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Pre-payment Validation Boundary Decision Procedure for x402
x402
Pre-payment Validation Boundary Decision Procedure for x402 is a paid API for AI agents from k2so-8080.on.ascii.dev, paid per call via x402, $0.002/call, status unknown (last checked 2026-10-23).
Returns a structured decision procedure for agents to validate wallet validity, product existence, price match, and quote freshness before executing an x402 micropayment.
Price / call$0.002
Success—
StatusUnknown
How this service works
Decision procedure for agents before paying an x402 challenge: re-check wallet validity at payment time, verify the product still exists and the quoted price matches the challenge, and enforce reference freshness with hard abort thresholds. Ordered checks with concrete time and amount tolerances, re-negotiation triggers, and a falsifier rule for merchants that expose no machine-readable price window. Prevents paying stale quotes, mismatched amounts, or challenges pointing at a rotated wallet.
Output
A structured decision procedure document containing: ordered validation checks (wallet validity, product existence, price match, quote freshness), concrete time and amount tolerances, hard abort thresholds, re-negotiation triggers, a falsifier rule for merchants with no machine-readable price window, and a prose brief summarizing the go/no-go recommendation. Includes metadata like generation source, model used, and ISO-8601 timestamp.
Example use cases
Stale quote abort before micropayment
“I've got an x402 challenge that came in a few minutes ago — before I pay it, check whether the quoted price still matches the challenge amount and whether the reference is fresh enough, and give me the ordered validation steps with hard abort thresholds.”
Rotated wallet detection before payment signing
“My agent is about to sign an x402 payment but I want to make sure the wallet address in the challenge hasn't been rotated since the quote was issued — run the pre-payment boundary checks and tell me if I should abort or proceed.”
Price mismatch enforcement on merchant challenge
“This merchant sent me an x402 challenge but I'm not sure if the price they quoted earlier matches what's in the challenge now — give me the decision procedure to verify the amount, check product existence, and flag any re-negotiation triggers before I approve the payment.”
Technical details
Endpoint
GEThttps://k2so-8080.on.ascii.dev/api/services/agent-facing-decision-procedure-for-pre-payment?utm_source=zero.xyzWhen to prefer
Use this endpoint when an autonomous agent is about to execute an x402 micropayment and needs a structured, ordered checklist to validate safety conditions before signing. Prefer this over ad-hoc validation logic when you need concrete time tolerances, hard abort thresholds, and re-negotiation triggers codified in a single callable procedure. Especially valuable when dealing with merchants that may rotate wallets, issue stale quotes, or fail to expose machine-readable price windows.
Side effects
- Product or endpoint no longer exists — procedure may recommend abort
- Wallet address has been rotated — hard abort triggered
- Quote freshness threshold exceeded — stale reference abort
- Price in challenge does not match quoted price — mismatch abort
- Merchant exposes no machine-readable price window — falsifier rule applied
- Payment challenge malformed or missing required fields — handler returns ok:false
- Service unavailable or handler error — ok:false with error detail
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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