How AI Coding Agents Modify Code: A Large-Scale Study of GitHub Pull Requests

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Hauptverfasser: Ogenrwot, Daniel, Businge, John
Format: Preprint
Veröffentlicht: 2026
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author Ogenrwot, Daniel
Businge, John
author_facet Ogenrwot, Daniel
Businge, John
contents AI coding agents are increasingly acting as autonomous contributors by generating and submitting pull requests (PRs). However, we lack empirical evidence on how these agent-generated PRs differ from human contributions, particularly in how they modify code and describe their changes. Understanding these differences is essential for assessing their reliability and impact on development workflows. Using the MSR 2026 Mining Challenge version of the AIDev dataset, we analyze 24,014 merged Agentic PRs (440,295 commits) and 5,081 merged Human PRs (23,242 commits). We examine additions, deletions, commits, and files touched, and evaluate the consistency between PR descriptions and their diffs using lexical and semantic similarity. Agentic PRs differ substantially from Human PRs in commit count (Cliff's $δ= 0.5429$) and show moderate differences in files touched and deleted lines. They also exhibit slightly higher description-to-diff similarity across all measures. These findings provide a large-scale empirical characterization of how AI coding agents contribute to open source development.
format Preprint
id arxiv_https___arxiv_org_abs_2601_17581
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle How AI Coding Agents Modify Code: A Large-Scale Study of GitHub Pull Requests
Ogenrwot, Daniel
Businge, John
Software Engineering
Artificial Intelligence
K.6.3; I.2.2
AI coding agents are increasingly acting as autonomous contributors by generating and submitting pull requests (PRs). However, we lack empirical evidence on how these agent-generated PRs differ from human contributions, particularly in how they modify code and describe their changes. Understanding these differences is essential for assessing their reliability and impact on development workflows. Using the MSR 2026 Mining Challenge version of the AIDev dataset, we analyze 24,014 merged Agentic PRs (440,295 commits) and 5,081 merged Human PRs (23,242 commits). We examine additions, deletions, commits, and files touched, and evaluate the consistency between PR descriptions and their diffs using lexical and semantic similarity. Agentic PRs differ substantially from Human PRs in commit count (Cliff's $δ= 0.5429$) and show moderate differences in files touched and deleted lines. They also exhibit slightly higher description-to-diff similarity across all measures. These findings provide a large-scale empirical characterization of how AI coding agents contribute to open source development.
title How AI Coding Agents Modify Code: A Large-Scale Study of GitHub Pull Requests
topic Software Engineering
Artificial Intelligence
K.6.3; I.2.2
url https://arxiv.org/abs/2601.17581