Architecture · May 15, 2026

Trade Lifecycle

Redis pub/sub → Steam → Bull — how every user trade, deposit, sell listing, and instant sell executes across tradeit-backend and tradeit-tradebot-server

1. At-a-glance

2. Purpose & boundaries

3. Process / runtime model

Bot intervals (index.ts:3567–3585)

4. Architecture (data flow)

Deposit flow (user → bot)

graph LR
  subgraph "tradeit-backend"
    A["POST /trade"] --> B["create :259"]
    B --> C["createTrades :172"]
    C --> D["lockTradeItems :756"]
    C --> E["selectBot :226"]
    C --> F["PUBLISH bot {botId}"]
  end

  subgraph "Redis"
    F --> G["bot {botId} channel"]
    H["tradeitQueue Bull"] --> J["mainQueue consumer"]
    K["tradestate channel"] --> L["Socket.IO → Frontend"]
  end

  subgraph "tradeit-tradebot-server"
    G --> M["redisMessage :810"]
    M --> N["trade() :3064"]
    N --> O["createOffer + send"]
    O --> P["Steam API"]
    P --> Q["accepted: insertBotTrades"]
    Q --> R["PUBLISH tradestate"]
    Q --> S["PUBLISH finishedtrades"]
    Q --> T["tradeItQueue.add"]
  end

  subgraph "MySQL"
    Q --> U["INSERT bot_trades :3737"]
    Q --> V["UPDATE bot_users.balance :1234"]
  end

  R --> K
  T --> H

  classDef ok fill:#0e2a1e,stroke:#10b981,stroke-width:2px,color:#a7f3d0
  classDef hi fill:#1e2438,stroke:#a855f7,stroke-width:2px,color:#e9d5ff
  classDef warn fill:#2a1f0e,stroke:#f59e0b,stroke-width:2px,color:#fde68a
  class F,G,K ok
  class P hi
  class H,J warn

Sell listing flow (user deposits item for payout)

graph LR
  subgraph "tradeit-backend"
    A2["POST /sell/listing"] --> B2["listingSell"]
    B2 --> C2["sendTradeSaleRequest :314"]
    C2 --> D2["PUBLISH bot {botId} sell"]
  end

  subgraph "tradeit-tradebot-server"
    D2 --> E2["redisMessage case sell :816"]
    E2 --> F2["trade() isSale=true :3064"]
    F2 --> G2["addMyItems only"]
    G2 --> H2["Steam offer sent"]
    H2 --> I2["UPDATE sale_offers :1856"]
    I2 --> J2["tradeItQueue.add InstantSellCompleted"]
  end

  J2 --> K2["mainQueue: Amplitude + OAuth2 webhook :146"]

  classDef ok fill:#0e2a1e,stroke:#10b981,stroke-width:2px,color:#a7f3d0
  classDef hi fill:#1e2438,stroke:#a855f7,stroke-width:2px,color:#e9d5ff
  class D2,J2 ok
  class H2 hi

5. Inputs & outputs

HTTP inputs (tradeit-backend)

Outputs

6. Redis surface

7. MySQL surface

tradeit-backend (Aurora MySQL 8)

tradeit-tradebot-server (direct MySQL, same Aurora)

8. OpenSearch surface

OpenSearch is queried at the beginning of trade creation to verify item availability and filter reserved assets. After trade completion, the TradedAssetIds Bull task drives an inventory re-sync which leads to a new OS index via the parser.

• openSearchService.queryByAssetIds(assetIds, context, appId) — verifies site availability, applies reserved-asset must_not filter
• Single-game-cart invariant (DEV-4815): appId scopes query to one game's alias
• See OpenSearch Patterns for index/alias details

9. Async continuations

Shared Bull queue: tradeitQueue

10. Configuration flags & guards

11. Failure modes

12. Observability

• Structured logs: Datadog — module names trade-service, main-queue, trade-redis, controllers-sell
• Trade creation failure: log query trade -> create failed (includes steamId + stack)
• Blocked items: Slack TI_SLACK_BLOCKED_ITEMS_WEBHOOK — deposit limit breaches, x_content_parse_exception
• Bot heartbeat gap: Redis stayingalive:{i} missing — monitored by tradeRedis init
• Send offer error: Slack via notifySlack('Send trade offer error') — Steam error codes (16), (26)
• Datadog trade funnel dashboard: [OPEN — URL not confirmed]

13. Code map (file:line)

tradeit-backend

tradeit-tradebot-server

14. Open questions

Generated 2026-05-15 · tradeit.gg engineering