diff --git a/Cargo.lock b/Cargo.lock
index e60125ac4..c4d17a78c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -6,7 +6,7 @@ version = 4
 name = "OpenCADStudio"
 version = "0.9.4"
 dependencies = [
- "acadifc 0.5.0 (git+https://github.com/OpenAEC-Foundation/acadifc.git?rev=6059bae)",
+ "acadifc",
  "ashpd",
  "bincode",
  "bytemuck",
@@ -70,25 +70,11 @@ checksum = "366ffbaa4442f4684d91e2cd7c5ea7c4ed8add41959a31447066e279e432b618"
 [[package]]
 name = "acadifc"
 version = "0.5.0"
-source = "git+https://github.com/OpenAEC-Foundation/acadifc.git?rev=6059bae#6059baed781c6399d8259aa85c19be803ba95205"
+source = "git+https://github.com/OpenAEC-Foundation/acadifc.git?rev=c15cbf0#c15cbf0ac5c61202f1d9b1a5d344a03bb1e65871"
 dependencies = [
- "acadrust 0.4.1 (git+https://github.com/HakanSeven12/cadcodec.git?rev=36e841f)",
+ "acadrust",
  "base64",
- "cadkernel 0.1.0 (git+https://github.com/HakanSeven12/cadkernel.git?rev=6f34deb)",
- "serde",
- "serde_json",
- "sha2 0.10.9",
- "thiserror 1.0.69",
-]
-
-[[package]]
-name = "acadifc"
-version = "0.5.0"
-source = "git+https://github.com/OpenAEC-Foundation/acadifc.git?rev=c65d396#c65d396abc3defcf96b1d71a3f812c8ad993e77c"
-dependencies = [
- "acadrust 0.4.1 (git+https://github.com/HakanSeven12/cadcodec.git?rev=d645c7f)",
- "base64",
- "cadkernel 0.1.0 (git+https://github.com/HakanSeven12/cadkernel.git)",
+ "cadkernel",
  "serde",
  "serde_json",
  "sha2 0.10.9",
@@ -118,29 +104,6 @@ dependencies = [
  "web-time",
 ]
 
-[[package]]
-name = "acadrust"
-version = "0.4.1"
-source = "git+https://github.com/HakanSeven12/cadcodec.git?rev=d645c7f#d645c7f526c199c02fcab7272d6b6f2d1c6b91ae"
-dependencies = [
- "ahash 0.8.12",
- "anyhow",
- "bitflags 2.13.1",
- "byteorder",
- "encoding_rs",
- "flate2",
- "indexmap",
- "itoa",
- "memmap2",
- "nom 7.1.3",
- "once_cell",
- "rayon",
- "ryu",
- "serde",
- "thiserror 1.0.69",
- "web-time",
-]
-
 [[package]]
 name = "adler2"
 version = "2.0.1"
@@ -927,16 +890,11 @@ checksum = "fc652a48c352aef3ea3aed32080501cf3ef6ed5da78602a020c991775b0aff04"
 [[package]]
 name = "cadkernel"
 version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/cadkernel.git?rev=6f34deb#6f34deb57eedf0dc5908bf225917f19c9707682d"
+source = "git+https://github.com/HakanSeven12/cadkernel.git?rev=691c477#691c47756f30bb32fad2342afeec14d5985783ac"
 dependencies = [
  "cavalier_contours",
 ]
 
-[[package]]
-name = "cadkernel"
-version = "0.1.0"
-source = "git+https://github.com/HakanSeven12/cadkernel.git#860b9df7e5fc4a495334a6329560a4cde33659db"
-
 [[package]]
 name = "calloop"
 version = "0.13.0"
@@ -3788,7 +3746,7 @@ dependencies = [
 name = "ocs_plugin_api"
 version = "0.1.0"
 dependencies = [
- "acadifc 0.5.0 (git+https://github.com/OpenAEC-Foundation/acadifc.git?rev=6059bae)",
+ "acadifc",
  "bincode",
  "getrandom 0.2.17",
  "interprocess",
@@ -3803,7 +3761,7 @@ dependencies = [
 name = "ocs_web_worker"
 version = "0.1.0"
 dependencies = [
- "acadifc 0.5.0 (git+https://github.com/OpenAEC-Foundation/acadifc.git?rev=c65d396)",
+ "acadifc",
  "bincode",
  "console_error_panic_hook",
  "getrandom 0.3.4",
diff --git a/Cargo.toml b/Cargo.toml
index ef60849ea..d3382c904 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -30,7 +30,7 @@ env_logger = "0.11"
 # The CAD stack is reached through acadifc, which re-exports the codec and
 # the geometry kernel. Aliased to `acadrust` so existing `use acadrust::…`
 # paths keep resolving.
-acadrust = { package = "acadifc", git = "https://github.com/OpenAEC-Foundation/acadifc.git", rev = "6059bae", features = ["serde", "offset"] }
+acadrust = { package = "acadifc", git = "https://github.com/OpenAEC-Foundation/acadifc.git", rev = "c15cbf0", features = ["serde", "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 a2d3b544e..f58c08c7b 100644
--- a/crates/ocs_plugin_api/Cargo.toml
+++ b/crates/ocs_plugin_api/Cargo.toml
@@ -9,7 +9,7 @@ license = "GPL-3.0-only"
 # 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 = { package = "acadifc", git = "https://github.com/OpenAEC-Foundation/acadifc.git", rev = "6059bae", optional = true, features = ["serde"] }
+acadrust = { package = "acadifc", git = "https://github.com/OpenAEC-Foundation/acadifc.git", rev = "c15cbf0", optional = true, features = ["serde"] }
 
 # Runtime IPC and serialization (host feature only).
 interprocess = { version = "2", optional = true }
diff --git a/crates/ocs_web_worker/Cargo.toml b/crates/ocs_web_worker/Cargo.toml
index 03dda7e9f..7c366ab85 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 = { package = "acadifc", git = "https://github.com/OpenAEC-Foundation/acadifc.git", rev = "c65d396", features = ["serde"] }
+acadrust = { package = "acadifc", git = "https://github.com/OpenAEC-Foundation/acadifc.git", rev = "c15cbf0", features = ["serde"] }
 bincode = "1.3"
 console_error_panic_hook = "0.1"
 getrandom = { version = "0.3", features = ["wasm_js"] }
diff --git a/src/entities/common.rs b/src/entities/common.rs
index 1a7339c31..f17bbe8b2 100644
--- a/src/entities/common.rs
+++ b/src/entities/common.rs
@@ -670,14 +670,7 @@ pub(crate) fn thick_band_tube(
     (fill_tris, lines)
 }
 
-/// Build a continuous WCS point list + a per-point FULL band width for a
-/// tapered wide polyline, so the wire shader can interpolate each segment's two
-/// endpoint widths. Each `verts` entry is `(location_xy, bulge_to_next,
-/// start_width, end_width)` — the effective full widths at that vertex's segment
-/// start and end (already resolved against the polyline's constant width). Arcs
-/// are sampled in 16 steps with the width interpolated linearly along the arc.
-/// A shared vertex is emitted once (carrying the previous segment's end width),
-/// which is exact for the usual continuous taper.
+/// Build a continuous WCS point list and full width for a tapered polyline.
 pub(crate) fn tapered_band_points(
     verts: &[([f64; 2], f64, f64, f64)],
     is_closed: bool,
@@ -701,9 +694,10 @@ pub(crate) fn tapered_band_points(
         if bulge.abs() < 1e-9 {
             push(p1[0], p1[1], ew0 as f32);
         } else if let Some(arc) = BulgeArc::from_bulge(p0, p1, bulge) {
-            for j in 1..=16usize {
-                let t = j as f64 / 16.0;
-                let s = arc.sample(t);
+            let samples = arc.tessellate_angle(acadrust::kernel::tessellation::DEFAULT_ANGLE);
+            let segments = samples.len().saturating_sub(1).max(1);
+            for (index, s) in samples.into_iter().enumerate().skip(1) {
+                let t = index as f64 / segments as f64;
                 push(s[0], s[1], (sw0 + (ew0 - sw0) * t) as f32);
             }
         }
@@ -792,4 +786,3 @@ pub(crate) fn polyline_segment_fill(
         Some(boundary)
     }
 }
-
diff --git a/src/entities/curve.rs b/src/entities/curve.rs
index 7ae3801f3..ec3f877f5 100644
--- a/src/entities/curve.rs
+++ b/src/entities/curve.rs
@@ -331,53 +331,9 @@ pub fn entity_curve_xy(entity: &EntityType) -> Option<Curve> {
     })
 }
 
-/// World-space wire points for a curve, cut to the render pass's current
-/// chord tolerance.
-///
-/// The density comes from how far a chord may sag from the curve, not from a
-/// segment count: an arc a metre across and one a kilometre across need
-/// different numbers of points to look equally round, and the tolerance the
-/// render pass carries is already zoom-adaptive.
-///
-/// Everything stays `f64` to the end. The narrowing belongs at the GPU
-/// boundary, where the residual is kept as the low half of a double-single
-/// pair; casting local coordinates on the way in throws away precision the
-/// shader was built to reconstruct.
+/// World-space wire points sampled by the kernel's angular policy.
 pub fn curve_points(curve: &PlanarCurve) -> Vec<[f64; 3]> {
-    let tolerance = crate::scene::convert::curve_tol::curve_tol_for(curve_size(&curve.curve));
-    curve.tessellate_within(tolerance)
-}
-
-/// How big a curve is, for deciding how finely to sample it.
-///
-/// A radius where there is one, since that is what the chord-height relation
-/// is written in terms of. `0` for the kinds whose sampling density is not a
-/// question of curvature — a straight run needs its two ends and nothing in
-/// between — which leaves those on the frame's own tolerance.
-fn curve_size(curve: &Curve) -> f64 {
-    match curve {
-        Curve::Circle(circle) => circle.radius,
-        Curve::Arc(arc) => arc.radius,
-        Curve::Ellipse(arc) => arc.ellipse.major_radius,
-        // A polyline's bulges and a spline's bends are the same question asked
-        // of a chain, and its own extent is the nearest thing to a radius.
-        Curve::Polyline(_) | Curve::Nurbs(_) => {
-            let sampled = curve.tessellate(64.0);
-            let (mut low, mut high) = ([f64::INFINITY; 2], [f64::NEG_INFINITY; 2]);
-            for point in &sampled {
-                for axis in 0..2 {
-                    low[axis] = low[axis].min(point[axis]);
-                    high[axis] = high[axis].max(point[axis]);
-                }
-            }
-            if low[0] > high[0] {
-                0.0
-            } else {
-                (high[0] - low[0]).max(high[1] - low[1]) * 0.5
-            }
-        }
-        Curve::Line(_) | Curve::Ray(_) | Curve::XLine(_) => 0.0,
-    }
+    curve.tessellate_angle(acadrust::kernel::tessellation::DEFAULT_ANGLE)
 }
 
 /// The snap candidates an entity's curve offers, in the two channels the
diff --git a/src/entities/ellipse.rs b/src/entities/ellipse.rs
index aca22680d..36016e359 100644
--- a/src/entities/ellipse.rs
+++ b/src/entities/ellipse.rs
@@ -24,11 +24,7 @@ fn to_render(ell: &Ellipse) -> RenderEntity {
         .map(crate::entities::curve::snap_from)
         .unwrap_or_default();
 
-    // The points come from the entity's own curve, cut to the render pass's
-    // chord tolerance. The two fixed counts this replaced — sixteen per half
-    // for a full ellipse, thirty-two for an arc — faceted visibly on
-    // anything large, and the local coordinates were built in `f32`, which
-    // threw away precision the double-single vertex path exists to keep.
+    // The points come from the entity's own kernel curve and angular policy.
     //
     // What does not change is the shape of the object. EXTRUDE, REVOLVE and
     // SWEEP read their profile out of `Contour` / `Curve` and have no arm for
diff --git a/src/entities/hatch.rs b/src/entities/hatch.rs
index 022fc3f9c..b53513dd2 100644
--- a/src/entities/hatch.rs
+++ b/src/entities/hatch.rs
@@ -11,7 +11,7 @@ use crate::command::EntityTransform;
 use crate::entities::common::{center_grip, circle_grip, edit_angle_prop as edit_angle, edit_prop as edit, parse_f64, ro_prop as ro};
 use crate::entities::traits::{FallbackTess, Grippable, PropertyEditable, Transformable};
 use crate::scene::model::object::{GripApply, GripDef, PropSection, PropValue, Property};
-use crate::scene::convert::tess_util::{arc_segments, arc_signed_span, wire_chord_tol, FallbackGeometry};
+use crate::scene::convert::tess_util::FallbackGeometry;
 use crate::scene::model::wire_model::SnapHint;
 
 /// The area the hatch's boundary paths enclose.
@@ -49,19 +49,20 @@ fn boundary_area(h: &Hatch) -> f64 {
 }
 
 /// A hatch boundary edge as a kernel curve, in the hatch's own OCS.
-fn edge_curve(edge: &BoundaryEdge) -> Option<KernelCurve> {
+pub(crate) fn edge_curve(edge: &BoundaryEdge) -> Option<KernelCurve> {
     Some(match edge {
         BoundaryEdge::Line(l) => KernelCurve::Line(KernelLine {
             start: [l.start.x, l.start.y],
             end: [l.end.x, l.end.y],
         }),
         BoundaryEdge::CircularArc(a) => {
-            // A clockwise edge is the same arc walked the other way, so the
-            // stored angles swap rather than the sweep going negative.
             let (start, end) = if a.counter_clockwise {
                 (a.start_angle, a.end_angle)
             } else {
-                (a.end_angle, a.start_angle)
+                (
+                    std::f64::consts::TAU - a.end_angle,
+                    std::f64::consts::TAU - a.start_angle,
+                )
             };
             KernelCurve::Arc(KernelArc {
                 centre: [a.center.x, a.center.y],
@@ -79,7 +80,10 @@ fn edge_curve(edge: &BoundaryEdge) -> Option<KernelCurve> {
             let (start, end) = if e.counter_clockwise {
                 (e.start_angle, e.end_angle)
             } else {
-                (e.end_angle, e.start_angle)
+                (
+                    std::f64::consts::TAU - e.end_angle,
+                    std::f64::consts::TAU - e.start_angle,
+                )
             };
             KernelCurve::Ellipse(KernelEllipseArc {
                 ellipse: KernelEllipse {
@@ -991,146 +995,41 @@ impl FallbackTess for Hatch {
         let mut snap_pts: Vec<(Vec3, SnapHint)> = Vec::new();
         for path in &self.paths {
             for edge in &path.edges {
+                let Some(curve) = edge_curve(edge) else {
+                    continue;
+                };
+                let local = curve
+                    .tessellate_angle(acadrust::kernel::tessellation::DEFAULT_ANGLE);
+                if local.len() < 2 {
+                    continue;
+                }
+                if !pts.is_empty() {
+                    pts.push([f64::NAN; 3]);
+                }
+                let world: Vec<[f64; 3]> = local
+                    .into_iter()
+                    .map(|point| to_wcs(point[0], point[1]))
+                    .collect();
                 match edge {
-                    BoundaryEdge::Polyline(poly) => {
-                        // Hatch-boundary polyline vertices encode bulge in
-                        // `Vector3.z`; straight segments emit just the
-                        // start vertex, bulged segments tessellate the arc
-                        // between v0 → v1.
-                        let verts = &poly.vertices;
-                        let count = verts.len();
-                        if count == 0 {
-                            continue;
-                        }
-                        // Break the wire between this polyline and whatever
-                        // preceded it — without the separator the renderer
-                        // draws a ghost segment from the previous edge / path
-                        // straight to this polyline's first vertex, which
-                        // shows up as a stray boundary line between hatch
-                        // regions.
-                        if !pts.is_empty() {
-                            pts.push([f64::NAN; 3]);
-                        }
-                        let start_idx = pts.len();
-                        let seg_count = if poly.is_closed {
-                            count
-                        } else {
-                            count.saturating_sub(1)
-                        };
-                        for i in 0..seg_count {
-                            let v0 = &verts[i];
-                            let v1 = &verts[(i + 1) % count];
-                            let bulge = v0.z;
-                            let arc = if bulge.abs() < 1e-9 {
-                                None
-                            } else {
-                                crate::entities::common::BulgeArc::from_bulge(
-                                    [v0.x, v0.y],
-                                    [v1.x, v1.y],
-                                    bulge,
-                                )
-                            };
-                            let Some(arc) = arc else {
-                                let p = to_wcs(v0.x, v0.y);
-                                pts.push(p);
-                                key_verts.push(p);
-                                continue;
-                            };
-                            let segs = arc_segments(
-                                arc.radius,
-                                arc.sweep.abs(),
-                                wire_chord_tol(arc.radius),
-                            );
-                            for j in 0..segs {
-                                let s = arc.sample(j as f64 / segs as f64);
-                                let p = to_wcs(s[0], s[1]);
-                                pts.push(p);
-                                if j == 0 {
-                                    key_verts.push(p);
-                                }
-                            }
-                        }
-                        // Close the loop visually for closed polylines by
-                        // returning to the first emitted point.
-                        if poly.is_closed {
-                            if let Some(first) = pts.get(start_idx).cloned() {
-                                if first[0].is_finite() {
-                                    pts.push(first);
-                                }
-                            }
-                        } else if let Some(last) = verts.last() {
-                            let p = to_wcs(last.x, last.y);
-                            pts.push(p);
-                            key_verts.push(p);
-                        }
-                    }
-                    BoundaryEdge::Line(ln) => {
-                        let p0 = to_wcs(ln.start.x, ln.start.y);
-                        let p1 = to_wcs(ln.end.x, ln.end.y);
-                        if !pts.is_empty() {
-                            pts.push([f64::NAN; 3]);
-                        }
-                        pts.push(p0);
-                        pts.push(p1);
-                        key_verts.push(p0);
-                        key_verts.push(p1);
-                    }
-                    BoundaryEdge::CircularArc(arc) => {
-                        let (sa, span) =
-                            arc_signed_span(arc.start_angle, arc.end_angle, arc.counter_clockwise);
-                        let segs = arc_segments(arc.radius, span.abs(), wire_chord_tol(arc.radius));
-                        if !pts.is_empty() {
-                            pts.push([f64::NAN; 3]);
-                        }
-                        for i in 0..=segs {
-                            let t = sa + span * (i as f64 / segs as f64);
-                            let p = to_wcs(
-                                arc.center.x + arc.radius * t.cos(),
-                                arc.center.y + arc.radius * t.sin(),
-                            );
-                            pts.push(p);
-                            if i == 0 || i == segs {
-                                key_verts.push(p);
-                            }
-                        }
-                        snap_pts.push((
-                            snap_at(to_wcs(arc.center.x, arc.center.y)),
-                            SnapHint::Center,
-                        ));
-                    }
-                    BoundaryEdge::EllipticArc(ell) => {
-                        let r_maj = (ell.major_axis_endpoint.x * ell.major_axis_endpoint.x
-                            + ell.major_axis_endpoint.y * ell.major_axis_endpoint.y)
-                            .sqrt();
-                        let r_min = r_maj * ell.minor_axis_ratio;
-                        let rot = ell.major_axis_endpoint.y.atan2(ell.major_axis_endpoint.x);
-                        let (sa, span) =
-                            arc_signed_span(ell.start_angle, ell.end_angle, ell.counter_clockwise);
-                        let segs = arc_segments(r_maj, span.abs(), wire_chord_tol(r_maj));
-                        if !pts.is_empty() {
-                            pts.push([f64::NAN; 3]);
-                        }
-                        let (cr, sr) = (rot.cos(), rot.sin());
-                        for i in 0..=segs {
-                            let t = sa + span * (i as f64 / segs as f64);
-                            let lx = r_maj * t.cos();
-                            let ly = r_min * t.sin();
-                            let p = to_wcs(
-                                ell.center.x + lx * cr - ly * sr,
-                                ell.center.y + lx * sr + ly * cr,
-                            );
-                            pts.push(p);
-                            if i == 0 || i == segs {
-                                key_verts.push(p);
-                            }
-                        }
-                        snap_pts.push((
-                            snap_at(to_wcs(ell.center.x, ell.center.y)),
-                            SnapHint::Center,
-                        ));
-                    }
+                    BoundaryEdge::Polyline(poly) => key_verts.extend(
+                        poly.vertices
+                            .iter()
+                            .map(|point| to_wcs(point.x, point.y)),
+                    ),
+                    _ => key_verts.extend([world[0], *world.last().unwrap()]),
+                }
+                match edge {
+                    BoundaryEdge::CircularArc(arc) => snap_pts.push((
+                        snap_at(to_wcs(arc.center.x, arc.center.y)),
+                        SnapHint::Center,
+                    )),
+                    BoundaryEdge::EllipticArc(ellipse) => snap_pts.push((
+                        snap_at(to_wcs(ellipse.center.x, ellipse.center.y)),
+                        SnapHint::Center,
+                    )),
                     _ => {}
                 }
+                pts.extend(world);
             }
         }
         if pts.is_empty() {
diff --git a/src/entities/lwpolyline.rs b/src/entities/lwpolyline.rs
index f3c1e12ed..be0d5664e 100644
--- a/src/entities/lwpolyline.rs
+++ b/src/entities/lwpolyline.rs
@@ -308,8 +308,11 @@ fn to_render(pline: &LwPolyline) -> RenderEntity {
                     center: [wcx as f32, wcy as f32, wcz as f32],
                     radius: arc.radius as f32,
                 });
-                for j in 1..=16usize {
-                    let s = arc.sample(j as f64 / 16.0);
+                for s in arc
+                    .tessellate_angle(acadrust::kernel::tessellation::DEFAULT_ANGLE)
+                    .into_iter()
+                    .skip(1)
+                {
                     let (wx, wy, wz) = to_wcs(s[0], s[1]);
                     path.push([wx, wy, wz]);
                 }
@@ -406,8 +409,11 @@ fn to_render(pline: &LwPolyline) -> RenderEntity {
             } else if let Some(arc) =
                 crate::entities::common::BulgeArc::from_bulge([ox0, oy0], [ox1, oy1], bulge)
             {
-                for j in 1..=16usize {
-                    let s = arc.sample(j as f64 / 16.0);
+                for s in arc
+                    .tessellate_angle(acadrust::kernel::tessellation::DEFAULT_ANGLE)
+                    .into_iter()
+                    .skip(1)
+                {
                     let (wx, wy, wz) = to_wcs(s[0], s[1]);
                     pts.push([wx, wy, wz]);
                 }
diff --git a/src/entities/polyline.rs b/src/entities/polyline.rs
index 87d912e40..258651407 100644
--- a/src/entities/polyline.rs
+++ b/src/entities/polyline.rs
@@ -258,8 +258,11 @@ fn tessellate_polyline2d(pl: &Polyline2D) -> RenderEntity {
                     center: [wcx as f32, wcy as f32, wcz as f32],
                     radius: arc.radius as f32,
                 });
-                for j in 1..=16usize {
-                    let s = arc.sample(j as f64 / 16.0);
+                for s in arc
+                    .tessellate_angle(acadrust::kernel::tessellation::DEFAULT_ANGLE)
+                    .into_iter()
+                    .skip(1)
+                {
                     let (wx, wy, wz) = to_wcs(s[0], s[1]);
                     path.push([wx, wy, wz]);
                 }
diff --git a/src/entities/spline.rs b/src/entities/spline.rs
index fe95b27c5..ac8fa7893 100644
--- a/src/entities/spline.rs
+++ b/src/entities/spline.rs
@@ -157,25 +157,7 @@ pub(crate) fn measurement_polyline(spl: &Spline) -> Vec<[f64; 3]> {
     if degree == 0 || degree >= count {
         return spl.control_points.iter().map(|p| [p.x, p.y, p.z]).collect();
     }
-    let mut min = [f64::INFINITY; 3];
-    let mut max = [f64::NEG_INFINITY; 3];
-    for point in &spl.control_points {
-        min[0] = min[0].min(point.x);
-        min[1] = min[1].min(point.y);
-        min[2] = min[2].min(point.z);
-        max[0] = max[0].max(point.x);
-        max[1] = max[1].max(point.y);
-        max[2] = max[2].max(point.z);
-    }
-    let diagonal = ((max[0] - min[0]).powi(2)
-        + (max[1] - min[1]).powi(2)
-        + (max[2] - min[2]).powi(2))
-    .sqrt();
-    let tolerance = crate::scene::convert::tess_util::fill_chord_tol(diagonal.max(1.0));
-
-    // The kernel's space curve holds the rational and the polynomial case
-    // alike — weights absent means polynomial — and samples to a chord
-    // tolerance, refined where the curve bends rather than evenly.
+    // The kernel's space curve holds rational and polynomial curves alike.
     let controls: Vec<[f64; 3]> = spl
         .control_points
         .iter()
@@ -188,7 +170,9 @@ pub(crate) fn measurement_polyline(spl: &Spline) -> Vec<[f64; 3]> {
             .collect()
     });
     match NurbsCurve3::new(degree, controls, spl.knots.clone(), weights) {
-        Some(curve) => curve.tessellate_within(tolerance),
+        Some(curve) => {
+            curve.tessellate_angle(acadrust::kernel::tessellation::DEFAULT_ANGLE)
+        }
         None => spl.control_points.iter().map(|p| [p.x, p.y, p.z]).collect(),
     }
 }
@@ -197,7 +181,6 @@ pub(crate) fn measurement_polyline(spl: &Spline) -> Vec<[f64; 3]> {
 /// passes through every input point; open ends use reflected phantom points so
 /// they don't kink, closed curves wrap around.
 fn catmull_rom_polyline(pts: &[acadrust::types::Vector3], closed: bool) -> Vec<[f64; 3]> {
-    const STEPS: usize = 16;
     let n = pts.len();
     if n < 2 {
         return pts.iter().map(|p| [p.x, p.y, p.z]).collect();
@@ -212,7 +195,7 @@ fn catmull_rom_polyline(pts: &[acadrust::types::Vector3], closed: bool) -> Vec<[
         [pts[j].x, pts[j].y, pts[j].z]
     };
     let seg_count = if closed { n } else { n - 1 };
-    let mut out: Vec<[f64; 3]> = Vec::with_capacity(seg_count * STEPS + 1);
+    let mut out = Vec::new();
     for seg in 0..seg_count {
         let p1 = get(seg as isize);
         let p2 = get(seg as isize + 1);
@@ -235,15 +218,7 @@ fn catmull_rom_polyline(pts: &[acadrust::types::Vector3], closed: bool) -> Vec<[
         } else {
             get(seg as isize + 2)
         };
-        // Emit t in [0, 1); the final segment also emits t = 1 so the curve
-        // closes onto the last point (no duplicate shared vertices otherwise).
-        let last = if seg == seg_count - 1 {
-            STEPS
-        } else {
-            STEPS - 1
-        };
-        for s in 0..=last {
-            let t = s as f64 / STEPS as f64;
+        let point_at = |t: f64| {
             let (t2, t3) = (t * t, t * t * t);
             let mut q = [0.0f64; 3];
             for k in 0..3 {
@@ -253,8 +228,24 @@ fn catmull_rom_polyline(pts: &[acadrust::types::Vector3], closed: bool) -> Vec<[
                         + (2.0 * p0[k] - 5.0 * p1[k] + 4.0 * p2[k] - p3[k]) * t2
                         + (-p0[k] + 3.0 * p1[k] - 3.0 * p2[k] + p3[k]) * t3);
             }
-            out.push(q);
-        }
+            q
+        };
+        let tangent_at = |t: f64| {
+            let mut q = [0.0; 3];
+            for k in 0..3 {
+                let a = -p0[k] + p2[k];
+                let b = 2.0 * p0[k] - 5.0 * p1[k] + 4.0 * p2[k] - p3[k];
+                let c = -p0[k] + 3.0 * p1[k] - 3.0 * p2[k] + p3[k];
+                q[k] = 0.5 * (a + 2.0 * b * t + 3.0 * c * t * t);
+            }
+            q
+        };
+        let sampled = acadrust::kernel::tessellation::sample_curve3_angle(
+            point_at,
+            tangent_at,
+            acadrust::kernel::tessellation::DEFAULT_ANGLE,
+        );
+        out.extend(sampled.into_iter().skip(usize::from(seg > 0)));
     }
     out
 }
@@ -340,12 +331,9 @@ fn fit_spline_polyline(spl: &Spline) -> Vec<[f64; 3]> {
     }
 
     // Evaluate each segment as a cubic Hermite (dP/du = slope · h_i).
-    const STEPS: usize = 32;
-    let mut out = Vec::with_capacity((n - 1) * STEPS + 1);
+    let mut out = Vec::new();
     for i in 0..n - 1 {
-        let last = if i == n - 2 { STEPS } else { STEPS - 1 };
-        for s in 0..=last {
-            let u = s as f64 / STEPS as f64;
+        let point_at = |u: f64| {
             let (u2, u3) = (u * u, u * u * u);
             let h00 = 2.0 * u3 - 3.0 * u2 + 1.0;
             let h10 = u3 - 2.0 * u2 + u;
@@ -357,8 +345,30 @@ fn fit_spline_polyline(spl: &Spline) -> Vec<[f64; 3]> {
                 let m1 = slopes[k][i + 1] * h[i];
                 q[k] = h00 * p[i][k] + h10 * m0 + h01 * p[i + 1][k] + h11 * m1;
             }
-            out.push(q);
-        }
+            q
+        };
+        let tangent_at = |u: f64| {
+            let u2 = u * u;
+            let (h00, h10, h01, h11) = (
+                6.0 * u2 - 6.0 * u,
+                3.0 * u2 - 4.0 * u + 1.0,
+                -6.0 * u2 + 6.0 * u,
+                3.0 * u2 - 2.0 * u,
+            );
+            let mut q = [0.0; 3];
+            for k in 0..3 {
+                let m0 = slopes[k][i] * h[i];
+                let m1 = slopes[k][i + 1] * h[i];
+                q[k] = h00 * p[i][k] + h10 * m0 + h01 * p[i + 1][k] + h11 * m1;
+            }
+            q
+        };
+        let sampled = acadrust::kernel::tessellation::sample_curve3_angle(
+            point_at,
+            tangent_at,
+            acadrust::kernel::tessellation::DEFAULT_ANGLE,
+        );
+        out.extend(sampled.into_iter().skip(usize::from(i > 0)));
     }
     out
 }
diff --git a/src/scene/cache/block_cache.rs b/src/scene/cache/block_cache.rs
index 34024dc05..67aa9d110 100644
--- a/src/scene/cache/block_cache.rs
+++ b/src/scene/cache/block_cache.rs
@@ -1961,17 +1961,11 @@ fn transform_tangent(
     }
 }
 
-/// Radius / coordinate cap above which adaptive curve tessellation will
-/// allocate hundreds of millions of points. `parameter_division` samples
-/// to a fixed chord tolerance, so a Circle of radius 1e10 already produces
-/// tens of millions of points.
+/// Coordinate cap for invalid or impractical extents.
 const SANE_EXTENT: f64 = 1.0e8;
 
 fn is_unreasonable_extent(e: &EntityType) -> bool {
-    // Adaptive curve tessellation also explodes on degenerate primitives
-    // (radius = 0, axes of length 0): `parameter_division` allocates
-    // proportional to range/tolerance, which underflows when the curve
-    // collapses to a point. Drop both ends of the spectrum.
+    // Drop degenerate primitives and impractical coordinate ranges.
     match e {
         EntityType::Circle(c) => c.radius.abs() < 1.0e-9 || c.radius.abs() > SANE_EXTENT,
         EntityType::Arc(a) => a.radius.abs() < 1.0e-9 || a.radius.abs() > SANE_EXTENT,
diff --git a/src/scene/convert/acis_kernel.rs b/src/scene/convert/acis_kernel.rs
index 16c12a9cc..2dedcf9c5 100644
--- a/src/scene/convert/acis_kernel.rs
+++ b/src/scene/convert/acis_kernel.rs
@@ -15,9 +15,6 @@ use acadrust::kernel::brep;
 use crate::scene::convert::solid3d_tess::{body_transform, finalize_mesh};
 use crate::scene::model::mesh_model::{CurvedGen, MeshLodSet};
 
-/// Relative chord tolerance, resolved once per body.
-const CHORD_FRAC: f64 = 0.002;
-
 /// ACIS topology fit tolerance.
 const TOL: f64 = 1e-6;
 
@@ -56,7 +53,7 @@ pub fn tessellate_sat(
     } else {
         1.0
     };
-    let frac = CHORD_FRAC / resolution;
+    let max_angle = acadrust::kernel::tessellation::DEFAULT_ANGLE / resolution;
 
     // Positions stay f64 until `finalize_mesh` splits them into the coarse
     // and fine pair, so a solid at survey coordinates keeps its millimetres.
@@ -101,7 +98,7 @@ pub fn tessellate_sat(
     // parameters leaves a hole, the same as one that never lifted — so both
     // are counted before calling the mesh whole.
     let mut undrawn = 0usize;
-    let tolerance = brep::mesh::TessellationTolerance::relative(frac, TOL)
+    let tolerance = brep::mesh::TessellationTolerance::new(max_angle, TOL)
         .with_isolines(isolines);
     for body in &bodies {
         let tessellation = brep::mesh::tessellate(body, tolerance);
@@ -237,23 +234,15 @@ mod tests {
         assert_eq!(moved, [10.0, 20.0, 30.0]);
     }
 
-    /// How many sides a circle of `radius` gets at a sag of `frac × radius`.
-    fn sides(frac: f64) -> f64 {
-        let step = 2.0 * (1.0 - frac).clamp(-1.0, 1.0).acos();
-        std::f64::consts::TAU / step
+    fn sides(max_angle: f64) -> f64 {
+        std::f64::consts::TAU / max_angle
     }
 
     #[test]
     fn a_round_surface_gets_the_same_sides_whatever_its_size() {
-        // The fault: `facet_res` is a resolution multiplier and was used as a
-        // sag in world units. At the default that asked for a whole unit of
-        // departure, so nothing smaller than a metre subdivided at all and a
-        // pipe came out as coarse as its own rim.
-        //
-        // A fraction of the radius carries no unit, so a bolt and a pipeline
-        // are sampled alike.
-        assert!(sides(CHORD_FRAC) > 24.0, "{}", sides(CHORD_FRAC));
-        assert!(sides(CHORD_FRAC) < 96.0, "{}", sides(CHORD_FRAC));
+        let angle = acadrust::kernel::tessellation::DEFAULT_ANGLE;
+        assert!(sides(angle) > 24.0, "{}", sides(angle));
+        assert!(sides(angle) < 96.0, "{}", sides(angle));
     }
 
 }
diff --git a/src/scene/convert/curve_tol.rs b/src/scene/convert/curve_tol.rs
deleted file mode 100644
index 250c0912b..000000000
--- a/src/scene/convert/curve_tol.rs
+++ /dev/null
@@ -1,140 +0,0 @@
-// How finely a curve is sampled, for the whole of one render frame.
-//
-// Every curve in a drawing is tessellated to a chord height — how far the
-// polyline drawn for it may sit from the curve itself — and the right value
-// depends on the zoom. At a metre per pixel a millimetre of error is
-// invisible; zoomed to a millimetre per pixel it is the whole picture.
-//
-// The Scene sets this once per frame from `world_per_pixel`, targeting about
-// half a pixel. Every tessellation inside that frame reads the same atomic,
-// including the ones running on rayon workers, which is why it is a global
-// rather than a parameter: threading a tolerance through every entity
-// converter's signature would touch every one of them to say the same thing.
-//
-// Zero means "no frame is being drawn" — a load, a snap, a hit test — and the
-// floor is used instead. That is what `BlockCache::build` expects.
-
-use std::sync::atomic::{AtomicU64, Ordering};
-
-/// The finest a curve is ever sampled, in world units, and the value used
-/// when no frame has set one.
-const CURVE_TOL: f64 = 0.005;
-
-static CURVE_TOL_BITS: AtomicU64 = AtomicU64::new(0);
-
-/// Sets the per-frame curve tolerance. `None` — or anything not finite and
-/// positive — reverts to the floor.
-pub fn set_curve_tol_override(tol: Option<f64>) {
-    let bits = match tol {
-        Some(value) if value > 0.0 && value.is_finite() => value.to_bits(),
-        _ => 0,
-    };
-    CURVE_TOL_BITS.store(bits, Ordering::Relaxed);
-}
-
-/// The tolerance to sample a curve of a given size at.
-///
-/// A chord tolerance is an absolute length, so a fixed floor carries an
-/// assumption about the drawing's units. Five thousandths is a fine sampling
-/// for a part measured in millimetres and a coarse one for a building
-/// measured in metres — it turns a ten-centimetre pipe into a decagon and a
-/// five-centimetre bolt into a heptagon, and zooming in cannot recover them,
-/// because the floor is what stops the frame asking for better.
-///
-/// Bounded against the curve's own size instead, which carries no unit. The
-/// two ends are worth stating as segment counts, since that is what they
-/// really are: a circle gets at least about fifty sides and never more than
-/// about a hundred and sixty, wherever the camera is and whatever the drawing
-/// is measured in.
-pub(crate) fn curve_tol_for(size: f64) -> f64 {
-    if !(size > 0.0) || !size.is_finite() {
-        return current_curve_tol();
-    }
-    // The frame's own request, before the absolute floor — that floor is the
-    // very thing being replaced here, and letting it through first would pin
-    // every curve to it however close the camera came.
-    let bits = CURVE_TOL_BITS.load(Ordering::Relaxed);
-    let asked = if bits == 0 {
-        // Nothing is being drawn — a load, a snap, a hit test. Ask for the
-        // middle of the range, which is smooth without being extravagant.
-        size / 1_500.0
-    } else {
-        f64::from_bits(bits)
-    };
-    asked.clamp(size / 5_000.0, size / 500.0)
-}
-
-/// The tolerance to sample at, never below the floor — so zooming a long way
-/// in cannot ask for a sampling finer than the baseline quality.
-pub(crate) fn current_curve_tol() -> f64 {
-    let bits = CURVE_TOL_BITS.load(Ordering::Relaxed);
-    if bits == 0 {
-        CURVE_TOL
-    } else {
-        f64::from_bits(bits).max(CURVE_TOL)
-    }
-}
-
-/// `Some(tol)` only while a frame's override is in force — that is, while
-/// something is being drawn rather than loaded, snapped or hit-tested. Hatch
-/// boundaries use it to decide whether zoom-adaptive sampling applies at all.
-pub(crate) fn active_curve_tol() -> Option<f64> {
-    let bits = CURVE_TOL_BITS.load(Ordering::Relaxed);
-    (bits != 0).then(|| f64::from_bits(bits).max(CURVE_TOL))
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    /// How many chords a circle of `radius` needs at chord height `tol`.
-    ///
-    /// From the sagitta: a chord subtending `θ` departs from the arc by
-    /// `r(1 − cos(θ/2))` in the middle.
-    fn sides(radius: f64, tol: f64) -> f64 {
-        let step = 2.0 * (1.0 - tol / radius).clamp(-1.0, 1.0).acos();
-        std::f64::consts::TAU / step
-    }
-
-    #[test]
-    fn a_circle_gets_the_same_number_of_sides_whatever_it_is_measured_in() {
-        // The fault: the floor was an absolute length, so the same circle drawn
-        // in millimetres and in metres came out smooth and faceted. Ten
-        // centimetres of pipe had ten sides.
-        set_curve_tol_override(None);
-        let in_millimetres = sides(100.0, curve_tol_for(100.0));
-        let in_metres = sides(0.1, curve_tol_for(0.1));
-        assert!(
-            (in_millimetres - in_metres).abs() < 1.0,
-            "{in_millimetres} vs {in_metres}"
-        );
-        assert!(in_metres > 40.0, "a circle should not read as a decagon: {in_metres}");
-    }
-
-    #[test]
-    fn zooming_in_buys_detail_and_zooming_out_does_not_cost_it() {
-        // Between the two bounds the frame decides, so a curve fills in as the
-        // camera closes on it.
-        set_curve_tol_override(Some(0.01));
-        let far = sides(1.0, curve_tol_for(1.0));
-        set_curve_tol_override(Some(0.0001));
-        let near = sides(1.0, curve_tol_for(1.0));
-        assert!(near > far, "{near} vs {far}");
-        // And neither end runs away: a circle is never a polygon and never a
-        // thousand-sided one that costs more than it shows.
-        set_curve_tol_override(Some(1e-12));
-        assert!(sides(1.0, curve_tol_for(1.0)) < 200.0);
-        set_curve_tol_override(Some(1e9));
-        assert!(sides(1.0, curve_tol_for(1.0)) > 40.0);
-        set_curve_tol_override(None);
-    }
-
-    #[test]
-    fn a_curve_with_no_size_is_left_to_the_frame() {
-        // A straight run needs its two ends; there is no curvature to sample.
-        set_curve_tol_override(Some(0.02));
-        assert_eq!(curve_tol_for(0.0), current_curve_tol());
-        assert_eq!(curve_tol_for(f64::NAN), current_curve_tol());
-        set_curve_tol_override(None);
-    }
-}
diff --git a/src/scene/convert/mod.rs b/src/scene/convert/mod.rs
index 2a4bb17ee..61ba2f246 100644
--- a/src/scene/convert/mod.rs
+++ b/src/scene/convert/mod.rs
@@ -2,7 +2,6 @@ pub mod acad_to_render;
 pub mod acis_export;
 pub mod acis_kernel;
 pub mod dgn_linestyle;
-pub mod curve_tol;
 pub mod tessellate;
 pub(crate) mod tess;
 pub mod proxy_graphics;
diff --git a/src/scene/convert/tess_util.rs b/src/scene/convert/tess_util.rs
index e60d87fc0..7c8492bb0 100644
--- a/src/scene/convert/tess_util.rs
+++ b/src/scene/convert/tess_util.rs
@@ -1,9 +1,7 @@
 // Shared helpers used by per-entity tessellation impls in `crate::entities`
 // and the dispatcher in `crate::scene::convert::tessellate`.
 //
-// Anything cross-entity (colour resolution, arc sampling, chord tolerance)
-// lives here. Entity-specific helpers (dim format strings, mleader path
-// types, etc.) stay with their entity file.
+// Cross-entity rendering helpers live here.
 
 use acadrust::types::Color as AcadColor;
 use glam::Vec3;
@@ -28,81 +26,6 @@ pub type FallbackGeometry = (
     Vec<[f64; 3]>,
 );
 
-// ── Arc tessellation helpers ─────────────────────────────────────────────
-
-/// Convert hatch-boundary arc `(start, end, ccw)` into a
-/// `(start, signed_span)` ready for the sampling loop. Matches the
-/// legacy `(TAU - sa, TAU - ea)` flip used here for years — direction
-/// semantics are preserved on real files. (Wrap-through-2π is a known
-/// edge case in that convention; do not "fix" it without a wider audit
-/// of how upstream writers emit CW boundary arcs.)
-///
-/// VERIFIED against real AutoCAD output (KSR-039 DWG, CW arc edges with
-/// line neighbours): the stored angles of a `ccw = false` arc edge are
-/// MIRRORED — the true point is `center + r·(cos(TAU-θ), sin(TAU-θ))`.
-/// Sampling the mirrored parameter directly (this function's flip) gives
-/// exact endpoint continuity with the adjacent edges (Δ = 0.000000),
-/// while interpreting them as true angles lands tens of units away. Any
-/// code that *produces* CW boundary arcs (mirror transforms, explode)
-/// must therefore store mirrored angles, not geometric ones.
-pub fn arc_signed_span(start: f64, end: f64, ccw: bool) -> (f64, f64) {
-    const TAU: f64 = std::f64::consts::TAU;
-    let (sa, ea) = if ccw {
-        (start, end)
-    } else {
-        (TAU - start, TAU - end)
-    };
-    (sa, ea - sa)
-}
-
-/// Segment count for an arc, targeting `chord_tol_world` chord-height
-/// error in world units. Floor 8, cap 512.
-///
-/// Two production callers:
-/// - hatch fill polygon (built at load / on edit) passes a radius-
-///   relative tol via [`fill_chord_tol`] — ~0.1% radius, zoom-free so
-///   the polygon stays sharp at extreme zoom-in without re-tessellation.
-/// - hatch wire outline (re-tessellated every frame inside the render
-///   scope) passes a zoom-adaptive tol via [`wire_chord_tol`] — pulls
-///   from the per-frame override set by `Scene::wires_for_block` so
-///   far-out arcs collapse to a handful of segments.
-pub fn arc_segments(radius: f64, span_abs: f64, chord_tol_world: f64) -> u32 {
-    arc_segments_floored(radius, span_abs, chord_tol_world, 8)
-}
-
-/// Like [`arc_segments`] but with a caller-chosen segment floor. The 2-D wire
-/// wants floor 8 so a circle reads as round; a curved-surface grid patch or a
-/// short arc wants a lower floor so a small span isn't forced to 8 steps. Cap
-/// stays 512.
-pub fn arc_segments_floored(radius: f64, span_abs: f64, chord_tol_world: f64, floor: u32) -> u32 {
-    if span_abs < 1e-9 || radius < 1e-9 {
-        return floor.max(1);
-    }
-    let tol = chord_tol_world.max(1e-9).min(radius * 0.99);
-    // θ where r * (1 - cos(θ/2)) = tol  →  θ = 2 * acos(1 - tol/r).
-    let max_step = (2.0 * (1.0 - tol / radius).acos()).max(1e-6);
-    ((span_abs / max_step).ceil() as u32).clamp(floor, 512)
-}
-
-/// Chord tolerance for the load-time fill polygon: 0.1% of radius,
-/// floor 1 µm so degenerate radii still produce a workable count.
-pub fn fill_chord_tol(radius: f64) -> f64 {
-    (radius * 0.001).max(1e-6)
-}
-
-/// Chord tolerance for the per-frame wire outline: pulls the active
-/// `curve_tol::set_curve_tol_override` value (Scene sets it to
-/// `world_per_pixel × 0.5` so curves stay at ~half-pixel chord error at
-/// the current zoom). When no override is active (snap / hit-test
-/// passes, load-time builds), falls back to [`fill_chord_tol`] so we
-/// never under-sample.
-pub fn wire_chord_tol(radius: f64) -> f64 {
-    match crate::scene::convert::curve_tol::active_curve_tol() {
-        Some(t) => t.min(fill_chord_tol(radius)).max(1e-9),
-        None => fill_chord_tol(radius),
-    }
-}
-
 // ── Colour helper ──────────────────────────────────────────────────────────
 
 /// Convert an acadrust Color (ACI index or true-color) to a GPU RGBA value.
diff --git a/src/scene/convert/tessellate.rs b/src/scene/convert/tessellate.rs
index 4bc0e2542..31c4f87ef 100644
--- a/src/scene/convert/tessellate.rs
+++ b/src/scene/convert/tessellate.rs
@@ -4,7 +4,7 @@
 //   EntityType
 //     ↓  acad_to_render::convert()
 //   RenderEntity  { object: RenderObject, snap_pts, tangent_geoms, key_vertices }
-//     ↓  curve_tol::tessellate_*()
+//     ↓
 //   RenderObject::Lines → WireModel
 //   RenderObject::Dot   → WireModel (a dot sized in pixels)
 //   RenderObject::Text  → WireModel (glyph strokes) + SDF quads
diff --git a/src/scene/entity.rs b/src/scene/entity.rs
index e1f5bccd7..ae1d71c4e 100644
--- a/src/scene/entity.rs
+++ b/src/scene/entity.rs
@@ -1398,195 +1398,14 @@ impl Scene {
 
             let mut edge_polys: Vec<Vec<[f64; 2]>> = Vec::new();
             for edge in &path.edges {
-                match edge {
-                    BoundaryEdge::Polyline(poly) => {
-                        let verts = &poly.vertices;
-                        let count = verts.len();
-                        if count == 0 {
-                            continue;
-                        }
-                        let seg_count = if poly.is_closed {
-                            count
-                        } else {
-                            count.saturating_sub(1)
-                        };
-                        for i in 0..seg_count {
-                            let v0 = &verts[i];
-                            let v1 = &verts[(i + 1) % count];
-                            let bulge = v0.z;
-                            // Tess in f64 to preserve ~1 cm precision at
-                            // UTM-scale WCS (the f32 path used to produce
-                            // visibly wavy hatch arcs at 1e5+ magnitude).
-                            let arc = if bulge.abs() < 1e-9 {
-                                None
-                            } else {
-                                crate::entities::common::BulgeArc::from_bulge(
-                                    [v0.x, v0.y],
-                                    [v1.x, v1.y],
-                                    bulge,
-                                )
-                            };
-                            let Some(arc) = arc else {
-                                boundary.push(to_xy(v0.x, v0.y));
-                                continue;
-                            };
-                            let segs = convert::tess_util::arc_segments(
-                                arc.radius,
-                                arc.sweep.abs(),
-                                convert::tess_util::fill_chord_tol(arc.radius),
-                            );
-                            for j in 0..segs {
-                                let s = arc.sample(j as f64 / segs as f64);
-                                boundary.push(to_xy(s[0], s[1]));
-                            }
-                        }
-                        if poly.is_closed {
-                            if let Some(&first) = boundary.get(path_start) {
-                                boundary.push(first);
-                            }
-                        }
-                    }
-                    BoundaryEdge::Line(line) => {
-                        edge_polys.push(vec![
-                            to_xy(line.start.x, line.start.y),
-                            to_xy(line.end.x, line.end.y),
-                        ]);
-                    }
-                    BoundaryEdge::CircularArc(arc) => {
-                        let (sa, span) = convert::tess_util::arc_signed_span(
-                            arc.start_angle,
-                            arc.end_angle,
-                            arc.counter_clockwise,
-                        );
-                        let segs = convert::tess_util::arc_segments(
-                            arc.radius,
-                            span.abs(),
-                            convert::tess_util::fill_chord_tol(arc.radius),
-                        );
-                        let mut pts = Vec::with_capacity(segs as usize + 1);
-                        for i in 0..=segs {
-                            let t = sa + span * (i as f64 / segs as f64);
-                            pts.push(to_xy(
-                                arc.center.x + arc.radius * t.cos(),
-                                arc.center.y + arc.radius * t.sin(),
-                            ));
-                        }
-                        edge_polys.push(pts);
-                    }
-                    BoundaryEdge::EllipticArc(ell) => {
-                        let r_maj = (ell.major_axis_endpoint.x * ell.major_axis_endpoint.x
-                            + ell.major_axis_endpoint.y * ell.major_axis_endpoint.y)
-                            .sqrt();
-                        let r_min = r_maj * ell.minor_axis_ratio;
-                        let rot = ell
-                            .major_axis_endpoint
-                            .y
-                            .atan2(ell.major_axis_endpoint.x);
-                        let (sa, span) = convert::tess_util::arc_signed_span(
-                            ell.start_angle,
-                            ell.end_angle,
-                            ell.counter_clockwise,
-                        );
-                        let segs = convert::tess_util::arc_segments(
-                            r_maj,
-                            span.abs(),
-                            convert::tess_util::fill_chord_tol(r_maj),
-                        );
-                        let (cr, sr) = (rot.cos(), rot.sin());
-                        let mut pts = Vec::with_capacity(segs as usize + 1);
-                        for i in 0..=segs {
-                            let t = sa + span * (i as f64 / segs as f64);
-                            let lx = r_maj * t.cos();
-                            let ly = r_min * t.sin();
-                            pts.push(to_xy(
-                                ell.center.x + lx * cr - ly * sr,
-                                ell.center.y + lx * sr + ly * cr,
-                            ));
-                        }
-                        edge_polys.push(pts);
-                    }
-                    BoundaryEdge::Spline(spline) => {
-                        // DXF spline control_points pack (x, y, weight) into
-                        // a Vector3 — the z field is the rational weight, NOT
-                        // a Z coordinate. The legacy code dropped weight and
-                        // sampled with a fixed 16 segments; both bugs
-                        // produced visibly wrong fill regions for spline-
-                        // bounded hatches (especially block-internal ones,
-                        // where boundaries are often spline curves with
-                        // rational weights and short cubic segments).
-                        //
-                        // The kernel's plane NURBS holds the rational and
-                        // the polynomial case alike — weights absent means
-                        // polynomial — and tessellates to a chord tolerance,
-                        // the same one the fill polygon uses for arcs.
-                        let degree = spline.degree.max(0) as usize;
-
-                        // Rough chord-tolerance: 0.1% of the control-poly
-                        // diagonal so adaptive sampling produces enough
-                        // points to follow the curve without exploding on
-                        // huge splines.
-                        let (mut sp_min_x, mut sp_min_y) = (f64::INFINITY, f64::INFINITY);
-                        let (mut sp_max_x, mut sp_max_y) = (f64::NEG_INFINITY, f64::NEG_INFINITY);
-                        for cp in &spline.control_points {
-                            sp_min_x = sp_min_x.min(cp.x);
-                            sp_min_y = sp_min_y.min(cp.y);
-                            sp_max_x = sp_max_x.max(cp.x);
-                            sp_max_y = sp_max_y.max(cp.y);
-                        }
-                        let diag = ((sp_max_x - sp_min_x).powi(2)
-                            + (sp_max_y - sp_min_y).powi(2))
-                        .sqrt();
-                        let tol = convert::tess_util::fill_chord_tol(diag.max(1.0));
-
-                        let mut epts: Vec<[f64; 2]> = Vec::new();
-                        let mut sampled = false;
-                        let points: Vec<[f64; 2]> = spline
-                            .control_points
-                            .iter()
-                            .map(|p| [p.x, p.y])
-                            .collect();
-                        let weights = spline.rational.then(|| {
-                            spline
-                                .control_points
-                                .iter()
-                                .map(|p| if p.z.abs() > 1e-12 { p.z } else { 1.0 })
-                                .collect()
-                        });
-                        if let Some(curve) = acadrust::kernel::geom2d::NurbsCurve::new(
-                            degree,
-                            points,
-                            spline.knots.clone(),
-                            weights,
-                        ) {
-                            for point in
-                                acadrust::kernel::geom2d::Curve::Nurbs(curve).tessellate_within(tol)
-                            {
-                                epts.push(to_xy(point[0], point[1]));
-                            }
-                            sampled = epts.len() >= 2;
-                        }
-                        if !sampled {
-                            // Fallback: prefer fit_points (which lie on the
-                            // curve) over control_points (which usually
-                            // don't). A control-point polyline would draw
-                            // the convex-hull silhouette — visibly wrong.
-                            let pts: &[_] = if !spline.fit_points.is_empty() {
-                                &spline.fit_points
-                            } else {
-                                &[]
-                            };
-                            if !pts.is_empty() {
-                                for p in pts {
-                                    epts.push(to_xy(p.x, p.y));
-                                }
-                            } else {
-                                for cp in &spline.control_points {
-                                    epts.push(to_xy(cp.x, cp.y));
-                                }
-                            }
-                        }
-                        edge_polys.push(epts);
-                    }
+                if let Some(curve) = crate::entities::hatch::edge_curve(edge) {
+                    edge_polys.push(
+                        curve
+                            .tessellate_angle(acadrust::kernel::tessellation::DEFAULT_ANGLE)
+                            .into_iter()
+                            .map(|point| to_xy(point[0], point[1]))
+                            .collect(),
+                    );
                 }
             }
             boundary.extend(chain_path_edges(edge_polys));
diff --git a/src/scene/mod.rs b/src/scene/mod.rs
index b61a30da7..ce62bf1ec 100644
--- a/src/scene/mod.rs
+++ b/src/scene/mod.rs
@@ -8207,21 +8207,6 @@ impl Scene {
         let paper = anno_scale_override.is_some();
         let blk_cache = self.block_cache_arc_for(annotation_scale_handle, all_visible, style_viewport);
         let blk_ref: &cache::block_cache::BlockCache = &blk_cache;
-        // Zoom-adaptive curve sampling for top-level Edge tessellation. Target
-        // ~0.5 px chord height — far-out arcs that used to emit hundreds of
-        // segments now collapse to a handful. The guard clears the override
-        // when this scope exits so off-render tessellation (snap previews,
-        // hit-test, block_cache rebuild) sees the default.
-        struct CurveTolGuard;
-        impl Drop for CurveTolGuard {
-            fn drop(&mut self) {
-                crate::scene::convert::curve_tol::set_curve_tol_override(None);
-            }
-        }
-        let _tol_guard = wpp.map(|w| {
-            crate::scene::convert::curve_tol::set_curve_tol_override(Some((w * 0.5) as f64));
-            CurveTolGuard
-        });
         // Per-entity tessellation memo. Same classify/tessellate logic, two
         // SEPARATE stores so they can't thrash each other:
         //   * culled path (`view_aabb == Some`) → `tess_memo`, guard keyed on the
diff --git a/src/scene/model/solid_model.rs b/src/scene/model/solid_model.rs
index 8e56333cc..e578df458 100644
--- a/src/scene/model/solid_model.rs
+++ b/src/scene/model/solid_model.rs
@@ -17,16 +17,17 @@ use acadrust::kernel::brep::{self, Body};
 
 use crate::scene::model::mesh_model::{MeshLodSet, MeshModel};
 
-/// How far a triangle may sit from the surface it lies on. A drawing is
-/// measured in millimetres, and a twentieth of one is past what a screen
-/// resolves at any sane zoom.
-const SAG: f64 = 0.05;
-
 /// What counts as the same point when the kernel checks a body over.
 const TOL: f64 = 1e-9;
 
 fn tessellation(body: &Body) -> brep::mesh::BodyMesh {
-    brep::mesh::tessellate(body, brep::mesh::TessellationTolerance::new(SAG, TOL))
+    brep::mesh::tessellate(
+        body,
+        brep::mesh::TessellationTolerance::new(
+            acadrust::kernel::tessellation::DEFAULT_ANGLE,
+            TOL,
+        ),
+    )
 }
 
 /// Axis-aligned box from its center and full extents.
diff --git a/src/scene/model/sweep_model.rs b/src/scene/model/sweep_model.rs
index ef25826bb..3ddda1860 100644
--- a/src/scene/model/sweep_model.rs
+++ b/src/scene/model/sweep_model.rs
@@ -112,26 +112,26 @@ use crate::scene::model::mesh_model::{MeshLodSet, MeshModel};
 
 /// SWEEP through the kernel's tolerance-driven mesh API.
 pub fn swept(profile: &EntityType, path: &EntityType, color: [f32; 4]) -> Option<MeshLodSet> {
-    let tolerance = crate::scene::convert::curve_tol::current_curve_tol();
+    let max_angle = acadrust::kernel::tessellation::DEFAULT_ANGLE;
     let surface = brep::mesh::sweep_surface(
         &entity_curve(profile)?,
         &entity_curve(path)?,
-        tolerance,
+        max_angle,
     )?;
-    mesh_set(surface, color, tolerance)
+    mesh_set(surface, color, 1e-9)
 }
 
 /// LOFT through the kernel's tolerance-driven mesh API.
 pub fn lofted(profiles: &[EntityType], color: [f32; 4]) -> Option<MeshLodSet> {
     let curves: Vec<PlanarCurve> = profiles.iter().filter_map(entity_curve).collect();
-    let tolerance = crate::scene::convert::curve_tol::current_curve_tol();
-    mesh_set(brep::mesh::loft_surface(&curves, tolerance)?, color, tolerance)
+    let max_angle = acadrust::kernel::tessellation::DEFAULT_ANGLE;
+    mesh_set(brep::mesh::loft_surface(&curves, max_angle)?, color, 1e-9)
 }
 
 fn mesh_set(
     surface: brep::mesh::SurfaceMesh,
     color: [f32; 4],
-    tolerance: f64,
+    precision: f64,
 ) -> Option<MeshLodSet> {
     if surface.mesh.is_empty() {
         return None;
@@ -141,7 +141,7 @@ fn mesh_set(
     for point in &surface.mesh.positions {
         push_point(&mut verts, &mut verts_low, *point);
     }
-    let silhouette = surface.silhouette_source(tolerance);
+    let silhouette = surface.silhouette_source(precision);
     let mut set = MeshLodSet::from_single(MeshModel {
         name: String::new(),
         verts,