x402 duplicate-grant guard
x402 duplicate-grant guard: derive the canonical idempotency key from (payment_nonce, resource), analyze supplied settlement txs, and return a verdict + recommended action (stateless key derivation, or stateful allow/reject/replay-cache against supplied seen_keys). Cites duplicate-grant Attack II (arXiv:2605.11781). Ed25519-signed.
Answeringour last check, 2026-10-20
1 of 1checks answered this week
269 msmedian answer time
$0.01listed price per call
$0.01price it asked us
Paid test badge: not yet. The checks above are free: we call the tool without paying and read the payment request it sends back. The Verified badge needs paid calls whose answers match the promised output, and nobody can buy a badge.
Endpoint
POST https://agents.daedalusdevelopmentgroup.com/v1/x402/dup-guard
| Category | Everything else |
|---|---|
| Provider host | agents.daedalusdevelopmentgroup.com |
| Networks | eip155:8453 |
| Payment schemes | exact |
| Self-reported calls, 30 days | 1 from 1 payers (the provider's figure, not ours) |
Our checks, last 30 days
| Day | Result | HTTP | Asked | Time |
|---|---|---|---|---|
| 2026-10-20 | valid payment request | 402 | $0.01 | 269 ms |
Example input (from the provider)
{
"body": {
"derived_key": "string",
"payment_nonce": "string",
"resource": "https://example.com",
"seen_keys": [
"string"
],
"settlement_txs": [
{}
]
},
"bodyType": "json",
"method": "POST",
"type": "http"
}
Promised output schema (from the provider)
{
"$schema": "https://json-schema.org/draft/2020-12/schema",
"properties": {
"input": {
"additionalProperties": true,
"properties": {
"body": {
"type": "object"
},
"bodyType": {
"enum": [
"json",
"form-data",
"text"
],
"type": "string"
},
"method": {
"enum": [
"POST",
"PUT",
"PATCH"
],
"type": "string"
},
"type": {
"const": "http",
"type": "string"
}
},
"required": [
"type",
"method",
"bodyType",
"body"
],
"type": "object"
},
"output": {
"additionalProperties": true,
"properties": {
"example": {
"ok": true
},
"type": {
"type": "string"
}
},
"required": [
"type",
"example"
],
"type": "object"
}
},
"required": [
"input",
"output"
],
"type": "object"
}