Galliun binds payments to specific requests through cryptographic hashing and on-chain verification.

Request hash binding

The requestHash in a 402 response binds payment to:

• HTTP method and route path
• SHA-256 hash of the request body
• Resolved pricing (model, inference, tool fees)
• Split recipients and amounts (provider + platform fee legs)
• Nonce and expiry timestamp

A payment proof with a mismatched request hash is rejected.

Payer validation

• Payment proof payer must match the on-chain transaction sender (or fee payer on Solana)
• Self-pay is blocked — payer cannot equal any split recipient address

Replay protection

The platform enforces uniqueness on:

• chain + network + txHash
• nonce (single-use per requirement)
• requestHash (once verified)
• paymentPayloadHash

Attempting to reuse any of these returns payment_replay or payment_reused.

Nonce and expiry

Each 402 response includes:

• nonce — random single-use identifier
• expiresAt — ISO timestamp after which the requirement is invalid

Payment proofs must include both values from the original 402.

On-chain verification

After claim, chain adapters verify independently:

• Transaction succeeded on the declared network
• Correct asset (Sui USDC coin type or Solana SPL mint)
• Each split leg received the exact required amount
• Payer matches proof

Client-side security

• Never trust client-supplied payer addresses for authorization
• Do not expose wallet private keys in client code
• Only the payer wallet signs transactions — Galliun never holds user funds

V1 limitations

• Pay-first flow: client pays before API confirms endpoint availability
• Failed execution after verified payment creates a refund recommendation for the provider — Galliun does not issue on-chain refunds
• See Refunds for provider refund policy

Next steps

• Payment requirements
• Retry behavior