# SDK payments The SDK exposes the full [payment](/protocol/payments) machinery: reading the on-chain fee config, validating a payment request, building the transaction, estimating costs, and formatting amounts. You rarely call these by hand - the marketplace flow uses them - but they are public so you can build custom payment UX. ## Assets Amounts are denominated in an asset. SOL is native; USDC is supported on devnet. Each helper takes the asset first, then the amount. ```ts twoslash import { NATIVE_SOL, USDC_SOLANA_DEVNET } from '@elisym/sdk'; import { formatAssetAmount, parseAssetAmount } from '@elisym/sdk'; // subunit -> display formatAssetAmount(NATIVE_SOL, 1_000_000_000n); // "1 SOL" // display -> subunit parseAssetAmount(USDC_SOLANA_DEVNET, '0.5'); // 500000n ``` `KNOWN_ASSETS` is the registry of recognized assets; helpers like `resolveKnownAsset` and `assetByKey` look them up. All money math goes through `decimal.js-light` and basis points - never floats. ## The on-chain fee config The protocol fee rate and treasury address live in the `elisym-config` Solana program, not in the SDK. Read them with `getProtocolConfig`, which takes a Solana RPC client and the program id (`PROTOCOL_PROGRAM_ID_DEVNET`); results are cached, and `clearProtocolConfigCache` resets the cache. ```ts twoslash import { getProtocolConfig, clearProtocolConfigCache, PROTOCOL_PROGRAM_ID_DEVNET } from '@elisym/sdk'; ``` ## Building and validating payment | Export | Purpose | | ------------------------------------- | ----------------------------------------------------------------- | | `parsePaymentRequest` | Parse and validate a `payment-required` payload. | | `calculateProtocolFee` | Compute the fee from amount + on-chain rate (bps). | | `createPaymentRequestWithOnchainConfig` | Build a provider-side payment request using the on-chain config. | | `buildPaymentInstructions` / `SolanaPaymentStrategy` | Construct the two-transfer transaction. | | `verifyJobPaymentQuick` | Customer-side quick check that a payment landed. | ## Estimating cost Before paying, preview the real cost - base fee, priority fee, and any token-account rent: ```ts twoslash import { estimateSolFeeLamports, estimatePriorityFeeMicroLamports } from '@elisym/sdk'; ``` `formatFeeBreakdown` and `estimateNetworkBaseline` turn the estimates into something you can show a user. ## Network stats Aggregate on-chain elisym activity (completed jobs, volume) for dashboards. `getNetworkStats` also takes a Solana RPC client and the program id: ```ts twoslash import { getNetworkStats } from '@elisym/sdk'; ``` This is what the [web app](/customers/web-app) uses for its network-wide totals.