fix(render): match model lineweight preview curve

src/scene/pipeline/uniforms.rs

@@ -25,8 +25,9 @@ pub struct Uniforms {
     /// zooming inside MSPACE changes one scalar instead of re-tessellating and
     /// re-uploading every dashed wire.
     pub linetype_scale: f32,
-    /// Multiplier for screen-space lineweights. Model space uses the user's
-    /// preview scale; paper layouts derive it from the current paper zoom.
+    /// Positive values scale paper-space lineweights directly. Negative values
+    /// carry the model-space preview scale; lineweight shaders then apply the
+    /// model preview curve before multiplying by its magnitude.
     pub lineweight_scale: f32,
 
     // ── Relative-to-eye (double-single) additions ───────────────────────────

src/scene/view/render.rs

@@ -3848,7 +3848,7 @@ impl Scene {
             self.document.header.lineweight_display || display_plot_lineweights,
         );
         if self.current_layout == "Model" {
-            uniforms.lineweight_scale = self.model_lineweight_scale;
+            uniforms.lineweight_scale = -self.model_lineweight_scale;
         } else {
             let paper_per_pixel = 2.0 * self.camera.borrow().ortho_size() / canvas.1.max(1.0);
             let paper_units_per_mm = self.paper_space_unit_factor() as f32;