What
Plugins can register handlers for events (using on("event")) and hooks. Two new validators now check this registration at load time: one confirms that a plugin's event patterns actually match a real, known event or method, and the other confirms that hooks the plugin declares were actually found when its hooks module was scanned. If either check fails, Claude Code now throws a descriptive error, such as one saying a pattern 'selects no event' or that a hook 'the scan of its hooks module did not see'.
Why
This gives plugin authors clearer, more specific errors when they misconfigure event or hook registrations, instead of the problem failing silently or surfacing as a confusing downstream error.