Stapal

Demo

About

## Stapal — On-chain Taiwan Receipt Lottery Powered by PYUSD ### 🧩 **What It Does** **Stapal** transforms Taiwan’s decades-old _Uniform Invoice Lottery_ — one of the world’s most successful civic financial systems — into a fully automated, transparent, and borderless on-chain version. In Taiwan, every government-issued sales receipt carries a unique 8-digit number. Every two months, the Ministry of Finance publicly draws winning numbers, and citizens whose receipts match can win between NT$200 and NT$10 million. The system’s core purpose is to combat tax evasion and promote transaction transparency by encouraging consumers to always request official receipts. Stapal replicates this system **exactly as it works today**, but with two key blockchain-driven improvements: 1. **Instant PYUSD Payouts:** Users pay approved merchants using **PYUSD**. Each transaction automatically generates a receipt entry tied to their wallet. When the official draw occurs, prizes are **automatically converted from TWD to PYUSD** and distributed instantly on-chain — solving the real-world pain point where users forget to claim winnings or miss deadlines. 2. **Provable Fairness and Price Transparency:** Stapal uses **Pyth Entropy** to generate a verifiable random draw, ensuring fairness without any centralized control. The **Pyth USD/TWD pull price feed** dynamically converts prize amounts (denominated in TWD per Taiwan’s official rules) into the equivalent PYUSD value, allowing prize distribution to remain stable and pegged to real-world currency. --- ### 💡 **Why It Matters** Stapal demonstrates how **PYUSD** can power real-world, large-scale payment experiences beyond Web3 — modernizing proven public systems with programmable transparency. - **Payments Applicability:** It uses PYUSD as the transactional and reward medium, proving its capacity to handle high-frequency microtransactions, reward flows, and merchant adoption use cases. - **Transformative Finance:** It showcases how governments and fintechs could use PYUSD for citizen engagement, tax incentive programs, and universal rebate systems — with instant settlement, zero manual claiming, and verifiable fairness. - **Pyth Integration:** It leverages both **Pyth Entropy** for randomness and **Pyth Pull Price Feeds** for real-time FX rates (USD/TWD), demonstrating real composability of oracle infrastructure in civic-grade financial automation. In short, Stapal doesn’t reinvent the wheel — it **puts a proven wheel on rails**, combining the trust of a national system with the efficiency and global reach of PYUSD payments. --- ### 🚀 **Future Vision** - **Merchant SDK:** Allow businesses globally to register as “Stapal merchants” and issue receipt entries automatically for PYUSD payments. - **Global Adaptation:** Extend beyond Taiwan — governments and fintechs can use the same protocol for rebate programs, tax credits, or savings lotteries. - **Official Partnerships:** Integrate with PYUSD ecosystem wallets or PayPal consumer products for mass user onboarding. --- ### 🏁 **Final Words** Stapal is the **most faithful real-world replication** of a proven national finance system ever brought on-chain. It demonstrates how **PYUSD and Pyth together** can create an **autonomous, transparent, and programmable payments network** — bridging fiat systems and Web3 infrastructure at national scale. It’s not a new idea. It’s the _right idea_, made real with **PYUSD precision and Pyth truth.**

How it's made

--- ## ⚙️ **How It’s Made** **Architecture Overview:** Stapal is built entirely on smart contracts deployed on **Arbitrum Sepolia**, integrating **PYUSD**, **Pyth Entropy**, and **Pyth Pull Price Feeds**. ### 🧠 **Smart Contract Components (Solidity)** - **`Stapal.sol`** — the main contract managing merchants, receipts, and prize draws: - `buy(sender, receiver, amount)`: Processes PYUSD payments from buyers to approved merchants and stores receipt data (address + pseudo-random 8-digit number). - `requestRandomNumber()`: Requests entropy from **Pyth Entropy** to generate verifiable randomness for each draw. - `entropyCallback(...)`: Receives callback with the random value and stores the current 8-digit winning seed (`currentVrf`). - `drawWinners()`: Derives the 4–7 digit winning patterns from `currentVrf` and maps them to stored receipts to determine eligible winners. - `updatePriceAndDistribute(bytes[] priceUpdate)`: Fetches the latest **Pyth USD/TWD price** from Hermes, converts each TWD prize tier into its PYUSD equivalent, and sends rewards directly to winning wallets. - **`MockPYUSD.sol`** — minimal ERC20 token for local testing and demonstration. **Prize Rules Implemented (1:1 official structure):** - Match 7 digits → 1,000,000 TWD - Match 6 digits → 50,000 TWD - Match 5 digits → 10,000 TWD - Match 4 digits → 1,000 TWD All prizes are converted to PYUSD based on the latest **Pyth USD/TWD exchange rate**, ensuring accuracy and real-world parity. --- ### 🌐 **Frontend & API Layer** - **Frontend**: A minimal Next.js interface where users can: - Pay merchants in PYUSD. - View past receipts and see draw results. - **Backend (API Route)**: - `/api/draw`: Executes a full draw sequence: 1. Read entropy fee and request randomness via **Pyth Entropy**. 2. Wait for callback with random value. 3. Trigger `drawWinners()` and `updatePriceAndDistribute()` after pulling FX data. **Contracts Deployed:** - `Stapal`: [0x6e6ba8c9960b6B94dFDafB3EB31D4BC7398e34A5](https://arbitrum-sepolia.blockscout.com/address/0x6e6ba8c9960b6B94dFDafB3EB31D4BC7398e34A5) - `MockPYUSD`: [0x6bfC592fB6779BE62346C76347f8aed209D28346](https://arbitrum-sepolia.blockscout.com/address/0x6bfC592fB6779BE62346C76347f8aed209D28346) --- ### 🧩 **Partner Tech Stack** | Technology | Purpose | Benefit | | ---------------------------------- | ---------------------------- | ------------------------------------------------------------------------------- | | **PYUSD** | Medium of payment and payout | Real, stable, and composable digital dollar for programmable civic rewards | | **Pyth Entropy** | Random draw generation | Fully decentralized, verifiable randomness replacing centralized draw officials | | **Pyth Pull Price Feed (USD/TWD)** | FX conversion | Real-time on-chain conversion from TWD prizes to PYUSD |