CoreCoder — AI skill for Claude Code

CoreCoder

Formerly **NanoCoder** — renamed to avoid confusion with [Nano-Collective/nanocoder](https://github.com/Nano-Collective/nanocoder). All links from the old repo redirect here automatically.

[](https://pypi.org/project/corecoder/) [](https://python.org) [](LICENSE) [](https://github.com/he-yufeng/CoreCoder/actions)

[中文](README_CN.md) | [English](README.md) | [Claude Code Architecture Deep Dive (7 articles)](article/)

**512,000 lines of TypeScript → ~1,400 lines of Python.**

I spent two days reverse-engineering the leaked Claude Code source — all half a million lines. Then I stripped it down to the load-bearing walls and rebuilt them in Python. The result: **every key architectural pattern from Claude Code, in a codebase you can read in one sitting.**

CoreCoder is not another AI coding tool. It's a **blueprint** — the [nanoGPT](https://github.com/karpathy/nanoGPT) of coding agents. Read it, fork it, build your own.

---

$ corecoder -m kimi-k2.5

You > read main.py and fix the broken import

  > read_file(file_path='main.py')
  > edit_file(file_path='main.py', ...)

--- a/main.py
+++ b/main.py
@@ -1 +1 @@
-from utils import halper
+from utils import helper

Fixed: halper → helper.

What You Get

Claude Code's 512K lines distilled into ~1,400 lines across 7 patterns that actually matter:

Pattern	Claude Code	CoreCoder
Search-and-replace editing (unique match + diff)	FileEditTool	tools/edit.py — 70 lines
Parallel tool execution	StreamingToolExecutor (530 lines)	agent.py — ThreadPool
3-layer context compression	HISTORY_SNIP → Microcompact → CONTEXT_COLLAPSE	context.py — 145 lines
Sub-agent with isolated context	AgentTool (1,397 lines)	`t