This is a market-making and arbitrage bot for Polymarket written in Rust. Experimental and not production ready.

Polymarket Market-Making Bot — High-Level Architecture

Data Sources

• Market WebSocket (websocket.rs)

  • book snapshots used to derive best bid and ask
  • price_change (new schema) with per-asset best_bid and best_ask for fast deltas

• User WebSocket (user_ws.rs)

  • Order updates and fills
  • Used to keep inventory in sync

• REST API (execution.rs)

  • GET /positions?user= on startup to seed inventory and persist positions across restarts
  • get_orders for optional open-order debugging

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Strategy (trading.rs)

• Quote placement

  • Quotes are anchored to book edges, not the mid-price
  • Bid: 10% below current best bid
  • Ask: 10% above current best ask (scaled toward 1.0)

• Inventory-based skew

  • Applied only when dollar imbalance exceeds MAX_INVENTORY_IMBALANCE
  • Long YES:
    • Lower ask (sell faster)
    • Lower bid (discourage buying more YES)
  • Short YES:
    • Raise bid (buy faster)
    • Raise ask (discourage selling more YES)

• Conditional re-quoting

  • Orders are replaced only if the mid-price bucket changes
  • Bucket definition: ceil(mid * 100)
  • Reduces churn on small price movements

• Risk guards

  • Cancel all orders and pause if total position value exceeds MAX_POSITION_SIZE
  • Pause quoting if prices are extreme:
    • Bid ≤ 0.02
    • Ask ≥ 0.98

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Channels

• market_tx / market_rx
  Market WebSocket → Trading Logic
  Real-time MarketUpdate

• cmd_tx / cmd_rx
  Trading Logic → Order Execution
  BotCommand::{Create, Cancel, CancelAll, Shutdown}

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Shared State (Arc<Mutex<AppState>>)

• my_open_orders: active bot orders
• inventory: token_id → quantity
• token_pairs / yes_token: explicit YES/NO mapping
  (1st / 2nd entries in ASSETS_IDS)
• last_prices: latest (bid, ask, timestamp) per token
• last_mid_bucket: ceil(mid * 100) per market
• risk_paused, shutting_down: control flags
• max_inventory_imbalance, max_position_size: dollar risk limits

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Kill Switch

• Ctrl + C sets shutting_down
• Issues CancelAll
• All tasks shut down cleanly