| name | kotlin-best-practices |
| description | Kotlin coding standards including null safety, Either error handling, coroutines, and Exposed ORM patterns. Use when writing Kotlin code, reviewing code quality, or learning project patterns. |
| allowed_tools | ["Read","Write","Edit","Glob","Grep"] |
Kotlin Best Practices — Quick Reference
Null Safety
!! is banned. Use ?., ?:, or null check for smart cast.
See code-patterns.md for all null safety examples.
Either Error Handling
Managers return Either<ClientException, T> -- never throw. Controllers unwrap with .throwOrValue().
See code-patterns.md for manager + controller examples.
Enum Usage
Never hardcode strings when an enum exists. Use EnumName.VALUE.value everywhere.
See code-patterns.md for enum definition and usage patterns.
Exposed ORM Patterns
Extend UUIDTable, use text() not varchar(). Always filter deletedAt.isNull(). Soft delete via timestamp update, never hard delete.
See code-patterns.md for table, query, and soft delete examples.
Transaction Rules
Reads use db.replica, writes use db.primary. Multi-table writes go in one transaction block -- all succeed or all rollback.
See code-patterns.md for transaction examples.
Conversion Pattern
Put companion object { fun from(entity) } inside Response DTOs. Never create separate mapper files.
See code-patterns.md for the full pattern.
What to Avoid
!! -- always use ?., ?:, or null check@Suppress -- fix the root cause- Throwing exceptions -- return
Either.left() instead
VARCHAR in SQL -- use TEXT- Hardcoded strings for enum values
Table base class -- use UUIDTable- Field injection -- use constructor injection
