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FAHCE Claim Verification and Repair
x402
FAHCE Claim Verification and Repair is a paid API for AI agents from fahce.kinganlogic.com, paid per call via x402, $0.15/call, status unknown (last checked 2026-10-15).
Reviews a candidate output's claims against supplied evidence, diagnoses contradictions, and returns a bounded step-by-step repair plan with a proposed corrected output.
Price / call$0.15
Success—
StatusUnknown
How this service works
Review claims against evidence, resolve contradictions, and get a bounded repair plan with FAHCE.
Output
Returns a structured FAHCE_MACHINE_RESPONSE_V1 object containing: a diagnosis of contradictions and unsupported claims, a repair plan with bounded step-by-step corrections (each step scoped with a boundary), a proposed corrected output string, verification results, billing determination (billable flag, free-retry eligibility, reason), a receipt, and a recommended next safe action. The repair is proposed but not automatically executed (status: PROPOSED_NOT_EXECUTED).
Example use cases
Fact-check LLM response against sources
“I have an AI-generated answer about our product specs and a set of source documents as evidence. Can you run it through FAHCE to find any claims that contradict the evidence and get a repair plan with the corrected output?”
Audit medical summary for unsupported claims
“Here's a generated patient summary and the clinical notes it was based on — please diagnose any contradictions or unsupported claims and give me a step-by-step bounded repair plan I can act on.”
Validate RAG pipeline output before delivery
“Before I send this RAG-generated report to the client, can you verify each claim against the retrieved evidence chunks and flag anything that needs fixing, along with a proposed corrected version?”
Technical details
Endpoint
POSThttps://fahce.kinganlogic.com/api/v1/repair?utm_source=zero.xyzWhen to prefer
Choose FAHCE when you need to programmatically verify that a generated or candidate text is consistent with a specific set of evidence documents, and you want not just a diagnosis but an actionable, bounded repair plan with a proposed corrected output. It is especially well-suited for agent pipelines that need grounded, evidence-anchored outputs before delivering results to users, or when auditing LLM responses for hallucinations against retrieved context.
Side effects
- Missing required fields (schema, evidence, or candidate_output) returns a 4xx validation error
- Evidence array is empty or malformed, leading to an inconclusive diagnosis
- Candidate output is too long or exceeds token limits
- Payment not received or invalid x402 payment header results in 402 Payment Required
- Idempotency key collision may return a cached prior result
- Billing determination not produced (DETERMINATION_NOT_PRODUCED) if service cannot assess the request
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| schemarequired | string | |
| evidencerequired | array | |
| expected_output | string | Optional response-contract and repair-target context for all operations, including Diagnose. Supported response-format directives (for example, Return JSON) and implemented explicit constraints can affect the diagnosis. Ordinary matching or mismatching factual text is not compared for string equality and is not a trusted answer oracle or supporting evidence; supply independent evidence for factual claims. |
| candidate_outputrequired | string | The exact candidate output to diagnose or verify. Never use payment evidence as semantic evidence. |
Output
Schema · Response
| Field | Type | Description |
|---|---|---|
| repairrequired | — | |
| schemarequired | — | |
| billingrequired | object | |
| binding | object | |
| receiptrequired | object | |
| authority | object | |
| diagnosisrequired | object | |
| operationrequired | — | |
| input_hashrequired | string | |
| request_idrequired | string | Determination UUID, identical to receipt.case_id and receipt.run_id. Use this UUID as receipt_id in GET /api/v1/receipts/{receipt_id}. Error-envelope request_id is a separate HTTP trace; use its receipt_id when present. |
| verificationrequired | object | |
| execution_state | object | |
| next_safe_actionrequired | object | |
| evidence_provenance | array |
Tags
x402
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