System Design.

flowchart TD
    %% Define Styles
    classDef client fill:#6D28D9,stroke:#fff,stroke-width:2px,color:#fff,border-radius:8px
    classDef gateway fill:#1E293B,stroke:#334155,stroke-width:2px,color:#fff
    classDef core fill:#27C93F,stroke:#fff,stroke-width:2px,color:#000,font-weight:bold
    classDef service fill:#0F172A,stroke:#6D28D9,stroke-width:1px,color:#FFF
    classDef database fill:#FFBD2E,stroke:#fff,stroke-width:2px,color:#000
    
    %% Nodes
    Client(["👤 User App / API Client"]):::client
    API{"API Gateway"}:::gateway
    Orchestrator{"⚙️ Workflow Orchestrator"}:::core
    
    Features("Feature Builder"):::service
    Rules("Rules Engine"):::service
    ML("AI / ML Service"):::service
    
    Cache[("Redis Cache")]:::database
    DB[("PostgreSQL DB")]:::database
    
    Policy{"⚖️ Policy Engine"}:::core
    Explain("🔍 Explainability Trace"):::service
    Response(["🚀 Final Workflow Result"]):::client
    
    %% Connections
    Client -->|POST /workflow| API
    API -->|Rate Limit OK| Orchestrator
    
    Orchestrator -->|1. Fetch Data| Features
    Orchestrator -->|2. Evaluate| Rules
    Orchestrator -->|3. Predict| ML
    
    Features -.-> Cache
    Rules -.-> DB
    
    Features & Rules & ML --> Policy
    Policy --> Explain
    Explain --> Response