We are transiting from Scrum to Kanban. One of the things we need to still have to stick to some deadlines (stakeholders need to know some dates).
We have some classes of tasks negotiated with clients (SLA levels). They also have:
Fixed deadline - ordinary tasks that turn into high priority if the deadline is very close.
High priority - tasks to be done as soon as possible.
Expendite - all current work needs to be abandoned and this issue should be addressed. (like PROD env is down or equivalent)
We do grooming of backlog, break deadline items into tasks, decorate them with deadline time. After some time the deadline is approaching, some of the tasks turn to be high priority. Still we are confident about our commitment.
But our boss comes and tells to start working on something equally important (other thing or PROD issue). Now, we understand that we can't deliver committed features on time.
1. How those situation are managed in Kanban?
2. Are there any application that can calculate automatically new delivery date?
P.S. Team is multifunctional so not everybody can do all the work, so personal WIP are also imposed and should be calculated towards new dates.