viem — Безопасное взаимодействие с Ethereum на TypeScript

--- name: viem description: TypeScript patterns for low-level EVM blockchain interactions using Viem. Use when writing Node scripts, CLI tools, or backend services that read/write to Ethereum or EVM chains. Triggers on contract interactions, wallet operations, transaction signing, event watching, ABI encoding, or any non-React blockchain TypeScript code. Do NOT use for React/Next.js apps with hooks (use wagmi skill instead). version: "2.x" docs: https://viem.sh --- # Viem Skill > **Version:** Viem 2.x | [Official Docs](https://viem.sh) Viem is the modern TypeScript interface for Ethereum. This skill ensures correct patterns for contract interactions, client setup, and type safety. ## Quick Reference ```typescript import { createPublicClient, createWalletClient, http } from 'viem' import { mainnet } from 'viem/chains' import { privateKeyToAccount } from 'viem/accounts' ``` ## Critical Patterns ### 1. Client Setup **Public Client** (read-only operations): ```typescript const publicClient = createPublicClient({ chain: mainnet, transport: http('https://eth-mainnet.g.alchemy.com/v2/YOUR_KEY'), }) ``` **Wallet Client** (write operations): ```typescript const account = privateKeyToAccount('0x...') const walletClient = createWalletClient({ account, chain: mainnet, transport: http('https://eth-mainnet.g.alchemy.com/v2/YOUR_KEY'), }) ``` ### 2. ABI Type Safety (CRITICAL) Always use `as const` for ABIs to get full type inference: ```typescript // ✅ CORRECT - Full type safety const abi = [ { name: 'balanceOf', type: 'function', stateMutability: 'view', inputs: [{ name: 'owner', type: 'address' }], outputs: [{ name: '', type: 'uint256' }], }, ] as const // ❌ WRONG - No type inference const abi = [{ name: 'balanceOf', ... }] // Missing `as const` ``` ### 3. Contract Read Pattern ```typescript const balance = await publicClient.readContract({ address: '0x...', // Contract address abi, functionName: 'balanceOf', args: ['0x...'], // Args are fully typed when using `as const` }) ``` ### 4. Contract Write Pattern (Simulate First!) Always simulate before writing to catch errors early: ```typescript // Step 1: Simulate const { request } = await publicClient.simulateContract({ account, address: '0x...', abi, functionName: 'transfer', args: ['0x...', 1000000n], // Use BigInt for uint256 }) // Step 2: Execute const hash = await walletClient.writeContract(request) // Step 3: Wait for receipt const receipt = await publicClient.waitForTransactionReceipt({ hash }) ``` ### 5. Event Watching ```typescript const unwatch = publicClient.watchContractEvent({ address: '0x...', abi, eventName: 'Transfer', onLogs: (logs) => { for (const log of logs) { console.log(log.args.from, log.args.to, log.args.value) } }, }) // Clean up unwatch() ``` ### 6. Multicall for Batch Reads ```typescript const results = await publicClient.multicall({ contracts: [ { address: '0x...', abi, functionName: 'balanceOf', args: ['0x...'] }, { address: '0x...', abi, functionName: 'totalSupply' }, ], }) // results[0].result, results[1].result ``` ## Common Mistakes | Mistake | Fix | |---------|-----| | Missing `as const` on ABI | Add `as const` for type inference | | Using `Number` for amounts | Use `BigInt` literals: `1000000n` | | Writing without simulate | Always `simulateContract` first | | Hardcoding gas | Let viem estimate, or use `gas: await publicClient.estimateGas(...)` | | Not awaiting receipts | Use `waitForTransactionReceipt` for confirmation | ## Chain Configuration ```typescript import { mainnet, polygon, arbitrum, optimism, base } from 'viem/chains' // Custom chain const customChain = { id: 123, name: 'My Chain', nativeCurrency: { name: 'ETH', symbol: 'ETH', decimals: 18 }, rpcUrls: { default: { http: ['https://rpc.mychain.com'] }, }, } ``` ## Error Handling ```typescript import { BaseError, ContractFunctionRevertedError } from 'viem' try { await publicClient.simulateContract({ ... }) } catch (err) { if (err instanceof BaseError) { const revertError = err.walk(e => e instanceof ContractFunctionRevertedError) if (revertError instanceof ContractFunctionRevertedError) { const errorName = revertError.data?.errorName // Handle specific revert reason } } } ``` ## References For detailed patterns, see: - `references/contract-patterns.md` - Advanced contract interaction patterns - `references/common-errors.md` - Error handling and debugging guide - [Viem Documentation](https://viem.sh) - Official docs - [Viem GitHub](https://github.com/wevm/viem) - Source and releases