Your sprint planning is deeper than sprint planning some other places. Some places that at least claim to be doing Scrum will groom the backlog in one meeting,

Your sprint planning is deeper than sprint planning some other places. Some places that at least claim to be doing Scrum will groom the backlog in one meeting, then choose which stories go on the sprint in another. Anything that needs agreement among developers is then tackled in pair programming or fairly ad-hoc "hack sessions". Implementation details, including details of code interfaces, user interfaces, and system interfaces, are left up to the contributor unless there's a need to align effort before that story is done.