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Systematic diagnosis for common SpriteKit issues with time-cost annotations.

Core principle 90% of file storage problems stem from choosing the wrong storage location, misunderstanding file protection levels, or missing backup exclusions—not iOS file system bugs.

Core Data issues manifest as production crashes from schema mismatches, mysterious concurrency errors, performance degradation under load, and data corruption from unsafe migrations. Core principle 85% of Core Data problems stem from misunderstanding thread-confinement, schema migration requirements, and relationship query patterns—not Core Data defects.

SwiftData migration failures manifest as production crashes, data loss, corrupted relationships, or simulator-only success. Core principle 90% of migration failures stem from missing models in VersionedSchema, relationship inverse issues, or untested migration paths—not SwiftData bugs.

Systematic troubleshooting for Vision framework issues: subjects not detected, missing landmarks, low confidence, performance problems, coordinate mismatches, text recognition failures, barcode detection issues, and document scanning problems.

Symptom-based troubleshooting for Core Location issues.

Foundation Models issues manifest as context window exceeded errors, guardrail violations, slow generation, availability failures, and unexpected output. Core principle 80% of Foundation Models problems stem from misunderstanding model capabilities (3B parameter device-scale model, not world knowledge), context limits (4096 tokens), or availability requirements—not framework bugs.

Core principle 85% of networking problems stem from misunderstanding connection states, not handling network transitions, or improper error handling—not Network.framework defects.

Core principle 85% of navigation problems stem from path state management errors, view identity issues, or placement mistakes—not SwiftUI defects.

Systematic troubleshooting for AVFoundation camera issues: frozen preview, wrong rotation, slow capture, session interruptions, and permission problems.