It's a one-line item on the roadmap. "Send a push notification when X happens." Estimate is two days, three if the backend doesn't have FCM credentials yet. There's a library for it. The library is the visible part. The other 90% is platform lifecycle, registration state machines, race conditions with navigation, payload archaeology, and a half-dozen iOS and Android quirks. Nobody writes them down. You learn them after you ship, when the bug reports start coming in. I built this stack with custom native modules, wrapping APNs on iOS and FCM on Android directly, instead of reaching for Notifee, React Native Firebase, or OneSignal. The trade was the obvious one. I gave up the abstraction the libraries provide and got control over every edge case in return. The decision wasn't ideological. The failure modes I cared about were already filed against those libraries, unfixed. This post is what's underneath. Not the library you import. The work the library is hiding from you, or trying to.…