MCP & Agentic Commerce · T629 · x402 VPSF claim algebra

VPSF Claim Algebra Verifier

Paste one or more x402 Payment Claims (PaymentIntent, SettlementReceipt, RefundClaim, DelegationGrant) and a VPSF composite built over them, then verify the composite structurally against draft-vauban-x402-vpsf-algebra-01: the five composition operators (Conjunction ∧, Implication →, Aggregation ⊕, Selective Disclosure ▷, Revocation ¬), each operator's JCS preimage rule, and the same-subject preimage discipline. The tool recomputes every JCS Preimage Hash (SHA-256 over the RFC 8785 canonical form) rather than trusting a hash it is handed, resolves component references against the claims you supply, and rejects anything it cannot resolve.

⚠ This is a structural verifier only. It checks preimage well-formedness, hash recomputation, and the operator/subject rules the draft states; it does NOT verify a STARK proof, a signature, or any other cryptographic evidence attached to a component Claim (draft §6.2: proof-system verification is an optional enhancement, not required for algebra conformance). A PASS means the composite is internally consistent with the claims you supplied and the algebra's own rules; it says nothing about whether those claims' evidence fields are themselves valid.
x402 VPSF RFC 8785 JCS Zero PII Client-Side
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1 · Claims manifest (JSON array)
Each entry needs a claim_type (one of PaymentIntent, SettlementReceipt, RefundClaim, DelegationGrant, per §3.2) plus the claim's own fields. Its JCS Preimage Hash is recomputed from the entry as given (minus claim_type, which is this tool's own bookkeeping field, not part of the draft's preimage). A composite operand referencing a hash not resolvable against this manifest, or against an inline nested composite, is UNVERIFIABLE and rejected (§4.4.3).
2 · Composite (JSON: an operator node, operands may be a manifest claim's claim_type+object inline, a nested composite, or a bare "sha256:..." hash string to resolve)
Operator shapes per draft §4: conjunction {left,right,issued_at}; implication {antecedent,consequent,issued_at}; aggregation {operands:[...],currency,total_amount,issued_at}; selective_disclosure {source,disclosed_fields,issued_at} (withheld_commitment is recomputed, not trusted from input); revocation {target,reason,revoked_at,issued_at}.
Self-test · 11 pinned conformance vectors (JCS hash reproduction)
The published VPSF conformance vector suite (x402-stark-receipts-conformance, commit c2a27dee, 11 vectors) does not itself exercise the five composition operators; it covers JCS canonicalisation discipline and the DelegationGrant/SettlementReceipt claim shape. Run below reproduces each vector's own pinned SHA-256 digest from its receipt_core / delegation_grant / settlement_receipt / preimage object using this tool's own JCS pipeline (RFC 8785, ported verbatim from chaingraph/kernels/_hash.mjs's cgCanon), proving the hash primitive this tool applies to every operator preimage above is the byte-correct one, independent of the operator logic itself.