• Does omitting attributes from types constitute a breaking change?

Copied this to a change, preventing quoting high-level comments.

• Should Search Field and Switch get an invalid prop? Are there situations in which these can be invalid?

Well, there are theoretical situations. Both implement the HTMLInputElement interface which has properties like required and minLength that may fail a validation rule.

We offer Switch to toggle UI states only, so it can never become invalid in practice. We can remove all validation fields from the type, or not even use the input interface at all.

A Search Field might have a minimum length of e.g. 3 characters to facilitate meaningful results, although I would not expect it to turn red if the field gets blurred with a content of less than 3 characters. On the other hand, if people press Enter or click the Search Button, there should be a way to inform them of this rule.

So maybe yes for Search Field, and tighten the props for Switch?