What
A plugin is an add-on that brings extra skills, commands or hooks into Claude Code. Claude Code now has checks that can refuse parts of a synced plugin when plugin sync is off or no folder exists for it. The parts covered are:
- Forked skills, which are skills that run as a separate task: Claude Code checks where the skill came from both before and after it loads the skill's contents, and a skill from a synced plugin is refused as
Unknown skill. - Hooks, which are commands that run automatically at set points in a session.
These checks sit behind a setting that Claude Code receives from Anthropic's servers.
Why
If you rely on skills or hooks that come from a synced plugin, they may not run in some sessions. A skill reported as Unknown skill may be one of these refusals.