# CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

## Common Commands

```bash
# Activate the venv (required before all commands below)
source .venv/bin/activate

# Run all acceptance tests
pytest tests/ -v

# Run a single test
pytest tests/test_acceptance.py::test_assign_battery -v

# Seed the database (safe to skip if batteries.db already exists)
python seed.py

# Start the dev server
flask run

# Start production server (same as systemd service uses)
waitress-serve --host=127.0.0.1 --port=5000 app:app

# Install/reinstall systemd user service
bash sbin/install-service.sh

# Service management
systemctl --user start|stop|restart|status battery-tracker
journalctl --user -u battery-tracker -f
```

## Architecture

### Request lifecycle
`app.py` contains `create_app(config_object)` which builds the Flask app, creates the SQLAlchemy engine from `config.SQLALCHEMY_DATABASE_URI`, calls `Base.metadata.create_all(engine)`, and wires a `scoped_session` as the `db` local. All routes close over this `db` via `@app.teardown_appcontext`. There is no Flask-SQLAlchemy — the ORM session is raw SQLAlchemy so that `models.py` can be imported by `migrate_to_mariadb.py` without an app context.

### Database config
`config.py` reads `DATABASE_URL` from the environment, falling back to `sqlite:///batteries.db`. Swapping to MariaDB is entirely a matter of setting that env var — no code changes needed. All column types are restricted to `Integer`, `String`, `Text`, `Boolean`, `DateTime` for MariaDB compatibility. Status is stored as `String(20)` (not `Enum`) to avoid DDL differences between SQLite and MariaDB.

### Models
- `Battery`: label (unique), brand, status (`available`/`installed`/`retired`), device_id (FK nullable, `ondelete=SET NULL`), notes, size, chemistry, capacity_mah, tested_capacity_mah, tested_date, charge_cycles, purchase_date, storage_location, battery_percentage
- `Device`: name (unique), battery_slots, device_type, notes, ha_entity_id
- Helper methods: `Battery.is_available/installed/retired()`, `Device.installed_count()`, `Device.installed_brands()`, `Device.has_mixed_brands()`

### Business rules (enforced in routes, not DB constraints)
- Assigning a retired battery → hard block with flash error
- Assigning to a full device → hard block with flash error
- Mixed brands on same device → flash warning, assignment still proceeds
- Deleting a battery → requires GET confirmation page first, then POST
- Bulk install into device: capacity check before write; batteries already in target device are skipped; retired batteries are skipped
- Unretire: sets status back to `available`
- Unassign with `next` form field → redirects to that URL (must start with `/`); falls back to dashboard
- Logging a charge entry → sets `battery.battery_percentage = 100`

### Home Assistant integration (optional)
`ha_client.py` wraps the HA REST API (`GET /api/states/<entity_id>`). `ha_poller.py` runs a daemon thread started in `create_app` only when `HOMEASSISTANT_URL` and `HOMEASSISTANT_API_KEY` are set. The poller queries all `Device` rows with `ha_entity_id IS NOT NULL`, fetches the current percentage from HA, and writes it to `battery_percentage` on each installed battery in that device. The poller uses its own `sessionmaker` session (not the request-scoped `scoped_session`). When HA is not configured the app behaves exactly as before — all HA UI is gated on `ha_enabled` passed to templates.

### Adding new columns to existing DB
`create_all()` won't add columns to existing tables. Run via Python:
```python
import sqlite3
conn = sqlite3.connect('batteries.db')
conn.execute('ALTER TABLE <table> ADD COLUMN <col> <type>')
conn.commit(); conn.close()
```
Always snapshot the DB first: `cp batteries.db batteries.db.$(date +%Y-%m-%d).snapshot`

### Testing
Tests use a temporary file-based SQLite DB (via `tempfile.mkstemp`) created fresh per test — avoids SQLite in-memory per-connection isolation issues. The `seeded_client` fixture in `conftest.py` pre-populates via HTTP POST calls (not direct DB access), so tests exercise the full stack. Battery IDs in tests are positional (id=1 is always the first battery POSTed by the fixture).

`TestConfig` sets `HOMEASSISTANT_URL = None` to prevent the HA poller thread from starting during tests. HA integration tests live in `tests/test_ha_integration.py` and use a separate `ha_app` fixture with a fake HA URL; they call `poller._poll_once()` directly rather than waiting for the background thread to fire. HA API calls are mocked with `unittest.mock.patch("ha_client.requests.get")`.

### MariaDB migration
`migrate_to_mariadb.py` opens two SQLAlchemy sessions simultaneously (SQLite source, MariaDB destination), migrates Devices first (FK dependency), then Batteries with explicit `id=` values to preserve FK links, then resets `AUTO_INCREMENT` via `text("ALTER TABLE ...")`. Takes `MARIADB_URL` from env or CLI arg. See `MIGRATION.md` for the full procedure.