Replace Python numerical kernels with native C execution

tests/test_simulation_warmup.py

@@ -8,7 +8,6 @@ from unittest.mock import patch
 from app.main import _app_lifespan, app
 from app.simulation.warmup import (
     SimulationWarmupReport,
-    _run_numerical_warmup,
     _reset_simulation_warmup_for_tests,
     warm_up_simulation_runtime,
 )
@@ -17,6 +16,9 @@ from app.simulation.warmup import (
 class SimulationWarmupTests(unittest.TestCase):
     def setUp(self) -> None:
         _reset_simulation_warmup_for_tests()
+        self.engine_environment = patch.dict(os.environ, {"SIMULATION_NUMERIC_ENGINE": "native"})
+        self.engine_environment.start()
+        self.addCleanup(self.engine_environment.stop)
 
     def tearDown(self) -> None:
         _reset_simulation_warmup_for_tests()
@@ -24,7 +26,7 @@ class SimulationWarmupTests(unittest.TestCase):
     def test_warmup_runs_only_once_per_process(self) -> None:
         with (
             patch.dict(os.environ, {"SIMULATIONAPP_WARMUP": "on"}),
-            patch("app.simulation.warmup._run_numerical_warmup") as run_warmup,
+            patch("app.simulation.warmup._run_native_warmup") as run_warmup,
         ):
             first = warm_up_simulation_runtime()
             second = warm_up_simulation_runtime()
@@ -36,7 +38,7 @@ class SimulationWarmupTests(unittest.TestCase):
     def test_disabled_warmup_does_not_touch_numerical_runtime(self) -> None:
         with (
             patch.dict(os.environ, {"SIMULATIONAPP_WARMUP": "off"}),
-            patch("app.simulation.warmup._run_numerical_warmup") as run_warmup,
+            patch("app.simulation.warmup._run_native_warmup") as run_warmup,
         ):
             report = warm_up_simulation_runtime()
 
@@ -47,7 +49,7 @@ class SimulationWarmupTests(unittest.TestCase):
         with (
             patch.dict(os.environ, {"SIMULATIONAPP_WARMUP": "on"}),
             patch(
-                "app.simulation.warmup._run_numerical_warmup",
+                "app.simulation.warmup._run_native_warmup",
                 side_effect=RuntimeError("broken warmup"),
             ),
             self.assertLogs("app.simulation.warmup", level="ERROR"),
@@ -61,7 +63,7 @@ class SimulationWarmupTests(unittest.TestCase):
         with (
             patch.dict(os.environ, {"SIMULATIONAPP_WARMUP": "on"}),
             patch(
-                "app.simulation.warmup._run_numerical_warmup",
+                "app.simulation.warmup._run_native_warmup",
                 side_effect=MemoryError("out of memory"),
             ),
             self.assertRaises(MemoryError),
@@ -77,6 +79,7 @@ class SimulationWarmupTests(unittest.TestCase):
                 return_value=report,
             ) as warmup:
                 async with _app_lifespan(app):
+                    self.assertEqual(app.state.simulation_numeric_engine, "native")
                     self.assertEqual(
                         app.state.simulation_warmup,
                         report.as_dict(),
@@ -85,6 +88,31 @@ class SimulationWarmupTests(unittest.TestCase):
 
         asyncio.run(enter_lifespan())
 
+    def test_default_startup_checks_native_without_python_warmup(self) -> None:
+        with (
+            patch.dict(os.environ, {"SIMULATIONAPP_WARMUP": "on"}),
+            patch("app.simulation.warmup._run_native_warmup") as native,
+        ):
+            os.environ.pop("SIMULATION_NUMERIC_ENGINE", None)
+
+            async def enter_lifespan() -> None:
+                async with _app_lifespan(app):
+                    self.assertEqual(app.state.simulation_numeric_engine, "native")
+                    self.assertEqual(app.state.simulation_warmup["status"], "completed")
+
+            asyncio.run(enter_lifespan())
+        native.assert_called_once_with()
+
+    def test_native_failure_does_not_fall_back_to_python(self) -> None:
+        with (
+            patch.dict(os.environ, {"SIMULATION_NUMERIC_ENGINE": "native", "SIMULATIONAPP_WARMUP": "on"}),
+            patch("app.simulation.warmup._run_native_warmup", side_effect=RuntimeError("C compiler unavailable")),
+            self.assertLogs("app.simulation.warmup", level="ERROR"),
+        ):
+            report = warm_up_simulation_runtime()
+        self.assertEqual(report.status, "failed")
+        self.assertIn("C compiler unavailable", report.error or "")
+
     def test_real_numerical_warmup_completes(self) -> None:
         with patch.dict(os.environ, {"SIMULATIONAPP_WARMUP": "on"}):
             report = warm_up_simulation_runtime()
@@ -92,29 +120,6 @@ class SimulationWarmupTests(unittest.TestCase):
         self.assertEqual(report.status, "completed", report.error)
         self.assertGreater(report.duration_ms, 0.0)
 
-    def test_numerical_warmup_exercises_sparse_lsmr_algebraic_path(self) -> None:
-        import scipy.optimize
-
-        actual_least_squares = scipy.optimize.least_squares
-        optimizer_calls: list[dict[str, object]] = []
-
-        def recording_least_squares(*args, **kwargs):
-            optimizer_calls.append(dict(kwargs))
-            return actual_least_squares(*args, **kwargs)
-
-        with patch.object(
-            scipy.optimize,
-            "least_squares",
-            recording_least_squares,
-        ):
-            _run_numerical_warmup()
-
-        self.assertEqual(len(optimizer_calls), 1)
-        call = optimizer_calls[0]
-        self.assertEqual(call["tr_solver"], "lsmr")
-        sparsity = call["jac_sparsity"]
-        self.assertEqual(sparsity.shape, (2, 2))
-        self.assertEqual(sparsity.nnz, 2)
 
 
 if __name__ == "__main__":