Under the hood
Plugin API event chains can now skip requiring a locally-registered core handler
What
Claude Code's plugin API introduces the idea of an externally-provided "core" handler. When this external core is present, calls to plugin API events ($.<event>) can now proceed even if neither the site nor the specific call registered a local core handler, skipping the error that would otherwise be raised for having no core at the bottom of the chain.
Why
This allows plugin event chains to complete successfully in setups where the core handler is supplied externally rather than registered locally, instead of failing with a missing-core error.