SwiftData and Core Data Migrations

Protect the user's existing store first. Select the persistence and migration mechanism from requirements and the installed base, not from framework novelty.

Inspect before designing

Identify every supported source version, store configuration, target, and sync mode before editing models.

xcodebuild -version
xcrun swiftc --version
xcodebuild -showBuildSettings -project App.xcodeproj -target App \
  | rg 'IPHONEOS_DEPLOYMENT_TARGET|MACOSX_DEPLOYMENT_TARGET|SWIFT_VERSION'
rg --files | rg '\.(xcdatamodel|xcdatamodeld|mom|momd)$|\.entitlements$|\.storekit$'
rg -n 'VersionedSchema|SchemaMigrationPlan|MigrationStage|ModelContainer|NSPersistent(Container|CloudKitContainer)|NSMigrationManager'

Record: