graph TB
    subgraph Client_Layer ["Client Applications"]
        Candidate["Candidate App<br/>(React + Vite)"]
        Dashboard["Recruiter Dashboard<br/>(React + Vite)"]
    end

    subgraph API_Gateway ["API Layer"]
        Express["Express.js API<br/>(TypeScript)"]
        Auth["OAuth 2.0 Handler"]
        RateLimit["Rate Limiter"]
    end

    subgraph Business_Logic ["Business Logic"]
        MatchEngine["Intent Matching Engine"]
        SwipeLogic["Swipe & Match Logic"]
        ConstraintFilter["Constraint Validator"]
    end

    subgraph Data_Layer ["Data Persistence"]
        Postgres[("PostgreSQL<br/>(Neon)")]
        Redis[("Redis Cache<br/>(Upstash)")]
        Cloudinary["Cloudinary<br/>(Image Storage)"]
    end

    subgraph External_Services ["External Services"]
        Google["Google OAuth"]
        GitHub["GitHub OAuth"]
        LinkedIn["LinkedIn OAuth"]
    end

    Candidate --> Express
    Dashboard --> Express
    Express --> Auth
    Express --> RateLimit
    RateLimit --> MatchEngine
    RateLimit --> SwipeLogic
    MatchEngine --> ConstraintFilter
    SwipeLogic --> Postgres
    ConstraintFilter --> Postgres
    Express --> Redis
    Express --> Cloudinary
    Auth --> Google
    Auth --> GitHub
    Auth --> LinkedIn