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Independently of mode, a payment executes one of two ways. Which one you get depends on where the funds start.

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Quote flow

The backend returns transaction data; the payer’s connected wallet signs and broadcasts it.
This is the EVM path, and the one most integrations see.

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Deposit flow

There is no connected wallet to sign with — the payer is sending from Bitcoin, Solana, TON, or an exchange. The backend mints a deposit address; the payer sends funds to it.
A deposit flow needs a refund address up front — refundTo when you mint the address. There is no connected wallet to refund to if settlement fails, so it cannot be collected after the fact; by then the payer may be long gone. This is the one field the deposit flow adds that the quote flow has no use for.The swap API spells the same idea refundRecipient on POST /quote. Two names for one concept is a wart rather than a subtlety — check which endpoint you are calling.

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Price and fees

For a payment session, the server resolves the destination, amount and fee terms before the payer executes. The fee configuration is read by the backend’s resolveFees path and snapshotted on the session; a browser cannot replace the recipient or fee by changing a request after creation. The merchant should display the returned session values and treat the server response as the contract. That resolver applies one rule to Checkout, Deposit, and Withdrawal. The Hypermid fee is the global rate unless a partner override replaces the global rate outright. An optional developer fee is added on the same input amount; it defaults to 0 and is restricted to 0–100 basis points. The payer-visible total is hypermidBps + partnerBps. There are two rail facts to keep visible:
  • A same-token EVM transfer quotes a zero fee because a plain token transfer has no route that can collect either leg.
  • On the Near deposit-address rail, the provider keeps half of each declared app fee. Hypermid therefore declares twice each net leg on the provider request; the payer-visible provider charge is double the net Hypermid and developer amounts shown by the Payments policy. The developer leg is paid directly by that provider. On EVM routes, the developer leg is held by Hypermid and settled periodically by manual transfer.

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Telling them apart

The SDK makes this a discriminated result rather than something to infer:
execute is a union discriminated on kind, so the compiler forces the branch rather than trusting you to remember it. See Swap.
On a non-EVM source the API still returns {to, data, value}, but those are an inert placeholder — broadcasting them does nothing useful. The SDK omits them from the returned object entirely so the mistake is not reachable.