public enum ThemeMode

The look a build asks the platform for.

ONE enum for every hint that selects a theme, not one per platform. The domains overlap almost entirely and differ in a constant or two, which is not a reason to make a developer learn three names for modern – and three enums drift, which is worse than the thing they were separated to prevent.

Where a hint really does accept less than all of this, its attribute says so with @Hint(valuePattern = ...) and the annotation processor refuses the rest. That is a build error naming the constant and the hint, which is what the old arrangement could not give: passing a constant the builder does not recognise is not an error there, it is a silent fallback to the default.