Learn harness engineering by building Claude Code from scratch. Free, open-source course: 8 articles, 6 videos, 1 codebase.
3 files for Claude Code, Codex and OpenCode: building-a-coding-agent-from-scratch-course, building-a-coding-agent-from-scratch-course AGENTS.md, building-a-coding-agent-from-scratch-course CLAUDE.md — 5,643 tokens loaded in every session.
AGENTS.md A 5,638 tok CLAUDE.md A 5 tok .claude/settings.json A — These files are decodingai-magazine/building-a-coding-agent-from-scratch-course's own configuration — they tell Claude Code, Codex and OpenCode how to work on this repository, so they are not mods to install elsewhere. Copy one as a starting point and replace the parts that are about this project.