Mobile

Use when choosing Core Data vs SwiftData, setting up the Core Data stack, modeling relationships, or implementing concurrency patterns - prevents thread-confinement errors and migration crashes

Use when working with ANY data persistence, database, storage, CloudKit, migration, or serialization. Covers SwiftData, Core Data, GRDB, SQLite, CloudKit sync, file storage, Codable, migrations.

Use when asking 'where should I store this data', 'should I use SwiftData or files', 'CloudKit vs iCloud Drive', 'Documents vs Caches', 'local or cloud storage', 'how do I sync data', 'where do app files go' - comprehensive decision framework for all iOS storage options

Use when adding/modifying database columns, encountering "FOREIGN KEY constraint failed", "no such column", "cannot add NOT NULL column" errors, or creating schema migrations for SQLite/GRDB/SQLiteData - prevents data loss with safe migration patterns and testing workflows for iOS/macOS apps

Use when migrating from Realm to SwiftData - comprehensive migration guide covering pattern equivalents, threading model conversion, schema migration strategies, CloudKit sync transition, and real-world scenarios

Complete background task API reference - BGTaskScheduler, BGAppRefreshTask, BGProcessingTask, BGContinuedProcessingTask (iOS 26), beginBackgroundTask, background URLSession, with all WWDC code examples

Use when working with Codable protocol, JSON encoding/decoding, CodingKeys customization, enum serialization, date strategies, custom containers, or encountering "Type does not conform to Decodable/Encodable" errors - comprehensive Codable patterns and anti-patterns for Swift 6.x

Use when writing ANY test, debugging flaky tests, making tests faster, or asking about Swift Testing vs XCTest. Covers unit tests, UI tests, fast tests without simulator, async testing, test architecture.

Use when structuring app entry points, managing authentication flows, switching root views, handling scene lifecycle, or asking 'how do I structure my @main', 'where does auth state live', 'how do I prevent screen flicker on launch', 'when should I modularize' - app-level composition patterns for iOS 26+

Use when you see memory warnings, 'retain cycle', app crashes from memory pressure, or when asking 'why is my app using so much memory', 'how do I find memory leaks', 'my deinit is never called', 'Instruments shows memory growth', 'app crashes after 10 minutes' - systematic memory leak detection and fixes for iOS/macOS

TextKit 2 complete reference (architecture, migration, Writing Tools, SwiftUI TextEditor) through iOS 26

Use when separating logic from SwiftUI views, choosing architecture patterns, refactoring view files, or asking 'where should this code go', 'how do I organize my SwiftUI app', 'MVVM vs TCA vs vanilla SwiftUI', 'how do I make SwiftUI testable' - comprehensive architecture patterns with refactoring workflows for iOS 26+

Use when implementing ANY Apple Intelligence or on-device AI feature. Covers Foundation Models, @Generable, LanguageModelSession, structured output, Tool protocol, iOS 26 AI integration.

Use when app feels slow, memory grows over time, battery drains fast, or you want to profile proactively - decision trees to choose the right Instruments tool, deep workflows for Time Profiler/Allocations/Core Data, and pressure scenarios for misinterpreting results

Use when integrating App Intents for Siri, Apple Intelligence, Shortcuts, Spotlight, or system experiences - covers AppIntent, AppEntity, parameter handling, entity queries, background execution, authentication, and debugging common integration issues for iOS 16+

Vulnerability review, OWASP patterns, secure coding practices, and threat modeling approaches. Use when reviewing code security, designing secure systems, performing threat analysis, or validating security implementations.

Apply consistent security, performance, and accessibility standards across all recommendations. Use when reviewing code, designing features, or validating implementations. Cross-cutting skill for all agents.

Consistent error patterns, validation approaches, and recovery strategies. Use when implementing input validation, designing error responses, handling failures gracefully, or establishing logging practices. Covers operational vs programmer errors, user-facing vs internal errors, and recovery mechanisms.

Apply scientific debugging methodology through conversational investigation. Use when investigating bugs, forming hypotheses, tracing error causes, performing root cause analysis, or systematically diagnosing issues. Includes progressive disclosure patterns, observable actions principle, and user-controlled dialogue flow.

User interview techniques, persona creation, journey mapping, and research synthesis patterns. Use when planning research studies, conducting interviews, creating personas, or translating research findings into actionable design recommendations.