sequenceDiagram
    participant User
    participant API
    participant DB
    participant Cache

    User->>API: GET /profile
    API->>Cache: Check cache
    alt Cache hit
        Cache-->>API: Return cached profile
    else Cache miss
        API->>DB: SELECT * FROM users WHERE id=?
        DB-->>API: User row
        API->>Cache: SET profile (TTL 300s)
    end
    API-->>User: 200 OK { profile }