x402 Permit2 Spend Evidence Pack

Linear two-step evidence pipeline for the Permit2 asset-transfer method of an x402 exact or upto payment, the sibling of the EIP-3009 pipeline. The first step recomputes the Permit2 typed-data digest the payer signed and reports the binding, window, nonce-space and signature-form facts around it; the second step recovers the signer from that digest and reports whether the recovered address matches the claimed payer. The two outputs compose into an evidence pack a downstream agent or a human reads before relying on an authorization. This is an evidence bundle and never a settlement proof: no chain is read, nothing is submitted, and any fact whose input was not declared reports NOT_EVALUATED.

OpenChainGraph · 2 Steps compliance control Hash-Anchored §4 chain_depth:2 Client-Side · Zero PII

Chain Stages · 2 Steps

1 ROOT node

X402 Permit2 Evidence Recomputer art-699-x402-permit2-evidence-recomputer

recomputes the Permit2 digest bytes and emits handoff_591, which carries that digest with the claimed payer and the signature components in the shape the next step reads

MCP Call · recompute_x402_permit2_digest

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "recompute_x402_permit2_digest",
    "arguments": {}
  },
  "id": 1
}

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2 TERMINAL · D2 node

x402 Signer Recovery Verifier art-591-x402-signer-recovery-verifier

recovers the signer address from those digest bytes and reports the claimed-from match, which is the terminal fact in the assembled evidence pack

MCP Call · verify_x402_signer_recovery

{
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "name": "verify_x402_signer_recovery",
    "arguments": {}
  },
  "id": 1
}

Question: A payer sent me a Permit2 authorization for an x402 charge. Did the key I think owns that wallet actually sign these exact terms? Run the AINumbers MCP tool `run_chain` with {"chain":"x402-permit2-spend-evidence"} and read `art-591-x402-signer-recovery-verifier.recovered_signer_matches_claimed_from`. Re-run with `inputs` for `art-591-x402-signer-recovery-verifier`, reusing the values that result echoed, with `claimedFrom` changed so any other twenty byte address, which breaks the claimed payer match. Compare the same field. Verify: call `verify_execution_hash` (https://mcp.ainumbers.co/mcp) with `claimed_hash` set to `composite_execution_hash` and the full `composite_artifact`. Ledger, for a human re-check: https://ledger.ainumbers.co/ PII rule: send synthetic or anonymised inputs only. The MCP server runs these kernels and logs no payloads. Chain page: https://ainumbers.co/chaingraph/chains/x402-permit2-spend-evidence.html

x402 Permit2 Spend Evidence Pack

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