{
  "$id": "https://stella-ops.org/schemas/zastava/observer_event.schema.json",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "title": "Zastava Observer Event",
  "type": "object",
  "required": [
    "tenant_id",
    "project_id",
    "sensor_id",
    "firmware_version",
    "policy_hash",
    "graph_revision_id",
    "event_type",
    "observed_at",
    "payload_hash",
    "signature" 
  ],
  "properties": {
    "tenant_id": { "type": "string" },
    "project_id": { "type": "string" },
    "sensor_id": { "type": "string" },
    "firmware_version": { "type": "string" },
    "policy_hash": { "type": "string" },
    "graph_revision_id": { "type": "string" },
    "ledger_id": { "type": "string" },
    "replay_manifest": { "type": "string" },
    "event_type": { "enum": ["runtime_fact", "drift", "policy_violation", "heartbeat"] },
    "observed_at": { "type": "string", "format": "date-time" },
    "monotonic_nanos": { "type": "integer" },
    "payload": { "type": "object" },
    "payload_hash": { "type": "string", "description": "sha256 over canonical JSON (JCS) of payload" },
    "signature": { "type": "string", "description": "DSSE envelope reference" }
  }
}