P6-b design 2: the Robin wall on the patch's Inner side — RobinWall { alpha, datum } with the wall velocity u_s + (t_f − datum)/α (explicit, damped by the wall's own viscous gain μ/(α d)) and the compliant-wall pressure term |S| p'/α implicit in the projection (the added-mass operator in the fluid's own response); Dirichlet bit for bit when off; MMS pin on the skewed annulus (orders 2.46/2.13 at α = 10 and 100 μ/h, the Dirichlet values; a 1e12 wall reproduces Dirichlet to 2e-6); OversetPisoSolver::patch_mut; harness knob RTX_FSI2O_ROBIN_ALPHA with the previous pass's tractions as the datum, printed in the header

Co-Authored-By: Claude Fable 5.1 <[email protected]>
Claude-Session: https://claude.ai/code/session_01YJPeT6WA2e7YvAnS875AHL

crates/specialized/rtx-cfd/src/solvers/incompressible/embedded_body.rs

@@ -322,7 +322,11 @@ pub fn polygon_signed_distance(vertices: &[(f64, f64)], x: f64, y: f64) -> f64 {
         }
     }
     let dist = dist2.sqrt();
-    if inside { -dist } else { dist }
+    if inside {
+        -dist
+    } else {
+        dist
+    }
 }
 
 /// Velocity of the point on a closed polygon nearest to `(x, y)`, where