Solana RPC (WebSocket)
    ↓
Transaction Monitor Service
    ↓
Marketplace Program Filter
    ↓
cNFT Sale Parser
    ↓
Probability Calculator
    ↓
PostgreSQL Database
    ↓
NestJS API Endpoints
    ↓
DePredict Frontend

Tech Stack

• Language: TypeScript
• Database: PostgreSQL (schema provided, you migrate as needed)
• RPC: WebSocket connections to Solana RPC
• Metadata: Helius DAS API for cNFT data
• Oracle: Switchboard
• Infrastructure: Existing AWS Setup
• Monitoring: Health checks + alerting

Architecture

Decision: WebSocket RPC

1. Connect to Solana RPC via WebSocket
2. Subscribe to logs for marketplace program IDs
3. Parse transaction data to extract:
   • cNFT mint address
   • Sale price (USDC or SOL)
   • Marketplace
   • Buyer/seller
4. Fetch cNFT metadata to get:
   • market_id
   • outcome_side (YES/NO)
   • shares
5. Calculate implied probability: sale_price / shares
6. Store in database (Postgres on AWS)
7. Expose via REST API (NestJS compatible)

Probable Challenges

Challenge 1: Monitoring 12+ Marketplaces