A fixed feature list and a fixed date is a promise that one of them is a lie. The alternative is not vagueness — it is a scope written as outcomes with an explicit priority order.
We open every engagement with a problem statement, a metric, and a ranked list. The ranking is the contract. When something new arrives mid-project, and it always does, we do not argue about whether it is in scope. We ask what it outranks.
This single change removes most of the friction from delivery. It also produces better products, because it forces a conversation about value at the moment the information is freshest.