---
name: netalertx-code-standards
description: NetAlertX coding standards and conventions. Use this when writing code, reviewing code, or implementing features.
---

# Code Standards

- ask me to review before going to each next step (mention n step out of x)  (AI only)
- before starting, prepare implementation plan  (AI only)
- ask me to review it and ask any clarifying questions first
- add test creation as last step - follow repo architecture patterns - do not place in the root of /test
- code has to be maintainable, no duplicate code
- follow DRY principle - maintainability of code is more important than speed of implementation
- code files should be less than 500 LOC for better maintainability

## File Length

Keep code files under 500 lines. Split larger files into modules.

## DRY Principle

Do not re-implement functionality. Reuse existing methods or refactor to create shared methods.

## Database Access

- Never access DB directly from application layers
- Use `server/db/db_helper.py` functions (e.g., `get_table_json`)
- Implement new functionality in handlers (e.g., `DeviceInstance` in `server/models/device_instance.py`)

## MAC Address Handling

Always validate and normalize MACs before DB writes:

```python
from plugin_helper import normalize_mac

mac = normalize_mac(raw_mac)
```

## Subprocess Safety

**MANDATORY:** All subprocess calls must set explicit timeouts.

```python
result = subprocess.run(cmd, timeout=60)  # Minimum 60s
```

Nested subprocess calls need their own timeout—outer timeout won't save you.

## Time Utilities

```python
from utils.datetime_utils import timeNowUTC

timestamp = timeNowUTC()
```

This is the ONLY function that calls datetime.datetime.now() in the entire codebase.

⚠️ CRITICAL: ALL database timestamps MUST be stored in UTC
This is the SINGLE SOURCE OF TRUTH for current time in NetAlertX
Use timeNowUTC() for DB writes (returns UTC string by default)
Use timeNowUTC(as_string=False) for datetime operations (scheduling, comparisons, logging)

## String Sanitization

Use sanitizers from `server/helper.py` before storing user input. MAC addresses are always lowercased and normalized. IP addresses should be validated.

## Devcontainer Constraints

- Never `chmod` or `chown` during operations
- Everything is already writable
- If permissions needed, fix `.devcontainer/scripts/setup.sh`

## Path Hygiene

- Use environment variables for runtime paths
- `/data` for persistent config/db
- `/tmp` for runtime logs/api/nginx state
- Never hardcode `/data/db` or use relative paths
