On the Maintenance and Co-evolution of Agent Plugins: An Empirical Study of Claude Code Plugin Marketplaces
Ahmed Hereiz and colleagues (Queen's University and Polytechnique Montreal, including Ahmed E. Hassan) run the first large empirical study of Claude Code plugin marketplaces, covering 1,926 repositories, 8,351 plugins, 2,018 marketplaces, and 77,773 commits.
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Growth: Plugin-touching commit activity grew 8.8x over the six months following the October 2025 launch, and Software Engineering tasks account for 61.3% of all plugins.
Not one-off artifacts: Plugin development is feature-driven at more than twice the rate of conventional OSS (39.6% vs 17.2% feature commits), so these are maintained artifacts rather than write-once files.
A new coupling: Inside skills directories, natural-language instruction files and implementation scripts co-evolve at above-chance rates, and 78% of those co-changes are functionally coupled. That is a maintenance dependency with no analogue in traditional software.
Claude in the history: Claude co-authors 34.9% of all commits, and four conventional commit types (docs, perf, style, refactor) carry substantially different meanings in plugin repos than in normal software.
Why it matters: Anyone maintaining a skill library now has empirical evidence that prose and code drift together and need to be versioned as one unit.
Abstract
AI coding agents, software tools that automate development tasks through reasoning and tool use, are increasingly extended through plugin marketplaces, yet the structure, maintenance, and co-evolution dynamics of these emerging repositories remain empirically unexplored. Unlike traditional software packages that deliver functionality through source code, agent plugins deliver functionality through a combination of natural-language instruction files, scripts, and configuration files, raising the question of whether these plugins are maintained artifacts that co-evolve across components, or one-off artifacts that developers write once and do not need to revisit. To study the maintenance and co-evolution of agent plugins, we conduct an empirical study of 1,926 repositories hosting Claude Code plugin marketplaces, analyzing 8,351 plugins and 77,773 commits across 2,018 marketplaces. We find that the marketplace is expanding rapidly, plugin-touching commit activity growing 8.8x over six months after the October 2025 launch, and plugins targeting Software Engineering tasks accounting for 61.3% of all plugins. Plugin development is predominantly feature-driven, with feature commits occurring at more than twice the rate of conventional open-source software (OSS) (39.6% vs. 17.2%). Claude co-authors 34.9% of all commits, and four commit types (docs, perf, style, and refactor) carry substantially different meanings in plugin repositories than in traditional software. Most component types evolve independently, but within skills directories, natural-language instruction files and implementation scripts co-evolve at above-chance rates, with 78% of co-changes being functionally coupled, representing a new class of maintenance dependency not observed in traditional software engineering.