Quantize manual rod steps to 0.025

tests/test_control.py

@@ -0,0 +1,40 @@
+import pytest
+
+from reactor_sim.control import ControlSystem
+from reactor_sim import constants
+from reactor_sim.state import CoreState
+
+
+def _core_state() -> CoreState:
+    return CoreState(
+        fuel_temperature=300.0,
+        neutron_flux=1e5,
+        reactivity_margin=0.0,
+        power_output_mw=0.0,
+        burnup=0.0,
+    )
+
+
+def test_manual_rods_quantized_to_step():
+    control = ControlSystem()
+    control.manual_control = True
+    core = _core_state()
+
+    control.set_rods(0.333)
+    assert control.rod_target == 0.325
+    control.update_rods(core, dt=100.0)
+    assert control.rod_fraction == pytest.approx(0.325, rel=1e-6)
+
+    control.increment_rods(0.014)
+    assert control.rod_target == pytest.approx(0.35)
+    control.update_rods(core, dt=100.0)
+    assert control.rod_fraction == pytest.approx(0.35, rel=1e-6)
+
+    # Clamp upper bound
+    control.set_rods(1.0)
+    control.update_rods(core, dt=100.0)
+    assert control.rod_fraction == 0.95
+
+
+def test_dashboard_step_constant_exposed():
+    assert constants.ROD_MANUAL_STEP == 0.025