fix: keep exact snapping, source drawing data and adaptive options layout

Resolve curve intersections through cadkernel, retain empty exact results, gather analytic candidates independently of tessellation, and bound material uploads. Preserve large MINSERT data while limiting rendering work; remove obsolete review narratives.

src/scene/render_graph.rs

@@ -1042,15 +1042,6 @@ pub fn document_block_uses(document: &CadDocument) -> Vec<BlockUse> {
     uses
 }
 
-/// A MINSERT's row/column counts are parsed `u16`s whose unchecked product
-/// (`Insert::instance_count`) would otherwise drive this function's
-/// allocation and a full per-instance render-graph walk after it — a corrupt
-/// or adversarial 65535x65535 pair requests over four billion instances (tens
-/// of GiB) long before any GPU-side chunking limit could help. The primary
-/// defense is the load-time filter in `io::is_entity_corrupt` (kept in sync
-/// with this constant), which drops such an insert before it ever reaches a
-/// `Scene`; this is the failsafe for an insert built or edited some other way
-/// (API/scripting) that skips that path.
 const MAX_MINSERT_INSTANCES: usize = 20_000;
 
 pub fn array_offsets(insert: &Insert) -> Vec<[f64; 3]> {
@@ -1093,16 +1084,6 @@ pub fn insert_instance_transform(
     if offset == [0.0; 3] {
         transform
     } else {
-        // Row/column spacing is defined in the insert's rotated/OCS-oriented
-        // space but is NOT subject to the block's x/y/z scale — this matches
-        // the pinned CAD model's own `Insert::array_points`, which rotates
-        // the offset but never scales it. Composing the raw offset ahead of
-        // the full (scaled) transform, as this used to do, let the block
-        // scale multiply the spacing too (e.g. an x-scale-2 insert with
-        // column spacing 10 would render 20 units between columns). Instead,
-        // orient the offset by rotation + OCS only, then translate the
-        // already-composed (scaled) instance transform by that world-space
-        // vector, applied after — never scaled.
         let orientation = Transform::from_matrix(Matrix4::rotation_z(insert.rotation))
             .then(&Transform::from_matrix(Matrix4::from_matrix3(Matrix3::arbitrary_axis(insert.normal))));
         let world_offset = orientation.apply_rotation(Vector3::new(offset[0], offset[1], offset[2]));
@@ -1201,10 +1182,6 @@ mod tests {
 
     #[test]
     fn array_offsets_clamps_pathological_minsert_counts() {
-        // A corrupt or adversarial row/column pair (parsed as u16, so this is
-        // reachable from a malformed file) must not drive a multi-billion-
-        // element allocation; the primary defense is the load-time filter in
-        // `io::is_entity_corrupt`, this is the render-graph-side failsafe.
         let mut insert = Insert::new("BLOCK", Vector3::ZERO);
         insert.row_count = u16::MAX;
         insert.column_count = u16::MAX;
@@ -1230,10 +1207,6 @@ mod tests {
 
     #[test]
     fn insert_instance_transform_does_not_scale_the_row_column_spacing() {
-        // github discussion-derived report: an INSERT with x-scale 2 and
-        // column spacing 10 was rendering 20 drawing units between columns
-        // instead of 10, because the offset translation was composed ahead
-        // of (and thus multiplied by) the block scale.
         let document = CadDocument::new();
         let mut insert = Insert::new("BLOCK", Vector3::new(100.0, 0.0, 0.0));
         insert.set_x_scale(2.0);