Collaborative expense sharing on Base: create bills with targets, contributors send ETH, receipt tokens mint/burn on contribution/refund, payees withdraw when funded, owner can seed/distribute rewards.

• Setup
• Local Run
• Deploy
• Architecture Overview

Create .env in repo root:

SEPOLIA_RPC_URL=<ethereum-sepolia-rpc>
BASE_SEPOLIA_RPC_URL=<base-sepolia-rpc>
PRIVATE_KEY=0x<owner/deployer key>
EXPENSE_ADDRESS=0x<current ExpenseShare address>        # for frontend

Install deps: npm install

• Frontend: python3 -m http.server 8080 --directory frontend then open http://127.0.0.1:8080
• Hardhat console (Base Sepolia): npx hardhat console --network baseSepolia

• Base Sepolia: npx hardhat run scripts/deploy.js --network baseSepolia

• Contracts:
  • ExpenseShare: bills (creator/payee/target/deadline/totalPaid/rewardPool/withdrawn), contribute with optional receipt tokens, withdraw (payee), refund (after deadline if unfunded), reward pool seed/distribute.
  • ReceiptToken: ERC-20 with setMinter, mint, burn used as contribution receipts.
• Frontend (frontend/index.html): vanilla JS + ethers v6 UMD; connects wallet, allows create/contribute/withdraw/refund, inspects bills, pulls token info, and logs contract events.