Swiftdata Code Review

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name: swiftdata-code-review description: Reviews SwiftData code for model design, queries, concurrency, and migrations. Use when reviewing .swift files with import SwiftData, @Model, @Query, @ModelActor, or VersionedSchema.

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SwiftData Code Review

Quick Reference

| Issue Type | Reference | |------------|-----------| | @Model, @Attribute, @Relationship, delete rules | references/model-design.md | | @Query, #Predicate, FetchDescriptor, #Index | references/queries.md | | @ModelActor, ModelContext, background operations | references/concurrency.md | | VersionedSchema, MigrationStage, lightweight/custom | references/migrations.md |

Hard gates (before reporting findings)

Run in order; do not assert an issue until the gate for that issue passes.

1. Scope — pass when: You have the target .swift path(s) and confirmed SwiftData surface in scope (e.g. import SwiftData, @Model, @Query, @ModelActor, VersionedSchema, or migration types). If none apply, stop or narrow scope with one sentence. 2. Reference — pass when: For each checklist area you evaluate (models, queries, concurrency, migrations), you opened the matching references/*.md from the Quick Reference table or wrote N/A: no in this review with a one-line reason. 3. Evidence — pass when: Every finding uses the [FILE:LINE] ISSUE_TITLE header (line range allowed) from the file you read; no finding without a cite. 4. Report — pass when: Findings list cites first (or inline) using [FILE:LINE] ISSUE_TITLE, then severity or checklist grouping—no uncited assertions.

Review Checklist

[ ] Models marked final (subclassing crashes)

[ ] @Relationship decorator on ONE side only (not both)

[ ] Delete rules explicitly set (not relying on default .nullify)

[ ] Relationships initialized to empty arrays, not default objects

[ ] Batch operations used for bulk inserts (append(contentsOf:))

[ ] @Query not loading thousands of items on main thread

[ ] External values in predicates captured in local variables

[ ] Scalar comparisons in predicates (not object references)

[ ] @ModelActor used for background operations

[ ] PersistentIdentifier/DTOs used to pass data between actors

[ ] VersionedSchema defined for each shipped version

[ ] MigrationPlan passed to ModelContainer

When to Load References

Reviewing @Model or relationships -> model-design.md

Reviewing @Query or #Predicate -> queries.md

Reviewing @ModelActor or background work -> concurrency.md

Reviewing schema changes or migrations -> migrations.md

Review Questions

1. Could this relationship assignment cause NULL foreign keys? 2. Is @Relationship on both sides creating circular references? 3. Could this @Query block the main thread with large datasets? 4. Are model objects being passed between actors unsafely? 5. Would schema changes require a migration plan?