# Gate audit events
`AuditEvent` is the stable record emitted once for each gate consultation, both to structured
tracing and, when configured, to the runtime event store.
## Stable JSON fields
| `timestamp` | UTC consultation time, RFC 3339 in JSON |
| `actor`, `namespace`, `verb` | request identity and operation |
| `decision` | lowercase `"allow"`, `"deny"`, or `"gate_unavailable"` |
| `deny_reason` | present only for a denial |
| `obligations` | policy obligations on allow; always `[]` on deny or gate unavailability |
| `gate_impl` | backend name from `Gate::impl_name` |
| `session_id` | request-context correlation token when present |
Field names are a public wire contract. Adding a field is compatible; removing or renaming one
requires an architectural compatibility decision. `obligations` is always serialized so non-Rust
consumers never need to distinguish absence from an empty array.
## `AuditEvent::from_check`
The constructor copies actor, namespace, verb, backend name, and optional session ID from the
request, uses the request-context timestamp when supplied (stamping the current UTC time only when it is absent), and projects the decision. Allow carries its obligations and
no deny reason; deny carries its reason and an empty obligation array.
## `AuditEvent::gate_unavailable`
The constructor preserves the request identity, namespace, verb, timestamp, optional session ID,
and gate implementation while recording `decision="gate_unavailable"`, no deny reason, and an
empty obligation array. Runtime dispatch persists this envelope with `EventOutcome::Error` before
returning `RuntimeError::GateUnavailable` without invoking the operation.