Currently the only way to validate bookings on the Schedule Board is via Booking Rules using JavaScript.

There is no support for C# plugin-based validation that surfaces errors directly on the Schedule Board UI.

Complex enterprise scenarios such as validating booking dates against Work Order scheduled dates, checking resource certifications, or enforcing territory rules require full Dataverse query capabilities that JavaScript Booking Rules cannot reliably handle.

Request: Allow C# plugins registered on bookableresourcebooking Create/Update to surface InvalidPluginExecutionException messages directly on the Schedule Board, just like errors appear on standard Dataverse forms.