@defuse-protocol/bridge-sdk

The Bridge SDK for Near Intents provides a set of tools for interacting with various bridge implementations. It simplifies the process of transferring assets from Near Intents to different blockchains.

Features

• Bridging from Near Intents:
  • Support for multiple bridge implementations (Hot, PoA)
  • Single and batch withdrawal operations
  • Automatic fee estimation
  • Built-in validation for withdrawal constraints:
    • PoA Bridge minimum withdrawal amounts
    • Hot Bridge Stellar trustline validation
  • Transfers within Near Intents
  • Transfers to NEAR blockchain
  • Transfers to Virtual Chains (e.g. Aurora)

Note: Bridging to Near Intents is not supported yet.

Installation

npm install @defuse-protocol/bridge-sdk --save-exact

Quick Start

import { BridgeSDK, createIntentSignerNearKeyPair } from '@defuse-protocol/bridge-sdk';
import { KeyPair } from 'near-api-js';

// Initialize the SDK with required configuration
const sdk = new BridgeSDK({
    referral: 'your-referral-code', // Only referral is required
});

// Set up intent signer (for NEAR)
const keypair = KeyPair.fromString('your-private-key');
const signer = createIntentSignerNearKeyPair({
  keypair: keypair,
  accountId: 'your-account.near'
});
sdk.setIntentSigner(signer);

// Method 1: Complete end-to-end withdrawal (orchestrated)
const result = await sdk.processWithdrawal({
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near', // Asset identifier
    amount: 1000000n, // Amount in smallest unit
    destinationAddress: '0x742d35Cc6634C0532925a3b8D84B2021F90a51A3',
    feeInclusive: false, // Whether amount includes fees
    // routeConfig is optional - will be auto-detected from assetId
  }
});

console.log('Intent hash:', result.intentHash);
console.log('Destination tx:', result.destinationTx);

// Method 2: Granular control with individual methods
const feeEstimation = await sdk.estimateWithdrawalFee({
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc6634C0532925a3b8D84B2021F90a51A3',
    feeInclusive: false
  }
});

const { intentHash } = await sdk.signAndSendWithdrawalIntent({
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc6634C0532925a3b8D84B2021F90a51A3',
    feeInclusive: false
  },
  feeEstimation
});

const intentTx = await sdk.waitForIntentSettlement({ intentHash });
const destinationTx = await sdk.waitForWithdrawalCompletion({ 
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc6634C0532925a3b8D84B2021F90a51A3',
    feeInclusive: false
  }, 
  intentTx 
});

Core Concepts

Route and Bridge Enums

The SDK uses two key concepts to organize withdrawal operations:

Routes

Routes define the path a withdrawal takes - the specific mechanism and destination for transferring assets. Each route represents a different withdrawal flow:

import { RouteEnum } from '@defuse-protocol/bridge-sdk';

console.log(RouteEnum.HotBridge);        // "hot_bridge" - Cross-chain via HOT protocol
console.log(RouteEnum.PoaBridge);        // "poa_bridge" - Cross-chain via PoA bridge
console.log(RouteEnum.NearWithdrawal);   // "near_withdrawal" - Direct to NEAR blockchain
console.log(RouteEnum.VirtualChain);     // "virtual_chain" - To Aurora Engine chains
console.log(RouteEnum.InternalTransfer); // "internal_transfer" - Between protocol users

Bridge Names

Bridge names identify the underlying bridge infrastructure that handles the cross-chain transfer. This determines which external protocol processes the withdrawal:

import { BridgeNameEnum } from '@defuse-protocol/bridge-sdk';

console.log(BridgeNameEnum.Hot);  // "hot" - HOT Labs bridge infrastructure
console.log(BridgeNameEnum.Poa);  // "poa" - Proof-of-Authority bridge by Defuse Labs  
console.log(BridgeNameEnum.None); // null - No external bridge (NEAR-native or internal)

Key Difference:

• Route = "How and where" the withdrawal goes (the path)
• Bridge Name = "Who operates" the underlying infrastructure (the bridge provider)

For example, both hot_bridge and poa_bridge routes perform cross-chain transfers, but use different bridge infrastructures (hot vs poa) with different fee structures and supported networks.

Asset Identifiers

The SDK uses standardized asset identifiers in the format:

• nep141:contract.near - NEP-141 tokens
• nep245:contract.near:tokenId - NEP-245 multi-tokens

Asset Identifier uniquely determines the corresponding route and destination chain.

Examples:

• nep141:usdt.tether-token.near - USDT on NEAR
• nep141:wrap.near - Wrapped NEAR (native NEAR)
• nep245:v2_1.omni.hot.tg:137_qiStmoQJDQPTebaPjgx5VBxZv6L - Polygon USDC through Hot
• nep141:base-0x833589fcd6edb6e08f4c7c32d4f71b54bda02913.omft.near - Base USDC through PoA

Intent Signers

Intent signers are required to authenticate and sign withdrawal operations. The SDK supports multiple signing methods:

• NEAR KeyPair Signer - Use NEAR account private keys for signing
• NEP-413 Signer - Custom message signing implementation
• EVM/Viem Signer - Use Ethereum-compatible wallets and accounts

You must set an intent signer before processing withdrawals:

// Example: Set up a NEAR KeyPair signer
const signer = createIntentSignerNearKeyPair({
  keypair: KeyPair.fromString('your-private-key'),
  accountId: 'your-account.near'
});
sdk.setIntentSigner(signer);

See the Intent Signers section below for detailed implementation examples.

Route Types

The SDK automatically detects and supports multiple route types based on asset identifiers:

Hot Bridge Route

• Purpose: Cross-chain transfers via HOT Labs infrastructure
• Supported Assets: Multi-tokens (NEP-245) from Hot protocol (contract v2_1.omni.hot.tg)
• Use Case: Cross-chain transfers for assets bridged through Hot protocol
• Route Type: hot_bridge

PoA Bridge Route

• Purpose: Proof-of-Authority bridge transfers operated by Defuse Labs
• Supported Assets: Fungible tokens (NEP-141) ending with .omft.near
• Use Case: Cross-chain transfers for assets bridged through PoA protocol
• Route Type: poa_bridge

Internal Transfer Route

• Purpose: Transfer between Near Intents users within the protocol
• Supported Assets: All NEP-141 and NEP-245 tokens
• Use Case: User A having funds in the protocol wants to transfer to User B
• Route Type: internal_transfer

Near Withdrawal Route

• Purpose: Transfers within the NEAR blockchain
• Supported Assets: NEP-141 tokens on NEAR, including native NEAR (wrap.near)
• Use Case: Same-chain transfers on NEAR
• Route Type: near_withdrawal

Virtual Chain Route

• Purpose: Transfers to Aurora Engine-powered chains (aka Virtual chains)
• Supported Assets: NEP-141 tokens with Aurora Engine integration
• Use Case: Near Intents to Aurora ecosystem transfers
• Route Type: virtual_chain
• Note: Requires explicit routeConfig with auroraEngineContractId

Fee Estimation

The SDK now supports both single and batch fee estimation:

// Single withdrawal fee estimation
const feeEstimation = await sdk.estimateWithdrawalFee({
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc6634C0532925a3b8D84B2021F90a51A3',
    feeInclusive: false
  }
});

console.log('Fee amount:', feeEstimation.amount);
console.log('Quote info:', feeEstimation.quote); // null if fee paid with withdrawn token

// Batch fee estimation
const batchFees = await sdk.estimateWithdrawalFee({
  withdrawalParams: [
    {
      assetId: 'nep141:usdt.tether-token.near',
      amount: 1000000n,
      destinationAddress: '0x742d35Cc...',
      feeInclusive: false
    },
    {
      assetId: 'nep245:v2_1.omni.hot.tg:137_qiStmoQJDQPTebaPjgx5VBxZv6L',
      amount: 500000n,
      destinationAddress: '0x742d35Cc...',
      feeInclusive: false
    }
  ]
});

console.log('Batch fees:', batchFees); // Array of FeeEstimation objects

Intent Signers

The SDK supports multiple intent signing methods using factory functions:

NEAR KeyPair Signer

import { createIntentSignerNearKeyPair, BridgeSDK } from '@defuse-protocol/bridge-sdk';
import { KeyPair } from 'near-api-js';

const keyPair = KeyPair.fromString('your-private-key');
const signer = createIntentSignerNearKeyPair({
  keypair: keyPair,
  accountId: 'your-account.near'
});

NEP-413 Signer

import { createIntentSignerNEP413 } from '@defuse-protocol/bridge-sdk';

const signer = createIntentSignerNEP413({
  signMessage: async (nep413Payload, nep413Hash) => {
    // Implement your custom signing logic here
    return {
      publicKey: 'ed25519:YourPublicKey',
      signature: 'base64-encoded-signature'
    };
  },
  accountId: 'your-account.near'
});

EVM/Viem Signer

import { createIntentSignerViem } from '@defuse-protocol/bridge-sdk';
import { privateKeyToAccount } from 'viem/accounts';

const account = privateKeyToAccount('0x...');
const signer = createIntentSignerViem(account);

// Set the signer at runtime
sdk.setIntentSigner(signer);

Advanced Usage

Custom RPC URLs

Set NEAR and EVM chains RPC URLs in the constructor:

import { Chains } from '@defuse-protocol/bridge-sdk'

const sdk = new BridgeSDK({
    ...,
    rpc: {
        [Chains.Near]: ['https://rpc.mainnet.near.org'],
        [Chains.Polygon]: ['https://polygon-rpc.com'],
        [Chains.BNB]: ['https://bsc-dataseed.binance.org'],
    }
});

Intent Publishing Hooks

Use the onBeforePublishIntent hook to intercept and process intent data before it's published to the relayer. This is useful for persistence, logging, analytics, or custom processing:

import { type OnBeforePublishIntentHook } from '@defuse-protocol/bridge-sdk';

// Define your hook function
const onBeforePublishIntent: OnBeforePublishIntentHook = async (intentData) => {
  // Save to database for tracking
  await saveIntentToDatabase({
    hash: intentData.intentHash,
    payload: intentData.intentPayload,
    timestamp: new Date(),
  });
  
  // Send analytics
  analytics.track('intent_about_to_publish', {
    intentHash: intentData.intentHash,
    intentType: intentData.intentPayload.intents[0]?.intent,
  });
};

// Use the hook with the functional API
const result = await sdk.processWithdrawal({
  withdrawalParams: { /* ... */ },
  intent: {
    onBeforePublishIntent, // Add the hook here
  }
});

// Or with granular control
const { intentHash } = await sdk.signAndSendWithdrawalIntent({
  withdrawalParams: { /* ... */ },
  feeEstimation: fee,
  intent: {
    onBeforePublishIntent, // Add the hook here
  }
});

// Or with generic intent publishing
const { intentHash } = await sdk.signAndSendIntent({
  intents: [/* ... */],
  onBeforePublishIntent, // Add the hook here
});

Hook Parameters:

• intentHash - The computed hash of the intent payload
• intentPayload - The unsigned intent payload
• multiPayload - The signed multi-payload containing signature and metadata
• relayParams - Additional parameters passed to the relayer (quote hashes)

Important Notes:

• The hook is called synchronously before publishing the intent
• If the hook throws an error, the withdrawal will fail
• The hook can be async and return a Promise

Batch Withdrawals

Process multiple withdrawals in a single intent:

const withdrawalParams = [
  {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc...',
    feeInclusive: false
  },
  {
    assetId: 'nep245:v2_1.omni.hot.tg:137_qiStmoQJDQPTebaPjgx5VBxZv6L',
    amount: 100000n,
    destinationAddress: '0x742d35Cc...',
    feeInclusive: false
  }
]

// Method 1: Complete end-to-end batch processing
const batchResult = await sdk.processWithdrawal({
  withdrawalParams,
  // feeEstimation is optional - will be estimated automatically if not provided
});

console.log('Batch intent hash:', batchResult.intentHash);
console.log('Destination transactions:', batchResult.destinationTx); // Array of results

// Method 2: Step-by-step batch processing for granular control
const feeEstimation = await sdk.estimateWithdrawalFee({
  withdrawalParams
});

const { intentHash } = await sdk.signAndSendWithdrawalIntent({
  withdrawalParams,
  feeEstimation
});

const intentTx = await sdk.waitForIntentSettlement({ intentHash });

const destinationTxs = await sdk.waitForWithdrawalCompletion({
  withdrawalParams,
  intentTx
});

console.log('All destination transactions:', destinationTxs);

Intent Management

The SDK provides direct access to intent operations for advanced use cases:

// Generic intent signing and publishing
const { intentHash } = await sdk.signAndSendIntent({
  intents: [/* array of intent primitives */],
  signer: customIntentSigner, // optional - uses SDK default if not provided
  onBeforePublishIntent: async (data) => {
    // Custom logic before publishing
    console.log('About to publish intent:', data.intentHash);
  }
});

// Wait for intent settlement
const intentTx = await sdk.waitForIntentSettlement({ 
  intentHash 
});

// or manual status check

// Check intent status at any time
const status = await sdk.getIntentStatus({ 
  intentHash: intentHash 
});

console.log('Intent status:', status.status); // "PENDING" | "TX_BROADCASTED" | "SETTLED" | "NOT_FOUND_OR_NOT_VALID"

if (status.status === 'SETTLED') {
  console.log('Settlement transaction:', status.txHash);
}

Intent Status Values:

• PENDING - Intent published but not yet processed
• TX_BROADCASTED - Intent being processed, transaction broadcasted
• SETTLED - Intent successfully completed
• NOT_FOUND_OR_NOT_VALID - Intent not found or invalid, it isn't executed onchain

Route Configuration Factory Functions

Recommended: Use factory functions to create route configurations. The SDK provides factory functions for type-safe and convenient route configuration creation:

import { 
  createVirtualChainRoute, 
  createNearWithdrawalRoute, 
  createInternalTransferRoute 
} from '@defuse-protocol/bridge-sdk';

// Create virtual chain route configuration (recommended)
const virtualChainRoute = createVirtualChainRoute(
  '0x4e45415f.c.aurora', // Aurora Engine contract ID
  null // Proxy token contract ID (optional)
);

// Create near withdrawal route with custom message
const nearWithdrawalRoute = createNearWithdrawalRoute(
  'Custom withdrawal message' // Optional message
);

// Create internal transfer route
const internalTransferRoute = createInternalTransferRoute();

// Use the factory-created route configuration in withdrawal
const result = await sdk.processWithdrawal({
  withdrawalParams: {
    assetId: 'nep141:a35923162c49cf95e6bf26623385eb431ad920d3.factory.bridge.near',
    amount: BigInt('1000000'),
    destinationAddress: '0x742d35Cc6634C0532925a3b8D84B2021F90a51A3',
    feeInclusive: false,
    routeConfig: virtualChainRoute // Recommended: Use factory function
  }
});

Asset Information Parsing

Get detailed information about supported assets:

try {
  const assetInfo = sdk.parseAssetId('nep141:usdt.tether-token.near');
  console.log('Bridge name:', assetInfo.bridgeName);
  console.log('Blockchain:', assetInfo.blockchain);
  console.log('Contract ID:', assetInfo.contractId);
  console.log('Standard:', assetInfo.standard);
} catch (error) {
  console.log('Asset not supported');
}

Waiting for Completion

Monitor withdrawal completion:

// Method 1: Using the orchestrated approach (automatic monitoring)
const result = await sdk.processWithdrawal({
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc...',
    feeInclusive: false
  }
});

console.log('Intent settled:', result.intentTx.hash);
console.log('Withdrawal completed:', result.destinationTx);

// Method 2: Step-by-step monitoring for granular control
const feeEstimation = await sdk.estimateWithdrawalFee({
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc...',
    feeInclusive: false
  }
});

const { intentHash } = await sdk.signAndSendWithdrawalIntent({
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc...',
    feeInclusive: false
  },
  feeEstimation
});

// Monitor intent settlement
const intentTx = await sdk.waitForIntentSettlement({ intentHash });
console.log('Intent settled:', intentTx.hash);

// Wait for withdrawal completion on destination chain
const completionResult = await sdk.waitForWithdrawalCompletion({
  withdrawalParams: {
    assetId: 'nep141:usdt.tether-token.near',
    amount: 1000000n,
    destinationAddress: '0x742d35Cc...',
    feeInclusive: false
  },
  intentTx
});

if ('hash' in completionResult) {
  console.log('Withdrawal completed with hash:', completionResult.hash);
} else {
  console.log('Withdrawal completion not trackable for this bridge');
}

Error Handling

import { FeeExceedsAmountError, MinWithdrawalAmountError } from '@defuse-protocol/bridge-sdk';

try {
  const result = await sdk.processWithdrawal({
    withdrawalParams: {
      assetId: 'nep141:usdt.tether-token.near',
      amount: BigInt('100'), // Very small amount
      destinationAddress: '0x742d35Cc...',
      feeInclusive: true // Fee must be less than amount
    }
  });
} catch (error) {
  if (error instanceof FeeExceedsAmountError) {
    console.log('Fee exceeds withdrawal amount');
    console.log('Required fee:', error.feeEstimation.amount);
    console.log('Withdrawal amount:', error.amount);
  } else if (error instanceof MinWithdrawalAmountError) {
    console.log('Amount below minimum withdrawal limit');
    console.log('Minimum required:', error.minAmount);
    console.log('Requested amount:', error.requestedAmount);
    console.log('Asset:', error.assetId);
  }
}

// Error handling with granular control
try {
  const feeEstimation = await sdk.estimateWithdrawalFee({
    withdrawalParams: {
      assetId: 'nep141:usdt.tether-token.near',
      amount: 100n,
      destinationAddress: '0x742d35Cc...',
      feeInclusive: true
    }
  });
  
  // Continue with other operations...
} catch (error) {
  // Handle specific errors at each step
  console.error('Fee estimation failed:', error);
}

PoA Bridge Minimum Withdrawal Amount Validation

PoA bridge has minimum withdrawal amount requirements that vary per token and blockchain. The SDK automatically validates this for all withdrawals.

// Validation happens automatically during withdrawal processing:
try {
  const result = await sdk.processWithdrawal({
    withdrawalParams: {
      assetId: 'nep141:zec.omft.near', // Zcash token
      amount: BigInt('50000000'), // 0.5 ZEC (in smallest units)
      destinationAddress: 'your-zcash-address',
      feeInclusive: false
    }
  });
} catch (error) {
  if (error instanceof MinWithdrawalAmountError) {
    console.log(`Minimum withdrawal for ${error.assetId}: ${error.minAmount}`);
    console.log(`Requested amount: ${error.requestedAmount}`);
    // For Zcash: minimum is typically 1.0 ZEC (100000000 in smallest units)
    // Plus 0.2 ZEC fee, so user needs at least 1.2 ZEC to withdraw 1.0 ZEC
  }
}

Note: Other routes (Near Withdrawal, Virtual Chain, Internal Transfer) don't have minimum withdrawal restrictions, so validation passes through for those routes.

Hot Bridge Stellar Trustline Validation

Hot Bridge validates that destination addresses have the required trustlines when withdrawing to Stellar blockchain. This prevents failed transactions due to missing trustlines.

import { TrustlineNotFoundError } from '@defuse-protocol/bridge-sdk';

// Validation happens automatically during withdrawal processing:
try {
  const result = await sdk.processWithdrawal({
    withdrawalParams: {
      assetId: 'nep245:v2_1.omni.hot.tg:stellar_1_USD_GBDMM6LG7YX7YGF6JFAEWX3KFUSBXGAEPZ2IHDLWH:1100', // Stellar USD token
      amount: BigInt('1000000'), // 1 USD (in smallest units)
      destinationAddress: 'GCKFBEIYTKP6RYVDYGMVVMJ6J6XKCRZL74JPWTFGD2NQNMPBQC2LGTVZ', // Stellar address
      feeInclusive: false
    }
  });
} catch (error) {
  if (error instanceof TrustlineNotFoundError) {
    console.log(`Trustline not found for token: ${error.assetId}`);
    console.log(`Destination address: ${error.destinationAddress}`);
    console.log('The destination address must have a trustline for this token before withdrawal');
    // User needs to create a trustline for the token on Stellar before withdrawing
  }
}

What is a trustline? On Stellar, accounts must explicitly create "trustlines" to hold non-native assets. Before receiving any token (except XLM), the destination address must:

1. Create a trustline for that specific token
2. Have sufficient XLM balance to maintain the trustline

Why this validation matters:

• Prevents failed withdrawals due to missing trustlines
• Saves gas fees and reduces user frustration
• Provides clear error messages for troubleshooting

Note: This validation only applies to Stellar destinations via Hot Bridge. Other blockchains and routes don't require trustline validation.

TBD

Supported Networks

For a list of supported chains, see the Chain Support page in the Near Intents documentation.

Development

Prerequisites

• Node.js (v20 or later)
• pnpm for package management

Setup

# Install dependencies (from the monorepo root)
pnpm install

Build

# Build the package
pnpm run build

# Build in watch mode
pnpm run dev

Test

# Run tests
pnpm run test

# Run tests in watch mode  
pnpm run test:watch

Lint and Format

# Check code style
pnpm run lint

# Format code
pnpm run format

Version History

See CHANGELOG.md for detailed version history and migration guides.

Contributing

This package is part of Near Intents SDK monorepo. Please refer to the main repository's contributing guidelines.

License

MIT