Aevum Event Schema v1

The machine-readable JSON Schema is at spec/aevum-event-v1.json.

The schema defines the structure of every AuditEvent as returned by Engine.get_ledger_entries(). See the Signing Specification for verification procedures.

Field summary

See the JSON Schema for full constraints. Key fields:

Field	Type	Description
event_id	string	UUID v7 (globally unique, time-ordered)
episode_id	string	Groups events into a logical workflow episode
sequence	integer	Chain position (1-based); always 1 for session.start
event_type	string	Dotted namespace (e.g. session.start, ingest.accepted)
actor	string	Who caused this event (e.g. aevum-core, agent)
system_time	integer	HLC nanoseconds — use for causal ordering
valid_from	string	Wall-clock ISO 8601 timestamp
valid_to	string|null	Validity end timestamp; null for point-in-time events
causation_id	string|null	audit_id of the causing event
correlation_id	string|null	Deployment-wide correlation token
trace_id	string|null	OTel W3C trace ID
span_id	string|null	OTel W3C span ID
prior_hash	string	SHA3-256 of previous event's signing fields
payload_hash	string	SHA3-256 of payload (JCS-canonical)
signature	string	Ed25519 over SHA3-256(signing fields), base64url
signer_key_id	string	Signing key identifier
schema_version	string	Always "1.0"
payload	object	Event-specific structured data
audit_id	string	urn:aevum:audit:{event_id}

Event types

event_type	Description
session.start	Kernel startup; always sequence 1
ingest.accepted	Data ingested through the governed membrane
ingest.rejected	Ingest denied by policy or consent
query.accepted	Graph traversal executed
review.created	Review checkpoint created
commit.accepted	Manual commit appended
replay.started	Replay of a past decision begun
capture.gap	Out-of-band capture surface call declared

session.start payload

{
  "capture_surface": {
    "llm": false,
    "mcp": false
  },
  "key_provenance": "in-process"
}

key_provenance values: in-process, external, vault-transit, aws-kms, pkcs11.

capture.gap payload

{
  "gap_type": "llm",
  "reason": "direct_api_call",
  "model_hint": "claude-opus-4-7"
}

gap_type values: llm, mcp, tool, custom. reason and gap_type are required; model_hint is optional.