pc-alerts

Two small always-on Windows tools that make noise when something needs your attention. Both run hidden in the background, start at login, and are restarted automatically if they ever die.

Tool	What it does
NetAlert	Watches the internet connection and sounds a siren within ~3 seconds of it dropping, then a chime when it returns.
MarketAlert	Speaks NSE/BSE trading session events — market open, the closing auction windows, expiry days, and a reminder the day before an exchange holiday.

Both share the same audio behaviour:

• Plays on the speaker you name, regardless of which output Windows treats as default — connected earbuds cannot silently steal an alert. The Windows default device is never changed.
• Low or muted volume cannot silence them. Volume is raised for the alert and restored to exactly what it was afterwards.
• Falls back rather than going quiet: if the named speaker is unreachable (unplugged, or hidden inside a Remote Desktop session) the alert re-scans the hardware and then plays on whatever output does exist.

Install on a new PC

Requires Windows and Python 3.9+ (python.org, tick Add python.exe to PATH during install).

git clone https://github.com/<you>/pc-alerts.git
cd pc-alerts
powershell -ExecutionPolicy Bypass -File install.ps1

That installs dependencies, creates each tool's config.json, registers autostart plus a restart watchdog, and starts both. It is safe to re-run.

Then name your speaker so alerts do not follow your earbuds:

python -c "import sounddevice as sd; print(sd.query_devices())"

Put the exact device name into netalert\config.json (alarm_device) and marketalert\config.json (speaker_device), then re-run install.ps1. Leaving them empty is fine — alerts play on the default output.

Everyday use

	NetAlert	MarketAlert
Start	netalert\start_netalert.vbs	marketalert\start_marketalert.vbs
Stop	netalert\stop_netalert.bat	marketalert\stop_marketalert.bat
History	netalert\netalert.log	marketalert\marketalert.log
Settings	netalert\config.json	marketalert\config.json, holidays.txt

To stop a tool permanently, delete its shortcut from the Startup folder (shell:startup) and its watchdog task:

Unregister-ScheduledTask -TaskName "NetAlert Watchdog" -Confirm:$false

How they stay alive

Being silent is the one way these tools fail badly — you assume you are covered when you are not. Three layers guard against that:

1. A failed check is logged and survived, never fatal.
2. A crash writes a traceback to the log (running under pythonw there is no console to print to, so an unlogged crash would be invisible).
3. A watchdog task relaunches each tool every 5 minutes if it is not running. An exclusive file lock makes that a no-op when it is already alive, so duplicates are impossible.

Layer 3 exists because of a real incident: the PC ran out of virtual memory, Windows killed NetAlert, and it stayed dead for two days unnoticed.

Tests

cd netalert     ; python -m unittest discover -p "test_*.py"
cd ..\marketalert ; python -m unittest discover -p "test_*.py"

154 tests covering outage detection and debouncing, the connectivity probe itself, audio device fallback, volume handling (including handing the volume back when the monitor is killed mid-outage), speech rendering and its cache, PowerShell quoting of announcement text, the market session calendar, expiry-day and holiday rules, holiday-calendar expiry, scheduling, log rotation, argument parsing, config values that are not numbers, and single-instance locking.

What is not committed

config.json, *.log, *.log.1, pythonw.txt, *.pid, *.lock and voice_cache/ are machine-specific or personal and are ignored by git. Everything needed to rebuild them is created by install.ps1 and the first run.

Each log rotates at 512 KB, keeping one previous generation as *.log.1, so an always-on tool cannot fill the disk.