# SettleProof
> Independent x402 settlement attestation & audit API. An agent or accountant bot submits Solana mainnet USDC tx signatures and receives Ed25519-signed attestation certificates ("this payment really settled") so merchants can distinguish real revenue from test/harness traffic. Payment: x402 v1 (HTTP 402, USDC on Solana mainnet via facilitator.payai.network). No API keys, no signup — pay per request, or use a provisioned X-API-Key pass. Not legal or accounting advice.

## Endpoints
- `GET /api/v1/settleproof` — free — API index: pricing, key, usage, disclaimer.
- `GET /api/v1/settleproof/key` — free — Ed25519 public key (PEM) for verifying attestation signatures.
- `POST /api/v1/settleproof/verify` — $0.01 — attest one settled payment: `{tx_signature}` (Solana base58) + optional `{payee, amount, memo}` filters → on-chain cross-check (getTransaction + getBlockTime, USDC TransferChecked) → Ed25519-signed cert `{status: settled|unverified, attestation_version, tx_signature, payer, payee, amount_usdc, network, block, timestamp, memo, filters_applied, verified_at, signer, signature}`.
- `POST /api/v1/settleproof/ledger` — $0.05 — merchant audit trail: `{signatures:[...≤50]}` → per-tx verdicts + summary + tax-ready RFC-4180 CSV (per payee), Ed25519-signed.
- `POST /api/v1/settleproof/watch` — $0.01 — register `{webhook_url, payee}` (SSRF-guarded) → 5 prepaid event credits; poller POSTs Ed25519-signed `payment.settled` events per new USDC transfer; 1 credit per event; top-up = re-register.

## Payment
1. Request → 402 with accepts:[{scheme:exact, network:solana, maxAmountRequired, payTo, maxTimeoutSeconds:60, asset}].
2. Retry with `X-PAYMENT: base64(payload)`.
3. Gateway verifies via facilitator, produces the resource, settles only on success. RPC failure, unknown tx, invalid input, facilitator down → honest 4xx/5xx, NEVER charged (verify ≠ capture).
4. Free tier: 1 successful verify/day/IP for browser clients. ledger + watch are paid-only.

## Pricing
| Route | Price |
|---|---|
| verify | $0.01 |
| ledger | $0.05 |
| watch | $0.01 (5-event credit, prepaid) |

## Contact
Monexus x402 R&D Lab — michael.poncana@themonexus.com