flowchart TD
    %% Modern Premium Styling
    classDef gateway fill:#1E293B,stroke:#475569,stroke-width:2px,color:#F8FAFC,rx:8,ry:8
    classDef orchestrator fill:#334155,stroke:#64748B,stroke-width:2px,color:#F8FAFC,rx:8,ry:8
    classDef security fill:#991B1B,stroke:#EF4444,stroke-width:2px,color:#FEF2F2,rx:8,ry:8
    classDef pipeline fill:#0F766E,stroke:#14B8A6,stroke-width:2px,color:#F0FDFA,rx:8,ry:8
    classDef database fill:#4338CA,stroke:#6366F1,stroke-width:2px,color:#EEF2FF,rx:8,ry:8
    classDef inference fill:#6B21A8,stroke:#A855F7,stroke-width:2px,color:#FAF5FF,rx:8,ry:8

    subgraph Edge ["🌐 API & Gateway Layer"]
        direction LR
        Client(["Client Apps"])
        API["API Gateway<br/><i>(Auth & Rate Limits)</i>"]
    end

    subgraph Security ["🛡️ Enterprise Security"]
        direction TB
        Threat["Threat Scanner<br/><i>(Prompt Injection / Quarantine)</i>"]
        PII["Compliance Agent<br/><i>(PII Scrubber & Masking)</i>"]
    end

    subgraph Core ["🔄 Two-Stage RAG Pipeline"]
        direction TB
        Router{"Semantic Router"}
        Embed["CPU Embeddings<br/><i>(FastEmbed / ONNX)</i>"]
        Retrieve["Initial Retrieval<br/><i>(Top-K Similarity)</i>"]
        Rerank["Cross-Encoder Reranker<br/><i>(FlashRank / High Precision)</i>"]
    end

    subgraph Storage ["💾 Data Sovereignty Layer"]
        direction LR
        Redis[("Redis<br/><i>(Session Memory)</i>")]
        Vector[("ChromaDB<br/><i>(Local Vector Store)</i>")]
    end

    subgraph Engine ["🧠 Local Inference Engine"]
        direction LR
        LLM("Open-Weights LLMs<br/><i>(Ollama / Zero Data Egress)</i>")
    end

    %% Flow Connections
    Client ===>|Requests| API
    API --->|Dispatch| Router
    
    %% Ingestion Flow
    Router -.->|Document Upload| Threat
    Threat -.->|Safe Data| PII
    PII -.->|Sanitized Text| Embed
    Embed -.->|Upsert Vectors| Vector

    %% Query Flow
    Router ===>|Query| Embed
    Embed ===>|Dense Vectors| Retrieve
    Retrieve <===>|Fetch Top 20| Vector
    Retrieve ===>|Pass Chunks| Rerank
    Rerank ===>|Top 5 Refined| LLM
    
    %% State
    Router <-->|Maintains Context| Redis

    %% Styling Application
    class Edge,Client,API gateway
    class Security,Threat,PII security
    class Core,Router,Embed,Retrieve,Rerank pipeline
    class Storage,Redis,Vector database
    class Engine,LLM inference