Building an AI Coding Agent in 100 lines of Kotlin

Coding agents like Claude Code look like magic: They generate, check and fix code without intervention which boosts developer productivity.

But in order to use tools efficiently it pays off to understand how they work.

Actually the way AI agents work is very simple. And in this presentation I will show you a simple coding agent and explain the concept behind it. All code is in Github.

Transcript

1. Building an AI Coding Agent in <100 lines of Kotlin A mental model about how agents work Sergio Carrilho Code: https://github.com/scarrilho/code-agent-example Post: https://sergiocarrilho.medium.com/building-an-ai-coding-agent-in-100-lines-of-kotlin-f9af28e6aeb0
3. Motivation Coding agents like Claude Code look like magic: They generate, check and fix code without intervention which boosts developer productivity. But in order to use tools efficiently it pays off to understand how they work. Actually the way AI agents work is very simple. And in this presentation I will show you a simple coding agent and explain the concept behind it. All code is in Github.
4. What is an AI agent “a system that can perceive its environment and act upon that environment to achieve specific goals”* * Book: AI Engineering: Building Applications with Foundation Models
5. Only a loop
6. The 3 pillars of agents
7. Show me the code
8. Repo: https://github.com/scarrilho/code-agent-example Agent.kt: The brain build.gradle.kts Tools: The hands libs.versions.toml Agent files Project files
9. Brain: LLM Configuration
10. Hands: Tools (1/2)
11. Hands: Tools (2/2)
12. The Loop: Agent Orchestration
14. Wrap in REPL
15. Demo “Make me a new file in kotlin called HelloWorld.kts file and implement hello world in it”
16. Result (Agent)
17. Result (file)
18. Conclusion Building a coding agent it’s about giving an LLM hands and a loop. The real complexity lies in the model’s reasoning capabilities and the quality of tools you provide. A AI agent concept is simple: Brain + hands + loop
19. Thank You!
20. References Books AI Engineering: Building Applications with Foundation Models Building Applications with AI Agents Web How to Build an Agent (or: The Emperor Has No Clothes): https://ampcode.com/how-to-build-an-agent Koog: https://www.jetbrains.com/koog/ Choose a design pattern for your agentic AI system: https://docs.cloud.google.com/architecture/choose- design-pattern-agentic-ai-system