SaaS-free notification of backups failing

I use borgbackup automated with borgmatic and launchd. This is a setup that needs no manual action from me. I like it that way.

Sometimes backups fail. And because it's not an app, there are no notifications. For a while, this was fine. I have several backup targets, and if one failed, I'd eventually notice and fix it without being overly concerned.

But recently, multiple backups failed because borgbackup unexpectedly now errors by default on missing source dirs.

There are solutions I'd read about but they all involve relying on a service. This is complexity and dependency I'd much rather avoid, to the point that I had previously accepted those occasional failed backups.

Then I was reminded by borgmatic docs that it can call an arbitrary script at pre-determined points of execution.

So I wrote a script. All it does is write given input to a new text file that's then saved to my default "working" directory.

On error, borgmatic now calls that script and gives it the error. The "working" directory is one I use routinely, because that's where I save new files. And it's sorted by time because I mostly operate from old to new. In the course of my day, I will invariably create a doc, make a screenshot, or download something. When I do, I will see that error.

As for being notified when AFK, I don't need that. When I'm away from keyboard, I can't fix the problem anyway.