Headless Panel Ownership

A file named headless at the runnable panel root selects headless composition. The headless runnable owns its UI components and styles and may reuse suitable headless components and shared panel behavior. Do not implicitly select or depend on simplePanel or complexPanel as its UI. Startup must honor the marker without requiring a panelUi selector file.

Philosophy

Headless composition enables an independent design without duplicating core behavior.

Fix

Compose the runnable-owned UI with panel core when the root headless marker exists.