11. Todo

11-Todo/README.md

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+# 11-Todo: A Decentralized Todo List on Core Testnet 2
+
+## Overview
+
+**11-Todo** is a decentralized application (dApp) deployed on **Core Testnet 2**, designed to manage a todo list directly on the blockchain. It combines a Solidity smart contract (`Task.sol`) for backend logic with a responsive React frontend for user interaction.
+
+Users can create todos, toggle their completion status, and view both completed and all todos, with all data stored immutably on the blockchain.
+
+## Technologies Used
+
+* **Solidity** (^0.8.13) — Smart contract language
+* **Foundry** — Smart contract development and deployment toolkit
+* **React** — Frontend framework
+* **Viem** — Blockchain interaction library for dApps
+* **Ethers.js** — Utility library for decoding and blockchain interactions
+* **MetaMask** — Wallet for user authentication and transactions
+* **Core Testnet 2** — Blockchain test network
+* **Node.js & npm** — Environment for managing frontend dependencies
+
+## Architecture
+
+### Smart Contract: `Task.sol`
+
+* **Functions**:
+
+  * `createTask(string _name)`: Adds a new todo
+  * `toggleTask(uint index)`: Marks a todo as completed/uncompleted
+  * `getAllTasks()`: Retrieves all todos with status and timestamp
+
+**Deployed Address**: `0xf4Cc3E6A0EFE70c007243591B9d500760361Bad2` (Core Testnet 2)
+
+### React Frontend: `core_frontal`
+
+* Connects to MetaMask
+* Displays all and completed todos
+* Allows creation and toggling of todos
+* Built using `ethers.js`, `viem`, and standard React hooks
+
+---
+
+## Getting Started
+
+### Prerequisites
+
+* [Node.js (v14.15.5+)](https://nodejs.org/)
+* npm (v7.5.3+)
+* [Foundry](https://book.getfoundry.sh/) (includes `forge` and `cast`)
+* [MetaMask](https://metamask.io/) (configured for Core Testnet 2)
+* Core Testnet 2 RPC URL (e.g., via [ChainList](https://chainlist.org))
+* Testnet ETH (via Core faucet)
+* Git
+
+---
+
+## Installation
+
+### 1. Clone the Repository
+
+```bash
+git clone https://github.com/your-username/dapp-tutorial.git
+cd dapp-tutorial/11-todo
+```
+
+---
+
+## Backend Setup (Foundry)
+
+### 1. Navigate to Contracts Folder
+
+```bash
+cd contracts
+```
+
+### 2. Set Environment Variables
+
+Create a `.env` file:
+
+```ini
+PRIVATE_KEY=<your-wallet-private-key>
+RPC_URL=<your-core-testnet2-rpc-url>
+```
+
+### 3. Install Dependencies
+
+```bash
+forge install
+```
+
+### 4. Compile Contract
+
+```bash
+forge build
+```
+
+### 5. Deploy Contract
+
+```bash
+forge create --rpc-url $RPC_URL --private-key $PRIVATE_KEY src/Task.sol:Tasks
+```
+
+Copy the deployed contract address and update `core_frontal/src/getContractInstance.js` accordingly:
+
+```js
+address: getAddress("<new-contract-address>")
+```
+
+---
+
+## Frontend Setup (React)
+
+### 1. Navigate to Frontend
+
+```bash
+cd ../frontend
+```
+
+### 2. Install Frontend Dependencies
+
+```bash
+npm install
+```
+
+### 3. Start the Development Server
+
+```bash
+npm start
+```
+
+Visit [http://localhost:3000](http://localhost:3000) in your browser with MetaMask connected to Core Testnet 2.
+
+---
+
+## Usage Guide
+
+### Smart Contract
+
+* **Create Todo**: `createTask(string _name)`
+* **Toggle Todo**: `toggleTask(uint index)`
+* **Get All Todos**: `getAllTasks()`
+
+Using Cast:
+
+```bash
+cast call 0xf4Cc3E6A0EFE70c007243591B9d500760361Bad2 \
+"getAllTasks()(bytes32[],bool[],uint256[])" \
+--rpc-url $RPC_URL
+```
+
+### Frontend (core\_frontal)
+
+* **Connect Wallet**: Use MetaMask on Core Testnet 2
+* **Create Todo**: Input text and click **"Create Todo"**
+* **View Todos**: Click **"Get Todos"**
+* **View Completed Todos**: Click **"Get Completed Todos"**
+* **Toggle Todo**: Click **"Complete"** (disabled if already completed)
+* **Clear Display**: Click **"Clear message"** to reset list
+
+---
+
+## Project Structure
+
+```
+11-Todo/
+├── contracts/                # Foundry contracts
+│   ├── src/Task.sol          # Main contract
+│   ├── test/                 # Tests (optional)
+│   ├── lib/, cache/, out/    # Foundry generated
+│   └── foundry.toml          # Config file
+├── frontend/                 # React frontend
+│   ├── src/
+│   │   ├── abi.json
+│   │   ├── App.js
+│   │   ├── Main.js
+│   │   ├── TodoList.jsx
+│   │   ├── Todo.jsx
+│   │   ├── getContractInstance.js
+│   │   ├── index.js
+│   │   ├── App.css
+│   │   └── reportWebVitals.js
+│   ├── public/
+│   ├── package.json
+│   └── package-lock.json
+├── README.md
+```
+
+---
+
+## Troubleshooting
+
+| Issue                         | Solution                                                                   |
+| ----------------------------- | -------------------------------------------------------------------------- |
+| **Contract deployment fails** | Ensure `PRIVATE_KEY`, `RPC_URL`, and testnet ETH are correctly set.        |
+| **MetaMask not connecting**   | Confirm network is set to **Core Testnet 2** and refresh the page.         |
+| **Frontend errors**           | Run `npm install` and ensure `getContractInstance.js` has correct address. |
+| **Foundry issues**            | Re-run `forge install` or consult Foundry Book for setup assistance.       |
+
+---
+
+## Acknowledgements
+
+* [Core DAO](https://coredao.org/) for providing the testnet infrastructure
+* [Foundry Book](https://book.getfoundry.sh/) for smart contract tooling
+* [MetaMask](https://metamask.io/) for dApp user interaction

11-Todo/contracts/README.md

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+## Foundry
+
+**Foundry is a blazing fast, portable and modular toolkit for Ethereum application development written in Rust.**
+
+Foundry consists of:
+
+-   **Forge**: Ethereum testing framework (like Truffle, Hardhat and DappTools).
+-   **Cast**: Swiss army knife for interacting with EVM smart contracts, sending transactions and getting chain data.
+-   **Anvil**: Local Ethereum node, akin to Ganache, Hardhat Network.
+-   **Chisel**: Fast, utilitarian, and verbose solidity REPL.
+
+## Documentation
+
+https://book.getfoundry.sh/
+
+## Usage
+
+### Build
+
+```shell
+$ forge build
+```
+
+### Test
+
+```shell
+$ forge test
+```
+
+### Format
+
+```shell
+$ forge fmt
+```
+
+### Gas Snapshots
+
+```shell
+$ forge snapshot
+```
+
+### Anvil
+
+```shell
+$ anvil
+```
+
+### Deploy
+
+```shell
+$ forge script script/Counter.s.sol:CounterScript --rpc-url <your_rpc_url> --private-key <your_private_key>
+```
+
+### Cast
+
+```shell
+$ cast <subcommand>
+```
+
+### Help
+
+```shell
+$ forge --help
+$ anvil --help
+$ cast --help
+```