TLDR; Would it be possible to extend the handlePartialAccept with metadata field, allowing to attach additional info, such as origin?

It would help understanding in the downstream completion metrics, where acceptances are comming from to better understand user behavior. The field could be later on extended with any additional information if neccessary, e.g. in the case of partial accept it might be helpful to report back also the length of the accepted token (not only the length of the full acceptance from start of insertion to cursor position ).