integrate-estimate

Integrate estimate

An estimate is a rate preview: "how much USDC for 100 EUR?" It hits the provider's live rate API and nothing else — no counterparty, no wallet, no DB. That makes it the first capability to build: if estimateOnramp works, your register-provider config reader and credentials are correct.

Choose the closest implementation in packages/sdp-payments/src/ramps/providers/ — GET- and POST-based estimate APIs, hosted-provider quote APIs, minor-unit conversion, and single-direction support are all represented.

Contract

Both methods are required on RampProvider (packages/sdp-payments/src/ramps/types.ts), even when one direction is unsupported:

estimateOnramp(ctx: RampRuntimeContext, input: RampEstimateOnrampInput): Promise<PaymentRampEstimate>
estimateOfframp(ctx: RampRuntimeContext, input: RampEstimateOfframpInput): Promise<PaymentRampEstimate>

Inputs (packages/sdp-payments/src/ramps/types.ts):

• onramp: { assetRail: CryptoRailId, fiatCurrency: RampFiatCurrency, fiatAmount: string }
• offramp: { assetRail: CryptoRailId, fiatCurrency: RampFiatCurrency, cryptoAmount: string }

Output PaymentRampEstimate (@sdp/types, packages/sdp-types/src/payments.ts):

{
  provider; direction: "onramp" | "offramp";
  fiatCurrency; assetRail; fiatAmount; cryptoAmount; exchangeRate;  // all strings
  fees: { currency; total; network?; provider? };
  minFiatAmount?; maxFiatAmount?; expiresAt?;
}

How to build it

ctx is { env, mode } — read your config with the mode-keyed reader from register-provider, then HTTP only. Convert the asset rail with getCryptoRailAssetLabel from @sdp/types/payment-rails; convert minor units with parseDecimalAmount / formatDecimalAmount from @sdp/solana/amount.

A common shape: GET the corridor's exchange rate once to learn decimals, again with the amount to get the quote, then map into PaymentRampEstimate.

Fail loud

A non-positive receiving amount is not a 0 estimate — it's a broken corridor. Throw, don't return zero: