how to pass text in prompt buffer to bottom toolbar or rprompt callables?

Sorry if I'm missing an obvious here:

How can I access the text being entered by the user in the prompt (in the buffer?) in the bottom_toolbar (or rprompt) callables that I define?

Just trying to do what is already doable with the Validator.validate(self, document) abstract method, which exposes the document object (and its text attribute) which provides access to the content of the buffer. This allows modification of the message in the bottom toolbar based on the user input, however is reliant on raising a ValidationError which also blocks "entering" the actual entry of the value which I'd like to avoid.

Thank you!

Start by reading the bottom_toolbar and rprompt callable APIs alongside Validator.validate(self, document), focusing on how each callable receives or accesses prompt state. Confirm whether the current buffer text can be exposed without raising ValidationError, and document or test the chosen behavior so toolbar output updates while normal submission remains possible.