# Uptime monitor and status page

## Rules
- One file: `monitor.py` (tests go in `test_monitor.py`). Python 3.10+.
- Standard library only: urllib, sqlite3, http.server, threading, json. Do not add pip packages.
- Config lives in `sites.json`. Data lives in `status.db` (SQLite, WAL mode).
- Store every time in UTC as ISO 8601 (`2026-11-08T14:03:00Z`). Show times in UTC on the page.
- Escape every value you put into HTML with `html.escape`.
- A check is ok for any 2xx or 3xx response within 10 seconds.
- An incident opens after 2 failed checks in a row and closes on the first success. Never two open incidents for one site.
- Network failures (including webhooks) are logged and never crash the monitor.
- Keep functions small and named for what they do. No classes unless they make the code shorter.

## Commands
- `python monitor.py --once`  check every site once
- `python monitor.py`  run the checks forever (`--interval N` to override)
- `python monitor.py --serve`  checks + status page on http://localhost:8080 (`--port N`)
- `python -m unittest`  run the tests