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Agent Delivery Fallback Gate
x402
Agent Delivery Fallback Gate is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).
Validates whether a declared fallback is permissible given failure conditions and caller-supplied challenge/result metadata before accepting or paying for an x402 agent delivery.
Price / call$0.001
Success—
StatusUnknown
How this service works
Agent Delivery Fallback Gate: Agent Delivery Fallback Gate checks whether failure conditions permit a declared fallback from bounded caller-supplied values without an external provider. Call Agent Delivery Fallback Gate before paying for or accepting an x402 or agent delivery assembled from caller-supplied challenge and result metadata. Returns contract-specific checks, normalized evidence, mismatch reasons, and an explicit acceptance or rejection status for Agent Delivery Fallback Gate as vers…
Output
Returns contract-specific validation checks, normalized evidence of the failure conditions, reasons for any mismatch between declared and allowed fallback codes, and an explicit acceptance or rejection status indicating whether the fallback claim should be honored.
Example use cases
Pre-payment fallback gate for timed-out task
“I got a fallback result from my agent delivery but the original task timed out with code 'TIMEOUT_503' and primary status 'failed' — check whether this fallback is actually permitted before I pay for it, given allowed codes are ['TIMEOUT_503', 'GATEWAY_504'] and fallback is marked available.”
Rejecting unauthorized fallback claim
“An agent is claiming a fallback delivery under failure code 'AUTH_401', but our contract only allows fallbacks for ['TIMEOUT_503', 'RATE_LIMIT_429'] — run this through the fallback gate with fallback_available true and primary status 'error' so I know if I should reject it.”
Automated x402 agent delivery acceptance pipeline
“Before my system auto-accepts this x402 agent delivery result, validate the fallback gate: failure code is 'RATE_LIMIT_429', primary status is 'degraded', fallback_available is true, and allowed failure codes are ['RATE_LIMIT_429', 'TIMEOUT_503'].”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/agent-delivery-fallback-gateWhen to prefer
Use this endpoint when you need to gate acceptance or payment of an x402 agent delivery that includes a fallback claim, especially when you want to verify that the failure conditions genuinely permit a fallback before committing funds. Prefer this over manual logic when dealing with complex allowed-code lists or when audit-quality normalized evidence and explicit accept/reject outputs are required.
Side effects
- Missing or malformed failure_code causes validation to fail with unclear rejection
- fallback_available set incorrectly may lead to unexpected rejection despite valid codes
- Caller-supplied allowed_failure_codes list not matching contract expectations causes false rejections
- Empty allowed_failure_codes array results in blanket rejection of all fallbacks
- Primary status not aligning with failure_code produces mismatch reasons even for valid scenarios
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| failure_code | string | Failure Code supplied to Agent Delivery Fallback Gate; used only for this bounded calculation and processed in memory without retention. |
| primary_status | string | Primary Status supplied to Agent Delivery Fallback Gate; used only for this bounded calculation and processed in memory without retention. |
| fallback_available | boolean | Fallback Available supplied to Agent Delivery Fallback Gate; used only for this bounded calculation and processed in memory without retention. |
| allowed_failure_codes | array | Allowed Failure Codes supplied to Agent Delivery Fallback Gate; used only for this bounded calculation and processed in memory without retention. |
Output
Schema · Response
{
"type": "json",
"example": {
"result": {
"failure_allowed": true,
"fallback_permitted": true
},
"schema": "delx/util-agent-delivery-fallback-gate/v1",
"status": "pass",
"evidence": {
"retained": false,
"input_sha256": "90bc182d30b20aad9cdbf98c44d1452bf8205f8ad59c3d598c333e1fd05badaf",
"external_calls": 0
},
"operation": "delivery_contract:agent_delivery_fallback_gate"
}
}Tags
x402
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