Improve deployment safety and chat reliability

README.md

@@ -19,7 +19,7 @@ A web-based tool for a German language teacher to provide clients with customize
 | Layer | Technology |
 |-------|-----------|
 | Backend | Python 3.12 + FastAPI |
-| Database | PostgreSQL (async via SQLAlchemy + asyncpg) |
+| Database | MySQL (async via SQLAlchemy + aiomysql) |
 | Auth | JWT + bcrypt |
 | LLM | LiteLLM (provider-agnostic) |
 | Voice | OpenAI Whisper/TTS or Web Speech API (feature flag) |
@@ -47,12 +47,26 @@ uvicorn app.main:app --reload
 ## Production Deployment (Debian)
 
 ```bash
-# Prerequisites: PostgreSQL and nginx already installed
+# Prerequisites: MySQL and nginx already installed
 sudo bash deploy/setup.sh
+```
 
-# Then edit the .env file:
+On a **fresh install** the script generates the database password and writes it
+into `.env`, then installs the service *without starting it* — so the app never
+goes live with the template's LLM key and default admin password:
+
+```bash
+# 1. Set LLM_API_KEY and ADMIN_PASSWORD (leave DATABASE_URL alone):
 sudo nano /opt/fluentgerman/backend/.env
 
+# 2. Start it:
+sudo systemctl start fluentgerman
+```
+
+Re-running `setup.sh` on an **existing install** keeps `.env` and the database
+password untouched, and restarts the service.
+
+```bash
 # Restart after config changes:
 sudo systemctl restart fluentgerman
 ```
@@ -64,7 +78,7 @@ sudo systemctl restart fluentgerman
 │   ├── app/
 │   │   ├── main.py              # FastAPI entry point
 │   │   ├── config.py            # Environment-based settings
-│   │   ├── database.py          # Async PostgreSQL setup
+│   │   ├── database.py          # Async MySQL setup
 │   │   ├── models.py            # User & Instruction models
 │   │   ├── schemas.py           # Pydantic request/response
 │   │   ├── auth.py              # JWT + bcrypt + dependencies
@@ -97,7 +111,7 @@ All settings via `.env` file (see `.env.example`):
 | Variable | Description |
 |----------|-------------|
 | `SECRET_KEY` | JWT signing key (generate a strong random one) |
-| `DATABASE_URL` | PostgreSQL connection string |
+| `DATABASE_URL` | MySQL connection string |
 | `LLM_API_KEY` | Your LLM provider API key |
 | `LLM_MODEL` | Model to use (e.g. `gpt-4o-mini`, `claude-3-haiku-20240307`) |
 | `VOICE_MODE` | `api` (OpenAI Whisper/TTS) or `browser` (Web Speech API) |