diff --git a/src/modules/home/inquiry/area.rs b/src/modules/home/inquiry/area.rs
index fbeb227fc..060a10579 100644
--- a/src/modules/home/inquiry/area.rs
+++ b/src/modules/home/inquiry/area.rs
@@ -41,14 +41,14 @@ impl CadCommand for AreaCommand {
         if self.points.len() < 3 {
             return CmdResult::Cancel;
         }
-        // Shoelace formula in the XZ plane (Y-up world)
+        // Shoelace formula in the world XY plane.
         let n = self.points.len();
         let mut area_sum = 0.0f32;
         let mut perimeter = 0.0f32;
         for idx in 0..n {
             let a = self.points[idx];
             let b = self.points[(idx + 1) % n];
-            area_sum += a.x * b.z - b.x * a.z;
+            area_sum += a.x * b.y - b.x * a.y;
             perimeter += (b - a).length();
         }
         let area = (area_sum * 0.5).abs();
diff --git a/src/modules/home/inquiry/dist.rs b/src/modules/home/inquiry/dist.rs
index 4c179f2ad..7290c5917 100644
--- a/src/modules/home/inquiry/dist.rs
+++ b/src/modules/home/inquiry/dist.rs
@@ -33,10 +33,10 @@ impl CadCommand for DistCommand {
             let delta = pt - p1;
             let dist = delta.length();
             let dx = delta.x;
-            let dy = delta.z; // Y-up world: Z is the "drawing Y"
-            let dz = delta.y; // Y-up world: Y is elevation
+            let dy = delta.y; // drawing plane is world XY
+            let dz = delta.z; // elevation
 
-            // Angle in XY plane (XZ in world coords) — degrees from +X
+            // Angle in XY plane — degrees from +X
             let angle_xy = dy.atan2(dx).to_degrees();
             // Angle from XY plane toward Z (elevation angle)
             let dist_xy = dx.hypot(dy);
diff --git a/src/modules/home/inquiry/id.rs b/src/modules/home/inquiry/id.rs
index e8e8540d5..ac4aa2ed1 100644
--- a/src/modules/home/inquiry/id.rs
+++ b/src/modules/home/inquiry/id.rs
@@ -22,10 +22,10 @@ impl CadCommand for IdCommand {
     }
 
     fn on_point(&mut self, pt: Vec3) -> CmdResult {
-        // Y-up world: X stays X, Z→drawing Y, Y→elevation Z
+        // Drawing plane is world XY (z = elevation).
         let x = pt.x;
-        let y = pt.z;
-        let z = pt.y;
+        let y = pt.y;
+        let z = pt.z;
         let msg = format!("X = {x:.4},  Y = {y:.4},  Z = {z:.4}");
         CmdResult::Measurement(msg)
     }
diff --git a/src/modules/home/modify/align.rs b/src/modules/home/modify/align.rs
index 0947a7460..5b76bb756 100644
--- a/src/modules/home/modify/align.rs
+++ b/src/modules/home/modify/align.rs
@@ -167,9 +167,9 @@ impl AlignCommand {
             );
         }
 
-        // Angle from src_vec to dst_vec in XZ plane
-        let src_angle = src_vec.z.atan2(src_vec.x);
-        let dst_angle = dst_vec.z.atan2(dst_vec.x);
+        // Angle from src_vec to dst_vec in the world XY plane
+        let src_angle = src_vec.y.atan2(src_vec.x);
+        let dst_angle = dst_vec.y.atan2(dst_vec.x);
         let angle = dst_angle - src_angle;
 
         let scale_factor = if with_scale { dst_len / src_len } else { 1.0 };
diff --git a/src/modules/home/modify/fillet.rs b/src/modules/home/modify/fillet.rs
index 729899f07..d81b873b7 100644
--- a/src/modules/home/modify/fillet.rs
+++ b/src/modules/home/modify/fillet.rs
@@ -1246,7 +1246,7 @@ impl CadCommand for FilletCommand {
         if handle.is_null() {
             return CmdResult::NeedPoint;
         }
-        let click = [pt.x as f64, pt.z as f64]; // Y-up: world Z = DXF Y
+        let click = [pt.x as f64, pt.y as f64]; // drawing plane is world XY
 
         match &self.step {
             FilletStep::WaitingForRadius => return CmdResult::NeedPoint,
@@ -1324,7 +1324,7 @@ impl CadCommand for FilletCommand {
         if handle.is_null() {
             return vec![];
         }
-        let click = [pt.x as f64, pt.z as f64];
+        let click = [pt.x as f64, pt.y as f64];
 
         match &self.step {
             FilletStep::WaitingForRadius => vec![],
diff --git a/src/modules/home/modify/lengthen.rs b/src/modules/home/modify/lengthen.rs
index e530e5878..5823b6a15 100644
--- a/src/modules/home/modify/lengthen.rs
+++ b/src/modules/home/modify/lengthen.rs
@@ -150,9 +150,9 @@ pub fn lengthen_entity(entity: &EntityType, pick_pt: Vec3, mode: &LenMode) -> Op
 }
 
 fn lengthen_line(line: &LineEnt, pick_pt: Vec3, mode: &LenMode) -> Option<EntityType> {
-    let s = Vec3::new(line.start.x as f32, line.start.z as f32, 0.0);
-    let e = Vec3::new(line.end.x as f32, line.end.z as f32, 0.0);
-    let p = Vec3::new(pick_pt.x, pick_pt.z, 0.0);
+    let s = Vec3::new(line.start.x as f32, line.start.y as f32, 0.0);
+    let e = Vec3::new(line.end.x as f32, line.end.y as f32, 0.0);
+    let p = Vec3::new(pick_pt.x, pick_pt.y, 0.0);
 
     let current_len = (e - s).length() as f64;
     if current_len < 1e-10 {
@@ -187,7 +187,7 @@ fn lengthen_line(line: &LineEnt, pick_pt: Vec3, mode: &LenMode) -> Option<Entity
 
 fn lengthen_arc(arc: &ArcEnt, pick_pt: Vec3, mode: &LenMode) -> Option<EntityType> {
     let cx = arc.center.x as f32;
-    let cy = arc.center.z as f32; // Y-up: DXF Y → world Z
+    let cy = arc.center.y as f32;
 
     // Current arc span
     let span = arc_span_rad(arc.start_angle, arc.end_angle);
@@ -290,7 +290,7 @@ fn lengthen_ellipse(ell: &EllipseEnt, pick_pt: Vec3, mode: &LenMode) -> Option<E
 
     // Determine which end is closer to pick_pt (use DXF XY plane).
     let p_x = pick_pt.x as f64;
-    let p_y = pick_pt.z as f64; // Y-up: world Z → DXF Y
+    let p_y = pick_pt.y as f64; // Y-up: world Z → DXF Y
     let pt_start_x = ell.center.x + a * t0.cos() * nx - b * t0.sin() * ny;
     let pt_start_y = ell.center.y + a * t0.cos() * ny + b * t0.sin() * nx;
     let pt_end_x = ell.center.x + a * t1.cos() * nx - b * t1.sin() * ny;
@@ -339,7 +339,7 @@ fn lengthen_lwpoly(poly: &LwPolyline, pick_pt: Vec3, mode: &LenMode) -> Option<E
 
     // Determine which end is closer to the pick point (DXF XY: pick_pt.x, pick_pt.z).
     let px = pick_pt.x as f64;
-    let py = pick_pt.z as f64; // Y-up: world Z = DXF Y
+    let py = pick_pt.y as f64; // Y-up: world Z = DXF Y
 
     let first = &poly.vertices[0];
     let last = &poly.vertices[n - 1];
@@ -428,8 +428,8 @@ fn lengthen_spline(spl: &SplineEnt, pick_pt: Vec3, mode: &LenMode) -> Option<Ent
     // Determine which end (start or end) is closer to pick_pt.
     let p_start = bs.subs(t0);
     let p_end = bs.subs(t1);
-    let dist_start = (p_start.x - pick_pt.x as f64).hypot(p_start.y - pick_pt.z as f64);
-    let dist_end = (p_end.x - pick_pt.x as f64).hypot(p_end.y - pick_pt.z as f64);
+    let dist_start = (p_start.x - pick_pt.x as f64).hypot(p_start.y - pick_pt.y as f64);
+    let dist_end = (p_end.x - pick_pt.x as f64).hypot(p_end.y - pick_pt.y as f64);
     let extend_end = dist_end <= dist_start;
 
     // Find the parameter `t_new` such that the arc length from the fixed end to t_new = new_len.