diff --git a/Cargo.lock b/Cargo.lock
index 395e2d542..640d6be60 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -72,7 +72,7 @@ checksum = "366ffbaa4442f4684d91e2cd7c5ea7c4ed8add41959a31447066e279e432b618"
 [[package]]
 name = "acadrust"
 version = "0.4.1"
-source = "git+https://github.com/HakanSeven12/cadcodec.git?rev=0908da7#0908da7b6e4f702a6c78359a57f53e2b79cf39eb"
+source = "git+https://github.com/HakanSeven12/cadcodec.git?rev=8a92803#8a9280381d75a52ac5a35663449bdd44827e1463"
 dependencies = [
  "ahash 0.8.12",
  "anyhow",
@@ -878,7 +878,7 @@ checksum = "fc652a48c352aef3ea3aed32080501cf3ef6ed5da78602a020c991775b0aff04"
 [[package]]
 name = "cadkernel"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/cadkernel.git?rev=ebeb2ec#ebeb2ecc2d17d92c588b0fa8bbe3864b156bc71f"
+source = "git+https://github.com/HakanSeven12/cadkernel.git?rev=b1901dd#b1901dde3351fc4bbcdffbdcf7328a5dec4d28d3"
 dependencies = [
  "acadrust",
  "cavalier_contours",
diff --git a/Cargo.toml b/Cargo.toml
index 8cbeac47b..329787163 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -27,8 +27,8 @@ glam = { version = "0.33", features = ["bytemuck"] }
 rfd = "0.17"
 clap = { version = "4", features = ["derive"] }
 env_logger = "0.11"
-acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "0908da7", features = ["serde"] }
-cadkernel = { git = "https://github.com/HakanSeven12/cadkernel.git", rev = "ebeb2ec", features = ["acis", "offset"] }
+acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "8a92803", features = ["serde"] }
+cadkernel = { git = "https://github.com/HakanSeven12/cadkernel.git", rev = "b1901dd", features = ["acis", "offset"] }
 dwg-thumbnailer = { path = "crates/dwg-thumbnailer" }
 flate2 = "1"
 image = { version = "0.25", default-features = false, features = ["png", "jpeg", "bmp", "tiff"] }
diff --git a/crates/ocs_plugin_api/Cargo.toml b/crates/ocs_plugin_api/Cargo.toml
index 3d393aa20..dd65e80be 100644
--- a/crates/ocs_plugin_api/Cargo.toml
+++ b/crates/ocs_plugin_api/Cargo.toml
@@ -14,7 +14,7 @@ serde = { version = "1", features = ["derive"] }
 # Pulled in only by the `host` feature, which adds the `acadrust`-typed
 # `HostApi` runtime surface. The default crate stays dependency-free so engine
 # crates and external tooling can depend on the manifest/ribbon contract cheaply.
-acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "0908da7", optional = true, features = ["serde"] }
+acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "8a92803", optional = true, features = ["serde"] }
 
 # Runtime IPC and serialization (host feature only).
 interprocess = { version = "2", optional = true }
@@ -37,7 +37,7 @@ serde_json = "1"
 serde = { version = "1", features = ["derive"] }
 cargo-lock = "11"
 # acadrust is scanned at build time to generate the embedded type registry.
-acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "0908da7", features = ["serde"] }
+acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "8a92803", features = ["serde"] }
 
 [dev-dependencies]
 serde_json = "1"
diff --git a/crates/ocs_web_worker/Cargo.toml b/crates/ocs_web_worker/Cargo.toml
index 671ef9eae..e80e1d9bc 100644
--- a/crates/ocs_web_worker/Cargo.toml
+++ b/crates/ocs_web_worker/Cargo.toml
@@ -8,7 +8,7 @@ publish = false
 crate-type = ["cdylib"]
 
 [dependencies]
-acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "0908da7", features = ["serde"] }
+acadrust = { git = "https://github.com/HakanSeven12/cadcodec.git", rev = "8a92803", features = ["serde"] }
 bincode = "1.3"
 serde = { version = "1", features = ["derive"] }
 console_error_panic_hook = "0.1"
diff --git a/src/entities/solid.rs b/src/entities/solid.rs
index 89505d3cf..bb4972f51 100644
--- a/src/entities/solid.rs
+++ b/src/entities/solid.rs
@@ -1,28 +1,35 @@
-// SOLID entity — 2D filled quadrilateral (or triangle when p3 == p4).
-//
-// Wireframe: the 4 perimeter edges as RenderObject::Lines.
-// Filled:    two triangles on `fill_tris`, preserving the entity's full WCS
-//            plane both at top level and through block expansion. The scene
-//            keeps a separate 2-D HatchModel only for plot projection; screen
-//            rendering filters that flattened copy out.
-// Grips:     4 corner grip points.
+// SOLID geometry comes from the kernel; entity coordinates stay in WCS here.
 
 use acadrust::entities::Solid;
 use crate::t;
 
 use crate::command::EntityTransform;
-use crate::entities::common::{edit_prop as edit, ro_prop as ro, square_grip};
+use crate::entities::common::{edit_prop as edit, square_grip};
 use crate::entities::traits::{Grippable, PropertyEditable, Transformable, RenderConvertible};
 use crate::scene::convert::acad_to_render::{RenderEntity, RenderObject};
 use crate::scene::model::object::{GripApply, GripDef, PropSection};
 use crate::scene::model::wire_model::SnapHint;
 
-fn dvec3(v: &acadrust::types::Vector3) -> glam::DVec3 {
-    glam::DVec3::new(v.x, v.y, v.z)
+type Edge = ([f64; 3], [f64; 3]);
+
+struct SolidGeometry {
+    edges: Vec<Edge>,
+    fill_tris: Vec<[f64; 3]>,
+    extruded: bool,
+}
+
+fn normal_tuple(solid: &Solid) -> (f64, f64, f64) {
+    let normal = glam::DVec3::new(solid.normal.x, solid.normal.y, solid.normal.z)
+        .normalize_or(glam::DVec3::Z);
+    (normal.x, normal.y, normal.z)
+}
+
+fn dvec3(v: [f64; 3]) -> glam::DVec3 {
+    glam::DVec3::from_array(v)
 }
 
 pub(crate) fn wcs_corners(solid: &Solid) -> [[f64; 3]; 4] {
-    let n = (solid.normal.x, solid.normal.y, solid.normal.z);
+    let n = normal_tuple(solid);
     let w = |v: &acadrust::types::Vector3| {
         let (x, y, z) = crate::scene::view::transform::ocs_point_to_wcs((v.x, v.y, v.z), n);
         [x, y, z]
@@ -35,140 +42,244 @@ pub(crate) fn wcs_corners(solid: &Solid) -> [[f64; 3]; 4] {
     ]
 }
 
-/// Return a non-self-intersecting perimeter for either conventional DXF SOLID
-/// Z-order or older/perimeter-ordered data. Prefer DXF order when both are
-/// valid, but recover legacy solids whose 1-2-4-3 walk forms a bow-tie.
-pub(crate) fn perimeter_indices(corners: &[[f64; 3]; 4]) -> [usize; 4] {
-    let p = |index: usize| glam::DVec3::from_array(corners[index]);
-    let edge = p(1) - p(0);
-    let mut normal = edge.cross(p(2) - p(0));
-    if normal.length_squared() < 1.0e-20 {
-        normal = edge.cross(p(3) - p(0));
-    }
-    if normal.length_squared() < 1.0e-20 {
-        return [0, 1, 3, 2];
-    }
-    let orient = |a: usize, b: usize, c: usize| {
-        (p(b) - p(a)).cross(p(c) - p(a)).dot(normal)
+fn set_wcs_corner(solid: &mut Solid, index: usize, point: glam::DVec3) {
+    let n = normal_tuple(solid);
+    let (x, y, z) = crate::scene::view::transform::wcs_point_to_ocs(
+        (point.x, point.y, point.z),
+        n,
+    );
+    let corner = match index {
+        0 => &mut solid.first_corner,
+        1 => &mut solid.second_corner,
+        2 => &mut solid.third_corner,
+        3 => &mut solid.fourth_corner,
+        _ => return,
     };
-    let segments_cross = |a: usize, b: usize, c: usize, d: usize| {
-        let ab_c = orient(a, b, c);
-        let ab_d = orient(a, b, d);
-        let cd_a = orient(c, d, a);
-        let cd_b = orient(c, d, b);
-        ((ab_c > 0.0 && ab_d < 0.0) || (ab_c < 0.0 && ab_d > 0.0))
-            && ((cd_a > 0.0 && cd_b < 0.0) || (cd_a < 0.0 && cd_b > 0.0))
-    };
-    let order_crosses = |order: [usize; 4]| {
-        segments_cross(order[0], order[1], order[2], order[3])
-            || segments_cross(order[1], order[2], order[3], order[0])
-    };
-    let dxf = [0, 1, 3, 2];
-    let perimeter = [0, 1, 2, 3];
-    if order_crosses(dxf) && !order_crosses(perimeter) {
-        perimeter
+    corner.x = x;
+    corner.y = y;
+    corner.z = z;
+}
+
+fn push_edge(lines: &mut Vec<[f64; 3]>, start: [f64; 3], end: [f64; 3]) {
+    lines.extend([start, end, [f64::NAN; 3]]);
+}
+
+fn boundary(solid: &Solid) -> Vec<[f64; 3]> {
+    let corners = wcs_corners(solid);
+    if solid.is_triangle() {
+        vec![corners[0], corners[1], corners[2]]
     } else {
-        dxf
+        vec![corners[0], corners[1], corners[3], corners[2]]
     }
 }
 
+fn boundary_edges(points: &[[f64; 3]]) -> Vec<Edge> {
+    (0..points.len())
+        .map(|index| (points[index], points[(index + 1) % points.len()]))
+        .collect()
+}
+
+fn kernel_tolerance(points: &[[f64; 3]]) -> f64 {
+    cadkernel::space::coplanarity_tolerance(points).max(1.0e-12)
+}
+
+fn extrusion_body(
+    solid: &Solid,
+    base: &[[f64; 3]],
+    tolerance: f64,
+    profile_valid: bool,
+) -> Option<cadkernel::brep::Body> {
+    if solid.thickness.abs() <= 1.0e-10 || !profile_valid {
+        return None;
+    }
+    let normal = glam::DVec3::new(solid.normal.x, solid.normal.y, solid.normal.z)
+        .normalize_or(glam::DVec3::Z);
+    let origin = glam::DVec3::from_array(base[0]);
+    let axis = base
+        .iter()
+        .skip(1)
+        .map(|point| glam::DVec3::from_array(*point) - origin)
+        .find(|axis| axis.length() > tolerance)?;
+    let plane = cadkernel::space::Plane::orthonormal(
+        base[0],
+        axis.to_array(),
+        normal.to_array(),
+    )?;
+    if base
+        .iter()
+        .any(|point| !plane.contains(*point, tolerance))
+    {
+        return None;
+    }
+    let projected = base
+        .iter()
+        .map(|point| plane.project(*point))
+        .collect::<Option<Vec<_>>>()?;
+    let profile = (0..projected.len())
+        .map(|index| {
+            cadkernel::geom2d::Curve::Line(cadkernel::geom2d::Line {
+                start: projected[index],
+                end: projected[(index + 1) % projected.len()],
+            })
+        })
+        .collect::<Vec<_>>();
+    cadkernel::brep::extrude(
+        plane,
+        &profile,
+        (normal * solid.thickness).to_array(),
+    )
+}
+
+fn solid_geometry(solid: &Solid) -> Option<SolidGeometry> {
+    let base = boundary(solid);
+    let tolerance = kernel_tolerance(&base);
+    let fill_tris = cadkernel::space::polygon::triangulate(
+        &base,
+        cadkernel::geom2d::Tolerance::new(tolerance),
+    );
+    if solid.thickness.abs() <= 1.0e-10 {
+        return Some(SolidGeometry {
+            edges: boundary_edges(&base),
+            fill_tris,
+            extruded: false,
+        });
+    }
+    let Some(body) = extrusion_body(solid, &base, tolerance, !fill_tris.is_empty()) else {
+        return Some(SolidGeometry {
+            edges: boundary_edges(&base),
+            fill_tris: Vec::new(),
+            extruded: false,
+        });
+    };
+    let mesh = cadkernel::brep::mesh::tessellate(
+        &body,
+        cadkernel::brep::mesh::TessellationTolerance::new(
+            cadkernel::tessellation::DEFAULT_ANGLE,
+            tolerance,
+        ),
+    );
+    if !mesh.missing_faces.is_empty() || mesh.mesh.is_empty() {
+        return Some(SolidGeometry {
+            edges: boundary_edges(&base),
+            fill_tris: Vec::new(),
+            extruded: false,
+        });
+    }
+    let edges = mesh
+        .edges
+        .iter()
+        .flat_map(|edge| edge.positions.windows(2).map(|pair| (pair[0], pair[1])))
+        .collect();
+    let mut fill_tris = Vec::with_capacity(mesh.mesh.triangles.len() * 3);
+    for triangle in mesh.mesh.triangles {
+        fill_tris.extend(triangle.map(|index| mesh.mesh.positions[index]));
+    }
+    Some(SolidGeometry {
+        edges,
+        fill_tris,
+        extruded: true,
+    })
+}
+
+pub(crate) fn wcs_bounds(solid: &Solid) -> Option<cadkernel::brep::Aabb> {
+    let base = boundary(solid);
+    let tolerance = kernel_tolerance(&base);
+    let profile_valid = !cadkernel::space::polygon::triangulate(
+        &base,
+        cadkernel::geom2d::Tolerance::new(tolerance),
+    )
+    .is_empty();
+    extrusion_body(solid, &base, tolerance, profile_valid)
+        .and_then(|body| cadkernel::brep::body_bounds(&body))
+        .or_else(|| cadkernel::brep::Aabb::around(base))
+}
+
 impl RenderConvertible for Solid {
     fn to_render(&self, _document: &acadrust::CadDocument) -> Option<RenderEntity> {
-        // SOLID corners are OCS. Map them to WCS, then resolve either the DXF
-        // Z-order or legacy perimeter order before building edges and fill.
-        let corners = wcs_corners(self);
-        let order = perimeter_indices(&corners);
-        let [p0, p1, p2, p3] = order.map(|index| corners[index]);
-        let pts = vec![
-            p0,
-            p1,
-            [f64::NAN; 3],
-            p1,
-            p2,
-            [f64::NAN; 3],
-            p2,
-            p3,
-            [f64::NAN; 3],
-            p3,
-            p0,
-        ];
-
-        let dvp = |p: [f64; 3]| glam::DVec3::from_array(p);
-        let snap = corners
-            .iter()
-            .copied()
-            .map(|point| (dvp(point), SnapHint::Node))
-            .collect();
-
-        // Fill the resolved perimeter as two triangles. For a triangle the last
-        // two points coincide and the second triangle degenerates harmlessly.
-        let fill_tris = vec![p0, p1, p2, p0, p2, p3];
+        let geometry = solid_geometry(self)?;
+        let mut lines = Vec::new();
+        for &(start, end) in &geometry.edges {
+            push_edge(&mut lines, start, end);
+        }
+        let mut nodes = Vec::new();
+        for &(start, end) in &geometry.edges {
+            for point in [start, end] {
+                if !nodes.contains(&point) {
+                    nodes.push(point);
+                }
+            }
+        }
+        let mut snap = Vec::with_capacity(nodes.len() * 2 + geometry.edges.len());
+        for point in nodes {
+            snap.push((dvec3(point), SnapHint::Node));
+            snap.push((dvec3(point), SnapHint::Endpoint));
+        }
+        snap.extend(geometry.edges.iter().map(|(start, end)| {
+            ((dvec3(*start) + dvec3(*end)) * 0.5, SnapHint::Midpoint)
+        }));
+        let pick_tris = geometry
+            .extruded
+            .then(|| geometry.fill_tris.clone())
+            .unwrap_or_default();
 
         Some(RenderEntity {
-            pick_tris: Vec::new(),
-            object: RenderObject::Lines(pts),
+            pick_tris,
+            object: RenderObject::Lines(lines),
             snap_pts: snap,
             tangent_geoms: vec![],
-            key_vertices: corners.to_vec(),
-            fill_tris,
+            key_vertices: Vec::new(),
+            fill_tris: geometry.fill_tris,
         })
     }
 }
 
 impl Grippable for Solid {
     fn grips(&self) -> Vec<GripDef> {
+        let corners = wcs_corners(self);
         vec![
-            square_grip(0, dvec3(&self.first_corner)),
-            square_grip(1, dvec3(&self.second_corner)),
-            square_grip(2, dvec3(&self.third_corner)),
-            square_grip(3, dvec3(&self.fourth_corner)),
+            square_grip(0, dvec3(corners[0])),
+            square_grip(1, dvec3(corners[1])),
+            square_grip(2, dvec3(corners[2])),
+            square_grip(3, dvec3(corners[3])),
         ]
     }
 
     fn apply_grip(&mut self, grip_id: usize, apply: GripApply) {
-        let corner = match grip_id {
-            0 => &mut self.first_corner,
-            1 => &mut self.second_corner,
-            2 => &mut self.third_corner,
-            3 => &mut self.fourth_corner,
-            _ => return,
+        let Some(current) = wcs_corners(self).get(grip_id).copied() else {
+            return;
         };
-        match apply {
-            GripApply::Translate(d) => {
-                corner.x += d.x as f64;
-                corner.y += d.y as f64;
-                corner.z += d.z as f64;
-            }
-            GripApply::Absolute(p) => {
-                corner.x = p.x as f64;
-                corner.y = p.y as f64;
-                corner.z = p.z as f64;
-            }
-        }
+        let point = match apply {
+            GripApply::Translate(delta) => dvec3(current) + delta,
+            GripApply::Absolute(point) => point,
+        };
+        set_wcs_corner(self, grip_id, point);
     }
 }
 
 impl PropertyEditable for Solid {
     fn geometry_properties(&self, _text_style_names: &[String]) -> Vec<PropSection> {
-        // Elevation is the OCS Z shared by the planar corners (no dedicated
-        // field on the entity); reported from the first corner's Z.
+        let corners = wcs_corners(self);
         let elevation = self.first_corner.z;
         vec![PropSection {
             title: t!("Geometry").into_owned(),
             props: vec![
-                edit(t!("Point 1 X").as_ref(), "sl_p1x", self.first_corner.x),
-                edit(t!("Point 1 Y").as_ref(), "sl_p1y", self.first_corner.y),
-                edit(t!("Point 1 Z").as_ref(), "sl_p1z", self.first_corner.z),
-                edit(t!("Point 2 X").as_ref(), "sl_p2x", self.second_corner.x),
-                edit(t!("Point 2 Y").as_ref(), "sl_p2y", self.second_corner.y),
-                edit(t!("Point 2 Z").as_ref(), "sl_p2z", self.second_corner.z),
-                edit(t!("Point 3 X").as_ref(), "sl_p3x", self.third_corner.x),
-                edit(t!("Point 3 Y").as_ref(), "sl_p3y", self.third_corner.y),
-                edit(t!("Point 3 Z").as_ref(), "sl_p3z", self.third_corner.z),
-                edit(t!("Point 4 X").as_ref(), "sl_p4x", self.fourth_corner.x),
-                edit(t!("Point 4 Y").as_ref(), "sl_p4y", self.fourth_corner.y),
-                edit(t!("Point 4 Z").as_ref(), "sl_p4z", self.fourth_corner.z),
-                ro(t!("Elevation").as_ref(), "sl_elev", format!("{:.4}", elevation)),
+                edit(t!("Point 1 X").as_ref(), "sl_p1x", corners[0][0]),
+                edit(t!("Point 1 Y").as_ref(), "sl_p1y", corners[0][1]),
+                edit(t!("Point 1 Z").as_ref(), "sl_p1z", corners[0][2]),
+                edit(t!("Point 2 X").as_ref(), "sl_p2x", corners[1][0]),
+                edit(t!("Point 2 Y").as_ref(), "sl_p2y", corners[1][1]),
+                edit(t!("Point 2 Z").as_ref(), "sl_p2z", corners[1][2]),
+                edit(t!("Point 3 X").as_ref(), "sl_p3x", corners[2][0]),
+                edit(t!("Point 3 Y").as_ref(), "sl_p3y", corners[2][1]),
+                edit(t!("Point 3 Z").as_ref(), "sl_p3z", corners[2][2]),
+                edit(t!("Point 4 X").as_ref(), "sl_p4x", corners[3][0]),
+                edit(t!("Point 4 Y").as_ref(), "sl_p4y", corners[3][1]),
+                edit(t!("Point 4 Z").as_ref(), "sl_p4z", corners[3][2]),
+                edit(t!("Elevation").as_ref(), "sl_elev", elevation),
+                edit(t!("Thickness").as_ref(), "sl_thickness", self.thickness),
+                edit(t!("Normal X").as_ref(), "sl_normal_x", self.normal.x),
+                edit(t!("Normal Y").as_ref(), "sl_normal_y", self.normal.y),
+                edit(t!("Normal Z").as_ref(), "sl_normal_z", self.normal.z),
             ],
         }]
     }
@@ -177,19 +288,56 @@ impl PropertyEditable for Solid {
         let Ok(v) = value.trim().parse::<f64>() else {
             return;
         };
+        let point_field = match field {
+            "sl_p1x" => Some((0, 0)),
+            "sl_p1y" => Some((0, 1)),
+            "sl_p1z" => Some((0, 2)),
+            "sl_p2x" => Some((1, 0)),
+            "sl_p2y" => Some((1, 1)),
+            "sl_p2z" => Some((1, 2)),
+            "sl_p3x" => Some((2, 0)),
+            "sl_p3y" => Some((2, 1)),
+            "sl_p3z" => Some((2, 2)),
+            "sl_p4x" => Some((3, 0)),
+            "sl_p4y" => Some((3, 1)),
+            "sl_p4z" => Some((3, 2)),
+            _ => None,
+        };
+        if let Some((point_index, component)) = point_field {
+            let mut point = dvec3(wcs_corners(self)[point_index]);
+            point[component] = v;
+            set_wcs_corner(self, point_index, point);
+            return;
+        }
+
         match field {
-            "sl_p1x" => self.first_corner.x = v,
-            "sl_p1y" => self.first_corner.y = v,
-            "sl_p1z" => self.first_corner.z = v,
-            "sl_p2x" => self.second_corner.x = v,
-            "sl_p2y" => self.second_corner.y = v,
-            "sl_p2z" => self.second_corner.z = v,
-            "sl_p3x" => self.third_corner.x = v,
-            "sl_p3y" => self.third_corner.y = v,
-            "sl_p3z" => self.third_corner.z = v,
-            "sl_p4x" => self.fourth_corner.x = v,
-            "sl_p4y" => self.fourth_corner.y = v,
-            "sl_p4z" => self.fourth_corner.z = v,
+            "sl_elev" => {
+                let delta = v - self.first_corner.z;
+                self.first_corner.z += delta;
+                self.second_corner.z += delta;
+                self.third_corner.z += delta;
+                self.fourth_corner.z += delta;
+            }
+            "sl_thickness" => self.thickness = v,
+            "sl_normal_x" | "sl_normal_y" | "sl_normal_z" => {
+                let world = wcs_corners(self);
+                let mut normal = glam::DVec3::new(self.normal.x, self.normal.y, self.normal.z);
+                match field {
+                    "sl_normal_x" => normal.x = v,
+                    "sl_normal_y" => normal.y = v,
+                    "sl_normal_z" => normal.z = v,
+                    _ => {}
+                }
+                if normal.length_squared() > 1.0e-20 {
+                    normal = normal.normalize();
+                    self.normal.x = normal.x;
+                    self.normal.y = normal.y;
+                    self.normal.z = normal.z;
+                    for (index, point) in world.into_iter().enumerate() {
+                        set_wcs_corner(self, index, dvec3(point));
+                    }
+                }
+            }
             _ => {}
         }
     }
diff --git a/src/modules/draw/draw/solid2d.rs b/src/modules/draw/draw/solid2d.rs
index 8a8221bac..170b5b068 100644
--- a/src/modules/draw/draw/solid2d.rs
+++ b/src/modules/draw/draw/solid2d.rs
@@ -1,11 +1,10 @@
 // 2D solid tool — interactive command.
 //
-// Command: SOLID (reachable as SO / SOLID2D — the bare SOLID verb currently
-// toggles the shaded display) — pick three or four corner points and commit a
-// filled triangle or quadrilateral. Four points may be picked either around
-// the perimeter (the natural order shown by the rubber band) or in the
-// traditional Z pattern. The command normalizes both forms to the DXF corner
-// order before committing. Enter after the third point commits a triangle.
+// Command: SOLID (reachable as SO / SOLID2D) — pick three or four corner points
+// and commit a filled triangle or quadrilateral. Four-point input is preserved
+// in the entity's documented Z order; after a quadrilateral, its opposite edge
+// starts the next connected shape. Enter after the third point commits a
+// triangle.
 
 use acadrust::entities::Solid;
 use acadrust::types::Vector3;
@@ -49,42 +48,12 @@ impl Solid2dCommand {
         Vector3::new(p.x, p.y, p.z)
     }
 
-    /// True when walking the four points in pick order produces a bow-tie.
-    /// SOLID2D currently commits into the default world-XY OCS, so use that
-    /// same plane when deciding whether the last two points need swapping.
-    fn pick_order_crosses(points: &[DVec3]) -> bool {
-        if points.len() != 4 {
-            return false;
-        }
-        let orient = |a: DVec3, b: DVec3, c: DVec3| {
-            (b.x - a.x) * (c.y - a.y) - (b.y - a.y) * (c.x - a.x)
-        };
-        let crosses = |a: DVec3, b: DVec3, c: DVec3, d: DVec3| {
-            let ab_c = orient(a, b, c);
-            let ab_d = orient(a, b, d);
-            let cd_a = orient(c, d, a);
-            let cd_b = orient(c, d, b);
-            ((ab_c > 0.0 && ab_d < 0.0) || (ab_c < 0.0 && ab_d > 0.0))
-                && ((cd_a > 0.0 && cd_b < 0.0) || (cd_a < 0.0 && cd_b > 0.0))
-        };
-        crosses(points[0], points[1], points[2], points[3])
-            || crosses(points[1], points[2], points[3], points[0])
-    }
-
-    /// Convert either perimeter picks (1-2-3-4) or classic SOLID Z picks
-    /// (1-2-4-3 around the perimeter) into the entity's DXF Z order.
     fn solid_from_four_points(points: &[DVec3]) -> Solid {
-        let perimeter_order = !Self::pick_order_crosses(points);
-        let (third, fourth) = if perimeter_order {
-            (points[3], points[2])
-        } else {
-            (points[2], points[3])
-        };
         Solid::new(
             Self::v3(points[0]),
             Self::v3(points[1]),
-            Self::v3(third),
-            Self::v3(fourth),
+            Self::v3(points[2]),
+            Self::v3(points[3]),
         )
     }
 }
@@ -126,7 +95,10 @@ impl CadCommand for Solid2dCommand {
                 .map(|point| self.plane.to_local(*point))
                 .collect();
             let solid = Self::solid_from_four_points(&local);
-            CmdResult::CommitAndExit(self.plane.place_entity(EntityType::Solid(solid)))
+            let next_edge = [self.points[2], self.points[3]];
+            self.points.clear();
+            self.points.extend(next_edge);
+            CmdResult::CommitEntity(self.plane.place_entity(EntityType::Solid(solid)))
         } else {
             CmdResult::NeedPoint
         }
@@ -154,14 +126,22 @@ impl CadCommand for Solid2dCommand {
         if self.points.is_empty() {
             return None;
         }
-        // Outline the corners picked so far plus the cursor, closed back to the
-        // first point, as a rubber-band hint.
+        // Outline the exact Z-ordered boundary that would be committed. Do not
+        // reorder a crossing shape: point order is intentional geometry.
         let mut preview = self.points.clone();
         preview.push(pt);
-        if preview.len() == 4 && Self::pick_order_crosses(&preview) {
-            preview.swap(2, 3);
-        }
-        let mut pts: Vec<[f64; 3]> = preview.iter().map(|p| [p.x, p.y, p.z]).collect();
+        let display_order: Vec<usize> = if preview.len() == 4 {
+            vec![0, 1, 3, 2]
+        } else {
+            (0..preview.len()).collect()
+        };
+        let mut pts: Vec<[f64; 3]> = display_order
+            .iter()
+            .map(|index| {
+                let point = preview[*index];
+                [point.x, point.y, point.z]
+            })
+            .collect();
         pts.push([preview[0].x, preview[0].y, preview[0].z]);
         Some(WireModel::solid_f64(
             "rubber_band".to_string(),
diff --git a/src/scene/convert/tess.rs b/src/scene/convert/tess.rs
index fe3d3ca94..b0feb44a0 100644
--- a/src/scene/convert/tess.rs
+++ b/src/scene/convert/tess.rs
@@ -1704,12 +1704,25 @@ pub(crate) fn set_wire_aabb(w: &mut WireModel, entity_box: [f32; 4]) {
     w.aabb = out;
 }
 
+fn entity_bounds(e: &acadrust::EntityType) -> ([f64; 3], [f64; 3]) {
+    if let acadrust::EntityType::Solid(solid) = e {
+        if let Some(bounds) = crate::entities::solid::wcs_bounds(solid) {
+            return (bounds.min, bounds.max);
+        }
+    }
+    let bounds = e.as_entity().bounding_box();
+    (
+        [bounds.min.x, bounds.min.y, bounds.min.z],
+        [bounds.max.x, bounds.max.y, bounds.max.z],
+    )
+}
+
 pub(crate) fn entity_aabb(e: &acadrust::EntityType) -> [f32; 4] {
-    let bbox = e.as_entity().bounding_box();
-    let min_x = (bbox.min.x) as f32;
-    let min_y = (bbox.min.y) as f32;
-    let max_x = (bbox.max.x) as f32;
-    let max_y = (bbox.max.y) as f32;
+    let (min, max) = entity_bounds(e);
+    let min_x = min[0] as f32;
+    let min_y = min[1] as f32;
+    let max_x = max[0] as f32;
+    let max_y = max[1] as f32;
     // The all-zero box is bounding_box()'s Default — returned by entities with
     // no usable box (unimplemented) — so treat it as UNBOUNDED (never
     // pre-rejected). A genuinely zero-size box *away* from the origin (e.g. a
@@ -1727,8 +1740,8 @@ pub(crate) fn entity_aabb(e: &acadrust::EntityType) -> [f32; 4] {
 /// indexing uses this so changing `world_offset` doesn't invalidate
 /// the index.
 pub(crate) fn entity_world_aabb_f64(e: &acadrust::EntityType) -> Option<[f64; 4]> {
-    let bbox = e.as_entity().bounding_box();
-    let (xmin, ymin, xmax, ymax) = (bbox.min.x, bbox.min.y, bbox.max.x, bbox.max.y);
+    let (min, max) = entity_bounds(e);
+    let (xmin, ymin, xmax, ymax) = (min[0], min[1], max[0], max[1]);
     if xmin == xmax && ymin == ymax {
         return None;
     }
diff --git a/src/scene/convert/tessellate.rs b/src/scene/convert/tessellate.rs
index 619dd248c..1c4dfa837 100644
--- a/src/scene/convert/tessellate.rs
+++ b/src/scene/convert/tessellate.rs
@@ -1260,7 +1260,7 @@ pub fn tessellate(
                         | EntityType::PolyfaceMesh(_)
                         | EntityType::PolygonMesh(_)
                         | EntityType::Mesh(_)
-                );
+                ) || matches!(entity, EntityType::Solid(solid) if solid.thickness.abs() > 1.0e-10);
                 // Thickness walls ride on the wire that carries their edges, not
                 // on a wire of their own: they are pick geometry for that entity,
                 // and `fill_tris` below deliberately splits off into a fill-only
diff --git a/src/scene/entity.rs b/src/scene/entity.rs
index 160ee2345..6045e881b 100644
--- a/src/scene/entity.rs
+++ b/src/scene/entity.rs
@@ -2222,8 +2222,8 @@ impl Scene {
     }
 
     /// Build a solid-fill HatchModel for a DXF Solid entity.
-    /// Conventional DXF SOLID corners use Z-order; legacy entities may already
-    /// be in perimeter order. Use the same non-crossing resolver as wire fill.
+    /// SOLID corners use Z-order. Preserve it in the projected hatch as well so
+    /// intentionally crossing geometry is not silently rewritten.
     pub(super) fn solid_hatch_model(solid: &DxfSolid, color: [f32; 4]) -> HatchModel {
         // Keep the corners in f64 until the AABB centre is known, then store
         // each as a small f32 offset from it — same precision-preserving anchor
@@ -2231,7 +2231,7 @@ impl Scene {
         // to f32 costs ~0.06 units of resolution at UTM magnitudes (~1e6), so
         // the quad snapped to a grid and the fill drifted off its outline.
         let wcs = crate::entities::solid::wcs_corners(solid);
-        let order = crate::entities::solid::perimeter_indices(&wcs);
+        let order = [0, 1, 3, 2];
         let corners: [[f64; 2]; 4] = order.map(|index| [wcs[index][0], wcs[index][1]]);
         let mut min = [f64::INFINITY; 2];
         let mut max = [f64::NEG_INFINITY; 2];
diff --git a/src/scene/pipeline/face3d_gpu.rs b/src/scene/pipeline/face3d_gpu.rs
index afb58bc6d..929d83d73 100644
--- a/src/scene/pipeline/face3d_gpu.rs
+++ b/src/scene/pipeline/face3d_gpu.rs
@@ -22,6 +22,48 @@ use crate::scene::model::wire_model::WireModel;
 use iced::wgpu;
 use iced::wgpu::util::DeviceExt;
 
+pub(crate) fn planar_solid_faces_view(wire: &WireModel, view_dir: glam::Vec3) -> bool {
+    if !wire.fill_is_2d_solid || wire.fill_is_3d {
+        return true;
+    }
+    let view = view_dir.as_dvec3().normalize_or_zero();
+    let point = |index: usize| {
+        let high = wire.fill_tris[index];
+        let low = wire
+            .fill_tris_low
+            .get(index)
+            .copied()
+            .unwrap_or([0.0; 3]);
+        glam::DVec3::new(
+            high[0] as f64 + low[0] as f64,
+            high[1] as f64 + low[1] as f64,
+            high[2] as f64 + low[2] as f64,
+        )
+    };
+    (0..wire.fill_tris.len() / 3).any(|triangle| {
+        let first = point(triangle * 3);
+        let second = point(triangle * 3 + 1);
+        let third = point(triangle * 3 + 2);
+        let normal = (second - first).cross(third - first).normalize_or_zero();
+        normal.length_squared() > 0.0 && normal.dot(view).abs() >= 1.0 - 1.0e-5
+    })
+}
+
+pub(crate) fn planar_solid_visibility_key(
+    wires: &[WireModel],
+    view_dir: glam::Vec3,
+) -> u64 {
+    let mut key = 0xcbf29ce484222325_u64;
+    for wire in wires
+        .iter()
+        .filter(|wire| wire.fill_is_2d_solid && !wire.fill_is_3d)
+    {
+        key ^= planar_solid_faces_view(wire, view_dir) as u64;
+        key = key.wrapping_mul(0x100000001b3);
+    }
+    key
+}
+
 // ── Vertex layout ──────────────────────────────────────────────────────────
 
 #[repr(C)]
@@ -74,8 +116,8 @@ impl Face3DVertex {
 // ── GPU handle ─────────────────────────────────────────────────────────────
 
 /// One vertex buffer + draw count. Fill data is split into as many chunks
-/// as the device's `max_buffer_size` requires: a mesh-heavy DWG (e.g. a
-/// Navisworks import) can hold tens of millions of fill triangles, and at
+/// as the device's `max_buffer_size` requires: a mesh-heavy drawing can hold
+/// tens of millions of fill triangles, and at
 /// 44 B/vertex a single batched buffer blows past the default 256 MB limit
 /// once enough layers are thawed — wgpu then raises an uncaptured
 /// validation error and aborts the process (#358). Same scheme as the
@@ -149,6 +191,7 @@ impl Face3DGpu {
         all_wires: &[WireModel],
         keep_3d_mesh_fills: bool,
         show_2d_solid_fills: bool,
+        view_dir: glam::Vec3,
         depth_map: &rustc_hash::FxHashMap<u64, [f32; 2]>,
     ) -> Self {
         let depth_of =
@@ -200,6 +243,9 @@ impl Face3DGpu {
             if !show_2d_solid_fills && wire.fill_is_2d_solid {
                 continue;
             }
+            if !planar_solid_faces_view(wire, view_dir) {
+                continue;
+            }
             // A real 3-D surface fill (PolyfaceMesh / PolygonMesh) carries a
             // double-single low residual paired with `fill_tris` — it lives at
             // true world coordinates and must keep its real depth. 2-D fills
@@ -259,6 +305,7 @@ impl Face3DGpu {
             all_wires,
             keep_3d_mesh_fills,
             show_2d_solid_fills,
+            view_dir,
             depth_map,
         );
         Self {
@@ -275,6 +322,7 @@ fn upload_block_chunks(
     wires: &[WireModel],
     keep_3d_mesh_fills: bool,
     show_2d_solid_fills: bool,
+    view_dir: glam::Vec3,
     depth_map: &rustc_hash::FxHashMap<u64, [f32; 2]>,
 ) -> (Vec<BlockFace3DChunk>, Vec<BlockFace3DChunk>) {
     let mut slots = rustc_hash::FxHashMap::default();
@@ -285,6 +333,7 @@ fn upload_block_chunks(
         };
         if wire.fill_tris.is_empty()
             || (!show_2d_solid_fills && wire.fill_is_2d_solid)
+            || !planar_solid_faces_view(wire, view_dir)
             || (wire.fill_is_3d && !keep_3d_mesh_fills)
         {
             continue;
diff --git a/src/scene/pipeline/mod.rs b/src/scene/pipeline/mod.rs
index a5954b35c..b6013f888 100644
--- a/src/scene/pipeline/mod.rs
+++ b/src/scene/pipeline/mod.rs
@@ -312,12 +312,8 @@ pub struct Pipeline {
     /// a pick bumps only `selection_generation`, refreshing the overlay without
     /// touching the main wire buffers.
     pub cached_selection: (u64, u64),
-    /// `(wire_content_id, face3d_fill_active, show_2d_solid_fills)` the Face3D
-    /// edge/fill buffers were uploaded for. A stable content id avoids retaining
-    /// the resident wire Arc:
-    /// that Arc must stay uniquely owned by Scene so a small edit can splice it
-    /// in place instead of rebuilding the whole drawing.
-    pub cached_face3d_key: (u64, bool, bool),
+    /// Face upload key; keeps the resident wire Arc uniquely owned by Scene.
+    pub cached_face3d_key: (u64, bool, bool, u64),
     /// Handle → indices into the resident wire set, built once per wire upload
     /// (when `cached_wire_id` changes). Lets the selection/hover xray overlay
     /// gather just the highlighted entity's wires (`O(highlighted)`) instead of
@@ -2323,7 +2319,7 @@ impl Pipeline {
             cached_epoch: (u64::MAX, u64::MAX, u64::MAX),
             cached_wire_id: u64::MAX,
             cached_selection: (u64::MAX, u64::MAX),
-            cached_face3d_key: (u64::MAX, false, false),
+            cached_face3d_key: (u64::MAX, false, false, u64::MAX),
             wire_handle_index: std::sync::Arc::new(rustc_hash::FxHashMap::default()),
             render_sig: u64::MAX,
             skip_geometry: false,
@@ -3023,6 +3019,7 @@ impl Pipeline {
         all_wires: &[WireModel],
         wireframe_only: bool,
         show_2d_solid_fills: bool,
+        view_dir: glam::Vec3,
         depth_map: &rustc_hash::FxHashMap<u64, [f32; 2]>,
     ) {
         let perf_started = crate::perf::enabled().then(iced::time::Instant::now);
@@ -3056,6 +3053,7 @@ impl Pipeline {
                 all_wires,
                 keep_3d_mesh_fills,
                 show_2d_solid_fills,
+                view_dir,
                 depth_map,
             ));
         }
diff --git a/src/scene/view/render.rs b/src/scene/view/render.rs
index 55424b5fe..cb96d6ea9 100644
--- a/src/scene/view/render.rs
+++ b/src/scene/view/render.rs
@@ -378,7 +378,7 @@ impl shader::Primitive for Primitive {
                 inner.cached_wire_id = u64::MAX;
                 inner.cached_selection = (u64::MAX, u64::MAX);
                 inner.cached_mesh_content_id = u64::MAX;
-                inner.cached_face3d_key = (u64::MAX, false, false);
+                inner.cached_face3d_key = (u64::MAX, false, false, u64::MAX);
                 inner.cached_hatch_source = None;
                 inner.cached_preview_hatch_source = None;
                 inner.cached_wipeout_source = None;
@@ -484,6 +484,12 @@ impl shader::Primitive for Primitive {
             // the view toggle so 2D fills stay on even when the user picks
             // the Wireframe overlay style.
             let face3d_fill_active = fill_mode && !vp.view_wireframe;
+            let solid_fill_active = fill_mode && vp.show_2d_solid_fills;
+            let solid_visibility_key =
+                crate::scene::pipeline::face3d_gpu::planar_solid_visibility_key(
+                    &vp_wires,
+                    vp.view_dir,
+                );
             let fill_changed = inner.cached_fill_mode != fill_mode;
             let hatch_changed = inner
                 .cached_hatch_source
@@ -574,14 +580,16 @@ impl shader::Primitive for Primitive {
                     && !face_pass_unchanged);
             if face3d_changed
                 || face3d_fill_active != inner.cached_face3d_key.1
-                || vp.show_2d_solid_fills != inner.cached_face3d_key.2
+                || solid_fill_active != inner.cached_face3d_key.2
+                || solid_visibility_key != inner.cached_face3d_key.3
             {
                 inner.upload_face3d(
                     device,
                     &vp.face3d_wires[..],
                     &vp_wires[..],
                     !face3d_fill_active,
-                    vp.show_2d_solid_fills,
+                    solid_fill_active,
+                    vp.view_dir,
                     &draw_depths,
                 );
                 inner.cached_face3d_source = Some(Arc::clone(&vp.face3d_wires));
@@ -590,7 +598,8 @@ impl shader::Primitive for Primitive {
             inner.cached_face3d_key = (
                 vp.wire_content_id,
                 face3d_fill_active,
-                vp.show_2d_solid_fills,
+                solid_fill_active,
+                solid_visibility_key,
             );
             // Wire buffers are world-space, so a camera move alone doesn't
             // change them — only the view_proj uniform (uploaded every frame).