Broadcasts the payment on-chain and returns the transaction signature. Re-runs screening, de-deduplicates the transaction in case of a double settle, then co-signs as fee-payer and submits. /settle is effectively synchronous — it returns once the transaction lands or fails. The request body is identical to /verify.

Always /verify first. /settle will re-screen and re-check, but verifying up front means you don't broadcast a transaction that was never going to land — and you don't hold the buyer's connection open for a settle that fails fast.

The transaction is the on-chain signature — view it at https://explorer.solana.com/tx/<transaction>?cluster=devnet.

Error reason codes (non-exhaustive)

Code	Meaning
`sanctioned_address` / `screener_unavailable`	Same as verify — screening blocked the settle.
`invalid_payload`	Couldn't decode the buyer's transaction to extract the payer.
`unsupported_network`	No adapter registered for the requested network.
`duplicate_settle_in_flight`	Another replica already reserved this exact payment within the dedup window.
`duplicate_settlement`	The transfer was already settled on-chain.
`persistence_unavailable`	Redis was unreachable for the dedup reservation; fail-closed.
`transaction_failed`	The transaction was broadcast but did not confirm.
`unexpected_settle_error`	Unhandled internal error.

200Settlement result (success or protocol-level failure).

400Malformed request body.