{
  "schema": "PSI-SEAL/1.0.0",
  "title": "APEX PSI Canonical Seal Schema",
  "copyright": "© 2026 APEX Infrastructure — PSI-SEAL/1 canonical seal schema. All rights reserved.",
  "status": "normative",
  "canonicalization": "RFC 8785 (JCS)",
  "hash": "SHA-256",
  "signature_suite": [
    "Ed25519",
    "LMS-W4-SHA256 (NIST SP 800-208)"
  ],
  "licensing": {
    "model": "dual",
    "verifier": {
      "license": "MIT",
      "package": "@apex/psi-verifier",
      "terms": "Free forever, for everyone, no permission required.",
      "version": "1.1.1",
      "packages": [
        "@apex/psi-verifier (npm)",
        "psi-verifier (PyPI)"
      ],
      "enforcement": "Enforced by default from v1.1.0: non-conformant seals are rejected, not merely reported. Legacy override: enforce=false.",
      "digest_parity": "TypeScript and Python distributions compute an identical schema digest.",
      "text_parity": "From v1.1.1 both distributions emit byte-identical rejection text with readable rule citations (e.g. PSI-SEAL v1.1.1 REJECT: schema_digest mismatch — rule 4.2)."
    },
    "generator": {
      "license": "APEX PSI Sealing Engine Licence v1",
      "url": "https://ai-governance-standard.com/license",
      "personal_use": "free",
      "commercial_use": "PSI-05 royalty terms",
      "acceptance": "click-through at point of use",
      "seal_url": "https://ai-governance-standard.com/seal"
    },
    "stewardship": "APEX PSI Foundation (in formation) — perpetual; verification remains MIT forever."
  },
  "field_order": [
    "schema",
    "schema_digest",
    "sealed_at",
    "subject",
    "hash",
    "merkle",
    "signature",
    "licence"
  ],
  "rules": [
    "R1  Envelope serialisation: RFC 8785 JSON Canonicalization Scheme (JCS), UTF-8, no BOM.",
    "R2  Field set is closed. Unknown top-level fields render a seal non-conformant.",
    "R3  Field order in the emitted receipt: schema, schema_digest, sealed_at, subject, hash, merkle, signature, licence.",
    "R4  Digests: lowercase hexadecimal, exactly 64 characters, no 'sha256:' prefix inside the envelope.",
    "R5  Hash algorithm: SHA-256 over the raw octet stream of the subject; no transport encoding, no trailing padding.",
    "R6  sealed_at: RFC 3339 UTC with exactly three fractional digits and a literal 'Z' (e.g. 2026-08-17T09:00:00.000Z).",
    "R7  subject.size_bytes: non-negative integer, exact octet length. subject.name: NFC-normalised UTF-8 string.",
    "R8  Merkle assembly: binary tree over leaf digests in submission order; each parent = SHA-256(left_bytes || right_bytes) over 32-byte raw digests; an odd node is promoted, never duplicated.",
    "R9  merkle.leaf = SHA-256 of the ASCII string 'PSI1:' || hash. Domain separation is mandatory.",
    "R10 seal_hash = SHA-256(JCS(envelope minus the signature and licence members)).",
    "R11 Signature suite: Ed25519 over the ASCII seal_hash; optional hybrid post-quantum LMS-W4-SHA256 (NIST SP 800-208).",
    "R12 Every seal MUST carry schema and schema_digest. Only schema-conformant seals are considered PSI-compliant."
  ],
  "conformance": "Only schema-conformant seals are considered PSI-compliant. Outputs that deviate from this specification fail verification even if functionally similar.",
  "disclaimer": "Seals are deterministic mathematical statements about byte state and time. They are never a personal certification or a statement of fact about the sealed content.",
  "spec_page": "https://ai-governance-standard.com/spec",
  "license_page": "https://ai-governance-standard.com/license",
  "conformance_enforcement": {
    "default": "reject",
    "error_code": "PSI_SEAL_INVALID",
    "remediation_url": "https://ai-governance-standard.com/seal",
    "override": "verify(seal, { enforce: false }) / verify(seal, enforce=False) — legacy data only"
  }
}