letscode-cli 0.1.4

A from-scratch coding agent — bring your own OpenRouter API key

██╗     ███████╗████████╗███████╗ ██████╗ ██████╗ ██████╗ ███████╗
██║     ██╔════╝╚══██╔══╝██╔════╝██╔════╝██╔═══██╗██╔══██╗██╔════╝
██║     █████╗     ██║   ███████╗██║     ██║   ██║██║  ██║█████╗  
██║     ██╔══╝     ██║   ╚════██║██║     ██║   ██║██║  ██║██╔══╝  
███████╗███████╗   ██║   ███████║╚██████╗╚██████╔╝██████╔╝███████╗
╚══════╝╚══════╝   ╚═╝   ╚══════╝ ╚═════╝ ╚═════╝ ╚═════╝╚══════╝

Building Claude Code from scratch — a minimal coding agent you own and understand.

---

What is this?

letscode is a coding agent built from first principles. It replicates the core loop of tools like Claude Code:

• You describe a coding task in plain English
• The agent calls tools (read files, list directories, edit files) to get the job done
• It keeps looping — reading, reasoning, editing — until the task is complete

The entire agent fits in a single file. No magic, no abstractions you didn't write yourself.

---

Features

• Model-agnostic — works with any model on OpenRouter: Claude, GPT-4o, Gemini, Llama, Mistral, DeepSeek, and more
• Free tier support — defaults to meta-llama/llama-3.3-70b-instruct:free (no cost)
• Built-in tools — read files, list directories, edit files, search file contents, run shell commands
• Interactive / menu — type / for a navigable dropdown of every command and tool (arrow keys + Enter), just like Claude Code; pick a tool to run it locally without spending tokens
• Text-protocol tool-calling — no vendor lock-in; the LLM emits tool calls as plain text
• Full conversation history — the agent remembers context across turns

---

Quickstart

1. Clone the repo

git clone https://github.com/srinivasankh/letscode.git
cd letscode

2. Set up your API key

Copy the example config and add your OpenRouter key:

cp .env.example .env

Edit .env:

OPENROUTER_API_KEY=sk-or-your-key-here

That's all you need. The default model is free — no credit card required.

3. Run it

uv run letscode

Or, if you prefer pip:

pip install -e .
letscode

---

Bring Your Own API Key (BYOK)

letscode routes all LLM calls through OpenRouter, which gives you a single API key that works with dozens of models.

Get a free key:

1. Sign up at openrouter.ai
2. Go to openrouter.ai/keys → create a key
3. Paste it into your .env file as OPENROUTER_API_KEY

Choose your model by setting OPENROUTER_MODEL in .env:

# Free models (no cost)
OPENROUTER_MODEL=meta-llama/llama-3.3-70b-instruct:free
OPENROUTER_MODEL=google/gemma-3-27b-it:free
OPENROUTER_MODEL=deepseek/deepseek-r1:free

# Frontier models (paid, best quality)
OPENROUTER_MODEL=anthropic/claude-sonnet-4
OPENROUTER_MODEL=openai/gpt-4o
OPENROUTER_MODEL=google/gemini-2.5-pro

Browse all available models at openrouter.ai/models.

---

How it works

The agent runs a simple loop:

User input
    └─▶ LLM reasons about the task
            └─▶ Emits a tool call  (e.g. tool: read_file({"filename": "app.py"}))
                    └─▶ Agent executes the tool
                            └─▶ Result fed back to LLM
                                    └─▶ Repeat until done

Available tools:

Tool	What it does
read_file(filename)	Read the full content of a file
list_files(path)	List files and directories at a path
edit_file(path, old_str, new_str)	Replace text in a file, or create a new file
search_text(pattern, path)	Recursively search file contents for a regex, returning file:line:text hits
run_command(command)	Run a shell command (with confirm-before-run gate)

Slash menu: type / to open an interactive dropdown of commands (/exit, /help) and tools. Use the arrow keys and Enter to select. Picking a command runs it; picking a tool inserts a /tool({"arg": "value"}) template you fill in — the tool then runs locally (no LLM call) and prints its result.

---

Project structure

src/letscode/
  agent.py       # the entire agent: tools, prompt, parser, loop
pyproject.toml   # package config
.env.example     # config template — copy to .env

---

Requirements

• Python 3.12+
• uv (recommended) or pip
• A free OpenRouter API key
• prompt_toolkit (installed automatically) — powers the interactive / menu