CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

A Hugging Face Spaces app that translates English text to ~400 languages using Google's MADLAD-400 3B Seq2Seq model. Built with Gradio and deployed on HF Spaces. Falls back to CPU with a warning when no GPU is available.

Commands

# Setup
python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

# Run (launches on http://localhost:7860)
python app.py

# Lint and format
ruff check .
ruff format .

# Type check
ty check

# Test
pytest                     # all tests (slow tests require GPU + model download)
pytest -m "not slow"       # fast tests only
pytest -m slow             # model tests only

Architecture

app.py — Single-file application. Uses @lru_cache for lazy loading of the google/madlad400-3b-mt tokenizer and model with float16 precision (no download on import). Translation prepends a language token to the input text (e.g., <2fr>Hello) before tokenization and generation. The @spaces.GPU decorator allocates GPU on HF Spaces infrastructure.

langmap/ — Package with langid_mapping.py, a hand-maintained dictionary mapping ~400 language tokens to human-readable language names (sourced from pages 16–21 of the MADLAD-400 paper). Available languages at runtime are the intersection of this mapping and the model's vocabulary.

tests/ — Pytest suite split into fast (test_langmap.py) and slow (test_app.py). Slow tests require GPU and model download; they are auto-skipped without MPS/CUDA. Fast tests in test_app.py verify the module imports without triggering model download.

Tooling

• Ruff — linter and formatter (ruff.toml). Rules: E, F, I, W. Line length: 120.
• ty — type checker (ty.toml). Python 3.12 target.
• pytest — test runner (pytest.ini). Custom slow marker for GPU-dependent tests.