up-7-implementing-use-cases

Implements or synchronizes exactly one approved use case in code, in any stack: checks the Status gate, reads only the use case, its linked requirement rows, the entity model and the guideline file, shows an element-to-code plan with the list of decisions the specification leaves open, then generates a new slice or applies only the behavioral difference between the previous and the current specification, marks rule-enforcing code with the rule identifier, audits the diff for out-of-scope changes and handles schema changes as a guarded sub-procedure. Use when the user says implement, build, generate, sync or synchronize UC-XXX, asks to bring code in line with a changed use case, or asks for a database migration or schema change after the entity model changed. Not for work that names no use case and not for deciding whether a report is a bug or a change.