hash-wallet/cw_evm

cw_evm

Shared EVM-chain wallet foundation for Cake Wallet. Provides common client/wallet abstractions used by cw_ethereum, cw_polygon, and other EVM chains.

What it provides

• EVMChainClient (Web3 + HTTP):
  • Connect to RPC (supports NowNodes short hosts with API key).
  • Read balance, gas price/base fee, estimate gas, send raw tx, watch tx.
  • Sign native and ERC‑20 transactions; build approval calldata.
  • Fetch ERC‑20 metadata (via Moralis) and balances.
• EVMChainWallet:
  • Derive keys from BIP‑39 or use private key / Ledger (EvmLedgerCredentials).
  • EIP‑1559 fee calculation with priority presets; Polygon-specific tuning.
  • ERC‑20 token box per wallet; add/remove tokens and maintain balances.
  • Transaction history assembly (external/internal + token transfers).
  • Message sign/verify helpers.
• EVMChainWalletService: common create/open/restore/rename lifecycle.

Secrets

Create cw_evm/lib/.secrets.g.dart (do not commit):

const String nowNodesApiKey = '...';      // used for eth.nownodes.io / matic.nownodes.io
const String etherScanApiKey = '...';     // Etherscan v2 API key (incl. Polygon)
const String moralisApiKey = '...';       // optional, ERC-20 metadata lookup

Extending to a new EVM chain

Create a client and wallet subclass:

class MyChainClient extends EVMChainClient {
  @override
  int get chainId => 8453; // example
  @override
  Uint8List prepareSignedTransactionForSending(Uint8List tx) => tx;
  @override
  Future<List<EVMChainTransactionModel>> fetchTransactions(String address, {String? contractAddress}) async { /* ... */ }
  @override
  Future<List<EVMChainTransactionModel>> fetchInternalTransactions(String address) async { /* ... */ }
}

Then wire into a WalletService similar to EthereumWalletService/PolygonWalletService.

Additional information

• Uses web3dart under the hood and integrates with Cake Wallet’s cw_core types.
• See lib/ for the reference implementation details.