Why @FetchRequest Doesn't Work with Share Extensions (And What Does)

If you've built an iOS Share Extension that writes to a shared Core Data store, you've probably hit this wall: the data saves fine, but your main app's SwiftUI list doesn't update until you kill and relaunch it. I hit this while building a bookmarking app during a live stream. I was using Claude Code to build the whole thing. Got the Share Extension working, got it saving to Core Data through an App Group, deployed to my phone, shared a YouTube link, and... the app just sat there showing the old data. Kill the app, relaunch, there it is. Cool. Very helpful. I spent the next few hours figuring out why, and I'm writing it up so you don't have to. The Setup Nothing exotic going on here. A main app and a Share Extension both access the same Core Data SQLite store through an App Group container: Main App ←→ App Group Container (ShareSaver.sqlite) ←→ Share Extension Both targets share a PersistenceController that points the persistent store at the App Group path: class PersistenceController