database-migration

What problem does it solve?

This Skill prevents catastrophic data loss and app crashes when evolving database schemas in production iOS/macOS apps. It addresses common pitfalls like NOT NULL column errors, foreign key failures, and the dangers of modifying shipped migrations.

Core Features & Use Cases

• Safe Migration Patterns: Guides for additive-only, idempotent, and transactional schema changes, ensuring data integrity.
• Comprehensive Testing Workflow: Mandatory tests for fresh installs, migration paths from previous versions, and idempotency to guarantee robustness.
• Framework-Specific Guidance: Includes safe patterns and best practices for SQLite, GRDB, and SwiftData migrations.
• Use Case: When you need to add a new nullable column to a live app's database without losing existing user data, use this skill to follow the safe additive pattern and ensure thorough testing across all scenarios.

Quick Start

To add a new nullable column newColumn to tableName, ensure idempotency by checking for its existence first, then execute ALTER TABLE tableName ADD COLUMN newColumn TEXT.