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The Resolver API is the direction Utexo calls on the resolver. Each resolver defines and configures its own callback URLs; there are no prescribed paths.
Resolver callbacks are not protected by X-API-Key. Agree the transport authentication for this direction with Utexo before exposing endpoints.

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Quote callback

Utexo calls the resolver to request a quote for a user swap.

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Request fields

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Response

The quote response carries the destination minimum and maximum, expiry in milliseconds, and affiliate and intermediate routing data. Confirm the exact response shape with Utexo during onboarding.

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Error responses

Use 400 for invalid or unsupported requests and 500 for unexpected resolver failures. Envelope:

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Bitcoin deposit PSBT callback

Utexo requests a PSBT for the user’s Bitcoin deposit.

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Request

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Response

x_only_public_key, refund_control_block, and fast_refund_control_block are only meaningful for deposit_type=escrowed.
For RGB USDT swaps, the request does not include the asset or amount; load them from the quote. See RGB USDT in Utexo Swap.

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Solana co-signed transaction callback

Utexo asks the resolver to co-sign a Solana transaction.

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Request

request_type is one of:
  • DepositSwap
  • Fulfill
  • WithdrawToUser
Source fields:
  • intent_id
  • quote_id
  • user_address
  • nonce
  • resolver_deposit
  • token_in
  • token_out
  • secret_hash
  • amount_in
  • deadline
  • resolver_id
  • intermediate_token_out and its bounds (optional)
  • min_amount_out
  • max_amount_out
  • swap_type
  • recent_blockhash (optional)
  • deposit_type = escrowed

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Response

Confirm the Solana co-signed callback response shape with Utexo before implementing.

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Fast-refund signing callback

Utexo requests a resolver signature for a fast refund.

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Request

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Response

The Bitcoin script field is currently named tapscipt. Validate the field name against the current implementation before you wire it up.