---
title: "Marks the nonce spent without naming what spent it — x402 defect class nonce-unbound-from-settlement"
description: "Marks the nonce spent without naming what spent it (nonce-unbound-from-settlement), an x402 defect class: A till that refuses an already-settled payment can name the settlement transaction that spent the authorization's nonce. Detectable by an paid probe. A buyer who paid and lost the response cannot be told apart from one who never paid. The seller can say 'spent' but not prove WHAT spent it, so honest recovery and fraud look identical — and any paid-retry lane (deliver again for the SAME settlement, charge nothing) has nothing to stand on. The money moved once; the proof of which movement is gone."
canonical: "https://scvd.store/defects/nonce-unbound-from-settlement"
url: "https://scvd.store/defects/nonce-unbound-from-settlement"
term_code: "nonce-unbound-from-settlement"
defined_in: "https://scvd.store/defects"
data: "https://scvd.store/defects.json"
vocabulary_version: "22"
license: "https://creativecommons.org/licenses/by/4.0/"
---

# Marks the nonce spent without naming what spent it

`nonce-unbound-from-settlement` — an x402 defect class.

Launch Check v4 compares complete response bytes. Transaction references alone do not establish redelivery; changed bytes alone do not establish fresh fulfillment. Historical v3 served_again and redelivered mappings were heuristics, and a fresh challenge alone proves no second charge. Read the report's battery, response evidence and payment_attempt.verification separately. The September 13 correction at /corrections withdraws the stronger interpretation; saved signed records retain their bytes.

**Asserts:** A till that refuses an already-settled payment can name the settlement transaction that spent the authorization's nonce.

**Costs:** A buyer who paid and lost the response cannot be told apart from one who never paid. The seller can say 'spent' but not prove WHAT spent it, so honest recovery and fraud look identical — and any paid-retry lane (deliver again for the SAME settlement, charge nothing) has nothing to stand on. The money moved once; the proof of which movement is gone.

**Detectable:** paid — only a settled payment reveals it

**Falsified by:** The door's replay refusal, or an equivalent receipt surface, producing the settlement transaction hash for the spent nonce at the stated moment.

**How an operator clears it:** Store the settlement transaction hash beside the nonce when you mark it spent, and return it on the replay refusal — one extra column, and a buyer's honest recovery becomes distinguishable from fraud.

**What a buyer does:** Keep the settlement transaction hash yourself, from your wallet or the facilitator's response, before you need it: this door cannot tell you what spent your nonce, so your honest recovery of a lost response rests on your own record.

**Our signal:** `this store's own replay refusals return the original settlement transaction (HTTP door since the paid-retry lane; MCP door since 2026-08-27 — it exhibited this class until that day's fix, found live by an outside reproduction, and that is recorded here rather than smoothed over).`

---

Vocabulary v22, CC BY 4.0. Every class: https://scvd.store/defects. Machine-readable, with falsifiers and cross-instrument mappings: https://scvd.store/defects.json.

A class describes a property of one endpoint at one moment and never accumulates into a judgment on an operator.