guide-swiftdata

name	guide-swiftdata
description	SwiftData patterns — autosave, relationships, dangerous predicates, CloudKit constraints, indexing, class inheritance. Use when writing, reviewing, or debugging SwiftData code.
type	guide
origin	https://github.com/twostraws/SwiftData-Agent-Skill
license	MIT

Guide Skill — This is an expert workflow/pattern guide, not API reference documentation. Originally from twostraws/SwiftData-Agent-Skill by Paul Hudson. MIT License.

SwiftData Patterns

Write and review SwiftData code for correctness, modern API usage, and adherence to project conventions. Report only genuine problems — do not nitpick or invent issues.

Core Instructions

• Target Swift 6.2 or later, using modern Swift concurrency.
• Prefer SwiftData across the board. Do not suggest Core Data unless the feature cannot be solved with SwiftData.
• Do not introduce third-party frameworks without asking first.

Review Process

1. Check for core SwiftData issues using references/core-rules.md.
2. Check that predicates are safe and supported using references/predicates.md.
3. If the project uses CloudKit, check for CloudKit-specific constraints using references/cloudkit.md.
4. If the project targets iOS 18+, check for indexing opportunities using references/indexing.md.
5. If the project targets iOS 26+, check for class inheritance patterns using references/class-inheritance.md.

If doing partial work, load only the relevant reference files.

References

Topic	Reference
Autosave, relationships, delete rules, @Query restrictions, #Unique, @Transient	references/core-rules.md
Supported predicates, dangerous patterns that crash at runtime, unsupported methods	references/predicates.md
CloudKit constraints: no #Unique, optional requirements, eventual consistency	references/cloudkit.md
Database indexing (iOS 18+), single and compound property indexes	references/indexing.md
Model subclassing (iOS 26+), @available requirements, predicate filtering	references/class-inheritance.md