I’ve used all the popular coding agents in the market, Claude Code, Codex, Gemini CLI (yes, even this), Cursor and they are all great but they don’t feel mine. Once the Claude Code codebase leaked, i figured it was the perfect time to build a coding agent for myself from scratch. I set out to distill Claude Code first by stripping its essential parts and i called it nano claude code. How it works The core loop is simple: load skills and rules → append user message → call Anthropic with tools → execute tool calls → loop until the model stops. The whole thing is 15 files: a CLI entrypoint, an agent loop, tools, MCP client, file-backed instructions (NANO.md), skills, transcripts, API wrapper, and a readline UI. One nice detail borrowed from Claude Code: file-changing tools return diffs via git diff --no-index , so the model gets structured change feedback instead of just “write succeeded.” What i kept from Claude Code The harness shape (model + tool loop), the CLAUDE.md idea (shrunk to just workspace-local NANO.md), skills as the extensibility seam, MCP as first-class capability expansion, approval gates for risky actions, and local transcripts as append-only JSONL. What i dropped The massive command surface, React/Ink UI, concurrent tool orchestration, the hardened permission engine, and all the productization layers — memory systems, analytics, billing, feature flags, telemetry, IDE integration, voice, desktop surfaces. All valuable product features, but they explode surface area for a solo fork. The design principle Keep the parts that make Claude Code feel powerful. Remove the parts that make the codebase hard to hold in your head. repo: https://github.com/Prat011/nano-claude-code submitted by /u/goddamnit_1
Originally posted by u/goddamnit_1 on r/ClaudeCode