coredata-swift6-pro

name	coredata-swift6-pro
description	Reviews Core Data code for Swift 6 strict concurrency compliance, modern context usage, and SPM compatibility. Use when reading, writing, or reviewing Core Data code under Swift 6.
license	MIT
metadata	{"author":"Kelvin Kosbab","version":"1.0"}

Review Core Data code for Swift 6 concurrency correctness, modern API usage, and SPM compatibility. Report only genuine problems - do not nitpick or invent issues.

Review process:

1. Validate viewContext access is @MainActor-isolated using references/main-actor.md.
2. Check background context usage with perform/performAndWait using references/background-contexts.md.
3. Verify SPM compatibility for .xcdatamodeld bundling using references/spm-limitations.md.
4. Check for modern persistent container patterns and fetch result types using references/modern-patterns.md.
5. Flag direct cross-context object passing (must pass NSManagedObjectID instead).

If doing a partial review, load only the relevant reference files.

Core Instructions

• Target Swift 6 with strict concurrency. Core Data + Swift 6 has specific rules that must be followed.
• viewContext is bound to the main queue — all synchronous access must be @MainActor or wrapped in MainActor.run.
• NSManagedObject subclasses are NOT Sendable. Never pass them across isolation boundaries — use NSManagedObjectID instead.
• All background context work goes through context.perform { } (async) or context.performAndWait { } (sync).
• For SPM packages, .xcdatamodeld cannot be compiled to .momd by swift build — only Xcode can. Tests run via swift test must build NSManagedObjectModel programmatically.
• Use NSPersistentContainer (or NSPersistentCloudKitContainer), not the deprecated NSPersistentStoreCoordinator directly.
• Prefer .viewContext.automaticallyMergesChangesFromParent = true so background changes propagate.
• For tests, use NSInMemoryStoreType so each test has an isolated store.

Output Format

Organize findings by file. For each issue:

1. State the file and relevant line(s).
2. Name the rule being violated.
3. Show a brief before/after code fix.

Skip files with no issues. End with a prioritized summary of the most impactful changes to make first.

Example output:

CoreStorage/Tests/EntityStoreTests.swift

Line 23: Sync viewContext test missing @MainActor — will fail under Swift 6 strict concurrency.

// Before
@Test func createUpdateDeleteObject() throws {
    let store = EntityStore(...)
    try store.create(...)
}

// After
@MainActor @Test func createUpdateDeleteObject() throws {
    let store = EntityStore(...)
    try store.create(...)
}

Line 45: Background context work missing perform { } block.

// Before
let bgContext = container.newBackgroundContext()
let object = MyObject(context: bgContext)
object.value = "foo"
try bgContext.save()

// After
let bgContext = container.newBackgroundContext()
try await bgContext.perform {
    let object = MyObject(context: bgContext)
    object.value = "foo"
    try bgContext.save()
}

CoreStorage/Tests/Utilities/KeyValue.swift

Line 14: Test relies on Bundle.module for .momd — will fail under swift test.

// Before
self.init(storeName: "MyModel", in: .module)

// After
let model = makeKeyValueManagedObjectModel()
self.init(storeName: "MyModel", managedObjectModel: model)

Summary

1. Concurrency (high): 4 sync viewContext tests missing @MainActor annotation.
2. SPM compatibility (high): Test container relies on Bundle.module for .momd — must build model programmatically.
3. Concurrency (medium): Background context work outside perform { } block on line 45.

End of example.

References

• references/main-actor.md — viewContext main-queue binding, @MainActor test patterns, isolation rules.
• references/background-contexts.md — perform/performAndWait, newBackgroundContext, async wrappers, merge policies.
• references/spm-limitations.md — .xcdatamodeld compilation, Bundle.module issues, programmatic NSManagedObjectModel.
• references/modern-patterns.md — NSPersistentContainer, fetch results, Codable transformers, CloudKit container.