--- name: axiom-ios-data description: Use when working with ANY data persistence, database, axiom-storage, CloudKit, migration, or serialization. Covers SwiftData, Core Data, GRDB, SQLite, CloudKit sync, file storage, Codable, migrations. license: MIT --- # 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 - Keychain / secure credential storage - Encryption, signing, key management (CryptoKit) ## 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` ### Keychain & Encryption **Keychain / secure credential storage** → `/skill axiom-keychain` **Keychain errors** → `/skill axiom-keychain-diag` **Keychain API reference** → `/skill axiom-keychain-ref` **Encryption / signing / key management** → `/skill axiom-cryptokit` **CryptoKit API reference** → `/skill axiom-cryptokit-ref` ### 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) **Database schema audit** → Launch `database-schema-auditor` agent or `/axiom:audit database-schema` (unsafe ALTER TABLE, DROP operations, missing idempotency, foreign key misuse) **SwiftData audit** → Launch `swiftdata-auditor` agent or `/axiom:audit swiftdata` (struct models, missing VersionedSchema, relationship defaults, background context misuse, N+1 patterns) ## Decision Tree 1. SwiftData? → swiftdata, swiftdata-migration 2. Core Data? → core-data, core-data-diag 3. GRDB? → grdb 4. SQLiteData? → sqlitedata, sqlitedata-ref 5. ANY schema migration? → database-migration (ALWAYS — prevents data loss) 6. Realm migration? → realm-migration-ref 7. SwiftData vs SQLiteData? → sqlitedata-migration 8. Cloud sync architecture? → cloud-sync 9. CloudKit? → cloudkit-ref 10. iCloud Drive? → icloud-drive-ref 11. Cloud sync errors? → cloud-sync-diag 12. Codable/JSON serialization? → codable 13. File storage strategy? → storage, storage-diag, storage-management-ref 14. File protection? → file-protection-ref 15. Keychain / storing tokens, passwords, secrets securely? → keychain, keychain-diag, keychain-ref 16. SecItem errors (errSecDuplicateItem, errSecItemNotFound, errSecInteractionNotAllowed)? → keychain-diag 17. Encryption, signing, Secure Enclave, CryptoKit? → cryptokit, cryptokit-ref 18. Quantum-secure cryptography, HPKE, ML-KEM? → cryptokit 19. Want Core Data safety scan? → core-data-auditor (Agent) 16. Want Codable anti-pattern scan? → codable-auditor (Agent) 17. Want iCloud sync audit? → icloud-auditor (Agent) 18. Want storage location audit? → storage-auditor (Agent) 19. Want database schema/migration safety scan? → database-schema-auditor (Agent) 20. Want SwiftData code audit? → swiftdata-auditor (Agent) 21. 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. | | "UserDefaults is fine for this token" | UserDefaults is unencrypted, backed up to iCloud, and visible to MDM profiles. One audit catches it. keychain stores tokens securely. | | "I'll encrypt it myself with CommonCrypto" | CryptoKit replaced CommonCrypto's buffer-management nightmares with one-line APIs. cryptokit prevents misuse. | ## 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: "Audit my database migrations for safety" → Invoke: `database-schema-auditor` agent User: "Check my SwiftData models for issues" → Invoke: `swiftdata-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` User: "How do I store an auth token securely?" → Invoke: `/skill axiom-keychain` User: "errSecDuplicateItem but I checked and the item doesn't exist" → Invoke: `/skill axiom-keychain-diag` User: "How do I encrypt data with AES in Swift?" → Invoke: `/skill axiom-cryptokit` User: "I need to sign data with the Secure Enclave" → Invoke: `/skill axiom-cryptokit` User: "What's ML-KEM and should I use it?" → Invoke: `/skill axiom-cryptokit` --- Source attribution: CharlesWiltgen Original project: https://github.com/CharlesWiltgen/Axiom/blob/a66a3c0b44011011fed256c49954ba3c77075a1e/.claude-plugin/plugins/axiom/skills/axiom-ios-data/SKILL.md License: MIT License information: https://opensource.org/license/mit Original upstream instructions; downloaded from Dave AI. ## Upstream license notice MIT License Copyright (c) 2025 Charles Wiltgen Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. # Dave AI resource metadata Creator / publisher: CharlesWiltgen Original project: https://github.com/CharlesWiltgen/Axiom/blob/a66a3c0b44011011fed256c49954ba3c77075a1e/.claude-plugin/plugins/axiom/skills/axiom-ios-data/SKILL.md Attribution basis: Recovered original package and original project license at a pinned revision Fields of work: Development & Engineering Roles: Backend Developer, Mobile Developer Specialties: Database, Mobile Tools: Cloudkit, Grdb, Sqlite, Swiftdata, Core Data Country applicability: Country not specified Classification basis: Source catalog labels Instruction SHA-256: bebfcbe632977314cb7716f577763188e284d2075711302ee2b34c9591c7d094 Metadata reviewed: 2026-10-27 This metadata supersedes earlier Dave AI catalog attribution. Original instruction and supporting files are preserved.