# FAHCE for Machines
Give FAHCE a candidate answer and the evidence available to your agent. FAHCE identifies unsupported claims, contradictory records, missing proof and reported actions not established by the submitted evidence. Receive a structured determination, proposed corrections when appropriate, verification state and a content-hashed receipt.
Version: 1.4.0
Machine facts: https://fahce.kinganlogic.com/capabilities/machines.json
Schemas: https://fahce.kinganlogic.com/openapi.json
Capabilities: https://fahce.kinganlogic.com/capabilities
MCP: https://fahce.kinganlogic.com/mcp
API catalog: https://fahce.kinganlogic.com/.well-known/api-catalog

## Use FAHCE when
- candidate claims exceed supplied evidence
- evidence contradicts a candidate answer
- a repaired answer needs an evidence-bound verification receipt

## Operations
- Diagnose: POST https://fahce.kinganlogic.com/api/v1/diagnose
  Check an AI-generated answer against supplied evidence. Identify unsupported claims, contradictions, missing proof, and reported actions that the available records do not establish.
  Use when: You need to understand what the supplied evidence establishes.
  Published price: $0.15 fixed, x402 exact. Actual settlement: $0.15 fixed.
- Repair: POST https://fahce.kinganlogic.com/api/v1/repair
  Evaluate an integrity problem and return a bounded, evidence-preserving correction plan when supported. Proposed corrections are not executed in the customer's systems.
  Use when: An identified deficiency needs a scoped correction with prerequisites and protected evidence.
  Published price: $0.15 fixed, x402 exact. Actual settlement: $0.15 fixed.
- Verify: POST https://fahce.kinganlogic.com/api/v1/verify
  Recheck a submitted or revised answer against supplied evidence. Return a scoped verification determination and content-hashed receipt without claiming independent external execution.
  Use when: A claimed fix or completed action needs evidence-bound review.
  Published price: $0.15 fixed, x402 exact. Actual settlement: $0.15 fixed.
- Repair Bundle: POST https://fahce.kinganlogic.com/api/v1/repair-bundle
  Receive diagnosis, a bounded proposed repair when required, verification state, and a receipt in one paid response. Authorize up to $0.39; eligible outcomes may settle at $0, $0.15, or $0.39.
  Use when: You need the connected diagnosis, proposed correction and current verification state in one determination.
  Published price: $0.39 maximum authorization, x402 upto. Actual settlement: $0.15 without repair required; $0.39 with repair required.

## Access and transactions
Paid commercial REST calls use wallet-only x402; gateway-verified PAYMENT-CONTEXT grants a machine-only principal. No pilot key or account setup. A pilot key alone never authorizes a commercial machine operation. Independently authenticated human and owner routes remain separate; cookie mutations require same-origin Origin.
Request headers: Content-Type: application/json; optional Idempotency-Key: <8-to-128-URL-safe-characters>. After HTTP402, retry unchanged with PAYMENT-SIGNATURE from an x402 v2 wallet client; no API key or prior account.
Request schema: FAHCE_MACHINE_REQUEST_V1. See OpenAPI for required candidate_output and evidence fields.
An authorization executes at most once. Repeating it returns a distinct 409; recover the saved result with the scoped credential. Optional keys bind unchanged input and a single authorization. Changed input or a new authorization conflicts with a reused key. Receipt recovery performs no determination.
Payment availability: {"source":"SERVER_MACHINE_PAID_ACCEPTANCE_ENABLED_NOT_SETTLEMENT_PROOF","gateway_enabled":true,"paid_settlement_enabled":true,"deployed_payment_verified":false,"activation":"ORIGIN_ACCEPTANCE_ENABLED","paid_access":"ORIGIN_ACCEPTANCE_ENABLED_GATEWAY_VERIFICATION_PENDING","payment_status":"origin_acceptance_enabled_gateway_verification_pending","pricing_status":"origin_acceptance_enabled_gateway_verification_pending"}
Legal publication: {"status":"PUBLISHED_OWNER_APPROVED","publication_hash":"1deba60d2149bae8aeb057a8198f044602a6a6bb4ee20e9d41dece64c87b2ea5","approved_at":"2026-10-14T05:56:09.873Z","urls":{"terms":"https://fahce.kinganlogic.com/legal/terms","refunds":"https://fahce.kinganlogic.com/legal/refunds","privacy":"https://fahce.kinganlogic.com/legal/privacy","acceptable-use":"https://fahce.kinganlogic.com/legal/acceptable-use","data-handling":"https://fahce.kinganlogic.com/legal/data-handling","security":"https://fahce.kinganlogic.com/legal/security"},"acceptance":{"header":"FAHCE-Terms-Accepted","value":"1deba60d2149bae8aeb057a8198f044602a6a6bb4ee20e9d41dece64c87b2ea5","notice":"Review these policies before payment; the authorized customer or its agent accepts this exact published version by sending this header on the purchase request."},"company":{"legal_entity":"Max R.O.I. LLC","operating_brand":"Kingan Logic","entity_type":"Alabama domestic limited liability company","entity_id":"001-160-677","formation_date":"2024-10-29","formation_state":"Alabama, United States","website":"https://kinganlogic.com","contact":"logan@kinganlogic.com","registry":"https://www.sos.alabama.gov/government-records/business-entity-records","identity_provenance":"Founder-provided company facts and September 22, 2026 Alabama certificate of existence reference"},"liability_cap":"GREATER_OF_USD100_OR_PRIOR_12_MONTH_CUSTOMER_FEES;MANDATORY_EXCEPTIONS"}
Paid settlement: origin acceptance enabled; four paid-path purchase successes demonstrated.
Pricing: https://fahce.kinganlogic.com/pricing. Published service prices: Diagnose, Repair and Verify are $0.15 fixed each ($0.45 for three separate billable calls). Bundle HTTP 402 requests a $0.39 maximum authorization even when actual eligible settlement is $0 for nonbillable free retry, $0.15 for verified no-repair work, or $0.39 for a required validated bounded plan. Held/invalid plans and unsupported processing are nonbillable; completed negative Verify is a billable determination; gateway exact-scheme charging on errors remains unverified. A bundle reports the supplied answer's state; a revised answer requires another submission. Confirmed receiving account: 0x22cf7241E3e24ed0d22d710C86a497084da625cd, USDC on Base (8453), receiving only. Paid-path HTTP 200 purchase acceptance has been demonstrated for all four operations. Independent transfer reconciliation remains separate.
request the operation; read the gateway's HTTP 402 PAYMENT-REQUIRED; authorize payment with an x402 v2 client; retry the same bound request using PAYMENT-SIGNATURE. No pilot key, invitation or prior account is required. The verified payment creates a machine-only principal for this operation. Before authorizing payment, review the published policies and send FAHCE-Terms-Accepted with their legal_documents.publication_hash on the bound request. Retain the random FAHCE-Recovery-Token for free recovery. It authorizes only this purchase's retained output and is not a refund or execution credential. If the first response is lost before the token arrives, original-purchase evidence must be verified separately; do not buy again automatically. The origin verifies the gateway-signed PAYMENT-CONTEXT; PAYMENT-SETTLEMENT is an origin-to-gateway instruction for upto only. Exact responses omit that instruction. The gateway returns PAYMENT-RESPONSE after settlement. Origin delivery intents are not charge receipts. Paid MCP execution uses the REST URLs.
Read an existing response: GET https://fahce.kinganlogic.com/api/v1/receipts/{receipt_id}

## Evidence boundaries
Only the evidence supplied by the caller is reviewed; no independent web retrieval is performed.
Unestablished claims remain UNVERIFIED or held; an unsupported operator cannot establish a clear result.
A proposed plan is not an executed repair. Verification reviews the separately submitted revised answer.
Content hashes bind the response; they are not a public-key signature, certification, trusted timestamp, or proof of external execution.
Payment authorizes service access; it does not establish claim correctness, external execution or permission to act.
For a completed determination, response.request_id is the receipt_id UUID and equals receipt.case_id and receipt.run_id. Error-envelope request_id is an HTTP trace; use error.receipt_id when present. Each receipt binds input/evidence hashes, engine version and response hash. Supply prior-case context as evidence text; this contract does not automatically load a human case or prior repair. Immutable origin charge fields remain null. Retain the gateway PAYMENT-RESPONSE separately; automated provider reconciliation is unverified; separately proven evidence is recorded through authorized accounting review.
Supported inputs: {"aggregate_limit":"The entire UTF-8 encoded JSON body must fit within 524288 bytes (512 KiB), including all fields, labels, escaping and JSON overhead. Per-field maxima are independent ceilings; they cannot all be used at once. MCP includes its JSON-RPC wrapper in the same body ceiling.","character_unit":"UTF-16 code units","candidate_output":"Required text, up to 200000 characters","expected_output":"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.","evidence":"Up to 12 caller-supplied log, paste, document (text only) or description items; each up to 200000 characters, within the aggregate body ceiling","provenance":"Caller-supplied source labels and text are retained with hashes; labels do not authenticate authority.","unsupported":["binary PDF/image interpretation through this API","independent web retrieval","authenticated third-party retrieval","external repair execution"]}
Error boundary: FAHCE application errors use a JSON envelope. Upstream WAF, Access or transport rejection can occur before the application and return HTML or another non-JSON response, including when Accept is application/json. Machine clients must inspect HTTP status and Content-Type before decoding and must never interpret a security block as an integrity determination. Security protections remain enforced.
Documentation: {"service_catalog":"https://fahce.kinganlogic.com/capabilities/machines.html#services","pricing":"https://fahce.kinganlogic.com/capabilities/machines.html#pricing","quickstart":"https://fahce.kinganlogic.com/capabilities/machines.html#quickstart","receipts":"https://fahce.kinganlogic.com/capabilities/machines.html#receipts","limits":"https://fahce.kinganlogic.com/capabilities","api":"https://fahce.kinganlogic.com/openapi.json","mcp":"https://fahce.kinganlogic.com/.well-known/mcp.json","security":"https://fahce.kinganlogic.com/capabilities/machines.html#boundaries","changelog":"https://fahce.kinganlogic.com/capabilities/machines.html#version"}
Unavailable discovery/integrations: A2A transport and Agent Card; OAuth authorization server; external MCP Registry publication; confirmed x402 Bazaar listing
Publication pending: