Is there some sort of feature in macOS 26 where Apple automatically quits its own applications if you don't talk to them for a while? Messages and Calendar keep spontaneously disappearing if I don't use them for a bit. They're visible on screen and then suddenly they're not. When I bring them back up, there's no window saying they crashed and would I like to submit a report.
And no, I'm not running Marco Arment's Quitter app.