{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://opencontextprotocol.org/schemas/v0.1/evidence-entry.schema.json",
  "title": "OCP Part 4 — Evidence chain entry",
  "type": "object",
  "required": [
    "timestamp", "agent_id", "tool", "input_hash", "output_tokens",
    "role", "event_type", "prev_hash", "entry_hash"
  ],
  "properties": {
    "timestamp": {
      "type": "string",
      "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(\\.\\d+)?([+-]\\d{2}:\\d{2}|Z)$"
    },
    "agent_id": { "type": "string", "minLength": 1 },
    "tool": { "type": "string", "minLength": 1 },
    "action": { "type": ["string", "null"] },
    "input_hash": { "$ref": "#/$defs/sha256hex" },
    "output_tokens": { "type": "integer", "minimum": 0 },
    "role": { "type": "string", "minLength": 1 },
    "event_type": {
      "type": "string",
      "oneOf": [
        {
          "enum": [
            "tool_call", "tool_denied", "path_jail_violation",
            "budget_exceeded", "cross_project_access", "rate_limited",
            "security_violation", "role_changed", "secret_detected",
            "agent_registered", "agent_suspended", "agent_resumed",
            "agent_decommissioned"
          ]
        },
        { "pattern": "^x-[a-z][a-z0-9_]*$" }
      ]
    },
    "prev_hash": {
      "oneOf": [
        { "const": "genesis" },
        { "$ref": "#/$defs/sha256hex" }
      ]
    },
    "entry_hash": { "$ref": "#/$defs/sha256hex" },
    "signature": { "$ref": "#/$defs/ed25519hex" }
  },
  "additionalProperties": false,
  "$defs": {
    "sha256hex": { "type": "string", "pattern": "^[0-9a-f]{64}$" },
    "ed25519hex": { "type": "string", "pattern": "^[0-9a-f]{128}$" }
  }
}