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A lightweight, incremental reimplementation of Claude Code in ~2,000 lines of TypeScript.
| Claude Code | nano-claude | |
|---|---|---|
| Lines of code | 512,685 | ~2,000 |
| Files | 1,902 | 19 |
| Tools | ~50 | 7 |
| Runtime | Bun | Node.js |
| UI | React + Ink | readline |
New here? Read the Learning Guide for a step-by-step walkthrough of every version.
npm install
cp .env.example .env # Windows CMD: copy .env.example .env
# Edit .env with your API key
npm run devEach version is a tagged, independently runnable milestone:
git checkout v0 # start from the chatbot baseline| Version | Tag | What's Added | Lines | Key Concept |
|---|---|---|---|---|
| v0 | v0 |
Chatbot baseline: streaming REPL | ~80 | API streaming, no tools |
| v1 | v1 |
MVP: REPL + 6 tools + streaming | ~900 | The agentic tool-use loop |
| v2 | v2 |
Markdown rendering | ~1,020 | Terminal styling |
| v3 | v3 |
Permission confirmation + bash safety | ~1,140 | Tool risk classification |
| v4 | v4 |
Session persistence + resume | ~1,320 | State management |
| v5 | v5 |
Smart conversation compaction | ~1,450 | Context window management |
| v6 | v6 |
Multi-level CLAUDE.md + memory | ~1,630 | Project awareness + persistent memory |
| v7 | v7 |
Sub-agent tool | ~1,780 | Multi-agent orchestration |
| v8 | v8 |
CLI arguments + non-interactive mode | ~2,000 | Scripting and automation |
nano-claude # interactive REPL
nano-claude "explain this project" # interactive with initial prompt
nano-claude -p "list all TODOs" # non-interactive, print and exit
nano-claude -c # continue last conversation
nano-claude -r <session-id> # resume specific session
nano-claude -p --max-turns 5 "refactor this function"
nano-claude --dangerously-skip-permissions "write hello.txt"| Flag | Description |
|---|---|
-p, --print |
Non-interactive mode: output text only, then exit |
-c, --continue |
Continue the most recent conversation |
-r, --resume <id> |
Resume a specific session by ID |
-m, --model <model> |
Override the model name |
--max-turns <n> |
Maximum agentic turns (default: unlimited) |
--dangerously-skip-permissions |
Skip all permission prompts |
-h, --help |
Show help |
-v, --version |
Show version |
| Command | Description |
|---|---|
/help |
Show available commands |
/cost |
Display token usage |
/clear |
Clear conversation history |
/compact |
Smart conversation compression |
/model |
Show or switch model |
/sessions |
List saved sessions |
/resume |
Resume a previous session |
/remember |
Save a persistent memory |
/forget |
Delete a memory |
/memory |
List saved memories |
src/
├── index.ts # Entry + REPL + CLI args + slash commands
├── api.ts # Anthropic SDK streaming wrapper
├── prompt.ts # System prompt construction
├── context.ts # Git context + multi-level CLAUDE.md
├── types.ts # Core type definitions
├── render.ts # Markdown terminal renderer
├── permissions.ts # Tool risk classification + confirmation
├── session.ts # Session save/load/list
├── compact.ts # Smart conversation compaction
├── memory.ts # Persistent key-value memory
└── tools/
├── index.ts # Tool registry
├── bash.ts # Shell command execution
├── read.ts # File reading with line numbers
├── write.ts # File creation / overwrite
├── edit.ts # String-replacement editing
├── glob.ts # File pattern search
├── grep.ts # Content search (ripgrep)
└── agent.ts # Sub-agent spawning
| Tool | Description | Risk |
|---|---|---|
| Bash | Execute shell commands | Classified per command |
| Read | Read files with line numbers | Safe |
| Write | Create/overwrite files | Write |
| Edit | String-replacement editing | Write |
| Glob | Find files by pattern | Safe |
| Grep | Search file contents (ripgrep) | Safe |
| Agent | Spawn read-only sub-agent | Safe |
npm run dev # Run with tsx
npm run build # Compile TypeScript
npm start # Run compiled JSMIT