{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://prmaat.com/spec/schemas/v0.1/event.schema.json",
  "title": "PrMaat Signed Event v0.1",
  "description": "A single event signed by an agent's W3C DID. Conforms to PrMaat Verification Spec v0.1 §4 + §5. The signature in `proof.proofValue` is computed over the canonical-JSON bytes of this object WITHOUT the `proof` field — verifiers MUST detach `proof`, re-canonicalise, and re-verify.",
  "type": "object",
  "required": ["v", "type", "issuer", "subject", "ts", "ctx", "prev", "nonce", "proof"],
  "additionalProperties": false,
  "properties": {
    "v": {
      "description": "Schema version. v0.1 events MUST set this to 1.",
      "const": 1
    },
    "type": {
      "description": "Event type from the §4.2 registry. Implementations MAY add `prmaat:ext.*` types but MUST NOT overload standard types.",
      "type": "string",
      "enum": [
        "agent.message.sent",
        "agent.tool.invoked",
        "agent.tool.completed",
        "agent.handoff.delegated",
        "agent.consent.affirmed",
        "passport.key.rotated"
      ]
    },
    "issuer": {
      "description": "DID of the entity signing this event. MUST resolve to a DID Document with at least one verificationMethod whose id matches `proof.verificationMethod`.",
      "type": "string",
      "pattern": "^did:[a-z0-9]+:.+$"
    },
    "subject": {
      "description": "DID the event is about. May equal `issuer`. For agent-to-agent events (e.g. `agent.handoff.delegated`) this is the agent receiving the action.",
      "type": "string",
      "pattern": "^did:[a-z0-9]+:.+$"
    },
    "ts": {
      "description": "Event timestamp, RFC-3339 UTC, millisecond precision (per §4.3, MUST be the runtime checkpoint time, NOT callback wall-clock — to avoid signature/trace desync under async streaming).",
      "type": "string",
      "format": "date-time",
      "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}\\.\\d{3}Z$"
    },
    "ctx": {
      "description": "Event-type-specific context. See §4.2 for required keys per type. Keys MUST be sorted lexicographically before canonicalisation.",
      "type": "object"
    },
    "prev": {
      "description": "SHA-256 hash of the prior event's canonical bytes (32 hex chars × 2 = 64), or null for the first event in a chain.",
      "oneOf": [
        { "type": "null" },
        { "type": "string", "pattern": "^[0-9a-f]{64}$" }
      ]
    },
    "nonce": {
      "description": "128-bit cryptographically random nonce (32 lowercase hex chars). Prevents replay across distinct events with otherwise-identical contents.",
      "type": "string",
      "pattern": "^[0-9a-f]{32}$"
    },
    "proof": { "$ref": "#/$defs/Proof" }
  },
  "$defs": {
    "Proof": {
      "title": "Ed25519Signature2020 proof",
      "type": "object",
      "required": ["type", "created", "verificationMethod", "proofPurpose", "proofValue"],
      "additionalProperties": false,
      "properties": {
        "type": {
          "description": "Signature suite. v0.1 supports Ed25519Signature2020 only. EcdsaSecp256k1 + JsonWebKey2020 land in v0.2.",
          "const": "Ed25519Signature2020"
        },
        "created": {
          "description": "Same value as outer `ts` — repeated here for compatibility with W3C VC Data Integrity 2.0.",
          "type": "string",
          "format": "date-time"
        },
        "verificationMethod": {
          "description": "URI identifying the key used to sign. MUST be present in the issuer's DID Document. Format: <DID>#<keyId>.",
          "type": "string",
          "pattern": "^did:[a-z0-9]+:[^#]+#[A-Za-z0-9_-]+$"
        },
        "proofPurpose": {
          "description": "Per W3C VC Data Integrity. v0.1 only accepts `assertionMethod`.",
          "const": "assertionMethod"
        },
        "proofValue": {
          "description": "Multibase-encoded signature. MUST be base58btc (`z` prefix) and decode to exactly 64 bytes (Ed25519 signature length).",
          "type": "string",
          "pattern": "^z[1-9A-HJ-NP-Za-km-z]+$"
        }
      }
    }
  }
}