SafeGate × nsgoods: two-sided verified paid commerce evidence on Base

A live, self-funded Base Mainnet run combining an x402-paid nsgoods sanctions verdict with SafeGate payment binding, fee collection, a signed CommerceProof and durable evidence delivery.

The pattern

nsgoods produces signed evidence about a screened address. SafeGate retains that response byte-for-byte, binds its hash and request identity into the commerce flow, verifies the relevant on-chain payments, and produces signed evidence about what it observed. The systems remain independent: nsgoods does not custody the merchant payment or SafeGate fee, and SafeGate does not rewrite the nsgoods verdict.

What was actually measured

This was one real production-path run on Base Mainnet on 25 September 2026. It used real USDC and completed end to end. It was self-funded, so it is not claimed as external customer revenue.

Two-sided verification

After the run, SafeGate sent nsgoods the exact retained verdict file without re-serialising or editing it. nsgoods independently checked the file on its side and confirmed all of the following:

• SHA-256 is cd88b53f10d143e38a68924c43a7d005255d5d471a6515712423166ec519c657.
• The file is exactly 1997 bytes, matching the server response for the paid call at 16:20:38Z.
• The EIP-191 signature recovers to 0x57fF0F084Cba33e6761503f90eEF0Da9F159350c.
• The signed body contains SG-EVM-REQ-NSGOODS-LIVE-64C85854050C4B7B855D4530.
• The retained file is byte-for-byte canonical; changing the verdict breaks the signature.

Result: the nsgoods verdict referenced by the SafeGate evidence is the exact verdict nsgoods issued and signed for this paid request, verified independently from both sides.

The binding

• Request: the same request_id appears inside the signed nsgoods body and the SafeGate flow. Bound.
• Bytes: the SafeGate-retained SHA-256 matches the exact nsgoods canonical response bytes. Bound.
• Signer: the verdict signature independently recovers to the published nsgoods signer. Verified.
• Economics: screening, SafeGate service fee and merchant payment are separate on-chain payments with separate roles. Separated.
• Outcome: SafeGate produced a signed CommerceProof and persisted paid evidence with explicit OBSERVED assurance. Delivered.

What this does and does not claim

• Sanctions evidence is negative evidence, not an allow decision. A clean verdict means the exact address was not in the OFAC SDN snapshot at the time stated by the signed response. In this run the per-list breakdown also reported no match on all four lists (OFAC, UN, EU, UK OFSI). It is not a safety rating or legal advice.
• SafeGate assurance is explicit. OBSERVED with commerce_verified=false does not claim independently validated merchant delivery.
• This run was self-funded. The 0.07 USDC SafeGate fee proved that the production fee path works; it is not represented as independent customer revenue.
• External buyer readiness is separate from this proof. After this run, SafeGate removed the fixed pilot-payer restriction from the authenticated production intent route. An independent customer transaction is the next commercial milestone and is not claimed here.

Why this matters

Payment proves that money moved. This pattern adds a portable evidence chain showing which signed screening record was used, which request it belonged to, which on-chain payments were observed, and which assurance level SafeGate is willing to state. Each party signs only what it actually knows, and the records remain independently verifiable.