X402 Permit2 Evidence Recomputer

Recomputes the Permit2 typed-data digest a payer’s wallet signs for an x402 payment, for the three single-item message shapes the exact and upto schemes use: a witness transfer that binds the destination, an unwitnessed signature transfer, and an allowance permit. Each type hash is derived at run time from its type string rather than carried as a transcribed constant. Against a caller-declared payment requirement it reports whether the spender is the pinned x402 proxy, whether the destination bound into the witness matches payTo, whether the token matches the asset, whether the chain matches the network, and whether the amount holds under the scheme rule, which is equality under exact and a ceiling under upto. Nonce facts stay in their own space: the unordered bitmap decomposition of the transfer shapes is never conflated with the sequential counter of the allowance shape, and an allowance expiration of zero is reported as lasting the current block only. Signature bytes are classified without recovery: length class, whether s sits above half the curve order, the recovery byte form including the raw parity case an on-chain call cannot use, and the counterfactual wrapper marker. HARD FENCE: this node reads no chain and recovers no signer. Nonce spend state, stored allowance and the current time are caller-declared inputs echoed back, an absent input reports NOT_EVALUATED rather than a pass, and nothing here originates, relays or submits a payment.