embedded3: cut predictor convection carries ρ (host + e3_cut.cu; density-scaling pin); operator load route includes the wall exchange (exchange.rs); reconstructed_parts, probe aperture floor knob; dfg_split diagnostic test

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

crates/specialized/rtx-cfd/tests/embedded3_dfg_2z.rs

@@ -201,6 +201,23 @@ fn dfg_3d_2z_on_the_device() {
         println!("  instant written to {}", path.display());
     }
     let (cd, cl, cd_cv, cl_cv, dp) = last.expect("samples");
+    {
+        // S2-1 diagnosis: each wall route split into its pressure and shear parts.
+        let body = solver.body().expect("body");
+        let (po, so) = mask
+            .cut_wall_force_parts(body, &field, RHO * NU, solver.time())
+            .expect("parts");
+        let (pr, sr) = mask
+            .cut_wall_force_reconstructed_parts(body, &field, RHO * NU, solver.time(), None)
+            .expect("parts");
+        println!(
+            "  SPLIT ny {ny}: operator c_D pressure {:.4} + shear {:.4}; reconstructed pressure {:.4} + shear {:.4}",
+            coef * po[0],
+            coef * so[0],
+            coef * pr[0],
+            coef * sr[0]
+        );
+    }
     println!(
         "  FINAL ny {ny}: c_D {cd:.4} (CV {cd_cv:.4}, routes {:.2e} apart; reconstructed {:.4}, {:.2e} from CV)  c_L {cl:.5} (CV {cl_cv:.5}, reconstructed {:.5})  Δp {dp:.4}  — reference c_D 6.05–6.25, c_L 0.008–0.010, Δp 0.165–0.175; {:.0} s",
         ((cd - cd_cv) / cd).abs(),