The host's modal-edit SESSION, as the commit policy needs to see it. What a session is differs
per field — a formula field is engaged on the reference-mode bus (grid picks write into it); a
plain field is simply focused — but the done rules only need "is one open" and "end it".
End the OPEN session: revert to the session baseline on a cancel, return to idle, and deliver the
commit channel (EditCommitApi.notifyDone). Never called while isActive is false.
The host's modal-edit SESSION, as the commit policy needs to see it. What a session is differs per field — a formula field is engaged on the reference-mode bus (grid picks write into it); a plain field is simply focused — but the done rules only need "is one open" and "end it".