diff --git a/rota_generator/shifts.py b/rota_generator/shifts.py
index 382d377..a8c34d4 100644
--- a/rota_generator/shifts.py
+++ b/rota_generator/shifts.py
@@ -470,6 +470,34 @@ class RotaBuilder(object):
 
         setattr(self.constraint_options_model, constraint, value)
 
+    @property
+    def constraint_options(self):
+        """Backward-compat dict-like proxy for the typed
+        `constraint_options_model`. This keeps older code/tests working
+        while the canonical storage is `constraint_options_model`.
+        """
+
+        class _Proxy:
+            def __init__(self, model):
+                self._m = model
+
+            def __getitem__(self, key):
+                return getattr(self._m, key)
+
+            def __setitem__(self, key, value):
+                setattr(self._m, key, value)
+
+            def get(self, key, default=None):
+                return getattr(self._m, key, default)
+
+            def items(self):
+                return self._m.model_dump().items()
+
+            def __contains__(self, key):
+                return hasattr(self._m, key)
+
+        return _Proxy(self.constraint_options_model)
+
     def set_rota_dates(self, start_date: datetime.date, weeks_to_rota: int):
         self.weeks_to_rota = weeks_to_rota
 
@@ -4663,7 +4691,7 @@ class RotaBuilder(object):
         <summary><h2>Rota settings</h2></summary>
         <div>
         <pre>
-        {json.dumps({k: _pydantic_to_dict(v) for k, v in self.constraint_options.items()}, indent=4)}
+        {json.dumps({k: _pydantic_to_dict(v) for k, v in self.constraint_options_model.model_dump().items()}, indent=4)}
         </pre>
         </details>
         </div>
diff --git a/test/rota_constraints/test_summed_shift_grade_constraints.py b/test/rota_constraints/test_summed_shift_grade_constraints.py
index 5c847b4..5fd5274 100644
--- a/test/rota_constraints/test_summed_shift_grade_constraints.py
+++ b/test/rota_constraints/test_summed_shift_grade_constraints.py
@@ -47,7 +47,7 @@ def test_summed_shift_grade_constraints():
     )
 
     # Add summed shift grade constraints
-    Rota.constraint_options["min_summed_grade_by_shifts_per_day"].append(
+    Rota.constraint_options_model.min_summed_grade_by_shifts_per_day.append(
         MinSummedGradeByShiftsPerDayConstraint(
             shifts=["a", "b"],
             min_grade_sum=4,
@@ -78,7 +78,7 @@ def test_summed_shift_grade_constraints():
     for summed_grade in summed_grades:
         assert summed_grade >= 4, f"Summed grade {summed_grade} is less than 4"
 
-    Rota.constraint_options["min_summed_grade_by_shifts_per_day"] = [
+    Rota.constraint_options_model.min_summed_grade_by_shifts_per_day = [
         MinSummedGradeByShiftsPerDayConstraint(
             shifts=["a", "b"],
             min_grade_sum=5,
diff --git a/test/test_limit_constraints.py b/test/test_limit_constraints.py
index f4f5633..9cadc21 100644
--- a/test/test_limit_constraints.py
+++ b/test/test_limit_constraints.py
@@ -257,7 +257,7 @@ def test_constraint_require_remote_site_presence_week2(limit_constraint_rota):
     Rota = limit_constraint_rota
     Rota.constraint_options["minimise_shift_diffs"] = False
     Rota.constraint_options["balance_shifts_quadratic"] = False
-    Rota.constraint_options["balance_shift"] = False
+    Rota.constraint_options["balance_shifts"] = False
     Rota.constraint_options["balance_nights_across_sites"] = True
     Rota.shifts = []
     Rota.add_shifts(
diff --git a/test/test_remote.py b/test/test_remote.py
index f3f52d5..6076e1f 100644
--- a/test/test_remote.py
+++ b/test/test_remote.py
@@ -51,7 +51,7 @@ class TestRemoteRotas:
         Rota.constraint_options["balance_blocks"] = False
         Rota.constraint_options["balance_weekends"] = False
         Rota.constraint_options["balance_nights"] = False
-        Rota.constraint_options["minimse_shift_diffs"] = False
+        Rota.constraint_options["minimise_shift_diffs"] = False
 
         Rota.add_workers(
             [Worker(
@@ -111,7 +111,7 @@ class TestRemoteRotas:
         Rota.constraint_options["balance_blocks"] = False
         Rota.constraint_options["balance_weekends"] = False
         Rota.constraint_options["balance_nights"] = False
-        Rota.constraint_options["minimse_shift_diffs"] = False
+        Rota.constraint_options["minimise_shift_diffs"] = False
 
         Rota.add_workers(
             [Worker(
diff --git a/test/test_rota.py b/test/test_rota.py
index a954000..bc3cd51 100644
--- a/test/test_rota.py
+++ b/test/test_rota.py
@@ -19,16 +19,16 @@ def demo_rota():
         weeks_to_rota=weeks_to_rota,
         balance_offset_modifier=1,
     )
-    Rota.constraint_options["max_shifts_per_week"] = 5
-    Rota.constraint_options["max_shifts_per_month"] = 31
-    Rota.constraint_options["constrain_time_off_after_nights"] = False
-    Rota.constraint_options["balance_nights_across_site"] = False
-    Rota.constraint_options["balance_shifts_quadratic"] = True
-    Rota.constraint_options["balance_shifts_over_workers"] = True
-    Rota.constraint_options["balance_nights"] = False
-    Rota.constraint_options["minimise_shift_diffs"] = False
-    Rota.constraint_options["balance_blocks"] = False
-    Rota.constraint_options["balance_bank_holidays"] = False
+    Rota.constraint_options_model.max_shifts_per_week = 5
+    Rota.constraint_options_model.max_shifts_per_month = 31
+    Rota.constraint_options_model.constrain_time_off_after_nights = False
+    Rota.constraint_options_model.balance_nights_across_sites = False
+    Rota.constraint_options_model.balance_shifts_quadratic = True
+    Rota.constraint_options_model.balance_shifts_over_workers = True
+    Rota.constraint_options_model.balance_nights = False
+    Rota.constraint_options_model.minimise_shift_diffs = False
+    Rota.constraint_options_model.balance_blocks = False
+    Rota.constraint_options_model.balance_bank_holidays = False
 
     # Add a few workers
     workers = [
diff --git a/test/test_rota_clear.py b/test/test_rota_clear.py
index 90b7057..f18e7e9 100644
--- a/test/test_rota_clear.py
+++ b/test/test_rota_clear.py
@@ -34,7 +34,7 @@ def demo_rota_clear():
         weeks_to_rota=weeks_to_rota,
         balance_offset_modifier=1,
     )
-    Rota.constraint_options["max_shifts_per_month"] = 20
+    Rota.constraint_options_model.max_shifts_per_month = 20
 
     workers = [
         Worker(name="worker1", site="group1", grade=1),
diff --git a/test/test_rota_nights.py b/test/test_rota_nights.py
index ee9ceec..d1b71ed 100644
--- a/test/test_rota_nights.py
+++ b/test/test_rota_nights.py
@@ -3,7 +3,7 @@ import pytest
 from pytest import approx
 from rota_generator.shifts import PostShiftConstraint, RotaBuilder, SingleShift, days
 from rota_generator.workers import Worker
-from web.rota.shifts import PreShiftConstraint
+from rota_generator.shifts import PreShiftConstraint
 
 @pytest.fixture
 def demo_rota_nights():
@@ -16,17 +16,17 @@ def demo_rota_nights():
         balance_offset_modifier=1,
     )
 
-    Rota.constraint_options["max_shifts_per_week"] = 5
-    Rota.constraint_options["max_shifts_per_month"] = 31
-    Rota.constraint_options["limit_to_1_st2_on_nights"] = False
-    Rota.constraint_options["constrain_time_off_after_nights"] = False
-    Rota.constraint_options["balance_nights_across_site"] = False
-    Rota.constraint_options["balance_shifts"] = True
-    Rota.constraint_options["balance_shifts_over_workers"] = True
-    Rota.constraint_options["balance_nights"] = False
-    Rota.constraint_options["minimise_shift_diffs"] = False
-    Rota.constraint_options["balance_blocks"] = False
-    Rota.constraint_options["max_night_frequency"] = 0
+    Rota.constraint_options_model.max_shifts_per_week = 5
+    Rota.constraint_options_model.max_shifts_per_month = 31
+    # legacy option `limit_to_1_st2_on_nights` removed; test omits it
+    Rota.constraint_options_model.constrain_time_off_after_nights = False
+    Rota.constraint_options_model.balance_nights_across_sites = False
+    Rota.constraint_options_model.balance_shifts = True
+    Rota.constraint_options_model.balance_shifts_over_workers = True
+    Rota.constraint_options_model.balance_nights = False
+    Rota.constraint_options_model.minimise_shift_diffs = False
+    Rota.constraint_options_model.balance_blocks = False
+    Rota.constraint_options_model.max_night_frequency = 0
 
     # Add workers
     workers = [
diff --git a/test/test_shift_constraints.py b/test/test_shift_constraints.py
index 5593e23..1da3fd1 100644
--- a/test/test_shift_constraints.py
+++ b/test/test_shift_constraints.py
@@ -36,36 +36,36 @@ def rota_3workers(rota_2workers):
     return Rota3
 
 def test_max_shifts(rota_2workers):
-    rota_2workers.constraint_options["max_shifts_per_month"] = 14
+    rota_2workers.constraint_options_model.max_shifts_per_month = 14
     rota_2workers.build_and_solve()
     assert rota_2workers.results.solver.status == "ok"
     assert rota_2workers.results.solver.termination_condition == "optimal"
 
 def test_max_shifts_fail(rota_2workers):
-    rota_2workers.constraint_options["max_shifts_per_month"] = 13
+    rota_2workers.constraint_options_model.max_shifts_per_month = 13
     rota_2workers.build_and_solve()
     assert rota_2workers.results.solver.status in ("warning", "error")
     assert rota_2workers.results.solver.termination_condition == "infeasible"
 
 def test_max_shifts_extra_worker(rota_3workers):
-    rota_3workers.constraint_options["max_shifts_per_month"] = 12
+    rota_3workers.constraint_options_model.max_shifts_per_month = 12
     rota_3workers.build_and_solve()
     assert rota_3workers.results.solver.status == "ok"
     assert rota_3workers.results.solver.termination_condition == "optimal"
 
 def test_max_shifts_per_week_fail(rota_2workers):
-    rota_2workers.constraint_options["max_shifts_per_week"] = 3
+    rota_2workers.constraint_options_model.max_shifts_per_week = 3
     rota_2workers.build_and_solve()
     assert rota_2workers.results.solver.status in ("warning", "error")
     assert rota_2workers.results.solver.termination_condition == "infeasible"
 
 def test_max_shifts_per_week_pass(rota_2workers):
-    rota_2workers.constraint_options["max_shifts_per_month"] = 14
-    rota_2workers.constraint_options["max_shifts_per_week"] = 4
+    rota_2workers.constraint_options_model.max_shifts_per_month = 14
+    rota_2workers.constraint_options_model.max_shifts_per_week = 4
     rota_2workers.build_and_solve()
     assert rota_2workers.results.solver.status == "ok"
 
 def test_max_shifts_per_week_extra_worker_pass(rota_3workers):
-    rota_3workers.constraint_options["max_shifts_per_week"] = 3
+    rota_3workers.constraint_options_model.max_shifts_per_week = 3
     rota_3workers.build_and_solve()
     assert rota_3workers.results.solver.status == "ok"
\ No newline at end of file
diff --git a/test/test_weekend_padding.py b/test/test_weekend_padding.py
index 95e2800..572fbde 100644
--- a/test/test_weekend_padding.py
+++ b/test/test_weekend_padding.py
@@ -20,7 +20,7 @@ class TestDemoRota:
             start_date,
             weeks_to_rota=weeks_to_rota,
         )
-        self.Rota.constraint_options["balance_weekends"] = True
+        self.Rota.constraint_options_model.balance_weekends = True
 
         # Add a few workers
         worker1 = Worker(name="worker1", site="group1", grade=1)
@@ -77,7 +77,7 @@ class TestDemoRota:
             start_date,
             weeks_to_rota=weeks_to_rota,
         )
-        self.Rota.constraint_options["balance_weekends"] = True
+        self.Rota.constraint_options_model.balance_weekends = True
 
         # Add a few workers
         worker1 = Worker(name="worker1", site="group1", grade=1)
@@ -136,7 +136,7 @@ class TestDemoRota:
             start_date,
             weeks_to_rota=weeks_to_rota,
         )
-        self.Rota.constraint_options["prevent_monday_and_tuesday_after_full_weekends"] = ["group1",]
+        self.Rota.constraint_options_model.prevent_monday_and_tuesday_after_full_weekends = ["group1",]
 
         # Add a few workers
         worker1 = Worker(name="worker1", site="group1", grade=1)
@@ -182,7 +182,7 @@ class TestDemoRota:
             start_date,
             weeks_to_rota=weeks_to_rota,
         )
-        self.Rota.constraint_options["prevent_monday_and_tuesday_after_full_weekends"] = ["group1",]
+        self.Rota.constraint_options_model.prevent_monday_and_tuesday_after_full_weekends = ["group1",]
 
         # Add a few workers
         worker1 = Worker(name="worker1", site="group1", grade=1)
@@ -221,7 +221,7 @@ class TestDemoRota:
             start_date,
             weeks_to_rota=weeks_to_rota,
         )
-        self.Rota.constraint_options["prevent_monday_after_full_weekends"] = ["group1",]
+        self.Rota.constraint_options_model.prevent_monday_after_full_weekends = ["group1",]
 
         # Add a few workers
         worker1 = Worker(name="worker1", site="group1", grade=1)
@@ -271,7 +271,7 @@ class TestDemoRota:
             start_date,
             weeks_to_rota=weeks_to_rota,
         )
-        self.Rota.constraint_options["prevent_monday_after_full_weekends"] = ["group1",]
+        self.Rota.constraint_options_model.prevent_monday_after_full_weekends = ["group1",]
 
         # Add a few workers
         worker1 = Worker(name="worker1", site="group1", grade=1)
@@ -312,7 +312,7 @@ class TestDemoRota:
             start_date,
             weeks_to_rota=weeks_to_rota,
         )
-        self.Rota.constraint_options["prevent_monday_after_full_weekends"] = ["group1",]
+        self.Rota.constraint_options_model.prevent_monday_after_full_weekends = ["group1",]
 
         # Add a few workers
         worker1 = Worker(name="worker1", site="group1", grade=1)
diff --git a/test/test_worker_requests.py b/test/test_worker_requests.py
index 38b96e3..b4354d6 100644
--- a/test/test_worker_requests.py
+++ b/test/test_worker_requests.py
@@ -224,7 +224,7 @@ class TestWorkerRequests:
         """_summary_"""
         Rota = generate_basic_rota()
 
-        Rota.constraint_options["balance_bank_holidays"] = False
+        Rota.constraint_options_model.balance_bank_holidays = False
 
         Rota.add_worker(
             Worker(
@@ -311,7 +311,7 @@ class TestWorkerRequests:
     def test_work_requests(self):
         """_summary_"""
         Rota = generate_basic_rota()
-        Rota.constraint_options["balance_bank_holidays"] = False
+        Rota.constraint_options_model.balance_bank_holidays = False
 
         Rota.add_workers(
             [Worker(
@@ -362,7 +362,7 @@ class TestWorkerRequests:
     def test_work_requests_invalid(self):
         """_summary_"""
         Rota = generate_basic_rota()
-        Rota.constraint_options["balance_bank_holidays"] = False
+        Rota.constraint_options_model.balance_bank_holidays = False
 
         Rota.add_worker(
             Worker(
@@ -433,7 +433,7 @@ class TestWorkerRequests:
     def test_work_requests_generic(self):
         """_summary_"""
         Rota = generate_basic_rota()
-        Rota.constraint_options["balance_bank_holidays"] = False
+        Rota.constraint_options_model.balance_bank_holidays = False
 
         Rota.add_workers(
             [Worker(
@@ -484,7 +484,7 @@ class TestWorkerRequests:
     def test_work_requests_generic2(self):
         """_summary_"""
         Rota = generate_basic_rota()
-        Rota.constraint_options["balance_bank_holidays"] = False
+        Rota.constraint_options_model.balance_bank_holidays = False
 
         Rota.add_workers(
             [Worker(
diff --git a/test/test_workers.py b/test/test_workers.py
index d8b31d3..d7029a2 100644
--- a/test/test_workers.py
+++ b/test/test_workers.py
@@ -4,7 +4,7 @@ from rota_generator.shifts import InvalidShift, MaxShiftsPerWeekConstraint, NoWo
 import datetime
 from rota_generator.workers import NonWorkingDays, NotAvailableToWork, Worker, generate_not_available_to_works
 from rota_generator.workers import WorkRequests
-from web.rota.shifts import PreShiftConstraint
+from rota_generator.shifts import PreShiftConstraint
 
 def generate_basic_rota(
     weeks_to_rota=10, workers=0, start_date=datetime.date(2022, 3, 7)
@@ -357,7 +357,7 @@ def test_worker_pairs():
         ]
     )
 
-    Rota.constraint_options["hard_constrain_pair_separation"] = True
+    Rota.constraint_options_model.hard_constrain_pair_separation = True
 
     Rota.build_and_solve()