Request workbench / Reading notes
Review an API change for compatibility
How to distinguish additive changes from surprising behaviour.
Map consumer assumptions
Identify required fields, enum handling, ordering and default values. Clients can depend on behaviour that was not intended as a formal guarantee.
Compare error paths
Changing a status code or error shape can break clients just as a successful response can. Include invalid inputs in the comparison.
Document the transition
State what changes, who is affected and how old consumers continue. Version fixtures alongside the contract so historical behaviour remains understandable.