@bitsocial/evm-contract-challenge

An automatic challenge for @pkcprotocol/pkc-js communities that verifies an author's EVM wallet address meets a condition from a smart contract call.

How it works

When an author publishes to a community with this challenge enabled, the community node calls a read-only smart contract method with the author's wallet address as the argument and compares the return value against a configured condition (e.g. >1000). The challenge tries three sources for the wallet address:

1. Wallet address — the author.wallets[chainTicker] address, verified via EIP-191 signature
2. ENS/BSO domain — if the author's address is a .eth or .bso domain, it resolves to an on-chain address
3. NFT avatar — the current owner of the author's avatar NFT

If any source produces a wallet that passes the contract call condition, the challenge succeeds. No user interaction is required.

Requirements

• Node.js >=22
• ESM-only environment

Install

With bitsocial-cli

bitsocial challenge install @bitsocial/evm-contract-challenge

Edit your community to use the challenge:

bitsocial community edit your-community.bso \
  '--settings.challenges[0].name' @bitsocial/evm-contract-challenge \
  '--settings.challenges[0].options.chainTicker' eth \
  '--settings.challenges[0].options.address' '0xEA81DaB2e0EcBc6B5c4172DE4c22B6Ef6E55Bd8f' \
  '--settings.challenges[0].options.abi' '{"constant":true,"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}' \
  '--settings.challenges[0].options.condition' '>10000000000000000000' \
  '--settings.challenges[0].options.error' 'You need at least 10 Bitsocial tokens to post.'

With pkc-js over RPC

If your RPC server is already running, first install the challenge on the server:

bitsocial challenge install @bitsocial/evm-contract-challenge

Then from your RPC client, connect and set the challenge on your community by name — no npm install or challenge registration needed on the client side:

import PKC from "@pkcprotocol/pkc-js";

const pkc = await PKC({
  pkcRpcClientsOptions: ["ws://localhost:9138"]
});

const community = await pkc.createCommunity({ address: "your-community-address.bso" });

await community.edit({
  settings: {
    challenges: [
      {
        name: "@bitsocial/evm-contract-challenge",
        options: {
          chainTicker: "eth",
          address: "0xEA81DaB2e0EcBc6B5c4172DE4c22B6Ef6E55Bd8f",
          abi: '{"constant":true,"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}',
          condition: ">10000000000000000000",
          error: "You need at least 10 Bitsocial tokens to post."
        }
      }
    ]
  }
});

With pkc-js (TypeScript)

If you are running your own node locally without connecting over RPC, you can install via npm and register the challenge manually:

npm install @bitsocial/evm-contract-challenge

import PKC from "@pkcprotocol/pkc-js";
import { evmContractChallenge } from "@bitsocial/evm-contract-challenge";

PKC.challenges["@bitsocial/evm-contract-challenge"] = evmContractChallenge;

Then set the challenge on your community:

await community.edit({
  settings: {
    challenges: [
      {
        name: "@bitsocial/evm-contract-challenge",
        options: {
          chainTicker: "eth",
          address: "0xEA81DaB2e0EcBc6B5c4172DE4c22B6Ef6E55Bd8f",
          abi: '{"constant":true,"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}',
          condition: ">10000000000000000000",
          error: "You need at least 10 Bitsocial tokens to post."
        }
      }
    ]
  }
});

Example Challenges

Each example uses a read-only contract function that takes a single address argument. The condition compares against the raw return value including decimal places (e.g. 10 USDC with 6 decimals = 10000000 raw).

Common ABIs

balanceOf — standard ERC-20 / ERC-721 token balance:

{"constant":true,"inputs":[{"internalType":"address","name":"account","type":"address"}],"name":"balanceOf","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"}

getScore — Gitcoin Passport score (returns uint256 with 4 decimals):

{"inputs":[{"internalType":"address","name":"user","type":"address"}],"name":"getScore","outputs":[{"internalType":"uint256","name":"","type":"uint256"}],"stateMutability":"view","type":"function"}

Examples

Description	chainTicker	address	ABI	condition
At least 10 Bitsocial (BSO) tokens	eth	0xEA81DaB2e0EcBc6B5c4172DE4c22B6Ef6E55Bd8f	balanceOf	>10000000000000000000
Minimum 10 USDC	eth	0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48	balanceOf	>10000000
Any WETH balance	eth	0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2	balanceOf	>0
Gitcoin Passport score above 20 (proof of personhood)	op	0xd6c51bB9E23bD7f1fEa22A3F2f85E3BFC8338Cb0	getScore	>200000
At least 10 MATIC on Polygon	matic	0x0000000000000000000000000000000000001010	balanceOf	>10000000000000000000
Any stETH balance (Lido staked ETH)	eth	0xae7ab96520DE3A18E5e111B5EaAb095312D7fE84	balanceOf	>0

For chains other than Ethereum mainnet (e.g. Optimism, Polygon), you will also need to set rpcUrls to one or more JSON-RPC endpoints for that chain.

Challenge Options

All option values must be strings.

Option	Default	Description
chainTicker	"eth"	The chain ticker (e.g. eth, matic)
rpcUrls	—	Comma-separated JSON-RPC URLs for the chain (uses viem defaults if omitted)
address	(required)	The contract address to call
abi	(required)	The ABI of the contract method as a JSON object (not an array)
condition	(required)	Condition the return value must pass (=, >, or < followed by a value, e.g. >1000)
error	"Contract call response doesn't pass condition."	Custom error message shown when the condition fails

Multiple RPC URLs

You can provide multiple RPC endpoints as a comma-separated string:

https://eth.llamarpc.com,https://rpc.ankr.com/eth,https://eth.drpc.org

When multiple URLs are provided, viem's fallback transport is used with automatic ranking enabled (rank: true). This means:

• Requests are sent to the highest-ranked RPC endpoint
• If a request fails, it automatically falls back to the next endpoint
• viem periodically pings all endpoints in the background and reorders them by latency and stability
• A single URL works the same as before (no fallback overhead)
• If rpcUrls is omitted, viem's built-in default RPCs are used

This improves reliability — if one RPC provider goes down, the challenge automatically uses the next available endpoint.

Scripts

npm run typecheck
npm run build
npm test