sprint-plan has two modes. Analyze mode assesses backlog health — flagging stories that need splitting, stale tickets, missing data stories, dependency conflicts, and oversized items that have been miscategorized as single stories. Draft mode builds a sprint plan: it does the capacity math, selects stories against priorities and constraints, sequences them by dependency, and writes sprint goals as outcomes rather than task lists.
Sprint planning fails in predictable ways — too much scope relative to capacity, carryover items that crowd out new work, goals that describe activity instead of outcomes, and backlog items that never get the scrutiny they'd need to be sprint-ready. sprint-plan catches these before the sprint starts. The Analyze mode is especially useful before a planning meeting: it surfaces the backlog problems a team would otherwise spend 40 minutes discovering in the room.
Day 4 is the planning skill in Week 1 because by now you've produced artifacts (Day 1), reviewed them (Day 2), and broken them into stories (Day 3). Sprint planning is where you decide what actually gets built next — it's the moment when all the prior work either becomes committed scope or gets deferred. After this week you'll have run the full writing-to-planning cycle.