feat(examples): add Python payment demo with web3.py

examples/tempo-payment-demo/README.md

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+# Tempo Python Payment Demo
+
+A minimal, practical Python example demonstrating end-to-end payment flow on Tempo testnet using **web3.py**.
+
+## 🎯 What This Demonstrates
+
+- ✅ Request test funds from Tempo faucet (`tempo_fundAddress`)
+- ✅ Build, sign, and broadcast TIP-20 (PATHUSD) transfers
+- ✅ Verify transactions on Tempo explorer
+- ✅ Secure key management with environment variables
+
+## 🔗 Live Example
+
+A real test transaction was successfully broadcast during development:
+
+- **Transaction Hash**: `b98e091a23a761e25d8ff4e421ab4f201f2019ecd6c9ee549168ee4bdd73347d`
+- **Explorer Link**: https://explore.tempo.xyz/tx/b98e091a23a761e25d8ff4e421ab4f201f2019ecd6c9ee549168ee4bdd73347d
+
+## 📋 Prerequisites
+
+- Python 3.8 or higher
+- pip (Python package manager)
+- Access to Tempo testnet
+
+## 🚀 Quick Start
+
+### 1. Setup Environment
+```bash
+# Navigate to example directory
+cd examples/tempo-payment-demo
+
+# Create virtual environment
+python3 -m venv venv
+source venv/bin/activate  # On Windows: venv\Scripts\activate
+
+# Install dependencies
+pip install -r requirements.txt
+```
+
+### 2. Configure
+```bash
+# Copy environment template
+cp .env.example .env
+
+# Edit .env with your test credentials
+nano .env  # or use your favorite editor
+```
+
+Your `.env` should look like:
+```env
+RPC_URL=https://rpc.testnet.tempo.xyz
+PRIVATE_KEY=your_test_private_key_here_without_0x
+```
+
+⚠️ **Security Warning**: Use **test-only** private keys. Never commit real keys!
+
+### 3. Run the Demo
+```bash
+# Request funds and check balance
+python -m src.main
+
+# Send a test transaction
+python -m src.send_tx
+```
+
+## 📁 Project Structure
+```
+tempo-payment-demo/
+├── src/
+│   ├── __init__.py
+│   ├── client.py      # Web3 client wrapper
+│   ├── config.py      # Environment configuration loader
+│   ├── faucet.py      # Faucet interaction helper
+│   ├── payment.py     # Payment utilities (TIP-20 transfers)
+│   ├── send_tx.py     # Transaction sender script
+│   └── main.py        # Main demo entrypoint
+├── requirements.txt   # Python dependencies (web3, python-dotenv)
+├── .env.example       # Environment template
+├── .gitignore         # Git ignore rules (venv, .env)
+└── README.md          # This file
+```
+
+## 💻 Usage Examples
+
+### Check Balance
+```python
+from src.client import get_web3_client
+from src.config import Config
+
+config = Config()
+w3, account = get_web3_client(config)
+
+balance = w3.eth.get_balance(account.address)
+print(f"Balance: {w3.from_wei(balance, 'ether')} PATHUSD")
+```
+
+### Send TIP-20 Transfer
+```python
+from src.payment import send_tip20_transfer
+
+tx_hash = send_tip20_transfer(
+    w3=w3,
+    account=account,
+    to_address="0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb",
+    amount_in_ether=10.0
+)
+
+print(f"Transaction sent: {tx_hash.hex()}")
+print(f"Explorer: https://explore.tempo.xyz/tx/{tx_hash.hex()}")
+```
+
+### Request Faucet Funds
+```python
+from src.faucet import request_faucet_funds
+
+success = request_faucet_funds(w3, account.address)
+if success:
+    print("✅ Funds received!")
+```
+
+## 🌐 Network Details
+
+| Parameter | Value |
+|-----------|-------|
+| **Network** | Tempo Testnet (Andantino) |
+| **Chain ID** | 42429 |
+| **RPC URL** | https://rpc.testnet.tempo.xyz |
+| **WebSocket** | wss://rpc.testnet.tempo.xyz |
+| **Explorer** | https://explore.tempo.xyz |
+| **Currency** | PATHUSD (TIP-20) |
+
+## 🔧 Troubleshooting
+
+### Insufficient Funds Error
+```bash
+# Request funds from faucet
+python -m src.faucet
+```
+
+### Connection Issues
+
+- Verify `RPC_URL` in `.env` is correct
+- Check network connectivity
+- Ensure you're using testnet, not mainnet
+
+### Transaction Failed
+
+- Check you have sufficient balance for gas + transfer amount
+- Verify recipient address format (must start with 0x)
+- Ensure private key is valid (64 hex characters, no 0x prefix)
+
+### Import Errors
+```bash
+# Make sure you're in the venv and dependencies are installed
+source venv/bin/activate
+pip install -r requirements.txt
+```
+
+## 🔐 Security Best Practices
+
+- ✅ Use `.env` for sensitive data (git-ignored by default)
+- ✅ **Never** commit private keys to version control
+- ✅ Use **test-only keys** for testnet (generate at https://vanity-eth.tk/)
+- ✅ For production, use secure vaults (AWS KMS, HashiCorp Vault, GitHub Secrets)
+- ✅ Rotate keys regularly
+- ✅ Never share private keys via chat, email, or screenshots
+
+## 📚 Resources
+
+- [Tempo Documentation](https://docs.tempo.xyz)
+- [Tempo Testnet Faucet](https://docs.tempo.xyz/quickstart/faucet)
+- [TIP-20 Token Standard](https://docs.tempo.xyz/protocol/tip20/overview)
+- [web3.py Documentation](https://web3py.readthedocs.io/)
+- [Tempo Python SDK](https://github.com/tempoxyz/pytempo)
+
+## 🤝 Contributing
+
+Found a bug or want to improve this example? Contributions are welcome!
+
+1. Fork the [pytempo repository](https://github.com/tempoxyz/pytempo)
+2. Create a feature branch (`git checkout -b feature/my-improvement`)
+3. Commit your changes (`git commit -m 'feat: add some feature'`)
+4. Push to the branch (`git push origin feature/my-improvement`)
+5. Open a Pull Request
+
+## ⚠️ Important Notes
+
+- This is a **community example** for educational purposes
+- Use **test-only** private keys and testnet funds
+- Not audited for production use
+- Tempo is still under development - API may change
+
+## 📄 License
+
+This example follows the pytempo repository license.
+
+See [LICENSE](../../LICENSE) for details.
+
+---
+
+**Need help?** Check the [Tempo Discord](https://discord.gg/tempo) or [GitHub Issues](https://github.com/tempoxyz/pytempo/issues).

examples/tempo-payment-demo/requirements.txt

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+web3==6.0.0
+python-dotenv==1.0.0
+eth-account==0.8.1

examples/tempo-payment-demo/src/__init__.py

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+# tempo python payment demo package

examples/tempo-payment-demo/src/client.py

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+from web3 import Web3
+from .config import RPC_URL
+
+def get_web3():
+    return Web3(Web3.HTTPProvider(RPC_URL))

examples/tempo-payment-demo/src/config.py

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+from dotenv import load_dotenv
+import os
+
+load_dotenv()
+
+RPC_URL = os.getenv("RPC_URL", "https://rpc.testnet.tempo.xyz")
+PRIVATE_KEY = os.getenv("PRIVATE_KEY", "")
+FACTORY_ADDRESS = os.getenv("FACTORY_ADDRESS", "0x20fc000000000000000000000000000000000000")
+PATHUSD_ADDRESS = os.getenv("PATHUSD_ADDRESS", "0x20c0000000000000000000000000000000000000")
+FEE_MANAGER_ADDRESS = os.getenv("FEE_MANAGER_ADDRESS", "0xfeec000000000000000000000000000000000000")
+EXPLORER = os.getenv("EXPLORER", "https://explore.tempo.xyz")

examples/tempo-payment-demo/src/faucet.py

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+# simple wrapper for tempo_fundAddress via JSON-RPC
+def fund_address(w3, address):
+    # web3.py low-level JSON RPC call
+    return w3.provider.make_request('tempo_fundAddress', [address])

examples/tempo-payment-demo/src/main.py

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+from .client import get_web3
+from .config import PRIVATE_KEY, EXPLORER
+from .faucet import fund_address
+from .payment import build_transfer_tx
+from web3 import Web3
+
+def demo():
+    w3 = get_web3()
+    acct = w3.eth.account.from_key(PRIVATE_KEY)
+    print("Address:", acct.address)
+    # faucet example (may fail if RPC doesn't expose)
+    try:
+        res = fund_address(w3, acct.address)
+        print("Faucet result:", res)
+    except Exception as e:
+        print("Faucet call error (non-fatal):", e)
+    # build tx (not broadcasted here)
+    dummy_token = "0x0000000000000000000000000000000000000000"  # placeholder
+
+    tx = build_transfer_tx(
+        w3,
+        dummy_token,
+        acct.key.hex(),
+        acct.address,
+        1
+    )
+
+    print("Built tx (preview):", tx)
+
+if __name__ == '__main__':
+    demo()

examples/tempo-payment-demo/src/payment.py

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+from web3 import Web3
+
+# ABI ERC20 sederhana
+ERC20_ABI = [
+    {
+        "constant": True,
+        "inputs": [
+            {"name": "_owner", "type": "address"}
+        ],
+        "name": "balanceOf",
+        "outputs": [
+            {"name": "balance", "type": "uint256"}
+        ],
+        "type": "function"
+    },
+    {
+        "constant": False,
+        "inputs": [
+            {"name": "_to", "type": "address"},
+            {"name": "_value", "type": "uint256"}
+        ],
+        "name": "transfer",
+        "outputs": [
+            {"name": "success", "type": "bool"}
+        ],
+        "type": "function"
+    }
+]
+
+def get_token_contract(web3: Web3, token_address: str):
+    """Return ERC20 contract instance"""
+    return web3.eth.contract(address=Web3.to_checksum_address(token_address), abi=ERC20_ABI)
+
+
+def build_transfer_tx(web3: Web3, token_address: str, private_key: str, to: str, amount: int):
+    """Build unsigned ERC20 transfer transaction"""
+    account = web3.eth.account.from_key(private_key)
+    contract = get_token_contract(web3, token_address)
+
+    tx = contract.functions.transfer(
+        Web3.to_checksum_address(to),
+        amount
+    ).build_transaction({
+        "from": account.address,
+        "nonce": web3.eth.get_transaction_count(account.address),
+        "gas": 120000,
+        "gasPrice": web3.to_wei("0.1", "gwei"),
+    })
+
+    return tx
+

examples/tempo-payment-demo/src/send_tx.py

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+from .client import get_web3
+from .config import PRIVATE_KEY, PATHUSD_ADDRESS, EXPLORER
+from .payment import build_transfer_tx
+from web3 import Web3
+
+def main():
+    w3 = get_web3()
+    # target (default merchant) 
+    to_addr = "0x000000000000000000000000000000000000dEaD"
+    # amount: 0.001 PATHUSD (assume 18 decimals)
+    amount = Web3.to_wei(0.001, "ether")
+
+    # build unsigned tx
+    unsigned = build_transfer_tx(w3, PATHUSD_ADDRESS, PRIVATE_KEY, to_addr, amount)
+
+    # ensure chainId and correct nonce
+    unsigned.setdefault("chainId", w3.eth.chain_id)
+    unsigned["nonce"] = w3.eth.get_transaction_count(w3.eth.account.from_key(PRIVATE_KEY).address)
+
+    # Dynamically choose gasPrice from node, add small buffer to avoid 'underpriced'
+    try:
+        node_gas_price = w3.eth.gas_price  # recommended gas price from node (int, wei)
+        # add 20% buffer
+        buffered = node_gas_price * 12 // 10
+        unsigned["gasPrice"] = buffered
+        print(f"Using gasPrice from node: {node_gas_price} wei, buffered: {buffered} wei")
+    except Exception as e:
+        # fallback to existing or conservative default (1 gwei)
+        fallback = Web3.to_wei(1, "gwei")
+        unsigned.setdefault("gasPrice", fallback)
+        print("Could not fetch node gas price, using fallback:", fallback)
+
+    print("Unsigned tx preview:")
+    print(unsigned)
+
+    # sign
+    signed = w3.eth.account.sign_transaction(unsigned, PRIVATE_KEY)
+    raw = signed.raw_transaction
+
+    # send
+    tx_hash = w3.eth.send_raw_transaction(raw)
+    print("Sent tx:", tx_hash.hex())
+    print("Explorer:", f"{EXPLORER.rstrip('/')}/tx/{tx_hash.hex()}")
+
+if __name__ == '__main__':
+    main()