For me Tryton code will never do planning. This must be delegated to specialized tools like https://frepple.org/.
But we can have similar modules like stock_quantity_issue and stock_quantity_early_planning based on the work center capacities.
I’m not sure the planning should be stored with time in most cases but just maybe just ordered over the day.
Calendar views are often not usable at large scale. Usually a PERT chart is better. The basis storage was implemented in project_plan but never took off.