Commitment works both ways. Teams that commit to delivering on little pieces of acceptable work based upon agreed-to acceptance criteria need to know that Product commits to accepting based upon those same requirements.
Once an acceptance criterion is "in-flight", it should not be adjusted without unanimous consent by all stakeholders who originally committed to the requirement, including developers. Any dissent leaves the old criterion in force.
This gives Product several options for changing their minds:
- Cancel a criterion and halt all work in that direction.
- Renegotiate a criterion with engineering.
- Add new criteria after the current ones are implemented.
Limiting your options to renegotiate creates an incentive to limit the size of an increment of work.
