This tutorial will guide you through building a liquidity-ready digital piggy bank on your EVM appchain. Users can deposit tokens, withdraw them, and access the broader Initia ecosystem via native bridging. By the end of this tutorial, you will have:

Generated and verified a Solidity smart contract for the bank logic.
Deployed the contract to your live appchain.
Scaffolded and connected a React frontend.
Verified the on-chain functionality.

Your Project Structure

The following steps will instruct your AI agent to create these directories inside your my-initia-project folder:

Project Structure

my-initia-project/
├── minibank/           # Solidity smart contract project
└── minibank-frontend/  # React frontend application

Prerequisite: Ensure you have an EVM-compatible appchain running locally. If you haven’t launched one yet, complete the Set Up Your Appchain first.

Readiness Check

Before you start, verify that your local infrastructure is healthy.

Prompt: Check local infrastructure health

Using the `initia-appchain-dev` skill, please verify that my appchain, executor bot, and relayer are running and that my Gas Station account has a balance.

Step 1: Create and Unit Test the Smart Contract

Instruct your AI agent to create the Solidity contract using the initia-appchain-dev skill. Your AI agent will generate the contract and automatically run unit tests to ensure the logic is sound.

Prompt: Create and test the MiniBank contract

Using the `initia-appchain-dev` skill, please create a Solidity smart contract project for our MiniBank in a new directory named `minibank`. The contract should:
- Allow users to deposit native tokens.
- Allow users to withdraw their own deposited tokens.
- Keep track of each user's total savings.
- Include a function to view the caller's current balance.
Please also create and run unit tests to verify these features.

Your AI agent will generate the minibank project and confirm that the tests (likely using Foundry or Hardhat) pass successfully.

Manual Approach: The Solidity Contract

Initialize a Foundry project first:

Initialize Foundry Project

# Use --no-git to avoid nested repos if you're already in a git project.
forge init minibank --no-git
cd minibank

If you prefer to create the contract manually, here is the Solidity code your AI agent would generate. Save this as MiniBank.sol in your minibank/src directory.

src/MiniBank.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

contract MiniBank {
    mapping(address => uint256) private balances;

    event Deposited(address indexed user, uint256 amount);
    event Withdrawn(address indexed user, uint256 amount);

    function deposit() public payable {
        require(msg.value > 0, "Cannot deposit 0");
        balances[msg.sender] += msg.value;
        emit Deposited(msg.sender, msg.value);
    }

    function withdraw(uint256 amount) public {
        require(amount > 0, "Withdrawal amount must be greater than zero");
        require(balances[msg.sender] >= amount, "Insufficient balance");

        balances[msg.sender] -= amount;
        (bool success, ) = payable(msg.sender).call{value: amount}("");
        require(success, "Transfer failed");

        emit Withdrawn(msg.sender, amount);
    }

    function myBalance() public view returns (uint256) {
      // NOTE: This returns the balance for the CALLER (msg.sender).
      // In tests or frontend calls, ensure the correct account is the caller.
      return balances[msg.sender];
    }

    function totalSavingsOf(address user) public view returns (uint256) {
      // Helper to check the balance of any user without needing a 'from' address.
      return balances[user];
    }

    receive() external payable {
        deposit();
    }
}

Unit Testing with Foundry

To verify your contract’s logic, create a test file named MiniBank.t.sol in the test directory.

test/MiniBank.t.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

import "forge-std/Test.sol";
import "../src/MiniBank.sol";

contract MiniBankTest is Test {
    MiniBank public bank;
    address public user = address(0x123);

    function setUp() public {
        bank = new MiniBank();
        vm.deal(user, 10 ether);
    }

    function testDeposit() public {
        vm.prank(user);
        bank.deposit{value: 1 ether}();
        assertEq(bank.totalSavingsOf(user), 1 ether);
    }

    function testWithdraw() public {
        vm.startPrank(user);
        bank.deposit{value: 2 ether}();
        bank.withdraw(1 ether);
        assertEq(bank.totalSavingsOf(user), 1 ether);
        vm.stopPrank();
    }

    function testWithdrawInsufficientBalance() public {
        vm.prank(user);
        bank.deposit{value: 1 ether}();

        vm.prank(user);
        vm.expectRevert("Insufficient balance");
        bank.withdraw(2 ether);
    }
}

Run your tests:

Run Foundry Tests

forge test

Step 2: Deploy to Your Appchain

Now that the logic is verified, build and publish the contract to your live appchain using the Gas Station account.

Prompt: Deploy the MiniBank contract

Using the `initia-appchain-dev` skill, please build, publish, and instantiate the MiniBank Solidity contract located in the `minibank` directory to my appchain using my Gas Station account, then return the deployed contract address.

Manual Approach: Deploy via CLI

First, compile your contract and extract the hex bytecode:

Compile And Extract Bytecode

# Navigate to the contract directory
cd minibank

# Compile with Foundry
forge build

# Extract bytecode (requires jq)
# Ensure NO '0x' prefix and NO trailing newlines
jq -r '.bytecode.object' out/MiniBank.sol/MiniBank.json | tr -d '\n' | sed 's/^0x//' > minibank.bin

Then deploy the binary. Find your Chain ID first if you don’t know it:

Get Chain ID

# Query the appchain ID directly
curl -s http://localhost:26657/status | jq -r '.result.node_info.network'

Now deploy:

Deploy Contract

# Replace `<YOUR_APPCHAIN_ID>` with the ID from the command above
minitiad tx evm create minibank.bin \
  --from gas-station \
  --keyring-backend test \
  --chain-id <YOUR_APPCHAIN_ID> \
  --node http://localhost:26657 \
  --gas auto --gas-adjustment 1.4 --yes --output json > deploy.json

Retrieve your contract address: The output will provide a txhash. Wait a few seconds for indexing, then find your contract address:

Get Contract Address

# Replace <YOUR_TX_HASH> with the hash from deploy.json
minitiad q tx <YOUR_TX_HASH> --node http://localhost:26657 --output json | jq -r '.events[] | select(.type=="contract_created") | .attributes[] | select(.key=="contract") | .value'

Step 3: Smoke Test the Deployed Contract On-Chain

Before moving to frontend integration, smoke test the deployed contract directly on chain from the CLI. This isolates contract-level issues before UI work.

Prompt: Smoke test the MiniBank contract

Using the `initia-appchain-dev` skill, I want to smoke test our live MiniBank contract. Using my Gas Station account on my appchain, please:
Deposit 1 token.
Check my balance.
Withdraw 0.5 tokens.
Check my balance again.

Manual Approach: On-Chain Interaction

Call deposit() and send exactly 1 token in base units (1e18 wei).

Deposit 1 Token

DATA=$(cast calldata "deposit()")
minitiad tx evm call <YOUR_CONTRACT_ADDRESS> $DATA \
  --from gas-station \
  --keyring-backend test \
  --chain-id <YOUR_APPCHAIN_ID> \
  --node http://localhost:26657 \
  --value 1000000000000000000 \
  --gas auto --gas-adjustment 1.4 --yes

Query myBalance() as your sender account so msg.sender resolves correctly.

Query Balance

SENDER=$(minitiad keys show gas-station -a --keyring-backend test)
DATA=$(cast calldata "myBalance()")
RAW=$(minitiad q evm call $SENDER <YOUR_CONTRACT_ADDRESS> $DATA --node http://localhost:26657 --output json | jq -r '.response')
echo "base_units: $(cast to-dec $RAW)"
echo "tokens: $(cast --from-wei $(cast to-dec $RAW) ether)"

Call withdraw(uint256) with 0.5 token in base units (5e17 wei).

Withdraw 0.5 Tokens

DATA=$(cast calldata "withdraw(uint256)" 500000000000000000)
minitiad tx evm call <YOUR_CONTRACT_ADDRESS> $DATA \
  --from gas-station \
  --keyring-backend test \
  --chain-id <YOUR_APPCHAIN_ID> \
  --node http://localhost:26657 \
  --gas auto --gas-adjustment 1.4 --yes

Query myBalance() again to confirm the post-withdraw balance.

Query Balance Again

SENDER=$(minitiad keys show gas-station -a --keyring-backend test)
DATA=$(cast calldata "myBalance()")
RAW=$(minitiad q evm call $SENDER <YOUR_CONTRACT_ADDRESS> $DATA --node http://localhost:26657 --output json | jq -r '.response')
echo "base_units: $(cast to-dec $RAW)"
echo "tokens: $(cast --from-wei $(cast to-dec $RAW) ether)"

Step 4: Create a Frontend

Let’s create a simple UI to interact with our bank. 1. Scaffold the Frontend:

Prompt: Scaffold the MiniBank frontend

Using the `initia-appchain-dev` skill, please scaffold a new Vite + React application named `minibank-frontend` in my current directory using the `scaffold-frontend` script. Create a component named Bank.jsx with Deposit and Withdraw buttons and an input field for the amount.

2. Connect to Appchain:

Prompt: Connect the frontend to the MiniBank contract

Using the `initia-appchain-dev` skill, modify the Bank.jsx component in the `minibank-frontend` directory to connect to our MiniBank contract on my appchain. Use the `@initia/interwovenkit-react` package for wallet connection and transaction signing.

Manual Approach: Scaffold and Connect

If you prefer to set up the frontend manually, follow these steps:1. Create the Project and Install Dependencies:

Create React App

npm create vite@latest minibank-frontend -- --template react
cd minibank-frontend
npm install
npm install @initia/interwovenkit-react wagmi viem @tanstack/react-query @initia/initia.js
npm install --save-dev vite-plugin-node-polyfills
npm install buffer util

2. Verify index.html: Vite scaffolding already creates index.html. Confirm it has this minimal structure in the root of your minibank-frontend directory:

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>MiniBank Frontend</title>
  </head>
  <body>
    <div id="root"></div>
    <script type="module" src="/src/main.jsx"></script>
  </body>
</html>

3. Configure Vite Polyfills: Update vite.config.js to include the Node polyfills:

vite.config.js

import { defineConfig } from 'vite'
import react from '@vitejs/plugin-react'
import { nodePolyfills } from 'vite-plugin-node-polyfills'

export default defineConfig({
  resolve: {
    dedupe: ['react', 'react-dom', 'wagmi', '@tanstack/react-query', 'viem'],
  },
  optimizeDeps: {
    include: ['wagmi', '@tanstack/react-query', 'viem'],
  },
  plugins: [
    react(),
    nodePolyfills({
      globals: {
        Buffer: true,
        process: true,
      },
    }),
  ],
})

4. Gather Runtime Values for Frontend Config: Before creating .env, collect the values you will use:

Gather Frontend Values

APPCHAIN_ID=$(curl -s http://localhost:26657/status | jq -r '.result.node_info.network')
NATIVE_DENOM=$(minitiad q evm params --output json | jq -r '.params.fee_denom')
NATIVE_SYMBOL=$(minitiad q bank denoms-metadata --output json \
  | jq -r --arg denom "$NATIVE_DENOM" '
      .metadatas[]
      | select(.base==$denom or .display==$denom)
      | .symbol
    ' \
  | head -n1)
[ -z "$NATIVE_SYMBOL" ] && NATIVE_SYMBOL="$NATIVE_DENOM"

# Use the contract address you retrieved in Step 2.
MINIBANK_CONTRACT=<YOUR_CONTRACT_ADDRESS>

echo "APPCHAIN_ID=$APPCHAIN_ID"
echo "NATIVE_DENOM=$NATIVE_DENOM"
echo "NATIVE_SYMBOL=$NATIVE_SYMBOL"
echo "MINIBANK_CONTRACT=$MINIBANK_CONTRACT"

5. Create .env from Runtime Values:

Create Frontend Env

cat > .env <<EOF
VITE_APPCHAIN_ID=$APPCHAIN_ID
VITE_NATIVE_DENOM=$NATIVE_DENOM
VITE_NATIVE_SYMBOL=$NATIVE_SYMBOL
VITE_NATIVE_DECIMALS=18
VITE_JSON_RPC_URL=http://localhost:8545
VITE_MINIBANK_CONTRACT=$MINIBANK_CONTRACT
VITE_BRIDGE_SRC_CHAIN_ID=initiation-2
VITE_BRIDGE_SRC_DENOM=uinit
EOF

6. Set up Providers in main.jsx:

src/main.jsx

import { Buffer } from 'buffer'
window.Buffer = Buffer
window.process = { env: { NODE_ENV: 'development' } }

import React from 'react'
import ReactDOM from 'react-dom/client'
import '@initia/interwovenkit-react/styles.css'
import {
  injectStyles,
  InterwovenKitProvider,
  TESTNET,
} from '@initia/interwovenkit-react'
import InterwovenKitStyles from '@initia/interwovenkit-react/styles.js'
import { WagmiProvider, createConfig, http } from 'wagmi'
import { mainnet } from 'wagmi/chains'
import { QueryClient, QueryClientProvider } from '@tanstack/react-query'
import App from './App.jsx'

injectStyles(InterwovenKitStyles)

const queryClient = new QueryClient()
const wagmiConfig = createConfig({
  chains: [mainnet],
  transports: { [mainnet.id]: http() },
})

const customChain = {
  chain_id: import.meta.env.VITE_APPCHAIN_ID,
  chain_name: 'minibank',
  pretty_name: 'MiniBank Appchain',
  network_type: 'testnet',
  bech32_prefix: 'init',
  logo_URIs: {
    png: 'https://raw.githubusercontent.com/initia-labs/initia-registry/main/testnets/initia/images/initia.png',
    svg: 'https://raw.githubusercontent.com/initia-labs/initia-registry/main/testnets/initia/images/initia.svg',
  },
  apis: {
    rpc: [{ address: 'http://localhost:26657' }],
    rest: [{ address: 'http://localhost:1317' }],
    indexer: [{ address: 'http://localhost:8080' }],
    'json-rpc': [{ address: 'http://localhost:8545' }],
  },
  fees: {
    fee_tokens: [
      {
        denom: import.meta.env.VITE_NATIVE_DENOM,
        fixed_min_gas_price: 0,
        low_gas_price: 0,
        average_gas_price: 0,
        high_gas_price: 0,
      },
    ],
  },
  staking: {
    staking_tokens: [{ denom: import.meta.env.VITE_NATIVE_DENOM }],
  },
  metadata: {
    minitia: { type: 'minievm' },
    is_l1: false,
  },
  native_assets: [
    {
      denom: import.meta.env.VITE_NATIVE_DENOM,
      name: 'Native Token',
      symbol: import.meta.env.VITE_NATIVE_SYMBOL,
      decimals: Number(import.meta.env.VITE_NATIVE_DECIMALS ?? 18),
    },
  ],
}

ReactDOM.createRoot(document.getElementById('root')).render(
  <React.StrictMode>
    <WagmiProvider config={wagmiConfig}>
      <QueryClientProvider client={queryClient}>
        <InterwovenKitProvider
          {...TESTNET}
          defaultChainId={customChain.chain_id}
          customChain={customChain}
          customChains={[customChain]}
        >
          <App />
        </InterwovenKitProvider>
      </QueryClientProvider>
    </WagmiProvider>
  </React.StrictMode>,
)

7. Create the App.jsx Layout:

src/App.jsx

import React from 'react'
import { useInterwovenKit } from '@initia/interwovenkit-react'
import Bank from './Bank'

function App() {
  const { initiaAddress, openConnect, openWallet } = useInterwovenKit()

  const containerStyle = {
    fontFamily: 'system-ui, -apple-system, sans-serif',
    minHeight: '100vh',
    display: 'flex',
    flexDirection: 'column',
    alignItems: 'center',
    justifyContent: 'center',
    backgroundColor: '#f1f5f9',
    padding: '20px',
  }

  const cardStyle = {
    backgroundColor: '#ffffff',
    borderRadius: '16px',
    boxShadow: '0 10px 25px -5px rgba(0, 0, 0, 0.1)',
    padding: '40px',
    width: '100%',
    maxWidth: '500px',
    display: 'flex',
    flexDirection: 'column',
    alignItems: 'center',
    textAlign: 'center',
  }

  const buttonStyle = {
    backgroundColor: '#3b82f6',
    color: 'white',
    border: 'none',
    padding: '12px 24px',
    borderRadius: '8px',
    fontSize: '16px',
    fontWeight: '600',
    cursor: 'pointer',
    width: '100%',
  }

  const secondaryButtonStyle = {
    backgroundColor: '#f1f5f9',
    border: '1px solid #e2e8f0',
    color: '#64748b',
    padding: '12px 24px',
    borderRadius: '10px',
    fontSize: '14px',
    fontWeight: '600',
    cursor: 'pointer',
    marginTop: '20px',
    width: '100%',
  }

  return (
    <div style={containerStyle}>
      <div style={cardStyle}>
        <h1
          style={{ fontSize: '32px', fontWeight: '800', marginBottom: '8px' }}
        >
          MiniBank
        </h1>

        {!initiaAddress ? (
          <>
            <p style={{ color: '#64748b', marginBottom: '32px' }}>
              Connect your wallet to manage your savings.
            </p>
            <button onClick={openConnect} style={buttonStyle}>
              Connect Wallet
            </button>
          </>
        ) : (
          <>
            <Bank />
            <button onClick={openWallet} style={secondaryButtonStyle}>
              Open Wallet
            </button>
          </>
        )}
      </div>
    </div>
  )
}

export default App

8. Create the Bank.jsx Component: Create src/Bank.jsx and add the contract interaction logic.

msg.sender in view Calls: For view functions that depend on msg.sender (like myBalance), provide a from address in your eth_call params so the appchain resolves the correct user balance. This tutorial assumes 18 decimals, so parseEther/formatEther are used.

src/Bank.jsx

import React, { useState, useEffect } from 'react'
import { useInterwovenKit } from '@initia/interwovenkit-react'
import { encodeFunctionData, parseEther, formatEther } from 'viem'
import { AccAddress } from '@initia/initia.js'

const MINI_BANK_ADDRESS = import.meta.env.VITE_MINIBANK_CONTRACT
const CHAIN_ID = import.meta.env.VITE_APPCHAIN_ID
const NATIVE_DENOM = import.meta.env.VITE_NATIVE_DENOM
const NATIVE_SYMBOL = import.meta.env.VITE_NATIVE_SYMBOL
const JSON_RPC_URL = import.meta.env.VITE_JSON_RPC_URL ?? 'http://localhost:8545'
const MINI_BANK_ABI = [
  { name: 'deposit', type: 'function', stateMutability: 'payable', inputs: [] },
  {
    name: 'withdraw',
    type: 'function',
    inputs: [{ name: 'amount', type: 'uint256' }],
  },
  {
    name: 'myBalance',
    type: 'function',
    stateMutability: 'view',
    inputs: [],
    outputs: [{ type: 'uint256' }],
  },
  {
    name: 'totalSavingsOf',
    type: 'function',
    stateMutability: 'view',
    inputs: [{ name: 'user', type: 'address' }],
    outputs: [{ type: 'uint256' }],
  },
]

const Bank = () => {
  const [amount, setAmount] = useState('')
  const [balance, setBalance] = useState('0')
  const [isPending, setIsPending] = useState(false)
  const { initiaAddress, requestTxBlock } = useInterwovenKit()

  const fetchBalance = async () => {
    if (!initiaAddress) return
    try {
      const hex = AccAddress.toHex(initiaAddress)
      const userHex = hex.startsWith('0x') ? hex : `0x${hex}`
      const data = encodeFunctionData({
        abi: MINI_BANK_ABI,
        functionName: 'myBalance',
      })
      const response = await fetch(JSON_RPC_URL, {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          jsonrpc: '2.0',
          method: 'eth_call',
          params: [{ from: userHex, to: MINI_BANK_ADDRESS, data }, 'latest'],
          id: 1,
        }),
      })
      const result = await response.json()
      if (result.result && result.result !== '0x') {
        setBalance(formatEther(BigInt(result.result)))
      }
    } catch (error) {
      console.error('Error fetching balance:', error)
    }
  }

  useEffect(() => {
    fetchBalance()
    const interval = setInterval(fetchBalance, 10000)
    return () => clearInterval(interval)
  }, [initiaAddress])

  const handleDeposit = async () => {
    if (!amount || !initiaAddress) return
    const data = encodeFunctionData({
      abi: MINI_BANK_ABI,
      functionName: 'deposit',
    })
    setIsPending(true)
    try {
      await requestTxBlock({
        chainId: CHAIN_ID,
        messages: [
          {
            typeUrl: '/minievm.evm.v1.MsgCall',
            value: {
              sender: initiaAddress.toLowerCase(),
              contractAddr: MINI_BANK_ADDRESS,
              input: data,
              value: parseEther(amount).toString(),
              accessList: [],
              authList: [],
            },
          },
        ],
      })
      alert('Deposit successful!')
      setAmount('')
      fetchBalance()
    } catch (error) {
      console.error('Deposit error:', error)
      alert('Transaction failed or was cancelled.')
    } finally {
      setIsPending(false)
    }
  }

  const handleWithdraw = async () => {
    if (!amount || !initiaAddress) return
    const data = encodeFunctionData({
      abi: MINI_BANK_ABI,
      functionName: 'withdraw',
      args: [parseEther(amount)],
    })
    setIsPending(true)
    try {
      await requestTxBlock({
        chainId: CHAIN_ID,
        messages: [
          {
            typeUrl: '/minievm.evm.v1.MsgCall',
            value: {
              sender: initiaAddress.toLowerCase(),
              contractAddr: MINI_BANK_ADDRESS,
              input: data,
              value: '0',
              accessList: [],
              authList: [],
            },
          },
        ],
      })
      alert('Withdrawal successful!')
      setAmount('')
      fetchBalance()
    } catch (error) {
      console.error('Withdraw error:', error)
      alert('Transaction failed or was cancelled.')
    } finally {
      setIsPending(false)
    }
  }

  const balanceContainerStyle = {
    backgroundColor: '#f1f5f9',
    padding: '30px',
    borderRadius: '16px',
    marginBottom: '30px',
    border: '1px solid #e2e8f0',
  }
  const balanceValueStyle = {
    fontSize: '42px',
    fontWeight: '800',
    color: '#2563eb',
    margin: '10px 0',
    fontFamily: 'monospace',
  }
  const inputStyle = {
    width: '100%',
    padding: '14px',
    marginBottom: '20px',
    borderRadius: '10px',
    border: '2px solid #e2e8f0',
    fontSize: '16px',
    boxSizing: 'border-box',
  }
  const buttonContainerStyle = { display: 'flex', gap: '15px' }
  const actionButtonStyle = {
    flex: 1,
    padding: '14px',
    borderRadius: '10px',
    border: 'none',
    fontWeight: '700',
    fontSize: '16px',
    cursor: 'pointer',
    color: 'white',
  }

  return (
    <div style={{ width: '100%', marginTop: '20px' }}>
      <div style={balanceContainerStyle}>
        <div
          style={{
            fontSize: '14px',
            color: '#64748b',
            textTransform: 'uppercase',
          }}
        >
          Your Savings Balance
        </div>
        <div style={balanceValueStyle}>{balance} {NATIVE_SYMBOL}</div>
      </div>
      <input
        type="number"
        value={amount}
        onChange={(e) => setAmount(e.target.value)}
        placeholder="0.00"
        style={inputStyle}
      />
      <div style={buttonContainerStyle}>
        <button
          onClick={handleDeposit}
          style={{
            ...actionButtonStyle,
            backgroundColor: '#10b981',
            opacity: isPending ? 0.5 : 1,
          }}
          disabled={!initiaAddress || isPending}
        >
          {isPending ? 'Pending...' : 'Deposit'}
        </button>
        <button
          onClick={handleWithdraw}
          style={{
            ...actionButtonStyle,
            backgroundColor: '#ef4444',
            opacity: isPending ? 0.5 : 1,
          }}
          disabled={!initiaAddress || isPending}
        >
          {isPending ? 'Pending...' : 'Withdraw'}
        </button>
      </div>
    </div>
  )
}

export default Bank

Step 5: Wallet Funding and UI Verification

Ask your AI agent to fund your browser wallet, then verify frontend behavior manually in the browser:

Start the frontend:

Start Vite Dev Server

cd minibank-frontend
npm run dev

Check the browser console if you encounter issues.

Open your browser wallet and copy your address (init1...).
Give this prompt to your AI agent, replacing <YOUR_WALLET_ADDRESS> with the address you just copied:

Using the `initia-appchain-dev` skill, please fund my wallet address <YOUR_WALLET_ADDRESS> with 100 of my appchain's native tokens on L2.

Connect your wallet in minibank-frontend.
Test the full flow by depositing and withdrawing from the UI, then confirm the displayed savings state updates correctly after each action.

If you get stuck, see the Debugging Workflow guide.

🪢 Native Feature: Interwoven Bridge

Adding bridge support allows users to bring liquidity from the broader Initia ecosystem into your rollup. This transforms your appchain from an isolated sandbox into a connected part of the Interwoven Stack, providing users with a seamless UI to bridge tokens into your application for use.

Local Dev Limitation: The Interwoven UI only resolves registered chain IDs, so your local appchain and token may not appear during local testing. You can still add bridge functionality now. In your hackathon submission, explain the user flow (for example: bridge INIT or other assets from L1 to your appchain, then deposit them in MiniBank) and why this matters (faster onboarding, easier liquidity access, and immediate utility in your app).

Step 6: Update the Frontend

The useInterwovenKit() hook provides openBridge, which opens the bridge modal for moving assets between chains.

Prompt: Add Interwoven Bridge support

Using the `initia-appchain-dev` skill, please enable Interwoven Bridge support in my MiniBank so I can move funds between chains on Initia.

Manual Approach: Bridge Integration

To implement this, update your src/Bank.jsx to include the bridge logic and UI:

Bridge Logic

// 1. Extract bridge functions from the hook
const { initiaAddress, openConnect, openBridge } = useInterwovenKit()

// 2. Add bridge handler
const handleBridge = () => {
  if (!initiaAddress) {
    openConnect()
    return
  }
  openBridge({
    srcChainId: 'initiation-2', // Public testnet ID
    srcDenom: 'uinit', // Native INIT
  })
}

// 3. Add the Bridge UI section to your render (conditionally)
const bridgeContainerStyle = {
  marginTop: '2rem',
  padding: '1.5rem',
  backgroundColor: '#fffbeb',
  borderRadius: '24px',
  border: '1px solid #fef3c7',
  textAlign: 'left',
}

const bridgeButtonStyle = {
  width: '100%',
  padding: '0.85rem',
  backgroundColor: '#d97706',
  color: 'white',
  border: 'none',
  borderRadius: '14px',
  fontSize: '13px',
  fontWeight: '800',
  cursor: 'pointer',
  display: 'flex',
  alignItems: 'center',
  justifyContent: 'center',
  gap: '0.5rem',
}

// Inside return (showing it only when connected)...
{
  initiaAddress && (
    <div style={bridgeContainerStyle}>
      <div
        style={{
          fontWeight: '700',
          fontSize: '11px',
          textTransform: 'uppercase',
          letterSpacing: '0.1em',
          color: '#92400e',
          marginBottom: '4px',
        }}
      >
        Interwoven Ecosystem
      </div>
      <p style={{ fontSize: '13px', color: '#b45309', margin: '0 0 12px 0' }}>
        Access the broader Initia network to move assets between chains.
      </p>
      <button onClick={handleBridge} style={bridgeButtonStyle}>
        Bridge Assets
      </button>
    </div>
  )
}

If you want a complete end-state after the manual steps above, use the consolidated reference below.

Manual Approach: Final Frontend Reference

This reference combines:

runtime config from .env,
InterwovenKit provider wiring in main.jsx,
wallet connect/display in App.jsx, and
live MiniBank interactions plus bridge entry point in Bank.jsx.

.env

.env

VITE_APPCHAIN_ID=<YOUR_APPCHAIN_ID>
VITE_NATIVE_DENOM=<YOUR_NATIVE_DENOM>
VITE_NATIVE_SYMBOL=<YOUR_NATIVE_SYMBOL>
VITE_NATIVE_DECIMALS=18
VITE_JSON_RPC_URL=http://localhost:8545
VITE_MINIBANK_CONTRACT=<YOUR_CONTRACT_ADDRESS>
VITE_BRIDGE_SRC_CHAIN_ID=initiation-2
VITE_BRIDGE_SRC_DENOM=uinit

src/main.jsx

src/main.jsx

import { Buffer } from 'buffer'
window.Buffer = Buffer
window.process = { env: { NODE_ENV: 'development' } }

import React from 'react'
import ReactDOM from 'react-dom/client'
import "@initia/interwovenkit-react/styles.css";
import { injectStyles, InterwovenKitProvider, TESTNET } from "@initia/interwovenkit-react";
import InterwovenKitStyles from "@initia/interwovenkit-react/styles.js";
import { WagmiProvider, createConfig, http } from "wagmi";
import { mainnet } from "wagmi/chains";
import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
import App from './App.jsx'

injectStyles(InterwovenKitStyles);

const queryClient = new QueryClient();
const wagmiConfig = createConfig({
  chains: [mainnet],
  transports: { [mainnet.id]: http() },
});

const customChain = {
  chain_id: import.meta.env.VITE_APPCHAIN_ID,
  chain_name: 'minibank',
  pretty_name: 'MiniBank Appchain',
  network_type: 'testnet',
  bech32_prefix: 'init',
  logo_URIs: {
    png: 'https://raw.githubusercontent.com/initia-labs/initia-registry/main/testnets/initia/images/initia.png',
    svg: 'https://raw.githubusercontent.com/initia-labs/initia-registry/main/testnets/initia/images/initia.svg',
  },
  apis: {
    rpc: [{ address: 'http://localhost:26657' }],
    rest: [{ address: 'http://localhost:1317' }],
    indexer: [{ address: 'http://localhost:8080' }],
    'json-rpc': [{ address: import.meta.env.VITE_JSON_RPC_URL ?? 'http://localhost:8545' }],
  },
  fees: {
    fee_tokens: [{
      denom: import.meta.env.VITE_NATIVE_DENOM,
      fixed_min_gas_price: 0,
      low_gas_price: 0,
      average_gas_price: 0,
      high_gas_price: 0,
    }],
  },
  staking: {
    staking_tokens: [{ denom: import.meta.env.VITE_NATIVE_DENOM }]
  },
  metadata: {
    is_l1: false,
    minitia: {
      type: 'minievm',
    },
  },
  native_assets: [
    {
      denom: import.meta.env.VITE_NATIVE_DENOM,
      name: 'Native Token',
      symbol: import.meta.env.VITE_NATIVE_SYMBOL,
      decimals: Number(import.meta.env.VITE_NATIVE_DECIMALS ?? 18)
    }
  ]
}

ReactDOM.createRoot(document.getElementById('root')).render(
  <React.StrictMode>
    <WagmiProvider config={wagmiConfig}>
      <QueryClientProvider client={queryClient}>
        <InterwovenKitProvider
          {...TESTNET}
          defaultChainId={customChain.chain_id}
          customChain={customChain}
          customChains={[customChain]}
        >
          <App />
        </InterwovenKitProvider>
      </QueryClientProvider>
    </WagmiProvider>
  </React.StrictMode>,
)

src/App.jsx

src/App.jsx

import React from 'react'
import { useInterwovenKit } from "@initia/interwovenkit-react";
import Bank from './Bank.jsx';

function App() {
  const { initiaAddress, openConnect, openWallet } = useInterwovenKit();

  const shortenAddress = (addr) => {
    if (!addr) return "";
    return `${addr.slice(0, 8)}...${addr.slice(-4)}`;
  };

  return (
    <div style={{ minHeight: '100vh', display: 'flex', flexDirection: 'column', alignItems: 'center' }}>
      <header style={{
        width: '100%',
        maxWidth: '1200px',
        display: 'flex',
        justifyContent: 'space-between',
        alignItems: 'center',
        padding: '2rem'
      }}>
        <h1 style={{ fontSize: '1.25rem', fontWeight: 800, margin: 0 }}>MiniBank</h1>

        {!initiaAddress ? (
          <button onClick={openConnect}>Connect Wallet</button>
        ) : (
          <button onClick={openWallet}>{shortenAddress(initiaAddress)}</button>
        )}
      </header>

      <main style={{ flex: 1, width: '100%', maxWidth: '760px', padding: '2rem' }}>
        <Bank />
      </main>
    </div>
  )
}

export default App

src/Bank.jsx

src/Bank.jsx

import React, { useEffect, useState } from 'react'
import { useInterwovenKit } from '@initia/interwovenkit-react'
import { AccAddress } from '@initia/initia.js'
import { encodeFunctionData, formatUnits, parseUnits } from 'viem'

const CHAIN_ID = import.meta.env.VITE_APPCHAIN_ID
const NATIVE_DENOM = import.meta.env.VITE_NATIVE_DENOM
const NATIVE_SYMBOL = import.meta.env.VITE_NATIVE_SYMBOL
const NATIVE_DECIMALS = Number(import.meta.env.VITE_NATIVE_DECIMALS ?? 18)
const JSON_RPC_URL = import.meta.env.VITE_JSON_RPC_URL ?? 'http://localhost:8545'
const MINI_BANK_ADDRESS = import.meta.env.VITE_MINIBANK_CONTRACT
const BRIDGE_SRC_CHAIN_ID = import.meta.env.VITE_BRIDGE_SRC_CHAIN_ID ?? 'initiation-2'
const BRIDGE_SRC_DENOM = import.meta.env.VITE_BRIDGE_SRC_DENOM ?? 'uinit'

const MINI_BANK_ABI = [
  { name: 'deposit', type: 'function', stateMutability: 'payable', inputs: [] },
  {
    name: 'withdraw',
    type: 'function',
    stateMutability: 'nonpayable',
    inputs: [{ name: 'amount', type: 'uint256' }],
  },
  {
    name: 'myBalance',
    type: 'function',
    stateMutability: 'view',
    inputs: [],
    outputs: [{ type: 'uint256' }],
  },
]

export default function Bank() {
  const { initiaAddress, openConnect, openBridge, requestTxBlock } = useInterwovenKit()
  const [amount, setAmount] = useState('')
  const [balance, setBalance] = useState('0')
  const [isPending, setIsPending] = useState(false)
  const [status, setStatus] = useState('')

  const fetchBalance = async () => {
    if (!initiaAddress) {
      setBalance('0')
      return
    }

    const data = encodeFunctionData({ abi: MINI_BANK_ABI, functionName: 'myBalance' })
    const from = AccAddress.toHex(initiaAddress).toLowerCase()

    const response = await fetch(JSON_RPC_URL, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({
        jsonrpc: '2.0',
        method: 'eth_call',
        params: [{ from, to: MINI_BANK_ADDRESS, data }, 'latest'],
        id: 1,
      }),
    })

    const result = await response.json()
    if (result.error) throw new Error(result.error.message || 'eth_call failed')
    const baseUnits = BigInt(result.result || '0x0')
    setBalance(formatUnits(baseUnits, NATIVE_DECIMALS))
  }

  useEffect(() => {
    fetchBalance().catch((err) => setStatus(String(err.message || err)))
  }, [initiaAddress])

  const handleDeposit = async () => {
    if (!initiaAddress || !amount || Number(amount) <= 0) return
    setIsPending(true)
    setStatus('Submitting deposit...')
    try {
      const input = encodeFunctionData({ abi: MINI_BANK_ABI, functionName: 'deposit' })
      const value = parseUnits(amount, NATIVE_DECIMALS).toString()
      const tx = await requestTxBlock({
        chainId: CHAIN_ID,
        messages: [{
          typeUrl: '/minievm.evm.v1.MsgCall',
          value: {
            sender: initiaAddress.toLowerCase(),
            contractAddr: MINI_BANK_ADDRESS,
            input,
            value,
            accessList: [],
            authList: [],
          },
        }],
      })
      setStatus(`Deposit confirmed: ${tx?.txhash ?? 'submitted'}`)
      setAmount('')
      await fetchBalance()
    } catch (err) {
      setStatus(`Deposit failed: ${String(err.message || err)}`)
    } finally {
      setIsPending(false)
    }
  }

  const handleWithdraw = async () => {
    if (!initiaAddress || !amount || Number(amount) <= 0) return
    setIsPending(true)
    setStatus('Submitting withdrawal...')
    try {
      const input = encodeFunctionData({
        abi: MINI_BANK_ABI,
        functionName: 'withdraw',
        args: [parseUnits(amount, NATIVE_DECIMALS)],
      })
      const tx = await requestTxBlock({
        chainId: CHAIN_ID,
        messages: [{
          typeUrl: '/minievm.evm.v1.MsgCall',
          value: {
            sender: initiaAddress.toLowerCase(),
            contractAddr: MINI_BANK_ADDRESS,
            input,
            value: '0',
            accessList: [],
            authList: [],
          },
        }],
      })
      setStatus(`Withdraw confirmed: ${tx?.txhash ?? 'submitted'}`)
      setAmount('')
      await fetchBalance()
    } catch (err) {
      setStatus(`Withdraw failed: ${String(err.message || err)}`)
    } finally {
      setIsPending(false)
    }
  }

  const handleBridge = async () => {
    if (!initiaAddress) {
      openConnect()
      return
    }
    await openBridge({
      srcChainId: BRIDGE_SRC_CHAIN_ID,
      srcDenom: BRIDGE_SRC_DENOM,
    })
  }

  return (
    <section>
      <p>My Savings: {balance} {NATIVE_SYMBOL}</p>
      <input
        type="number"
        min="0"
        step="any"
        value={amount}
        onChange={(e) => setAmount(e.target.value)}
        placeholder="Enter amount"
      />
      <div style={{ display: 'flex', gap: '12px', marginTop: '12px' }}>
        <button onClick={handleDeposit} disabled={!initiaAddress || isPending}>Deposit</button>
        <button onClick={handleWithdraw} disabled={!initiaAddress || isPending}>Withdraw</button>
        <button onClick={handleBridge} disabled={isPending}>Bridge Funds</button>
      </div>
      {status ? <p>{status}</p> : null}
    </section>
  )
}

This reference assumes:

the deployed contract address is stored in .env as VITE_MINIBANK_CONTRACT,
sender in MsgCall uses bech32 (initiaAddress) lowercased,
EVM balance reads use JSON-RPC eth_call with a from hex address, and
the Vite dev server is restarted after any .env change.

Native Feature Verification

Connect your wallet in minibank-frontend.
Click Bridge Funds.
Confirm the Interwoven Bridge modal opens.

Next Steps

Now that you’ve mastered an EVM application, you’re ready to build your own idea! Ensure your project meets all the Submission Requirements before submitting.

Developers

Quick Guides

VM Specific Tutorials

Integrating with Initia Apps

Tools

Programs

MiniBank - EVM

Your Project Structure

Readiness Check

Step 1: Create and Unit Test the Smart Contract

Unit Testing with Foundry

Step 2: Deploy to Your Appchain

Step 3: Smoke Test the Deployed Contract On-Chain

Step 4: Create a Frontend

Step 5: Wallet Funding and UI Verification

🪢 Native Feature: Interwoven Bridge

Step 6: Update the Frontend

Native Feature Verification

Next Steps

​Your Project Structure

​Readiness Check

​Step 1: Create and Unit Test the Smart Contract

​Unit Testing with Foundry

​Step 2: Deploy to Your Appchain

​Step 3: Smoke Test the Deployed Contract On-Chain

​Step 4: Create a Frontend

​Step 5: Wallet Funding and UI Verification

​🪢 Native Feature: Interwoven Bridge

​Step 6: Update the Frontend

​Native Feature Verification

​Next Steps

Your Project Structure

Readiness Check

Step 1: Create and Unit Test the Smart Contract

Unit Testing with Foundry

Step 2: Deploy to Your Appchain

Step 3: Smoke Test the Deployed Contract On-Chain

Step 4: Create a Frontend

Step 5: Wallet Funding and UI Verification

🪢 Native Feature: Interwoven Bridge

Step 6: Update the Frontend

Native Feature Verification

Next Steps