Nice! I really didn't want a company involved in my security, but I knew I didn't have time to build something like this.
I went the lazy way and used an Ademco Vista 20p. It is old school, but solid. I wanted to make it a little more friendly so I went with an AD2USB virtual terminal and raspberry pi. There is a python library for it and from there you can do whatever you want and the clucky old alarm system doesn't know the difference between you arming the alarm at the keypad or a cron job arming the alarm. Of course you also get all the events happening on the system.
Yeah the Ademco Vista series with the AlarmDecoder bridge is great for hardwired alarms as well as the Ademco remote sensors, and then can be handled through Home Assistant, OpenHab, or similar. One benefit of using conventional hardware is that you can connect it to an official alarm monitoring service and satisfy the requirement for a discount on your home insurance. Not sure if a completely DIY system can qualify for insurance purposes.
I went the lazy way and used an Ademco Vista 20p. It is old school, but solid. I wanted to make it a little more friendly so I went with an AD2USB virtual terminal and raspberry pi. There is a python library for it and from there you can do whatever you want and the clucky old alarm system doesn't know the difference between you arming the alarm at the keypad or a cron job arming the alarm. Of course you also get all the events happening on the system.