Function live_document_count 

pub fn live_document_count() -> usize

How many documents are alive in this process right now.

A TextDocument is a handle onto a shared body, so a single surviving clone keeps that document’s rope, block table and store resident. A host that opens a document per scene and closes a project has no other way to ask whether it actually let go: the memory shows up under the rope and the block table whoever is holding them, and an allocation profile names the allocation site rather than the owner.

Counted on the body, not on the handle, so cloning a TextDocument does not move it. It rises by one for each document successfully created and falls by one when the last handle to it is dropped.