iOS Data & Persistence Router

You MUST use this skill for ANY data persistence, database, axiom-storage, CloudKit, or serialization work.

When to Use

Use this router when working with:

• Databases (SwiftData, Core Data, GRDB, SQLiteData)

• Schema migrations

• CloudKit sync

• File storage (iCloud Drive, local storage)

• Data serialization (Codable, JSON)

• Storage strategy decisions

Routing Logic

SwiftData

Working with SwiftData → /skill axiom-swiftdata

Schema migration → /skill axiom-swiftdata-migration

Migration issues → /skill axiom-swiftdata-migration-diag

Migrating from Realm → /skill axiom-realm-migration-ref

SwiftData vs SQLiteData → /skill axiom-sqlitedata-migration

Other Databases

GRDB queries → /skill axiom-grdb

SQLiteData → /skill axiom-sqlitedata

Advanced SQLiteData → /skill axiom-sqlitedata-ref

Core Data patterns → /skill axiom-core-data

Core Data issues → /skill axiom-core-data-diag

Migrations

Database migration safety → /skill axiom-database-migration (critical - prevents data loss)

Serialization

Codable issues → /skill axiom-codable

Cloud Storage

Cloud sync patterns → /skill axiom-cloud-sync

CloudKit → /skill axiom-cloudkit-ref

iCloud Drive → /skill axiom-icloud-drive-ref

Cloud sync errors → /skill axiom-cloud-sync-diag

File Storage

Storage strategy → /skill axiom-storage

Storage issues → /skill axiom-storage-diag

Storage management → /skill axiom-storage-management-ref

File protection → /skill axiom-file-protection-ref

tvOS Storage

tvOS data persistence → /skill axiom-tvos (CRITICAL: no persistent local storage on tvOS) tvOS + CloudKit → /skill axiom-sqlitedata (recommended: SyncEngine as persistent store)

Automated Scanning

Core Data audit → Launch core-data-auditor agent or /axiom:audit core-data (migration risks, thread-confinement, N+1 queries, production data loss) Codable audit → Launch codable-auditor agent or /axiom:audit codable (try? swallowing errors, JSONSerialization, date handling) iCloud audit → Launch icloud-auditor agent or /axiom:audit icloud (entitlement checks, file coordination, CloudKit anti-patterns) Storage audit → Launch storage-auditor agent or /axiom:audit storage (wrong file locations, missing backup exclusions, data loss risks)

Decision Tree

• SwiftData? → swiftdata, swiftdata-migration

• Core Data? → core-data, core-data-diag

• GRDB? → grdb

• SQLiteData? → sqlitedata, sqlitedata-ref

• ANY schema migration? → database-migration (ALWAYS — prevents data loss)

• Realm migration? → realm-migration-ref

• SwiftData vs SQLiteData? → sqlitedata-migration

• Cloud sync architecture? → cloud-sync

• CloudKit? → cloudkit-ref

• iCloud Drive? → icloud-drive-ref

• Cloud sync errors? → cloud-sync-diag

• Codable/JSON serialization? → codable

• File storage strategy? → storage, storage-diag, storage-management-ref

• File protection? → file-protection-ref

• Want Core Data safety scan? → core-data-auditor (Agent)

• Want Codable anti-pattern scan? → codable-auditor (Agent)

• Want iCloud sync audit? → icloud-auditor (Agent)

• Want storage location audit? → storage-auditor (Agent)

• tvOS data persistence? → axiom-tvos (CRITICAL: no persistent local storage) + axiom-sqlitedata (CloudKit SyncEngine)

Anti-Rationalization

Thought Reality

"Just adding a column, no migration needed" Schema changes without migration crash users. database-migration prevents data loss.

"I'll handle the migration manually" Manual migrations miss edge cases. database-migration covers rollback and testing.

"Simple query, I don't need the skill" Query patterns prevent N+1 and thread-safety issues. The skill has copy-paste solutions.

"CloudKit sync is straightforward" CloudKit has 15+ failure modes. cloud-sync-diag diagnoses them systematically.

"I know Codable well enough" Codable has silent data loss traps (try? swallows errors). codable skill prevents production bugs.

"I'll use local storage on tvOS" tvOS has NO persistent local storage. System deletes Caches at any time. axiom-tvos explains the iCloud-first pattern.

Critical Pattern: Migrations

ALWAYS invoke /skill axiom-database-migration when adding/modifying database columns.

This prevents:

• "FOREIGN KEY constraint failed" errors

• "no such column" crashes

• Data loss from unsafe migrations

Example Invocations

User: "I need to add a column to my SwiftData model" → Invoke: /skill axiom-database-migration (critical - prevents data loss)

User: "How do I query SwiftData with complex filters?" → Invoke: /skill axiom-swiftdata

User: "CloudKit sync isn't working" → Invoke: /skill axiom-cloud-sync-diag

User: "Should I use SwiftData or SQLiteData?" → Invoke: /skill axiom-sqlitedata-migration

User: "Check my Core Data code for safety issues" → Invoke: core-data-auditor agent

User: "Scan for Codable anti-patterns before release" → Invoke: codable-auditor agent

User: "Audit my iCloud sync implementation" → Invoke: icloud-auditor agent

User: "Check if my files are stored in the right locations" → Invoke: storage-auditor agent

User: "How do I persist data on tvOS?" → Invoke: /skill axiom-tvos

• /skill axiom-sqlitedata

User: "My tvOS app loses data between launches" → Invoke: /skill axiom-tvos