embedded3: GuessBasis re-export behind the cuda feature (the host-only build broke); A2 build: no convective exchange with prescribed faces (RTX_E3_EXCHANGE_CONVECTION=off, host + device bit 10, load route consistent)

Co-Authored-By: Claude Fable 5.1 <[email protected]>

crates/specialized/rtx-cfd/src/solvers/incompressible/embedded3/exchange.rs

@@ -191,7 +191,9 @@ impl Mask {
                                         scheme.face_correction(up2, un, u0)
                                     };
                                     let u_face = upwind(m_plus, u0, un) + delta;
-                                    convective[c] -= -rho * m_plus * (u_face - u0);
+                                    if !self.exchange_convection_off {
+                                        convective[c] -= -rho * m_plus * (u_face - u0);
+                                    }
                                     force[c] -=
                                         mu * cv.ap[d][1] * a_d * (un - u0) / solid_spacing(1.0);
                                 }
@@ -208,7 +210,9 @@ impl Mask {
                                         scheme.face_correction(up1, u0, ud)
                                     };
                                     let u_face = upwind(m_minus, ud, u0) + delta;
-                                    convective[c] -= rho * m_minus * (u_face - u0);
+                                    if !self.exchange_convection_off {
+                                        convective[c] -= rho * m_minus * (u_face - u0);
+                                    }
                                     force[c] -=
                                         mu * cv.ap[d][0] * a_d * (ud - u0) / solid_spacing(-1.0);
                                 }