# Audit trail Every call, whatever its outcome, is written to an append-only log. Records are chained together with SHA-256, so later changes are detectable. ## What does an event contain? | Field | Meaning | | --- | --- | | `timestamp` | Event time. | | `orgId`, `agentId`, `sessionId`, `correlationId` | Who, which session, which call. | | `tool`, `argsRedacted` | The tool and its **redacted** arguments. | | `policyVerdict`, `egressVerdict`, `ingressVerdict` | Per-stage results. | | `finalDecision`, `reason`, `ruleId` | The final decision and its rationale. | | `latencyMs`, `isShadow` | Latency and shadow flag. | | `prevHash`, `entryHash` | The chain link. | | `traceId`, `spanId` | OpenTelemetry trace. | ## How the chain works Each record's `entryHash` is computed with SHA-256 over a canonical (key-sorted) JSON serialisation of all its security-relevant fields, and includes the previous record's hash. Altering, deleting, inserting or re-ordering a record breaks the chain, and verification shows **exactly which row** is corrupted. ## Verification and reporting ``` avertgate verify --db ./avertgate.sqlite avertgate report --format markdown --output report.md ``` > **Compliance**: The chained log makes later changes detectable. It is not a compliance certification in itself. ## Redaction The audit log stores arguments in *redacted* form. Only these redacted events go to the control plane.