Carry hatch origin through creation and pattern editing

src/scene/entity.rs

@@ -1674,6 +1674,7 @@ impl Scene {
                 let fill_plane_boundary = Some(Arc::new(fill_plane.1));
                 let fill_plane = Some(fill_plane.0);
                 models.push(HatchModel {
+                    pattern_origin: None,
                     render_instance,
                     boundary: Arc::new(boundary),
                     boundary_wcs: None,
@@ -2107,6 +2108,7 @@ impl Scene {
 
         let storage = crate::entities::curve::ocs_plane(dxf.normal, dxf.elevation);
         Some(HatchModel {
+            pattern_origin: Some([dxf.pattern_origin().x, dxf.pattern_origin().y]),
             render_instance: None,
             boundary: std::sync::Arc::new(boundary_f32),
             boundary_wcs: None,
@@ -2429,6 +2431,7 @@ impl Scene {
             })
             .collect();
         HatchModel {
+            pattern_origin: None,
             render_instance: None,
             boundary: std::sync::Arc::new(boundary),
             boundary_wcs: None,
@@ -2663,6 +2666,9 @@ impl Scene {
         // carries `world_origin: [0, 0]`, which after the world_offset removal
         // leaves the fill mis-placed and effectively invisible until a later
         // edit rebuilds it from the DXF — so keep the seed, don't overwrite it.
+        if let Some(origin) = model.pattern_origin {
+            dxf.record_pattern_origin(Vector2::new(origin[0], origin[1]));
+        }
         let mut entity = EntityType::Hatch(dxf);
 
         if let Some(layer) = layer {

src/scene/mod.rs

@@ -3794,6 +3794,7 @@ impl Scene {
         let ((x0, y0), (x1, y1)) = self.paper_limits()?;
         let (x0, y0, x1, y1) = (x0 as f32, y0 as f32, x1 as f32, y1 as f32);
         Some(HatchModel {
+            pattern_origin: None,
             render_instance: None,
             world_origin: [0.0, 0.0],
             boundary: Arc::new(vec![[x0, y0], [x1, y0], [x1, y1], [x0, y1], [x0, y0]]),

src/scene/model/hatch_model.rs

@@ -208,6 +208,8 @@ pub struct FillPlane {
 /// A hatched region defined by a closed polygon boundary.
 #[derive(Clone, Debug)]
 pub struct HatchModel {
+    /// Recorded hatch origin in its fill plane, independent of intrinsic PAT line bases.
+    pub pattern_origin: Option<[f64; 2]>,
     pub render_instance: Option<super::instance_model::RenderInstance>,
     /// World XY anchor (in the same offset-relative coordinate space as
     /// the rest of the scene — `world_offset` already subtracted, but

src/scene/preview.rs

@@ -154,6 +154,7 @@ impl Scene {
             return None;
         }
         let mut model = HatchModel {
+            pattern_origin: None,
             render_instance: None,
             world_origin: origin,
             boundary: std::sync::Arc::new(boundary),

src/scene/view/render.rs

@@ -2886,6 +2886,7 @@ impl Scene {
                 }
                 boundary.push(boundary[0]);
                 hatches.push(HatchModel {
+                    pattern_origin: None,
                     render_instance: wire.render_instance.clone(),
                     world_origin: [0.0, 0.0],
                     boundary: Arc::new(boundary),