graph TB
    subgraph Clients
        C1["OpenAI SDKs"]
        C2["IDE Extensions"]
        C3["Agent Frameworks"]
        C4["Custom Apps"]
    end

    subgraph Proxy["FastAPI Proxy · port 8082"]
        direction TB
        P1["Request Translator"]
        P2["Response Builder"]
        P3["Error Handler"]
    end

    subgraph Backend["Local Backend"]
        B1["claude.exe"]
        B2["Built-in Auth"]
    end

    C1 & C2 & C3 & C4 --> P1
    P1 --> B1
    B1 --> P2
    P2 --> C1 & C2 & C3 & C4
    P3 -. fallback .-> P2
    B1 --- B2

    style P1 fill:#6366f1,stroke:#4f46e5,color:#fff
    style P2 fill:#6366f1,stroke:#4f46e5,color:#fff
    style P3 fill:#6366f1,stroke:#4f46e5,color:#fff
    style B1 fill:#d97706,stroke:#b45309,color:#fff
    style B2 fill:#d97706,stroke:#b45309,color:#fff
    style C1 fill:#1e293b,stroke:#334155,color:#e2e8f0
    style C2 fill:#1e293b,stroke:#334155,color:#e2e8f0
    style C3 fill:#1e293b,stroke:#334155,color:#e2e8f0
    style C4 fill:#1e293b,stroke:#334155,color:#e2e8f0

sequenceDiagram
    participant C as Client
    participant P as Proxy
    participant CLI as claude.exe

    C->>+P: POST /v1/chat/completions
    Note over P: Parse messages, detect tools

    alt Has tool definitions
        Note over P: Augment system prompt with JSON schema
    end

    P->>+CLI: subprocess · --output-format json
    Note over CLI: Local auth · no API key
    CLI-->>-P: JSON envelope {result, usage, cost}

    alt Tool call response
        Note over P: Extract JSON args, build tool_calls
        P-->>C: finish_reason: tool_calls
    else Text response
        P-->>-C: finish_reason: stop
    end

flowchart LR
    A["Request"] --> B{"Tools?"}

    B -- yes --> C["Augment prompt\nwith schema"]
    B -- no --> D["Pass through\nmessages"]

    C & D --> E["claude.exe"]

    E --> F{"Exit\ncode"}

    F -- 0 --> G["Parse\nenvelope"]
    F -- fail --> H{"Rate\nlimited?"}

    H -- yes --> I["429"]
    H -- no --> J["500"]

    G --> K{"Tool\nresponse?"}

    K -- yes --> L["Build\ntool_calls"]
    K -- no --> M["Build text\nresponse"]

    L & M --> N["OpenAI-format\nresponse"]

    style A fill:#6366f1,stroke:#4f46e5,color:#fff
    style E fill:#d97706,stroke:#b45309,color:#fff
    style N fill:#10b981,stroke:#059669,color:#fff
    style I fill:#f59e0b,stroke:#d97706,color:#fff
    style J fill:#ef4444,stroke:#dc2626,color:#fff
    style B fill:#1e293b,stroke:#6366f1,color:#e2e8f0
    style F fill:#1e293b,stroke:#6366f1,color:#e2e8f0
    style H fill:#1e293b,stroke:#6366f1,color:#e2e8f0
    style K fill:#1e293b,stroke:#6366f1,color:#e2e8f0
    style C fill:#1e293b,stroke:#334155,color:#e2e8f0
    style D fill:#1e293b,stroke:#334155,color:#e2e8f0
    style G fill:#1e293b,stroke:#334155,color:#e2e8f0
    style L fill:#1e293b,stroke:#334155,color:#e2e8f0
    style M fill:#1e293b,stroke:#334155,color:#e2e8f0