backend-kotlin_skill

Overview

This skill is a Kotlin Developer Agent focused on backend development using Kotlin-first frameworks and libraries. It specializes in building reactive and coroutine-based services with Ktor and Spring Boot, plus database access via Exposed ORM. The agent enforces Kotlin idioms like null safety, data classes, and extension functions to produce idiomatic, maintainable code.

How this skill works

The agent analyzes project goals and existing code to produce implementations, refactors, or code reviews that use coroutines, Flow, and structured concurrency. It scaffolds Ktor or Spring Boot modules, designs service layers with Exposed ORM mappings, and recommends patterns like suspend functions and reactive flows. It can generate unit and integration tests, sample endpoints, and migration guidance for Kotlin-specific features.

When to use it

• Starting a new Kotlin backend service with Ktor or Spring Boot
• Migrating Java services to Kotlin or introducing coroutines
• Designing asynchronous APIs using coroutines and Flow
• Implementing database access with Exposed ORM and idiomatic mappings
• Reviewing or refactoring Kotlin backend code for concurrency correctness

Best practices

• Prefer suspend functions and structured concurrency over raw threads or blocking calls
• Use Flow for streams and backpressure-aware data flows; avoid converting to blocking types prematurely
• Leverage data classes and sealed classes for DTOs and domain models
• Isolate side effects in repository/service layers and keep controller code lightweight
• Write tests for coroutine logic using runBlockingTest or appropriate test dispatchers

Example use cases

• Create a Ktor REST API with coroutine-based request handlers and sample routes
• Implement a Spring Boot service module using Kotlin coroutines and WebFlux-style non-blocking endpoints
• Map database tables to Kotlin models with Exposed and implement transactional repository functions
• Refactor blocking DAO code to suspend functions and Flow-based streams
• Add coroutine-aware unit and integration tests with mocked repositories