CLAPP: The CLASS LLM Agent for Pair Programming

arXiv (Cornell University)

Abstract

We introduce CLAPP (CLASS LLM Agent for Pair Programming), an interactive AI assistant designed to support researchers working with the Einstein-Boltzmann solver CLASS. CLAPP leverages large language models (LLMs) and domain-specific retrieval to provide conversational coding support for CLASS-answering questions, generating code, debugging errors, and producing plots. Its architecture combines multi-agent LLM orchestration, semantic search across CLASS documentation, and a live Python execution environment. Deployed as a user-friendly web application, CLAPP lowers the entry barrier for scientists unfamiliar with AI tools and enables more productive human-AI collaboration in computational and numerical cosmology. The app is available at https://classclapp.streamlit.app

Authors 5

1. Santiago Casas Aachen Institute for Theoretical Particle Physics and Cosmology

   Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) · RWTH Aachen University

   Affiliation as printed

   German Aerospace Center (DLR) , Scientific Information , Linder Höhe , D-51147 Köln , Germany

   Institute for Theoretical Particle Physics and Cosmology (TTK) , RWTH Aachen University , D-52056 Aachen , Germany

2. Christian Fidler Aachen Institute for Theoretical Particle Physics and Cosmology

   RWTH Aachen University

   Affiliation as printed

   Institute for Theoretical Particle Physics and Cosmology (TTK) , RWTH Aachen University , D-52056 Aachen , Germany

3. Boris Bolliet

   University of Cambridge

   Affiliation as printed

   Department of Physics , University of Cambridge , 19 JJ Thomson Avenue , Cambridge , CB3 0US , UK

   Kavli Institute for Cosmology , University of Cambridge , Madingley Road , Cambridge CB3 0HA , UK

4. Francisco Villaescusa-Navarro

   Princeton University · Flatiron Institute

   Affiliation as printed

   Center for Computational Astrophysics , Flatiron Institute , 162 5th Ave. , New York , NY 10010 , USA

   Department of Astrophysical Sciences , Princeton University , Peyton Hall , Princeton , NJ 08544 , USA

5. Julien Lesgourgues Aachen Institute for Theoretical Particle Physics and Cosmology

   RWTH Aachen University

   Affiliation as printed

   Institute for Theoretical Particle Physics and Cosmology (TTK) , RWTH Aachen University , D-52056 Aachen , Germany