Pythacoin – CDP stablecoin on Cardano using Pyth Lazer

[nau]

Pyth Examples Contribution

Team Information

• Team Name: LANTR
• Submission Name: Pythacoin
• Team Members: Captain Alex Nemish (@nau)
• Contact: alex@lantr.io

Type of Contribution

• New Example Project
• Bug Fix
• Documentation Update
• Enhancement
• Hackathon Submission

Project Information

Project/Example Name: Pythacoin – CDP-based stablecoin on Cardano using Pyth Lazer

Pyth Product Used:

• Pyth Price Feeds
• Pyth Entropy
• Multiple Products
• Other

Blockchain/Platform:

• Ethereum/EVM
• Solana
• Aptos
• Sui
• Fuel
• Starknet
• TON
• Other: Cardano

Description

What does this contribution do?

Pythacoin is a fully functional CDP (Collateralized Debt Position) stablecoin protocol on Cardano. Users lock ADA as collateral to mint PUSD, a synthetic USD-pegged stablecoin. The protocol enforces a 95% max LTV for minting and a 90% liquidation threshold — when a CDP becomes undercollateralized, anyone can liquidate it.

How does it integrate with Pyth?

• On-chain: The Plutus V3 validator reads ADA/USD prices directly from Pyth Lazer withdrawal redeemers. It locates the Pyth State UTxO in reference inputs, extracts the withdraw script hash, then parses the binary price payload (feed ID 16, ADA/USD) from the corresponding withdrawal redeemer. This is a full on-chain Pyth Lazer integration in Scalus (Scala-to-Plutus compiler).
• Off-chain: The backend fetches signed price updates via the Pyth Lazer REST API (solana format) and includes them as withdrawal redeemers in every price-dependent transaction (open, borrow, liquidate).

What problem does it solve or demonstrate?

Demonstrates a complete DeFi lending protocol on Cardano powered by Pyth Lazer price feeds — from on-chain binary payload parsing to off-chain transaction building to a web frontend with wallet integration.

Directory Structure

lazer/cardano/pythacoin/
├── src/main/scala/pythacoin/onchain/  # Plutus V3 validator (Scalus)
├── src/main/scala/pythacoin/          # Backend: REST API, tx builder
├── src/test/scala/pythacoin/          # Unit tests (11 passing)
├── integration/                       # Integration tests (preprod)
├── frontend/                          # React 19 + TypeScript + Tailwind
├── build.sbt                          # Scala build config
├── flake.nix                          # Nix dev environment
└── README.md

Testing & Verification

How to Test This Contribution

Prerequisites

• Nix (recommended) or JDK 21 + sbt + Node.js 20+
• Blockfrost API key (preprod)
• Pyth Lazer API key

Setup & Run Instructions

cd lazer/cardano/pythacoin

# If you have Nix, just run `nix develop` to get all dependencies

# Backend
sbt "runMain pythacoin.main start"

# Tests
sbt test

# Frontend
cd frontend && npm install && npm run dev

Deployment Information

Network: Cardano PreProd
Demo: https://youtu.be/RK7WsZQiG54

Checklist

Code Quality

• Code follows existing patterns in the repository
• Proper error handling implemented
• No hardcoded values (use environment variables where appropriate)

Testing

• Tested locally and works as expected
• All existing functionality still works (no breaking changes)

Additional Context

Screenshots/Demo

Demo video: https://youtu.be/RK7WsZQiG54

Notes for Reviewers

• Built with Scalus (Scala-to-Plutus compiler) — first Pyth Lazer integration in Scala/Scalus
• Full on-chain Pyth Lazer binary parsing (no Aiken dependency)
• 11 unit tests + preprod integration test passing
• Apache 2.0 licensed