refactor(tess): rename LegacyTess → FallbackTess

The trait isn't deprecating anything — it carries the path entities
take when they're not covered by the truck topology pipeline
(Viewport, Insert, Hatch outline, Ole2Frame). "Fallback" names the
purpose; "Legacy" implied retirement that isn't actually on the
roadmap.

Same rename for LegacyGeometry → FallbackGeometry,
legacy_geometry() → fallback_geometry().

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/entities/hatch.rs

@@ -3,9 +3,9 @@ use glam::Vec3;
 
 use crate::command::EntityTransform;
 use crate::entities::common::{diamond_grip, edit_prop as edit, parse_f64, ro_prop as ro};
-use crate::entities::traits::{Grippable, LegacyTess, PropertyEditable, Transformable};
+use crate::entities::traits::{Grippable, FallbackTess, PropertyEditable, Transformable};
 use crate::scene::object::{GripApply, GripDef, PropSection, PropValue, Property};
-use crate::scene::tess_util::{arc_segments, arc_signed_span, wire_chord_tol, LegacyGeometry};
+use crate::scene::tess_util::{arc_segments, arc_signed_span, wire_chord_tol, FallbackGeometry};
 use crate::scene::wire_model::SnapHint;
 
 fn properties(h: &Hatch) -> PropSection {
@@ -350,8 +350,8 @@ impl Grippable for Hatch {
     }
 }
 
-impl LegacyTess for Hatch {
+impl FallbackTess for Hatch {
-    fn legacy_geometry(&self, world_offset: [f64; 3]) -> LegacyGeometry {
+    fn fallback_geometry(&self, world_offset: [f64; 3]) -> FallbackGeometry {
         let [ox, oy, oz] = world_offset;
         let normal = (self.normal.x, self.normal.y, self.normal.z);
         // Convert a 2D OCS hatch boundary point to WCS, then subtract world_offset.

src/entities/insert.rs

@@ -119,8 +119,8 @@ impl Transformable for Insert {
     }
 }
 
-impl crate::entities::traits::LegacyTess for Insert {
+impl crate::entities::traits::FallbackTess for Insert {
-    fn legacy_geometry(&self, world_offset: [f64; 3]) -> crate::scene::tess_util::LegacyGeometry {
+    fn fallback_geometry(&self, world_offset: [f64; 3]) -> crate::scene::tess_util::FallbackGeometry {
         let [ox, oy, oz] = world_offset;
         let ip = Vec3::new(
             (self.insert_point.x - ox) as f32,

src/entities/ole2frame.rs

@@ -202,8 +202,8 @@ impl Transformable for Ole2Frame {
     }
 }
 
-impl crate::entities::traits::LegacyTess for Ole2Frame {
+impl crate::entities::traits::FallbackTess for Ole2Frame {
-    fn legacy_geometry(&self, world_offset: [f64; 3]) -> crate::scene::tess_util::LegacyGeometry {
+    fn fallback_geometry(&self, world_offset: [f64; 3]) -> crate::scene::tess_util::FallbackGeometry {
         // OLE objects carry a bounding rectangle in model space.
         // Render a simple X-through-rectangle placeholder.
         let [ox, oy, oz] = world_offset;

src/entities/traits.rs

@@ -3,18 +3,18 @@ use acadrust::{CadDocument, EntityType};
 use crate::command::EntityTransform;
 use crate::scene::acad_to_truck::TruckEntity;
 use crate::scene::object::{GripApply, GripDef, PropSection};
-use crate::scene::tess_util::LegacyGeometry;
+use crate::scene::tess_util::FallbackGeometry;
 
 pub trait TruckConvertible {
     fn to_truck(&self, document: &CadDocument) -> Option<TruckEntity>;
 }
 
-/// Legacy fallback geometry for entities not covered by the truck
+/// Fallback geometry for entities not routed through the truck topology
-/// topology pipeline (Viewport, Insert, Hatch outline, Ole2Frame, …).
+/// pipeline (Viewport, Insert, Hatch outline, Ole2Frame). Returns
-/// Returns world-offset-relative `f32` points + snap/key vertices the
+/// world-offset-relative `f32` points + snap/key vertices the
 /// dispatcher wraps into a `WireModel`.
-pub trait LegacyTess {
+pub trait FallbackTess {
-    fn legacy_geometry(&self, world_offset: [f64; 3]) -> LegacyGeometry;
+    fn fallback_geometry(&self, world_offset: [f64; 3]) -> FallbackGeometry;
 }
 
 pub trait Grippable {

src/entities/viewport.rs

@@ -567,8 +567,8 @@ impl Transformable for Viewport {
     }
 }
 
-impl crate::entities::traits::LegacyTess for Viewport {
+impl crate::entities::traits::FallbackTess for Viewport {
-    fn legacy_geometry(&self, world_offset: [f64; 3]) -> crate::scene::tess_util::LegacyGeometry {
+    fn fallback_geometry(&self, world_offset: [f64; 3]) -> crate::scene::tess_util::FallbackGeometry {
         let [ox, oy, oz] = world_offset;
         let cx = (self.center.x - ox) as f32;
         let cy = (self.center.y - oy) as f32;

src/scene/mod.rs

@@ -1275,7 +1275,7 @@ impl Scene {
                 return false;
             }
             // Block/BlockEnd are block-defn sentinels, not drawable geometry.
-            // Without this skip they fall through to legacy_geometry's `_`
+            // Without this skip they fall through to fallback_geometry's `_`
             // arm and emit a 1-unit phantom segment at world_offset that
             // poisons fit_all and shows up in selection.
             if matches!(e, EntityType::Block(_) | EntityType::BlockEnd(_)) {

src/scene/tess_util.rs

@@ -10,14 +10,13 @@ use glam::Vec3;
 
 use crate::scene::wire_model::{SnapHint, TangentGeom, WireModel};
 
-/// Output of the legacy per-entity geometry path used by entities not
+/// Output of the fallback per-entity geometry path used by entities not
-/// (yet) covered by the truck topology pipeline (Viewport, Insert,
+/// covered by the truck topology pipeline (Viewport, Insert, Hatch
-/// Hatch outline, Ole2Frame, …). Tuple form preserved to avoid
+/// outline, Ole2Frame). Tuple form preserved to avoid touching every
-/// touching every callsite when the dispatcher wraps these into a
+/// callsite when the dispatcher wraps these into a WireModel.
-/// WireModel.
 ///
 /// Layout: `(points, snap_pts, tangent_geoms, key_vertices)`.
-pub type LegacyGeometry = (
+pub type FallbackGeometry = (
     Vec<[f32; 3]>,
     Vec<(Vec3, SnapHint)>,
     Vec<TangentGeom>,

src/scene/tessellate.rs

@@ -10,8 +10,8 @@
 //   TruckTessResult::Mesh  → MeshModel
 //   TruckObject::Text      → one WireModel per glyph stroke (elevation from entity Z)
 //
-// Entities not handled by acad_to_truck (Viewport, Hatch, …) are tessellated
+// Entities not handled by acad_to_truck (Viewport, Insert, Hatch, Ole2Frame)
-// by the legacy geometry() path so nothing regresses.
+// are tessellated by the FallbackTess fallback_geometry() path.
 
 use crate::entities::leader::LeaderTess;
 use acadrust::types::Color as AcadColor;
@@ -428,8 +428,8 @@ pub fn tessellate(
         }
     }
 
-    // ── Legacy fallback for Viewport and other unhandled types ────────────
+    // ── Fallback for Viewport / Insert / Hatch / Ole2Frame ────────────────
-    let (points, snap_pts, tangent_geoms, key_vertices) = legacy_geometry(entity, world_offset);
+    let (points, snap_pts, tangent_geoms, key_vertices) = fallback_geometry(entity, world_offset);
     vec![WireModel {
         name,
         points,
@@ -603,21 +603,21 @@ pub(crate) fn entity_z(entity: &EntityType) -> f32 {
     }
 }
 
-// ── Legacy geometry (Viewport, Hatch outline, unrecognised) ───────────────
+// ── Fallback geometry (Viewport, Insert, Hatch outline, Ole2Frame) ───────
 //
 // Per-entity blocks have moved to their respective `entities/*.rs` files
-// (Viewport, Insert, Hatch, Ole2Frame) via the `LegacyTess` trait. This
+// (Viewport, Insert, Hatch, Ole2Frame) via the `FallbackTess` trait. This
 // function stays as the dispatcher used by the main `tessellate()` path.
 
-use crate::entities::traits::LegacyTess;
+use crate::entities::traits::FallbackTess;
-use crate::scene::tess_util::LegacyGeometry as Geometry;
+use crate::scene::tess_util::FallbackGeometry as Geometry;
 
-fn legacy_geometry(entity: &EntityType, world_offset: [f64; 3]) -> Geometry {
+fn fallback_geometry(entity: &EntityType, world_offset: [f64; 3]) -> Geometry {
     match entity {
-        EntityType::Viewport(vp) => vp.legacy_geometry(world_offset),
+        EntityType::Viewport(vp) => vp.fallback_geometry(world_offset),
-        EntityType::Insert(ins) => ins.legacy_geometry(world_offset),
+        EntityType::Insert(ins) => ins.fallback_geometry(world_offset),
-        EntityType::Hatch(h) => h.legacy_geometry(world_offset),
+        EntityType::Hatch(h) => h.fallback_geometry(world_offset),
-        EntityType::Ole2Frame(ole) => ole.legacy_geometry(world_offset),
+        EntityType::Ole2Frame(ole) => ole.fallback_geometry(world_offset),
         _ => {
             let s = 0.5_f32;
             (vec![[-s, 0.0, 0.0], [s, 0.0, 0.0]], vec![], vec![], vec![])