active-record-patterns

name	active-record-patterns
description	Active Record patterns: models, queries, associations, transactions, locking, migrations. Triggers: "AR scope", "has_many through", "polymorphic". Do NOT use for: Sequel, N+1.
user-invocable	false
effort	medium

Active Record Patterns

Iron Laws

1. Use decimal or integer cents for money.
2. Prevent N+1 queries with intentional preload strategy.
3. Put invariants inside transactions and use locks when races matter.
4. Prefer after_commit for external side effects.
5. Keep schema constraints aligned with application validations.

Default Moves

• use foreign keys and indexes deliberately
• choose includes, preload, or eager_load intentionally
• use find_each for large backfills and batch work
• use optimistic or pessimistic locking where correctness depends on it
• make migrations reversible and production-safe

References

Need	Reference
transactions, locking, partial-failure recovery	${CLAUDE_SKILL_DIR}/references/transactions.md
validation patterns, update_columns audit trails	${CLAUDE_SKILL_DIR}/references/validations.md
query composition, scopes, subqueries, batched inserts	${CLAUDE_SKILL_DIR}/references/queries.md
production-safe migration recipes	${CLAUDE_SKILL_DIR}/references/migrations.md
PostgreSQL full-text + trigram + hybrid search	${CLAUDE_SKILL_DIR}/references/fulltext-search.md

Related — invoke manually if needed

• Sequel ORM (non-Active Record) work → /rb:sequel-patterns (Sequel ORM patterns)