fix: align mechanical dynamic port validation

app/simulation/systems/network.py

@@ -96,8 +96,8 @@ class SimulationNetwork:
                 f"Cannot connect component {endpoint_a.component} to itself."
             )
 
-        first_port = self._port_for(endpoint_a)
-        second_port = self._port_for(endpoint_b)
+        first_port = self._active_port_for(endpoint_a)
+        second_port = self._active_port_for(endpoint_b)
         first_definition = first_port.definition
         second_definition = second_port.definition
         if first_definition is None or second_definition is None:
@@ -168,6 +168,20 @@ class SimulationNetwork:
             raise ValueError(f"Unknown component: {endpoint.component}.") from exc
         return component.get_port(endpoint.port)
 
+    def _active_port_for(self, endpoint: Endpoint) -> PortState:
+        try:
+            component = self.components[endpoint.component]
+        except KeyError as exc:
+            raise ValueError(f"Unknown component: {endpoint.component}.") from exc
+        active_names = {
+            definition.name for definition in component.active_port_definitions
+        }
+        if endpoint.port not in active_names:
+            raise ValueError(
+                f"Port {endpoint} is not active for the component's current parameters."
+            )
+        return component.get_port(endpoint.port)
+
     def connection_equation_residuals(self) -> tuple[EquationResidual, ...]:
         """Evaluate connector equations that have a direct scalar residual.