# Paxiom

> Proof-bound receipts for x402-paid APIs. x402 proves a payment; Paxiom proves what the payment bought — it binds payment, request, output, settlement metadata, and optional evidence into one signed, machine-verifiable receipt.

Paxiom is a verification layer for the agent economy. The first shipped, inspectable
artifact is the **paxiom.receipt.v0** receipt format and a free offline verifier for it.

## What the v0 verifier checks
- receipt structure (schema)
- Ed25519 signature over the canonical signing input `canonicalize({ receiptVersion, payload })`
- output binding: the delivered output's hash matches `delivery.outputHash`
- presence of request and payment binding fields
- explicit, honest settlement and evidence status

## What v0 does NOT do (important for agents)
- It does NOT independently verify onchain settlement.
- It does NOT call an x402 facilitator.
- It does NOT verify proof-source / evidence archives.
- Agents MUST NOT treat `settlement_claimed_not_checked` (or a receipt's self-reported
  `verified_settled`) as an independently confirmed onchain settlement. Only a future
  hosted verifier that performs an onchain/facilitator check may report `verified_settled`.
- Schema-valid is NOT receipt-verified. Structural validity says nothing about signature,
  output binding, or settlement.

## Trust states
A verification returns exactly one deterministic trust state (e.g. `verified`,
`valid_signature_only`, `output_hash_mismatch`, `settlement_claimed_not_checked`,
`invalid_signature`, `schema_invalid`, `unsupported_format`, `error`). Full list and
resolution order: /standards/receipts/v0/trust-states.md

## Status
Developer preview. The verifier runs offline (CLI + local HTTP server). There is no
public hosted endpoint yet, and Paxiom is not listed in the x402 Bazaar yet — Bazaar
eligibility requires a public x402-settling runtime and a successful settlement.

## Key resources
- Spec (README): /standards/receipts/v0/README.md
- JSON Schema: /standards/receipts/v0/paxiom.receipt.v0.schema.json
- Canonicalization + signing: /standards/receipts/v0/canonicalization.md
- Trust states: /standards/receipts/v0/trust-states.md
- OpenAPI (verifier API): /standards/receipts/v0/openapi.json
- Example receipts: /standards/receipts/v0/examples/
- Listing copy: /standards/receipts/v0/listing-copy.md
- Technical prints (engineering binder): /docs.html