# Architecture

- [The Three-Layer AI Coding Stack That Nobody Planned (But Everyone Is Building)](https://sdd.sh/2026/04/the-three-layer-ai-coding-stack-that-nobody-planned-but-everyone-is-building.md): Cursor, Claude Code, and OpenAI Codex are not converging into a single winner-take-all tool. They are stratifying into three distinct layers — orchestration, execution, and review — and the most sophisticated developers are building workflows that use all three. Here is what each layer does, why Claude Code wins at the execution layer, and what the emergence of OpenAI's Codex plugin for Claude Code signals about where this is heading.