---

globs: backend/**/*.py,sdk/**/*.py

alwaysApply: false

description: Centralize env var access in backend/consts/const.py; no direct os.getenv outside

---

# Environment Variables: Single Source of Truth

All environment variable access must go through [backend/consts/const.py](mdc:backend/consts/const.py). No direct `os.getenv()` or `os.environ.get()` calls elsewhere.

## Do

```python

# backend/consts/const.py

APPID = os.getenv("APPID", "")

TOKEN = os.getenv("TOKEN", "")

# other modules

from consts.const import APPID, TOKEN

```

## Don't

```python

# direct calls in other modules

import os

appid = os.getenv("APPID")

token = os.environ.get("TOKEN")

```

## Architecture

- **Single source**: Only `backend/consts/const.py` may read env vars.

- **SDK (`sdk/`)**: Never read env. Accept configuration via parameters. Remove `from_env()`.

- **Services (`backend/services/`)**: Read from `consts.const`; pass config to SDK.

- **Apps (`backend/apps/`)**: Read from `consts.const`; pass through to services/SDK. No business logic here.

## Migration checklist

1. Add new vars to `backend/consts/const.py`.

2. Update `.env.example`.

3. Remove all direct `os.getenv()`/`os.environ.get()` outside `const.py`.

4. Import from `consts.const` in backend modules.

5. Pass configuration as parameters to SDK.

6. Remove `from_env()` methods from config classes.

7. Update service constructors to read from `const.py`.

## Validation

- No direct env access outside `const.py`.

- No `from_env()` in config classes.

- All env vars defined in `const.py`.

- SDK modules accept configuration via parameters.