AGENTICRAIL ENFORCEMENT SPECIFICATION v1.1
DATE: 2026-06-07 (amends v1.0, 2026-05-17)
ENTITY: TUARA KURI LIMITED

AMENDMENT: v1.1 records the activation of Ed25519 receipt signing and the
publication of the verification public key. The receipt schema, canonicalization,
pack_id derivation, and chain linkage are UNCHANGED from v1.0. Only the active
signature algorithm and key_id change. Receipts issued before 2026-06-07 remain
HMAC-SHA256 under k1_2026-02-22_01 and are unaffected; the verifier selects key
and algorithm per receipt by key_id, so chains spanning the cutover verify intact.

DECISIONS: ALLOW, DENY, HALT

ENFORCEMENT RULES:
1. Unknown function -> DENY
2. action_type not permitted for function -> DENY
3. step !== function name -> DENY
4. Sequence already sealed -> DENY:SEALED_SEQUENCE
5. Nonce already used -> DENY:REPLAY_NONCE
6. Step out of order -> DENY:SEQUENCE_VIOLATION
7. Timestamp stale (|ts_ms - now| > 300s) -> DENY:STALE_TIMESTAMP
8. All pass -> ALLOW

MSMD SPINE: intake,disruption,instability,state_read,internal_driver,execution,boundary,settle
HOKIANGA SPINE: dialect_request,hapuu_identity,corpus_query,provenance_token,compression_check,kaitiaki_gate,output_authorised,settle

ALLOW RECEIPT FIELDS: action,action_type,attestation,decision,function,key_id,nonce,pack_id,payload_hash,prev_receipt_id,schema_version,sequence_id,signature,step,ts_ms

DENY RECEIPT FIELDS: decision,denial_code,expected_step,function,nonce,pack_id,sequence_id,signature,step,ts_ms

DENIAL CODES: POLICY_VIOLATION,REPLAY_NONCE,SEALED_SEQUENCE,SEQUENCE_VIOLATION,STALE_TIMESTAMP

PACK_ID: SHA-256 of canonical JSON (alphabetically sorted keys)
PREV_RECEIPT_ID: SHA-256 of previous receipt (chain linkage)
PAYLOAD_HASH: SHA-256 of raw request body
SIGNATURE: Ed25519 over canonical JSON (receipt minus signature field), base64-encoded
           (legacy receipts before 2026-06-07: HMAC-SHA256, hex-encoded)
KEY_ID: k2_2026-06-07_ed25519 (active, Ed25519); k1_2026-02-22_01 (legacy, HMAC)

PUBLIC KEYS: agenticrail.nz/spec/receipt-public-keys.json (Ed25519 - offline-verifiable by anyone)
VERIFICATION: report.agenticrail.nz (no login, no operator required)