Architecture

System Architecture Overview

graph TD
    Users["Users<br/><small>Web Browser — Chrome / Edge</small>"]
    Nginx["Reverse Proxy — Nginx<br/><small>SSL Termination · Static Files</small>"]
    FE["Frontend<br/><small>SvelteKit · Port 5180</small>"]
    BE["Backend<br/><small>Python FastAPI · Port 8080</small>"]
    DB["PostgreSQL + pgvector"]
    AI["AI Model APIs"]

    Users -->|HTTPS| Nginx
    Nginx --> FE
    Nginx --> BE
    BE --> DB
    BE --> AI

    subgraph Frontend
        FE
        FE_detail["UI/UX · i18n TH/EN · Responsive"]
    end

    subgraph Backend
        BE
        BE_detail["REST API · Auth/JWT<br/>RAG Pipeline · Quota Engine<br/>Audit Logger"]
    end

    subgraph Data
        DB
        DB_detail["Users · Chats · Knowledge<br/>Audit Log · Quota"]
    end

    subgraph External
        AI
        AI_detail["OpenAI · Google Gemini<br/>Anthropic Claude · OpenRouter<br/>Ollama — Local"]
    end

    style Users fill:#e3f2fd,stroke:#1565c0,color:#0d47a1
    style Nginx fill:#fff3e0,stroke:#e65100,color:#bf360c
    style FE fill:#e8f5e9,stroke:#2e7d32,color:#1b5e20
    style BE fill:#fce4ec,stroke:#c62828,color:#b71c1c
    style DB fill:#f3e5f5,stroke:#6a1b9a,color:#4a148c
    style AI fill:#e0f7fa,stroke:#00695c,color:#004d40
    style FE_detail fill:none,stroke:none
    style BE_detail fill:none,stroke:none
    style DB_detail fill:none,stroke:none
    style AI_detail fill:none,stroke:none

Technology Stack

Layer	Technology	Version
Frontend	SvelteKit + TailwindCSS	Svelte 4.x
Backend	Python FastAPI	Python 3.11+
Database	PostgreSQL + pgvector	PostgreSQL 15+
Vector DB	pgvector (extension)	0.7+
Container	Docker + Docker Compose	24.0+
Reverse Proxy	Nginx	1.24+
Auth	JWT (PyJWT) + bcrypt

Database Schema (Core Tables)

Table	Description
user	User data (name, email, role, profile)
auth	Authentication data (password hash)
chat	Conversations (title, history, user_id)
chat_message	Messages in conversations (content, model, tokens)
group	User groups (name, description, permissions)
group_member	Group membership
knowledge	Knowledge Bases (name, description)
file	Uploaded files (metadata, storage path)
quota_policy	Quota policies (scope, limit)
audit_log	Activity records (user, action, timestamp)
model	Custom Models / Agents
prompt	Prompt Templates