unavailable. |
| 503 | report_generation_unavailable | Report generation is temporarily unavailable. |
| 503 | evidence_report_write_failed | Generated report could not be stored. |
| 503 | usage_recording_failed | Report usage could not be recorded. |
| 503 | current_usage_unavailable | Current usage information cannot currently be read safely. |
| 503 | idempotency_unavailable | Idempotency protection is temporarily unavailable. |
| 503 | idempotency_replay_unavailable | The original idempotent result cannot currently be restored safely. |
| 500 | internal_error | An unexpected internal error occurred. |