Agent skill
viem-celo
Viem with Celo chain configuration. Use when working with Celo blockchain interactions, public client setup, contract reads/writes, transaction encoding, or feeCurrency. Triggers on: "viem", "celo client", "publicClient", "readContract", "writeContract", "encodeFunctionData", "feeCurrency", "celo RPC".
Install this agent skill to your Project
npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/other/other/viem-celo
SKILL.md
Project Setup
Public Client (apps/api/src/lib/celo-client.ts)
import { createPublicClient, http } from 'viem';
import { celo } from 'viem/chains';
export const celoClient = createPublicClient({
chain: celo,
transport: http(process.env.CELO_RPC_URL || 'https://forno.celo.org'),
});
Chain Config
- Chain: Celo Mainnet
- Chain ID: 42220
- Import:
import { celo } from 'viem/chains' - Default RPC:
https://forno.celo.org - Block time: ~5 seconds
Common Patterns
Reading Contracts
const result = await celoClient.readContract({
address: CONTRACT_ADDRESS,
abi: contractAbi,
functionName: 'someFunction',
args: [arg1, arg2],
});
Encoding Transaction Data
import { encodeFunctionData } from 'viem';
const data = encodeFunctionData({
abi: contractAbi,
functionName: 'swapIn',
args: [provider, exchangeId, tokenIn, tokenOut, amountIn, minAmountOut],
});
Format / Parse Units
import { formatUnits, parseUnits } from 'viem';
// Mento tokens: 18 decimals
formatUnits(1000000000000000000n, 18); // "1.0"
parseUnits('100', 18); // 100000000000000000000n
// USDC/USDT: 6 decimals
formatUnits(1000000n, 6); // "1.0"
parseUnits('100', 6); // 100000000n
Address Types
Always use Address type from viem for addresses:
import type { Address } from 'viem';
const addr: Address = '0x765DE816845861e75A25fCA122bb6898B8B1282a';
Celo-Specific: feeCurrency (CIP-64)
Celo supports paying gas fees in tokens other than CELO. Use the feeCurrency field:
const hash = await walletClient.sendTransaction({
to: '0x...',
data: '0x...',
feeCurrency: '0x765DE816845861e75A25fCA122bb6898B8B1282a', // Pay gas in USDm
});
Common fee currencies on Celo:
- USDm (cUSD):
0x765DE816845861e75A25fCA122bb6898B8B1282a - USDC:
0xcebA9300f2b948710d2653dD7B07f33A8B32118C
Environment Variables
| Variable | Description |
|---|---|
CELO_RPC_URL |
Celo RPC endpoint (defaults to https://forno.celo.org) |
Important Notes
- All Mento stablecoin tokens use 18 decimals
- USDC and USDT on Celo use 6 decimals
- Use
getTokenDecimals()frompackages/sharedto get correct decimals - Always lowercase addresses when using them as map keys
- The project uses viem v2 — check
package.jsonfor exact version
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