{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "https://alxprotocol.com/protocol/1/schemas/defs.schema.json",
  "title": "ALX Shared Schema Definitions",
  "$comment": "Shared structural definitions only. These definitions do not verify cryptographic derivation, graph semantics, signature validity, or trace truth.",
  "$defs": {
    "hash": {
      "type": "string",
      "pattern": "^0x[a-f0-9]{64}$",
      "description": "A v1 domain-separated Keccak-256 protocol digest. 0x-prefixed, 64-character lowercase hex."
    },
    "definitionLevel": {
      "type": "string",
      "enum": ["opaque", "typed", "indexed", "schema-bound", "conformance-bound"],
      "description": "Content definition tier for a content envelope, from opaque (no structure) to conformance-bound (schema-validated with a named conformance profile)."
    },
    "contentType": {
      "type": "string",
      "pattern": "^[a-z][a-z0-9]*(\\.[a-z][a-z0-9-]*)+$",
      "maxLength": 256,
      "description": "Dot-delimited lower-case content type identifier."
    },
    "semver": {
      "type": "string",
      "pattern": "^(0|[1-9][0-9]*)\\.(0|[1-9][0-9]*)\\.(0|[1-9][0-9]*)(?:-[0-9A-Za-z.-]+)?(?:\\+[0-9A-Za-z.-]+)?$",
      "description": "Semantic version string."
    },
    "parentHashes": {
      "type": "array",
      "items": {
        "$ref": "#/$defs/hash"
      },
      "uniqueItems": true,
      "maxItems": 256,
      "description": "Declared upstream Block identities, bound into blockHash. Must be sorted and deduplicated; ordering is enforced by the protocol implementation."
    },
    "graphValidationStatus": {
      "type": "string",
      "enum": ["valid", "invalid", "incomplete", "resource_limit_reached"],
      "description": "Normative outcome of an attempted Graph validation. not_checked is intentionally excluded; use checked=false when validation was not performed."
    },
    "attestation": {
      "type": "object",
      "description": "Cryptographic claim over the canonical ALX-ATTESTATION-V1 payload. Signing is external to Block identity and does not affect blockHash computation.",
      "properties": {
        "blockHash": {
          "$ref": "#/$defs/hash"
        },
        "attester": {
          "type": "string",
          "minLength": 1
        },
        "algorithm": {
          "type": "string",
          "minLength": 1
        },
        "timestamp": {
          "type": "integer",
          "minimum": 0,
          "maximum": 9007199254740991
        },
        "signature": {
          "type": "string",
          "minLength": 1
        }
      },
      "required": [
        "blockHash",
        "attester",
        "algorithm",
        "timestamp",
        "signature"
      ],
      "additionalProperties": false
    },
    "error": {
      "type": "object",
      "description": "Structured error or warning from a protocol operation, identified by a stable ALX error code.",
      "properties": {
        "code": {
          "type": "string",
          "pattern": "^ALX_[A-Z0-9_]+$"
        },
        "message": {
          "type": "string",
          "minLength": 1,
          "maxLength": 1024
        }
      },
      "required": ["code", "message"],
      "additionalProperties": false
    }
  }
}