@zkp2p/client-sdk

@zkp2p/client-sdk

Browser-first TypeScript SDK for integrating ZKP2P into web apps. Built on the proven core from the React Native SDK and extended with peerauth browser extension integration.

Install

npm install @zkp2p/client-sdk viem

Quickstart

import { Zkp2pClient } from '@zkp2p/client-sdk';

const client = new Zkp2pClient({
  walletClient,         // viem wallet client
  apiKey: 'YOUR_API_KEY',
  chainId: 8453,        // Base mainnet
});

// Fetch quotes
const quotes = await client.getQuote({
  paymentPlatforms: ['wise'],
  fiatCurrency: 'USD',
  user: '0xYourAddress',
  recipient: '0xPayeeAddress',
  destinationChainId: 8453,
  destinationToken: client.getUsdcAddress(),
  amount: '100', // exact fiat by default
});

// Use the extension (optional)
import { PeerauthExtension } from '@zkp2p/client-sdk/extension';
const ext = new PeerauthExtension({ onVersion: v => console.log('Extension version', v) });
ext.fetchVersion();

// After generating proof via extension, fulfill intent (see Extension Flow section)
// await client.fulfillIntent({ intentHash, paymentProofs: [{ proof }], paymentMethod: 1 });

Notes

• Core APIs mirror the React Native SDK where applicable.
• The extension module is browser-only and exposed via subpath import @zkp2p/client-sdk/extension.
• Ensure you validate extension availability and version before relying on it.

Supported Platforms and Currencies

• Platforms: wise, venmo, revolut, cashapp, mercadopago, zelle, paypal, monzo.
• Currencies: AED, ARS, AUD, CAD, CHF, CNY, CZK, DKK, EUR, GBP, HKD, HUF, IDR, ILS, INR, JPY, KES, MXN, MYR, NOK, NZD, PHP, PLN, RON, SAR, SEK, SGD, THB, TRY, UGX, USD, VND, ZAR.

Examples

• See the repo examples/ folder for:
  • A Vite React walkthrough (get quotes and integrate the extension)
  • A minimal Node script to fetch quotes (examples/node-scripts/get-quote.ts)
  • A browser E2E journey demo with a mock extension (examples/e2e-browser/index.html)

Run the E2E browser demo

This demo simulates the peerauth extension with a small in-page mock so you can see the end-to-end flow.

Steps:

• Build the SDK: npm run build
• Serve the repo root (to ensure same-origin messaging works). For example:
  • npx http-server -p 5174 . or npx serve .
• Open http://localhost:5174/examples/e2e-browser/ in your browser.

What it shows:

• Requests the extension version via postMessage
• Generates a proof and receives a mock proof payload
• Converts the payload into a ReclaimProof with parseExtensionProof
• Shows the next step to call fulfillIntent with the proof

Wallet Setup (viem)

You can pass any viem WalletClient (from wagmi or raw viem). Example with injected wallet on Base:

import { createWalletClient, custom } from 'viem'
import { base } from 'viem/chains'

const walletClient = createWalletClient({
  chain: base,
  transport: typeof window !== 'undefined' ? custom((window as any).ethereum) : undefined,
});

const client = new Zkp2pClient({ walletClient, apiKey: 'YOUR_API_KEY', chainId: base.id });

Override RPC URL if desired by passing rpcUrl to the constructor.

const client = new Zkp2pClient({ walletClient, apiKey, chainId: base.id, rpcUrl: 'https://base-mainnet.g.alchemy.com/v2/<key>' });

Supported chains match DEPLOYED_ADDRESSES. Use client.getDeployedAddresses() and client.getUsdcAddress() when needed.

Configuration & Environment

Best practice: pass values into the SDK at initialization. The SDK does not read env directly.

• Vite (.env):

VITE_ZKP2P_API_KEY=your_public_key
VITE_ZKP2P_RPC_URL=https://base-mainnet.g.alchemy.com/v2/xxx

Code:

const apiKey = import.meta.env.VITE_ZKP2P_API_KEY;
if (!apiKey) throw new Error('Missing VITE_ZKP2P_API_KEY');

const client = new Zkp2pClient({
  walletClient,
  apiKey,
  chainId: 8453,
  rpcUrl: import.meta.env.VITE_ZKP2P_RPC_URL,
  // Optional overrides:
  // baseApiUrl: import.meta.env.VITE_ZKP2P_BASE_API_URL,
  // witnessUrl: import.meta.env.VITE_ZKP2P_WITNESS_URL,
});

• Next.js (.env.local):

NEXT_PUBLIC_ZKP2P_API_KEY=your_public_key
NEXT_PUBLIC_ZKP2P_RPC_URL=https://base-mainnet.g.alchemy.com/v2/xxx

Code:

const apiKey = process.env.NEXT_PUBLIC_ZKP2P_API_KEY;
if (!apiKey) throw new Error('Missing NEXT_PUBLIC_ZKP2P_API_KEY');

const client = new Zkp2pClient({
  walletClient,
  apiKey,
  chainId: 8453,
  rpcUrl: process.env.NEXT_PUBLIC_ZKP2P_RPC_URL,
});

Security: only use public runtime env vars in the browser (VITE_/NEXT_PUBLIC_). If keys must remain private, proxy via your server.

Types: Platforms and Currencies

• Payment platforms: PAYMENT_PLATFORMS is an exported as const array and PaymentPlatformType is the corresponding string union. Use it for extension calls to get autocomplete and type-safety.

import { PAYMENT_PLATFORMS, type PaymentPlatformType } from '@zkp2p/client-sdk';
const platform: PaymentPlatformType = 'wise'; // from PAYMENT_PLATFORMS

• Currencies: CurrencyType is the ISO-like currency code union (e.g., 'USD' | 'EUR' | …'). Use it in signalIntent.

import { type CurrencyType } from '@zkp2p/client-sdk';

await client.signalIntent({
  processorName: 'wise',
  depositId: '1',
  tokenAmount: '1000000',
  payeeDetails: '{"email":"[e-mail]"}',
  toAddress: '0xRecipient',
  currency: 'USD' as CurrencyType,
});

Extension Flow: Proof → Fulfill

The typical browser flow is:

• Detect the peerauth extension and request its version
• Ask the extension to generate a payment proof for a given intentHash
• Fetch the proof by ID and convert it to the on-chain ReclaimProof format
• Call fulfillIntent with the encoded proof

import { Zkp2pClient, assembleProofBytes, intentHashHexToDecimalString } from '@zkp2p/client-sdk';
import { PeerauthExtension, parseExtensionProof, ExtensionProofFlow, ExtensionMetadataFlow, metadataUtils } from '@zkp2p/client-sdk/extension';

// 1) Initialize the client
const client = new Zkp2pClient({ walletClient, apiKey, chainId: 8453 });

// 2) Set up the extension with callbacks
let cachedProofId: string | null = null;
const ext = new PeerauthExtension({
  onVersion: (v) => console.log('extension version:', v),
  onProofId: (id) => {
    cachedProofId = id;
    if (cachedProofId) ext.fetchProofById(); // 3) Request proof details once we have the id
  },
  onProof: async (notaryRequest) => {
    if (!notaryRequest) return;
    // 4) Convert extension proof → ReclaimProof shape expected by the contracts
    const reclaimProof = parseExtensionProof(notaryRequest.proof);
    // Submit proof on-chain
    await client.fulfillIntent({
      intentHash,
      paymentProofs: [{ proof: reclaimProof }],
      // optionally include a paymentMethod identifier (uint8) if needed by verifier
      // paymentMethod: 1,
    });
  },
  onError: (e) => console.error('extension error:', e),
});

// Kick off version check and proof generation
ext.fetchVersion();
ext.generateProof(
  'wise',        // platform identifier (e.g. 'wise', 'venmo', 'revolut', 'paypal', 'monzo', ...)
  intentHash,    // `0x…` intent hash to fulfill
  0              // originalIndex for the selected transaction/metadata
);

// Helper: Convert extension proof payload → ReclaimProof
const reclaimProof = parseExtensionProof(notaryRequest.proof);

Orchestrated, Platform‑Abstracted Flow (recommended)

Use the ExtensionOrchestrator to hide platform action strings and required proof counts. It requests metadata, lets you pick a transaction, generates the correct number of proofs, and builds the bytes for contract submission.

import { ExtensionOrchestrator } from '@zkp2p/client-sdk/extension';

const orch = new ExtensionOrchestrator({ debug: false, versionPollMs: 5000, metadataTimeoutMs: 60000 });

// 1) Request and render payments (internal action strings are abstracted)
const payments = await orch.requestAndGetPayments('revolut');
const selected = payments[0]; // render and let user pick in real apps

// 2) Generate the correct number of proofs, based on platform config
const proofs = await orch.generateProofs('revolut', intentHash, selected.originalIndex);

// 3) Submit on-chain
await client.fulfillIntent({
  intentHash,
  paymentProofs: proofs.map((p) => ({ proof: p })),
});

Orchestrated N‑proof flow (optional)

If you prefer manual control, but still want a helper to handle polling/timeout and parsing, use ExtensionProofFlow directly and assembleProofBytes to build the final payload:

const flow = new ExtensionProofFlow();
try {
const proofs = await flow.generateProofs(
  'wise',                                   // platform
  intentHashHexToDecimalString(intentHash), // safe decimal string for extension
  0,                                        // originalIndex from extension metadata
  { requiredProofs: 1, pollIntervalMs: 3000, timeoutMs: 60000 },
  (p) => console.log('progress', p)
);

  // Option A: assemble bytes and submit manually
  const bytes = assembleProofBytes(proofs, { paymentMethod: 1 });
  // ... submit via your own viem client if desired

  // Option B: submit via SDK using the raw proofs
  await client.fulfillIntent({
    intentHash,
    paymentProofs: proofs.map((proof) => ({ proof })),
    paymentMethod: 1,
  });
} finally {
  flow.dispose();
}

Advanced: Low‑Level Flows

Transaction Metadata → Selection → Proof (separation)

Surface transaction candidates first, let the user choose, then generate proofs. This gives integrators full control over selection logic.

// 1) Start metadata flow (receives metadata pushed from extension)
const meta = new ExtensionMetadataFlow({ versionPollMs: 5000 });
const unsubscribe = meta.subscribe((platform, record) => {
  if (platform !== 'wise') return;
  const visible = metadataUtils.filterVisible(record.metadata);
  const sorted = metadataUtils.sortByDateDesc(visible);
  // Render `sorted` to your UI and let the user pick one
});

// Optionally, request metadata via extension action (advanced; orchestrator handles this internally)
// meta.requestMetadata('<actionTypeFromPlatformConfig>', 'wise');

// 2) Once user picks a transaction, capture its `originalIndex`
const chosenOriginalIndex = 0; // from the user’s selection

// 3) Generate proof(s)
const flow = new ExtensionProofFlow({ debug: false });
const proofs = await flow.generateProofs('wise', intentHashHexToDecimalString(intentHash), chosenOriginalIndex, { requiredProofs: 1 });

// 4) Submit
await client.fulfillIntent({ intentHash, paymentProofs: proofs.map(p => ({ proof: p })), paymentMethod: 1 });

// Cleanup on unmount
unsubscribe();
meta.dispose();
flow.dispose();

Notes:

• The extension pushes metadata via postMessage; the SDK caches and emits the latest per-platform.
• expiresAt indicates when metadata becomes stale. Use meta.isExpired(platform) to decide re-fetch strategy.

Debugging

Enable debug logging to see postMessage traffic and progress:

import { ExtensionOrchestrator, ExtensionMetadataFlow, ExtensionProofFlow } from '@zkp2p/client-sdk/extension';

const orch = new ExtensionOrchestrator({ debug: true });
const meta = new ExtensionMetadataFlow({ debug: true });
const proofFlow = new ExtensionProofFlow({ debug: true });

Proof Helpers

• encode single: encodeProofAsBytes(proof)
• encode two: encodeTwoProofs(proof1, proof2)
• encode many: encodeManyProofs([proofs])
• tag method: encodeProofAndPaymentMethodAsBytes(bytes, method)
• assemble: assembleProofBytes(proofs, { paymentMethod? })
• parse extension payload: parseExtensionProof(payload)

API Overview

• createDeposit(params): creates a deposit on-chain and stores deposit details via API

  • Params: { token, amount, intentAmountRange, conversionRates, processorNames, depositData, onSuccess, onMined, onError }
  • Returns: { depositDetails, hash }

• signalIntent(params): verifies intent via API and emits on-chain signalIntent

  • Params: { processorName, depositId, tokenAmount, payeeDetails, toAddress, currency, onSuccess, onMined, onError }
  • Returns: SignalIntentResponse & { txHash?: Hash }

• fulfillIntent({ intentHash, paymentProofs, paymentMethod? }): submits proof bytes to fulfill an intent

• withdrawDeposit({ depositId }): withdraws a deposit

• cancelIntent({ intentHash }): cancels a pending intent

• releaseFundsToPayer({ intentHash }): releases escrowed funds back to payer

• getQuote(req): retrieves quotes from API (exact-fiat by default)

• getPayeeDetails({ platform, hashedOnchainId })

• validatePayeeDetails({ processorName, depositData }): validates payee details via API

• getAccountDeposits(address): reads deposit views from chain

• getAccountIntent(address): reads current intent view from chain

See TypeScript types exported from the package for full shapes.

Payee Validation

Use payee validation to pre-check user-provided payee details before creating a deposit or signaling an intent. The API returns a boolean and optional error strings.

import { Zkp2pClient } from '@zkp2p/client-sdk';

const client = new Zkp2pClient({ walletClient, apiKey, chainId: 8453 });

// Example: Revolut username
const res = await client.validatePayeeDetails({
  processorName: 'revolut',
  depositData: { revolutUsername: 'alice' },
});

if (!res.responseObject.isValid) {
  console.warn('Payee validation failed:', res.responseObject.errors || []);
  // Show user-friendly error, do not proceed to createDeposit/signalIntent
}

SSR and Extension

• The extension entry @zkp2p/client-sdk/extension is browser-only. In SSR environments (Next.js), use dynamic import or guards to avoid referencing window during server rendering.

Callbacks and Errors

• Callbacks (optional and per-method):

  • onSuccess({ hash }): emitted after the transaction is broadcast
  • onMined({ hash }): emitted after transaction is confirmed
  • onError(error): emitted when any step fails

• Error classes:

  • ZKP2PError (base), NetworkError, APIError, ContractError, ValidationError, ProofGenerationError

SSR vs Browser

• Core SDK is isomorphic; it does not require window.
• The extension entry @zkp2p/client-sdk/extension is browser-only. In SSR, import it dynamically or guard with typeof window !== 'undefined'.

End-to-End Outline

• Maker deposits liquidity:

await client.createDeposit({
  token: client.getUsdcAddress(),
  amount: 1000000n, // 1 USDC with 6 decimals
  intentAmountRange: { min: 500000n, max: 2000000n },
  processorNames: ['wise'],
  conversionRates: [[{ currency: 'USD', conversionRate: '1000000' }]],
  depositData: [{ /* payee details per processor */ }],
});

• Buyer signals intent (after quote selection):

await client.signalIntent({
  processorName: 'wise',
  depositId: '1',
  tokenAmount: '1000000',
  payeeDetails: '{"email":"[e-mail]"}',
  toAddress: '0xRecipient',
  currency: 'USD',
});

• Buyer proves payment in browser via extension and fulfills intent (see section above for proof flow):

// ext.generateProof(...)
// const proof = parseExtensionProof(...)
await client.fulfillIntent({ intentHash, paymentProofs: [{ proof }] });

Publishing

See PUBLISHING.md in this package for up‑to‑date publishing instructions.

License

MIT