Issue an x402 offer-receipt (EIP-712) plus a Tersign action record for a payment that has ALREADY settled, and counter-sign both into your hash chain when a ledger is configured. Use this for money that moved; use record_disclosure for a non-payment agent action. Side effects: signs with TERSIGN_SELLER_KEY, and performs ONE network write to the ledger when TERSIGN_LEDGER_URL/_API_KEY/_SELLER_ID are set (without them it signs locally and returns an unchained artifact). Returns the signed receipt artifact, its keccak256 canonical digest, and — when chained — the ledger counter-signature and sequence number.

Verify an offer-receipt artifact: recover the EIP-712 signature and confirm the payload digest binds to it. Fully OFFLINE — no network, no API key, no account; verifying someone else's receipt is the intended use. Use this for a receipt (money); use verify_compliance_record for an action record (a non-payment action). Returns { valid, signer, digest } and, when expectedSigner is supplied and does not match, valid:false with the recovered signer so you can see who actually signed.

One-call disclosure evidence (EU AI Act Art 50 dialect): digests the disclosure text LOCALLY, signs an action record with your key, and the public ledger counter-signs it into your per-signer hash chain. No API key needed — first call self-provisions a free signer-keyed account.

Verify a Tersign action record against its attestation: recompute the record's canonical digest, confirm the attestation commits to that exact digest, and recover the signature. Fully OFFLINE — no network, no API key, no account. Use this for an action record (a disclosure or other non-payment agent action); use verify_receipt for a payment receipt. PASS proves integrity and internal consistency only. Authorship needs an out-of-band signer address: pass expectedSigner, or the identity is whatever the artifact claims about itself. Returns { valid, signer, digest }; on mismatch, valid:false plus the recovered signer and the recomputed digest.

Record a refund against an already-chained receipt, as the SELLER. The refund becomes its own counter-signed entry that references the original — nothing is edited or deleted, so the chain stays append-only and both the charge and the refund remain visible. Requires ledger configuration (TERSIGN_LEDGER_URL/_API_KEY/_SELLER_ID) and performs one network write; errors if the original digest is not on your chain. This RECORDS a refund you have already made — it moves no money. Returns the refund record, its digest, the ledger counter-signature and sequence number.

Open an objective dispute against a counter-signed receipt as the PAYER (the configured key must be the receipt payer). Reasons: not_delivered, wrong_content, duplicate_charge. Contested non-mechanical claims escalate to the arbiter; duplicate_charge is decided instantly from ledger arithmetic.

Submit signed evidence to an open dispute. Claimant evidence must be signed by the payer key; respondent evidence additionally requires the seller API key (TERSIGN_LEDGER_API_KEY).

Trigger deterministic adjudication of an open dispute. The v0 rulebook is public and the verdict is recomputable by anyone from the chain — no discretion, no model in the loop. Side effects: writes a verdict entry, and a refund verdict automatically creates the corresponding refund record. Adjudicating twice is not meaningful; the first verdict stands. Returns the verdict, the rationale naming the rule applied, and the ledger signature over both.

Fetch a dispute in full: its state, both sides' evidence references, the verdict and rationale once adjudicated, and the ledger signature over the record. Read-only — one network read, no key required, and safe to poll while a dispute is open.