Large language models (LLMs) have demonstrated the promise to revolutionize the field of software engineering. Among other things, LLM agents are rapidly gaining momentum in software development, with practitioners reporting a multifold increase in productivity after adoption. Yet, empirical evidence is lacking around these claims. In this paper, we estimate the causal effect of adopting a widely popular LLM agent assistant, namely Cursor, on development velocity and software quality. The estimation is enabled by a state-of-the-art difference-in-differences design comparing Cursor-adopting GitHub projects with a matched control group of similar GitHub projects that do not use Cursor. We find that the adoption of Cursor leads to a statistically significant, large, but transient increase in project-level development velocity, along with a substantial and persistent increase in static analysis warnings and code complexity. Further panel generalized-method-of-moments estimation reveals that increases in static analysis warnings and code complexity are major factors driving long-term velocity slowdown. Our study identifies quality assurance as a major bottleneck for early Cursor adopters and calls for it to be a first-class citizen in the design of agentic AI coding tools and AI-driven workflows.

Talks at practitioner-focused open-source software conferences are a valuable source of information for software engineering researchers. They provide a pulse of the community and are valuable source material for grey literature analysis. We curated a dataset of 24,669 talks from 87 open-source conferences between 2010 and 2021. We stored all relevant metadata from these conferences and provide scripts to collect the transcripts. We believe this data is useful for answering many kinds of questions, such as: What are the important/highly discussed topics within practitioner communities? How do practitioners interact? And how do they present themselves to the public? We demonstrate the usefulness of this data by reporting our findings from two small studies: a topic model analysis providing an overview of open-source community dynamics since 2011 and a qualitative analysis of a smaller community-oriented sample within our dataset to gain a better understanding of why contributors leave open-source software.