Adopt MVC-ish architecture with Tauri + FastAPI; prefer Svelte UI for performance (vs React's Obesity)

[KoeppelSoftwareEngineer]

📌 Summary

📌 Proposal: A Tauri desktop app. It uses a Svelte (or SvelteKit) frontend and a FastAPI backend.
🧩 The layout follows MVC principles for clear separation of concerns. This makes the app maintainable and scalable.
🚫 Svelte avoids React’s “website obesity,” dependency bloat, and performance issues. It reduces security risks from third‑party library dependencies.
📦 Tauri provides small bundle sizes and a secure native shell.

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🧭 Recommended MVC-ish Layout (Option A)

my-farm-app/
├─ src/                       # Tauri frontend (View: React/Vue/Svelte)
├─ src-tauri/                 # Tauri shell, native config & helpers
│  ├─ src/
│  └─ tauri.conf.json
├─ backend/                   # FastAPI (Controller + Model + Services)
│  ├─ app/
│  └─ alembic/                # Migrations (or migration notes for MongoDB)
└─ scripts/
   └─ run_fastapi.py          # Entrypoint Tauri can spawn

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📈 Overview

+-----------------------------+             +------------------------------+
|         Tauri UI            |  HTTP/WS    |           FastAPI             |
|  SvelteKit (View)           +------------>+  Controllers (Routers)       |
|  State/Store (ViewModel*)   |             |  Services (Business Logic)    |
|                             |             |  Models (Pydantic)            |
+-----------------------------+             |  DB (SQLite/Postgres/MongoDB) |
               ^                             +------------------------------+
               |             IPC (process mgmt) via Tauri
               +------------------------------- start/stop backend

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Component (Architecture) Diagram

+--------------------+         HTTP/JSON          +----------------------+       ODM       +-------------------+
|  Browser (Svelte)  |  --->  http://127.0.0.1:5173  |  FastAPI (Uvicorn)  |  <----->  Beanie  |   MongoDB Server  |
|  Vite dev:5174     |         CORS allowed        |  app.main / routers  |   (models)       |  movies_db        |
+--------------------+                              +----------+-----------+                 +---------+---------+
                                                            |                                       |
                                                            | (CRUD /movies)                        | (collection "movies")
                                                            v                                       v
                                                     Controllers (api/movies.py)             Collection: movies

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Activity Diagram (Add Movie)

          +--------------------+
          | User enters title  |
          +---------+----------+
                    |
                    v
          +--------------------+
          | Click "Add"        |
          +---------+----------+
                    |
                    v
          +--------------------+
          | UI POST /movies    |
          | {title}            |
          +---------+----------+
                    |
                    v
          +-----------------------------+
          | FastAPI: validate payload   |
          | (MovieCreate via Pydantic)  |
          +---------+-------------------+
                    |
         [valid]    |    [invalid]
           |        |        |
           v        |        v
+------------------+|   +-------------------+
| Insert with       ||   | 400/422 response |
| Beanie -> MongoDB ||   +-------------------+
+---------+---------+|
          |          |
          v          |
+--------------------+      (invalid path ends)
| Return MovieRead   |
| {id, title}        |
+---------+----------+
          |
          v
+--------------------+
| UI updates list    |
+--------------------+

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🧰 Useful Libraries

• FastAPI: routers, DI, OpenAPI
• Pydantic v2: schemas
• Motor: async MongoDB driver
• Alembic: migrations (for relational DBs; MongoDB uses manual migration scripts)
• Uvicorn: ASGI server
• Tauri: process management, secure FS APIs, updater, autostart
• Frontend: SvelteKit (or React/Vue alternatives)

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🧩 Why MVC? (Model–View–Controller)

• Model: Data + business rules (Pydantic schemas, MongoDB collections or SQLAlchemy for relational DBs).
• View: UI and presentation (SvelteKit in Tauri window).
• Controller: FastAPI routers orchestrating requests and responses.

Benefits

• Clear separation of concerns → maintainable, testable, scalable.
• Swap UI frameworks or DB backends (SQLite/Postgres ↔ MongoDB) without rewriting the whole app.
• Keep frontend lean; backend handles heavy logic.

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🔧 Decision Proposal: Prefer SvelteKit for the View

• Lightweight, fast, compiles to minimal JS, works perfectly with Tauri.
• Alternatives: SolidJS, Vanilla JS, React (heavier).

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🧱 Data & Backend Choices

• Backend: FastAPI (Controllers + Services + Models).
• Database:
  • Start with MongoDB for document-oriented flexibility.
  • SQLite/Postgres remain options for relational needs later.
• Migrations: Alembic for relational DBs; manual scripts for MongoDB.

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⚠️ Risks & Mitigations

• Dependency bloat → Prefer SvelteKit, audit packages.
• Performance → Keep bundle small, offload heavy logic to backend.
• Security → Pin versions, use Tauri secure APIs.
• DB choice → MongoDB for flexibility now; Postgres later if relational needs arise.

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🎯 Acceptance Criteria

• Tauri app launches and spawns/stops FastAPI backend.
• SvelteKit UI loads and interacts with FastAPI endpoints.
• MongoDB integration works for CRUD operations.
• Clear MVC separation in codebase.

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✅ Next Steps

1. Confirm frontend: SvelteKit.
2. Confirm database: MongoDB now; Postgres optional later.
3. Scaffold repo with Tauri + SvelteKit + FastAPI + MongoDB.
4. Add CI and performance checks.

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