diff --git a/src/entities/dimension.rs b/src/entities/dimension.rs
index dbceea692..e88295f9d 100644
--- a/src/entities/dimension.rs
+++ b/src/entities/dimension.rs
@@ -1120,12 +1120,13 @@ fn tessellate_dimension_inner(
     };
 
     let snap_pts = dimension_snap_pts(dim, world_offset);
-    let key_vertices: Vec<[f32; 3]> = geom
+    let key_vertices: Vec<[f64; 3]> = geom
         .dim_lines
         .iter()
         .chain(geom.ext_lines.iter())
         .copied()
         .filter(|p| !(p[0].is_nan() || p[1].is_nan() || p[2].is_nan()))
+        .map(|[x, y, z]| [x as f64, y as f64, z as f64])
         .collect();
 
     // DIMLWD (dim line + arrows) and DIMLWE (extension lines). Negative
diff --git a/src/entities/leader.rs b/src/entities/leader.rs
index 643a4dc56..c5b993bb9 100644
--- a/src/entities/leader.rs
+++ b/src/entities/leader.rs
@@ -623,7 +623,7 @@ impl LeaderTess for Leader {
 
         let mut points: Vec<[f32; 3]> = verts.iter().map(|v| p3(v)).collect();
         let mut tangents: Vec<TangentGeom> = Vec::new();
-        let key_vertices: Vec<[f32; 3]> = verts.iter().map(|v| p3(v)).collect();
+        let key_vertices: Vec<[f64; 3]> = verts.iter().map(|v| [v.x, v.y, v.z]).collect();
         let mut fill_tris: Vec<[f32; 3]> = Vec::new();
 
         for i in 0..verts.len().saturating_sub(1) {
diff --git a/src/entities/multileader.rs b/src/entities/multileader.rs
index 4bc8646df..c2a8222e8 100644
--- a/src/entities/multileader.rs
+++ b/src/entities/multileader.rs
@@ -1161,7 +1161,7 @@ impl MultiLeaderTess for MultiLeader {
 
         // ── Leader / arrow / dogleg points ───────────────────────────────────────
         let mut points: Vec<[f32; 3]> = Vec::new();
-        let mut key_verts: Vec<[f32; 3]> = Vec::new();
+        let mut key_verts: Vec<[f64; 3]> = Vec::new();
         let mut snap_pts: Vec<(glam::DVec3, SnapHint)> = Vec::new();
         let mut tangents: Vec<TangentGeom> = Vec::new();
         let mut arrow_fill: Vec<[f32; 3]> = Vec::new();
@@ -1209,7 +1209,7 @@ impl MultiLeaderTess for MultiLeader {
                         ctrl.push(cp_f);
                     }
                     for &c in &ctrl {
-                        key_verts.push(c);
+                        key_verts.push([c[0] as f64, c[1] as f64, c[2] as f64]);
                         snap_pts.push((Vec3::from(c).as_dvec3(), SnapHint::Node));
                     }
 
diff --git a/src/scene/cache/block_cache.rs b/src/scene/cache/block_cache.rs
index 2f73535e1..6c5dbff10 100644
--- a/src/scene/cache/block_cache.rs
+++ b/src/scene/cache/block_cache.rs
@@ -38,7 +38,7 @@ pub struct LocalWire {
     /// Low-bit residual paired with `points` so block-instance wires keep
     /// sub-f32 precision once the renderer translates them to world space.
     pub points_low: Vec<[f32; 3]>,
-    pub key_vertices: Vec<[f32; 3]>,
+    pub key_vertices: Vec<[f64; 3]>,
     pub snap_pts: Vec<(glam::DVec3, SnapHint)>,
     pub tangent_geoms: Vec<TangentGeom>,
     pub fill_tris: Vec<[f32; 3]>,
@@ -1042,7 +1042,7 @@ struct BatchEntry {
     points: Vec<[f32; 3]>,
     points_low: Vec<[f32; 3]>,
     snap_pts: Vec<(glam::DVec3, SnapHint)>,
-    key_vertices: Vec<[f32; 3]>,
+    key_vertices: Vec<[f64; 3]>,
     tangent_geoms: Vec<TangentGeom>,
     fill_tris: Vec<[f32; 3]>,
     min_x: f32,
@@ -1454,9 +1454,7 @@ fn emit_wire(
             p[1] as f64 + lo_y,
             p[2] as f64 + lo_z,
         ));
-        entry
-            .key_vertices
-            .push([(v.x - ox) as f32, (v.y - oy) as f32, (v.z - oz) as f32]);
+        entry.key_vertices.push([v.x - ox, v.y - oy, v.z - oz]);
     }
     for (p, hint) in &lw.snap_pts {
         let v = accum_xform.apply(Vector3::new(
diff --git a/src/scene/convert/tessellate.rs b/src/scene/convert/tessellate.rs
index fb859668e..d5064d566 100644
--- a/src/scene/convert/tessellate.rs
+++ b/src/scene/convert/tessellate.rs
@@ -213,10 +213,10 @@ pub fn tessellate(
                 }
 
                 let snap_pts = offset_snap_pts(te.snap_pts, world_offset);
-                let key_vertices: Vec<[f32; 3]> = te
+                let key_vertices: Vec<[f64; 3]> = te
                     .key_vertices
                     .into_iter()
-                    .map(|[x, y, z]| [(x - ox) as f32, (y - oy) as f32, (z - oz) as f32])
+                    .map(|[x, y, z]| [x - ox, y - oy, z - oz])
                     .collect();
 
                 // Empty input (no glyphs) → emit a single empty wire so the
@@ -293,12 +293,10 @@ pub fn tessellate(
                         let s = 0.1_f32;
                         let snap_pts = offset_snap_pts(te.snap_pts, world_offset);
                         let [ox, oy, oz] = world_offset;
-                        let key_vertices: Vec<[f32; 3]> = te
+                        let key_vertices: Vec<[f64; 3]> = te
                             .key_vertices
                             .into_iter()
-                            .map(|[kx, ky, kz]| {
-                                [(kx - ox) as f32, (ky - oy) as f32, (kz - oz) as f32]
-                            })
+                            .map(|[kx, ky, kz]| [kx - ox, ky - oy, kz - oz])
                             .collect();
                         return vec![WireModel {
                             name,
@@ -339,10 +337,10 @@ pub fn tessellate(
                 {
                     let [ox, oy, oz] = world_offset;
                     let snap_pts = offset_snap_pts(te.snap_pts, world_offset);
-                    let key_vertices: Vec<[f32; 3]> = te
+                    let key_vertices: Vec<[f64; 3]> = te
                         .key_vertices
                         .into_iter()
-                        .map(|[x, y, z]| [(x - ox) as f32, (y - oy) as f32, (z - oz) as f32])
+                        .map(|[x, y, z]| [x - ox, y - oy, z - oz])
                         .collect();
                     return vec![WireModel {
                         name,
@@ -372,10 +370,10 @@ pub fn tessellate(
                 {
                     let [ox, oy, oz] = world_offset;
                     let snap_pts = offset_snap_pts(te.snap_pts, world_offset);
-                    let key_vertices: Vec<[f32; 3]> = te
+                    let key_vertices: Vec<[f64; 3]> = te
                         .key_vertices
                         .into_iter()
-                        .map(|[x, y, z]| [(x - ox) as f32, (y - oy) as f32, (z - oz) as f32])
+                        .map(|[x, y, z]| [x - ox, y - oy, z - oz])
                         .collect();
                     return vec![WireModel {
                         name,
@@ -409,10 +407,10 @@ pub fn tessellate(
                 let [ox, oy, oz] = world_offset;
                 let (local_pts, local_pts_low) = offset_to_ds(points, world_offset);
                 let snap_pts = offset_snap_pts(te.snap_pts, world_offset);
-                let key_vertices: Vec<[f32; 3]> = te
+                let key_vertices: Vec<[f64; 3]> = te
                     .key_vertices
                     .into_iter()
-                    .map(|[x, y, z]| [(x - ox) as f32, (y - oy) as f32, (z - oz) as f32])
+                    .map(|[x, y, z]| [x - ox, y - oy, z - oz])
                     .collect();
                 let (fill_tris, fill_tris_low) = offset_to_ds(te.fill_tris, world_offset);
                 return vec![WireModel {
@@ -440,10 +438,10 @@ pub fn tessellate(
                 let [ox, oy, oz] = world_offset;
                 let (local_pts, local_pts_low) = offset_to_ds(points, world_offset);
                 let snap_pts = offset_snap_pts(te.snap_pts, world_offset);
-                let key_vertices: Vec<[f32; 3]> = te
+                let key_vertices: Vec<[f64; 3]> = te
                     .key_vertices
                     .into_iter()
-                    .map(|[x, y, z]| [(x - ox) as f32, (y - oy) as f32, (z - oz) as f32])
+                    .map(|[x, y, z]| [x - ox, y - oy, z - oz])
                     .collect();
                 return vec![WireModel {
                     name,
@@ -491,6 +489,10 @@ pub fn tessellate(
     // f64 for the WireModel's double-single-era snap buffer.
     let snap_pts: Vec<(glam::DVec3, SnapHint)> =
         snap_pts.into_iter().map(|(p, h)| (p.as_dvec3(), h)).collect();
+    let key_vertices: Vec<[f64; 3]> = key_vertices
+        .into_iter()
+        .map(|[x, y, z]| [x as f64, y as f64, z as f64])
+        .collect();
     vec![WireModel {
         name,
         points,
diff --git a/src/scene/mod.rs b/src/scene/mod.rs
index 831a76bcd..8bf7d5247 100644
--- a/src/scene/mod.rs
+++ b/src/scene/mod.rs
@@ -3270,14 +3270,14 @@ impl Scene {
                 for &[x, y, z] in &wire.key_vertices {
                     if x.is_finite() && y.is_finite() && z.is_finite() {
                         min = min.min(glam::Vec3::new(
-                            x + ox as f32,
-                            y + oy as f32,
-                            z + oz,
+                            (x + ox) as f32,
+                            (y + oy) as f32,
+                            (z + oz as f64) as f32,
                         ));
                         max = max.max(glam::Vec3::new(
-                            x + ox as f32,
-                            y + oy as f32,
-                            z + oz,
+                            (x + ox) as f32,
+                            (y + oy) as f32,
+                            (z + oz as f64) as f32,
                         ));
                         any = true;
                     }
@@ -8593,7 +8593,7 @@ fn lod_stub_wire(
         line_weight_px: 1.0,
         snap_pts: vec![],
         tangent_geoms: vec![],
-        key_vertices: vec![[cx, cy, cz]],
+        key_vertices: vec![[cx as f64, cy as f64, cz as f64]],
         aabb,
         plinegen: true,
         vp_scissor: None,
diff --git a/src/scene/model/wire_model.rs b/src/scene/model/wire_model.rs
index 88528a627..dba9cd46a 100644
--- a/src/scene/model/wire_model.rs
+++ b/src/scene/model/wire_model.rs
@@ -64,7 +64,7 @@ pub struct WireModel {
     /// True polyline vertices used for Endpoint/Midpoint snap.
     /// Non-empty only for entities with distinct vertex positions (Line, LwPolyline).
     /// Empty for tessellated curves (Circle, Arc, Ellipse) which use snap_pts instead.
-    pub key_vertices: Vec<[f32; 3]>,
+    pub key_vertices: Vec<[f64; 3]>,
     /// World-space 2-D bounding box [min_x, min_y, max_x, max_y].
     /// Set from acadrust `bounding_box()` in `tessellate_entity()`.
     /// Preview / interim wires use `UNBOUNDED_AABB` so they are never pre-rejected
diff --git a/src/scene/pick/xclip.rs b/src/scene/pick/xclip.rs
index 7ac225b05..98a5bff42 100644
--- a/src/scene/pick/xclip.rs
+++ b/src/scene/pick/xclip.rs
@@ -103,7 +103,7 @@ pub fn clip_wires(wires: &mut Vec<WireModel>, poly: &[[f32; 2]]) {
             w.fill_tris = clip_triangles(&w.fill_tris, poly);
         }
         w.key_vertices
-            .retain(|v| point_in_poly(v[0], v[1], poly));
+            .retain(|v| point_in_poly(v[0] as f32, v[1] as f32, poly));
         w.snap_pts.retain(|(p, _)| point_in_poly(p.x as f32, p.y as f32, poly));
         w.aabb = recompute_aabb(&w.points, &w.fill_tris);
     }
diff --git a/src/scene/pipeline/face3d_gpu.rs b/src/scene/pipeline/face3d_gpu.rs
index 3515e1745..b9dc35e39 100644
--- a/src/scene/pipeline/face3d_gpu.rs
+++ b/src/scene/pipeline/face3d_gpu.rs
@@ -126,11 +126,21 @@ impl Face3DGpu {
                 let fill_color = [r * 0.45, g * 0.45, b * 0.45, a];
                 let depth = depth_of(wire);
                 let p = &wire.key_vertices;
-                let v = |i: usize| Face3DVertex {
-                    position: p[i],
-                    color: fill_color,
-                    draw_depth: depth,
-                    position_low: [0.0; 3],
+                // key_vertices are f64 (offset-relative); split into the
+                // double-single (high, low) pair the face3d shader expects.
+                let v = |i: usize| {
+                    let [x, y, z] = p[i];
+                    let h = [x as f32, y as f32, z as f32];
+                    Face3DVertex {
+                        position: h,
+                        color: fill_color,
+                        draw_depth: depth,
+                        position_low: [
+                            (x - h[0] as f64) as f32,
+                            (y - h[1] as f64) as f32,
+                            (z - h[2] as f64) as f32,
+                        ],
+                    }
                 };
                 verts_3d.push(v(0));
                 verts_3d.push(v(1));
diff --git a/src/snap/mod.rs b/src/snap/mod.rs
index ef4803d26..5d70aa4c3 100644
--- a/src/snap/mod.rs
+++ b/src/snap/mod.rs
@@ -542,7 +542,10 @@ impl Snapper {
                 if !wire.key_vertices.is_empty() {
                     // Use explicit vertices (Line, LwPolyline): every vertex is an endpoint.
                     for &p in &wire.key_vertices {
-                        try_pt(Vec3::from(p), SnapType::Endpoint);
+                        try_pt(
+                            Vec3::new(p[0] as f32, p[1] as f32, p[2] as f32),
+                            SnapType::Endpoint,
+                        );
                     }
                 } else {
                     // Tessellated curves (Circle, Arc, Ellipse): only arc endpoints.
@@ -571,8 +574,8 @@ impl Snapper {
                 }
                 if !wire.key_vertices.is_empty() {
                     for seg in wire.key_vertices.windows(2) {
-                        let a = Vec3::from(seg[0]);
-                        let b = Vec3::from(seg[1]);
+                        let a = Vec3::new(seg[0][0] as f32, seg[0][1] as f32, seg[0][2] as f32);
+                        let b = Vec3::new(seg[1][0] as f32, seg[1][1] as f32, seg[1][2] as f32);
                         if a.distance_squared(b) > 1e-12 {
                             try_pt((a + b) * 0.5, SnapType::Midpoint);
                         }