a few more fixes and improvements

rota/shifts.py

@@ -1385,6 +1385,7 @@ class RotaBuilder(object):
                         )
 
         # Most of our constraints apply per worker
+        # Worker constraint loop
         worker: Worker
         for worker in self.workers:
             console.rule(
@@ -1392,6 +1393,22 @@ class RotaBuilder(object):
             )
             logging.debug(f"Generate worker constraints: {worker.name}")
 
+
+            if hasattr(worker, "max_shifts_per_week_by_shift_name"):
+                for shift_type, max_per_week in worker.max_shifts_per_week_by_shift_name.items():
+                    if shift_type not in self.get_shift_names():
+                        raise InvalidShift(
+                            f"Worker '{worker.name}' has max_shifts_per_week_by_shift_name referencing non-existent shift: {shift_type}"
+                        )
+                    for week in self.weeks:
+                        self.model.constraints.add(
+                            sum(
+                                self.model.works[worker.id, week, day, shift_type]
+                                for day in days
+                                if shift_type in self.get_shift_names_by_week_day(week, day)
+                            ) <= max_per_week
+                        )
+
             for week, day, shift in self.get_all_shiftclass_combinations():
                 # Only apply if this shift has force_assign_with set
                 if hasattr(shift, "force_assign_with") and shift.force_assign_with: