diff --git a/src/entities/common.rs b/src/entities/common.rs
index 09a416c46..89d55ade5 100644
--- a/src/entities/common.rs
+++ b/src/entities/common.rs
@@ -462,7 +462,7 @@ pub fn rectangle_grip(id: usize, world: glam::DVec3, dir: [f32; 2]) -> GripDef {
         world,
         is_midpoint: true,
         shape: GripShape::Rectangle,
-        dir: Some(dir),
+        dir: Some(glam::DVec3::new(dir[0] as f64, dir[1] as f64, 0.0)),
         axis: None,
     }
 }
@@ -479,6 +479,18 @@ pub fn triangle_grip(id: usize, world: glam::DVec3) -> GripDef {
     }
 }
 
+/// Triangle grip pointing along a world-space direction.
+pub fn oriented_triangle_grip(id: usize, world: glam::DVec3, dir: glam::DVec3) -> GripDef {
+    GripDef {
+        id,
+        world,
+        is_midpoint: false,
+        shape: GripShape::Triangle,
+        dir: Some(dir),
+        axis: None,
+    }
+}
+
 /// Editable ANGLE row: displays via AUNITS/AUPREC. Angle rows used the
 /// LINEAR formatter, so LUNITS=Architectural showed a block rotation as
 /// feet-and-inches and the string wouldn't parse back (#297). Value in
diff --git a/src/entities/ellipse.rs b/src/entities/ellipse.rs
index 144c0fce1..297f140b6 100644
--- a/src/entities/ellipse.rs
+++ b/src/entities/ellipse.rs
@@ -1,11 +1,16 @@
 use acadrust::entities::Ellipse;
+use cadkernel::geom2d::{
+    Curve as KernelCurve, EllipseArc as KernelEllipseArc, Tolerance, Vec2 as KernelVec2,
+};
+use cadkernel::space::PlanarCurve;
 
 use crate::entities::curve::CurveSnap;
 use crate::t;
 
 use crate::command::EntityTransform;
 use crate::entities::common::{
-    center_grip, edit_prop as edit, parse_f64, ro_prop as ro, square_grip,
+    center_grip, edit_prop as edit, oriented_triangle_grip, parse_f64, ro_prop as ro,
+    square_grip,
 };
 use crate::entities::traits::RenderConvertible;
 use crate::scene::convert::acad_to_render::{RenderEntity, RenderObject};
@@ -58,33 +63,56 @@ fn to_render(ell: &Ellipse) -> RenderEntity {
     }
 }
 
-/// A curve through every one of `points` in order.
-///
-/// Degree one, so the control polygon *is* the curve — the same thing the
-/// hand-built sampling produced, without restating how a B-spline is put
-/// together at each site.
+fn ellipse_curves(ell: &Ellipse) -> Option<(PlanarCurve, PlanarCurve)> {
+    let arc = crate::entities::curve::ellipse_curve(ell)?;
+    let KernelCurve::Ellipse(piece) = &arc.curve else {
+        return None;
+    };
+    let full = PlanarCurve::new(
+        arc.plane,
+        KernelCurve::Ellipse(KernelEllipseArc::full(piece.ellipse)),
+    );
+    Some((arc, full))
+}
+
+fn is_closed(ell: &Ellipse) -> bool {
+    crate::entities::curve::ellipse_curve(ell).is_some_and(|curve| curve.curve.is_closed())
+}
+
+fn parameter_at_point(ell: &Ellipse, point: glam::DVec3) -> Option<f64> {
+    let (_, full) = ellipse_curves(ell)?;
+    Some(
+        (full.parameter_at(point.to_array())? * std::f64::consts::TAU)
+            .rem_euclid(std::f64::consts::TAU),
+    )
+}
 
 fn grips(ell: &Ellipse) -> Vec<GripDef> {
-    let ctr = glam::DVec3::new(ell.center.x, ell.center.y, ell.center.z);
-    let maj = glam::DVec3::new(
-        ell.center.x + ell.major_axis.x,
-        ell.center.y + ell.major_axis.y,
-        ell.center.z + ell.major_axis.z,
-    );
-    let major_xy =
-        ((ell.major_axis.x * ell.major_axis.x + ell.major_axis.y * ell.major_axis.y) as f64).sqrt();
-    let (px, py) = if major_xy > 1e-10 {
-        let s = ell.major_axis_length() * ell.minor_axis_ratio / major_xy;
-        (-ell.major_axis.y * s, ell.major_axis.x * s)
-    } else {
-        (0.0, ell.major_axis_length() * ell.minor_axis_ratio)
+    let fallback = glam::DVec3::new(ell.center.x, ell.center.y, ell.center.z);
+    let Some((arc, full)) = ellipse_curves(ell) else {
+        return vec![center_grip(0, fallback)];
     };
-    let min = glam::DVec3::new(ell.center.x + px, ell.center.y + py, ell.center.z);
-    vec![
+    let KernelCurve::Ellipse(piece) = &full.curve else {
+        return vec![center_grip(0, fallback)];
+    };
+    let ctr = glam::DVec3::from_array(full.plane.point_at(piece.ellipse.centre));
+    let axes = [0.0, 0.25, 0.5, 0.75].map(|t| glam::DVec3::from_array(full.point_at(t)));
+    let mut grips = vec![
         center_grip(0, ctr),
-        square_grip(1, maj),
-        square_grip(2, min),
-    ]
+        square_grip(1, axes[0]),
+        square_grip(2, axes[1]),
+        square_grip(3, axes[2]),
+        square_grip(4, axes[3]),
+    ];
+    if !arc.curve.is_closed() {
+        let start = glam::DVec3::from_array(arc.point_at(0.0));
+        let end = glam::DVec3::from_array(arc.point_at(1.0));
+        let start_outward = -glam::DVec3::from_array(arc.tangent_at(0.0));
+        let end_outward = glam::DVec3::from_array(arc.tangent_at(1.0));
+        grips.push(oriented_triangle_grip(5, start, start_outward));
+        grips.push(oriented_triangle_grip(6, end, end_outward));
+    }
+    grips
 }
 
 fn properties(ell: &Ellipse) -> Vec<PropSection> {
@@ -114,9 +142,7 @@ fn properties(ell: &Ellipse) -> Vec<PropSection> {
     let minor_vec = v * r_minor;
 
     let start_angle = ell.start_parameter.to_degrees().rem_euclid(360.0);
-    let end_angle = if crate::entities::curve::ellipse_curve(ell)
-        .is_some_and(|curve| curve.curve.is_closed())
-    {
+    let end_angle = if is_closed(ell) {
         360.0
     } else {
         ell.end_parameter.to_degrees().rem_euclid(360.0)
@@ -188,6 +214,73 @@ fn apply_geom_prop(ell: &mut Ellipse, field: &str, value: &str) {
     }
 }
 
+fn apply_axis_grip(ell: &mut Ellipse, grip_id: usize, point: glam::DVec3) {
+    let Some((_, full)) = ellipse_curves(ell) else {
+        return;
+    };
+    let KernelCurve::Ellipse(piece) = &full.curve else {
+        return;
+    };
+    let Some(projected) = full.plane.project(point.to_array()) else {
+        return;
+    };
+    let center = KernelVec2::from(piece.ellipse.centre);
+    let mut dragged = KernelVec2::from(projected) - center;
+    let tolerance = Tolerance::default().linear();
+
+    if matches!(grip_id, 1 | 3) {
+        if grip_id == 3 {
+            dragged = -dragged;
+        }
+        if dragged.length() <= tolerance {
+            return;
+        }
+        let axis = full.plane.vector_at(dragged.to_array());
+        ell.major_axis.x = axis[0];
+        ell.major_axis.y = axis[1];
+        ell.major_axis.z = axis[2];
+        return;
+    }
+
+    if grip_id == 4 {
+        dragged = -dragged;
+    }
+    let major_dir = KernelVec2::from(piece.ellipse.major_axis);
+    let minor_dir = major_dir.perpendicular();
+    let major_len = piece.ellipse.major_radius.abs();
+    let minor_len = piece.ellipse.minor_radius.abs();
+    if major_len <= tolerance || minor_len <= tolerance {
+        return;
+    }
+
+    let along_major = dragged.dot(major_dir).abs();
+    let along_minor = dragged.dot(minor_dir).abs();
+    let (drag_dir, dragged_len, fixed_dir, fixed_len) = if along_minor >= along_major {
+        (minor_dir, along_minor, major_dir, major_len)
+    } else {
+        (major_dir, along_major, minor_dir, minor_len)
+    };
+    if fixed_len <= tolerance {
+        return;
+    }
+    let (axis, ratio) = if dragged_len >= fixed_len {
+        (
+            drag_dir * dragged_len,
+            (fixed_len / dragged_len).clamp(0.001, 1.0),
+        )
+    } else {
+        (
+            fixed_dir * fixed_len,
+            (dragged_len / fixed_len).clamp(0.001, 1.0),
+        )
+    };
+    let axis = full.plane.vector_at(axis.to_array());
+    ell.major_axis.x = axis[0];
+    ell.major_axis.y = axis[1];
+    ell.major_axis.z = axis[2];
+    ell.minor_axis_ratio = ratio;
+}
+
 fn apply_grip(ell: &mut Ellipse, grip_id: usize, apply: GripApply) {
     match (grip_id, apply) {
         (0, GripApply::Translate(d)) => {
@@ -200,54 +293,15 @@ fn apply_grip(ell: &mut Ellipse, grip_id: usize, apply: GripApply) {
             ell.center.y = p.y as f64;
             ell.center.z = p.z as f64;
         }
-        (1, GripApply::Absolute(p)) => {
-            ell.major_axis.x = p.x as f64 - ell.center.x;
-            ell.major_axis.y = p.y as f64 - ell.center.y;
-            ell.major_axis.z = p.z as f64 - ell.center.z;
-        }
-        (2, GripApply::Absolute(p)) => {
-            // Minor-axis grip. The two axes are always perpendicular, so this
-            // grip stretches one of them along its fixed direction while the
-            // other stays put. Work in the ellipse's view plane (XY).
-            let mx = ell.major_axis.x;
-            let my = ell.major_axis.y;
-            let major_len = (mx * mx + my * my).sqrt();
-            if major_len <= 1e-10 {
+        (1 | 2 | 3 | 4, GripApply::Absolute(p)) => apply_axis_grip(ell, grip_id, p),
+        (5 | 6, GripApply::Absolute(p)) => {
+            let Some(parameter) = parameter_at_point(ell, p) else {
                 return;
-            }
-            let major_unit = (mx / major_len, my / major_len);
-            let minor_unit = (-major_unit.1, major_unit.0);
-            let minor_len = major_len * ell.minor_axis_ratio;
-
-            let dx = p.x as f64 - ell.center.x;
-            let dy = p.y as f64 - ell.center.y;
-            // Which stored axis is actually under the cursor? Below a circle it
-            // is the minor direction; once the drag pushes the minor past the
-            // major and the axes swap, the grabbed endpoint sits on the major
-            // direction. Decide by cursor alignment — NOT by recomputing a perp
-            // from the just-swapped major every frame — so a continuous drag
-            // stays stable instead of flipping the major 90° each move (which
-            // made both axes balloon once the minor reached the major). The
-            // perpendicular (non-dragged) axis keeps its length; the longer axis
-            // is stored as the major so the ratio stays <= 1 per the file format.
-            let along_major = (dx * major_unit.0 + dy * major_unit.1).abs();
-            let along_minor = (dx * minor_unit.0 + dy * minor_unit.1).abs();
-            let (drag_dir, dragged_len, fixed_dir, fixed_len) = if along_minor >= along_major {
-                (minor_unit, along_minor, major_unit, major_len)
-            } else {
-                (major_unit, along_major, minor_unit, minor_len)
             };
-            if fixed_len <= 1e-10 {
-                return;
-            }
-            if dragged_len >= fixed_len {
-                ell.major_axis.x = drag_dir.0 * dragged_len;
-                ell.major_axis.y = drag_dir.1 * dragged_len;
-                ell.minor_axis_ratio = (fixed_len / dragged_len).clamp(0.001, 1.0);
+            if grip_id == 5 {
+                ell.start_parameter = parameter;
             } else {
-                ell.major_axis.x = fixed_dir.0 * fixed_len;
-                ell.major_axis.y = fixed_dir.1 * fixed_len;
-                ell.minor_axis_ratio = (dragged_len / fixed_len).clamp(0.001, 1.0);
+                ell.end_parameter = parameter;
             }
         }
         _ => {}
diff --git a/src/scene/model/object.rs b/src/scene/model/object.rs
index 39c04dc27..6581f6b51 100644
--- a/src/scene/model/object.rs
+++ b/src/scene/model/object.rs
@@ -101,10 +101,8 @@ pub struct GripDef {
     pub is_midpoint: bool,
     /// Visual marker shape for the grip.
     pub shape: GripShape,
-    /// World-XY direction vector used to orient a `Rectangle` grip
-    /// along its segment. `None` for shapes that don't need rotation
-    /// (Square, Triangle in non-directional contexts).
-    pub dir: Option<[f32; 2]>,
+    /// World-space marker direction, projected with the grip position.
+    pub dir: Option<glam::DVec3>,
     /// World-space axis that constrains this grip's drag.
     pub axis: Option<glam::DVec3>,
 }
diff --git a/src/scene/pick/grip.rs b/src/scene/pick/grip.rs
index da19a4730..75a43c9ee 100644
--- a/src/scene/pick/grip.rs
+++ b/src/scene/pick/grip.rs
@@ -78,6 +78,10 @@ impl GripEdit {
 
 // ── Screen-space helpers ───────────────────────────────────────────────────
 
+fn marker_direction(from: Vec2, to: Vec2) -> [f32; 2] {
+    [to.x - from.x, from.y - to.y]
+}
+
 /// Project a slice of `GripDef`s to screen space.
 /// Returns `(grip_id, screen_pos, is_midpoint, shape)` for each grip.
 pub fn grips_to_screen(
@@ -91,11 +95,18 @@ pub fn grips_to_screen(
             // Project from the f64 grip position via the relative-to-eye path so
             // the grip stays glued to the wire at UTM-scale coordinates (an
             // `as_vec3` cast first would quantize it ~0.5 m off at high zoom).
-            let screen = match camera.project(g.world, bounds) {
+            let projected = camera.project(g.world, bounds);
+            let screen = match projected {
                 Some(p) => Point::new(bounds.x + p.x, bounds.y + p.y),
                 None => Point::new(f32::NAN, f32::NAN),
             };
-            (g.id, screen, g.is_midpoint, g.shape, g.dir)
+            let dir = g.dir.and_then(|dir| {
+                Some(marker_direction(
+                    projected?,
+                    camera.project(g.world + dir, bounds)?,
+                ))
+            });
+            (g.id, screen, g.is_midpoint, g.shape, dir)
         })
         .collect()
 }
@@ -110,14 +121,24 @@ pub fn grips_to_screen_paper(
     half_h: f32,
     bounds: Rectangle,
 ) -> Vec<(usize, Point, bool, GripShape, Option<[f32; 2]>)> {
+    let project = |world: DVec3| {
+        Vec2::new(
+            (world.x as f32 - tx + half_w) / (2.0 * half_w) * bounds.width,
+            (ty + half_h - world.y as f32) / (2.0 * half_h) * bounds.height,
+        )
+    };
     grips
         .iter()
         .map(|g| {
-            let screen = Point::new(
-                (g.world.x as f32 - tx + half_w) / (2.0 * half_w) * bounds.width,
-                (ty + half_h - g.world.y as f32) / (2.0 * half_h) * bounds.height,
-            );
-            (g.id, screen, g.is_midpoint, g.shape, g.dir)
+            let projected = project(g.world);
+            let screen = Point::new(projected.x, projected.y);
+            let dir = g.dir.map(|dir| {
+                [
+                    dir.x as f32 / (2.0 * half_w) * bounds.width,
+                    dir.y as f32 / (2.0 * half_h) * bounds.height,
+                ]
+            });
+            (g.id, screen, g.is_midpoint, g.shape, dir)
         })
         .collect()
 }
@@ -207,11 +228,18 @@ pub fn grips_to_screen_rte(
     grips
         .iter()
         .map(|g| {
-            let screen = match project_rte(g.world, view_rot, eye, bounds) {
+            let projected = project_rte(g.world, view_rot, eye, bounds);
+            let screen = match projected {
                 Some(p) => Point::new(bounds.x + p.x, bounds.y + p.y),
                 None => Point::new(f32::NAN, f32::NAN),
             };
-            (g.id, screen, g.is_midpoint, g.shape, g.dir)
+            let dir = g.dir.and_then(|dir| {
+                Some(marker_direction(
+                    projected?,
+                    project_rte(g.world + dir, view_rot, eye, bounds)?,
+                ))
+            });
+            (g.id, screen, g.is_midpoint, g.shape, dir)
         })
         .collect()
 }
diff --git a/src/ui/overlay.rs b/src/ui/overlay.rs
index 5b1d41d3d..0bb164047 100644
--- a/src/ui/overlay.rs
+++ b/src/ui/overlay.rs
@@ -81,9 +81,7 @@ pub struct GripMarker {
     pub is_hot: bool,
     /// True → pointer is over this grip (drawn with the hover fill).
     pub is_hovered: bool,
-    /// World-XY direction vector — only consumed by the `Rectangle`
-    /// shape to orient the box along its segment. `None` for grips
-    /// that don't need rotation.
+    /// Screen-plane direction with positive Y pointing up.
     pub dir: Option<[f32; 2]>,
 }
 
@@ -386,9 +384,20 @@ fn draw_grip_marker(frame: &mut canvas::Frame, grip: &GripMarker, theme: &Theme)
             })
         }
         GripShape::Triangle => canvas::Path::new(|b| {
-            b.move_to(Point::new(sp.x, sp.y - h));
-            b.line_to(Point::new(sp.x + h, sp.y + h));
-            b.line_to(Point::new(sp.x - h, sp.y + h));
+            let (forward_x, forward_y) = match grip.dir {
+                Some([dx, dy]) if (dx * dx + dy * dy) > 1e-12 => {
+                    let length = (dx * dx + dy * dy).sqrt();
+                    (dx / length, -dy / length)
+                }
+                _ => (0.0, -1.0),
+            };
+            let side_x = -forward_y;
+            let side_y = forward_x;
+            let tip = Point::new(sp.x + forward_x * h, sp.y + forward_y * h);
+            let base = Point::new(sp.x - forward_x * h, sp.y - forward_y * h);
+            b.move_to(tip);
+            b.line_to(Point::new(base.x + side_x * h, base.y + side_y * h));
+            b.line_to(Point::new(base.x - side_x * h, base.y - side_y * h));
             b.close();
         }),
         GripShape::Circle => canvas::Path::circle(Point::new(sp.x, sp.y), h),