Core Data to SwiftData Schema Evolution and Migration Specification

Role: Principal Apple Persistence Engineer specializing in Core Data and SwiftData migrations.

Context

• Schema Model Name: {{data_model_name}}
• Source Core Data Entities: {{core_data_entities}}
• Migration Strategy: {{migration_strategy}}
• CloudKit Integration: {{cloudkit_sync_enabled}}
• Data Integrity Invariants: {{data_integrity_rules}}
• Current Store Volume: {{sqlite_store_size}}

Task

Author a definitive schema evolution and migration engineering specification to transition {{data_model_name}} from Core Data to SwiftData using a {{migration_strategy}} approach, ensuring absolute adherence to {{data_integrity_rules}} for a database size of {{sqlite_store_size}}.

Method

1. Inspect source .xcdatamodeld definitions for {{core_data_entities}} and document all attribute types, relationships, and deletion rules.
2. Translate Core Data entities into native SwiftData @Model class structures with explicit relationship cardinality.
3. Establish schema versions using VersionedSchema and configure SchemaMigrationPlan stages for {{migration_strategy}}.
4. Design custom transformation stages for complex entity mutations where lightweight migration is insufficient.
5. Address CloudKit synchronization constraints if {{cloudkit_sync_enabled}} is active, ensuring default attribute values and optional relationships.
6. Specify fallback snapshot and rollback mechanics in case migration aborts midway on {{sqlite_store_size}} stores.
7. Detail background batch processing pipelines to prevent Main Thread hitching during data transformation.
8. Define automated migration test suites using transient in-memory and historical SQLite test artifacts.

Constraints

• MUST guarantee zero data loss and uphold all conditions in {{data_integrity_rules}}.
• MUST NOT execute heavy data transformations synchronously on the Main Actor.
• Migration plan MUST explicitly handle schema validation errors and corrupt store edge cases.
• Model definitions must adhere strictly to modern SwiftData macros without Core Data bridging leaks.

Output format

• Section 1: Schema Mapping Matrix (Core Data Entity to SwiftData Model)
• Section 2: Schema Migration Plan & Version Stages (Lightweight vs Custom)
• Section 3: CloudKit Sync & Concurrency Constraints (Sync topology)
• Section 4: Rollback, Fault Handling, & Validation Protocols
• Section 5: Migration Performance & Automated Test Harness

Self-review

• Ensure every entity in {{core_data_entities}} has a corresponding SwiftData representation.
• Verify that the migration plan strictly follows {{migration_strategy}} steps.
• Confirm CloudKit requirements are fully addressed if {{cloudkit_sync_enabled}} is set to true.