# 2. High Level Architecture

## Technical Summary

Project SYSTEM is a monolithic, self-hosted web application built on the Nuxt 4 framework. The architecture is designed for efficiency and transparency, running on a Raspberry Pi. It features a Vue-based frontend interacting with a PostgreSQL database via Nuxt's server-side API routes. The core of the system is an immutable, event-sourced "Main Ledger" where every action is a cryptographically signed transaction, ensuring data integrity and auditability. Identity management is decentralized, based on public/private key pairs.

## Platform and Infrastructure Choice

*   **Platform:** Self-hosted on a user-provided **Raspberry Pi** (Model 4+).
*   **Key Services:**
    *   **Application Server:** **Nuxt 4** running in Node.js mode.
    *   **Database:** **PostgreSQL**.
    *   **Containerization:** The entire stack will be managed and deployed via **Docker Compose**. This ensures a consistent and reproducible environment.
*   **Deployment Host and Regions:** Single host, located within the "Община's" private network.

## Repository Structure

*   **Structure:** **Monorepo**.
*   **Monorepo Tool:** Not required for this level of simplicity. A single `package.json` at the root will manage all dependencies.
*   **Package Organization:** A standard Nuxt 4 project structure will be used, as detailed in the Frontend Architecture. Server-side logic will reside within the `server/` directory.

## High Level Architecture Diagram

```mermaid
graph TD
    subgraph "Browser"
        A[Citizen's Browser]
    end

    subgraph "Raspberry Pi (Docker Compose)"
        B[Nuxt 4 Server]
        C[PostgreSQL Database]

        B -- "Serves Frontend" --> A
        A -- "API Calls ($fetch)" --> B
        B -- "Reads/Writes" --> C
    end

    style B fill:#2D3748,stroke:#fff,stroke-width:2px,color:#fff
    style C fill:#4A5568,stroke:#fff,stroke-width:2px,color:#fff
```

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