⚡ drop identity matrices before FFI output

render-wasm/src/shapes/modifiers.rs

@@ -482,11 +482,8 @@ pub fn propagate_modifiers(
         // are already reflowed before their parents.
         let mut layout_reflows_vec: Vec<Uuid> =
             std::mem::take(&mut layout_reflows).into_iter().collect();
-        layout_reflows_vec.sort_unstable_by(|id_a, id_b| {
-            let da = shapes.get_depth(id_a);
-            let db = shapes.get_depth(id_b);
-            db.cmp(&da)
-        });
+        // Deepest-first; cache get_depth (O(depth) parent walk) per id.
+        layout_reflows_vec.sort_by_cached_key(|id| std::cmp::Reverse(shapes.get_depth(id)));
 
         // This temporary bounds is necesary so the layouts can be calculated
         // correctly but will be discarded before the next iteration for the
@@ -501,8 +498,11 @@ pub fn propagate_modifiers(
         }
     }
 
+    // Drop identity matrices: the reflow-mark inserts a no-op entry for every
+    // descendant of a reflowed subtree; emitting them floods the FFI output.
     Ok(modifiers
         .iter()
+        .filter(|(_, val)| !identitish(val))
         .map(|(key, val)| TransformEntry::from_input(*key, *val))
         .collect())
 }

render-wasm/src/shapes/modifiers/constraints.rs

@@ -1,5 +1,5 @@
 use crate::error::{Error, Result};
-use crate::math::{is_move_only_matrix, Bounds, Matrix};
+use crate::math::{is_close_to, is_move_only_matrix, Bounds, Matrix};
 use crate::shapes::{ConstraintH, ConstraintV};
 
 pub fn calculate_resize(
@@ -36,7 +36,9 @@ pub fn calculate_resize(
         _ => 1.0,
     };
 
-    if (scale_width - 1.0).abs() < f32::EPSILON && (scale_height - 1.0).abs() < f32::EPSILON {
+    // 0.001 threshold (not f32::EPSILON) so near-identity resizes short-circuit
+    // before building the per-child parent matrix.
+    if is_close_to(scale_width, 1.0) && is_close_to(scale_height, 1.0) {
         None
     } else {
         Some((scale_width, scale_height))
@@ -91,7 +93,7 @@ pub fn calculate_displacement(
         _ => 0.0,
     };
 
-    if delta_x.abs() < f32::EPSILON && delta_y.abs() < f32::EPSILON {
+    if is_close_to(delta_x, 0.0) && is_close_to(delta_y, 0.0) {
         None
     } else {
         Some((delta_x, delta_y))

render-wasm/src/shapes/modifiers/grid_layout.rs

@@ -684,15 +684,13 @@ fn child_frame_aabb(child_bounds: &Bounds, hv: Vector, vv: Vector) -> (f32, f32,
 
 fn child_position(
     child: &Shape,
-    layout_bounds: &Bounds,
+    hv: Vector,
+    vv: Vector,
     layout_data: &LayoutData,
     child_bounds: &Bounds,
     layout_item: Option<LayoutItem>,
     cell: &CellData,
 ) -> Point {
-    let hv = layout_bounds.hv(1.0);
-    let vv = layout_bounds.vv(1.0);
-
     let margin_left = layout_item.map(|i| i.margin_left).unwrap_or(0.0);
     let margin_top = layout_item.map(|i| i.margin_top).unwrap_or(0.0);
     let margin_right = layout_item.map(|i| i.margin_right).unwrap_or(0.0);
@@ -779,13 +777,14 @@ pub fn reflow_grid_layout(
         false,
     );
 
+    // hv/vv are loop-invariant; compute once instead of per cell and per child.
+    let hv = layout_bounds.hv(1.0);
+    let vv = layout_bounds.vv(1.0);
+
     for cell in cells.iter() {
         let Some(child) = cell.shape else { continue };
         let child_bounds = bounds.find(child);
 
-        // Compute frame-axis projections once; used for both sizing and positioning.
-        let hv = layout_bounds.hv(1.0);
-        let vv = layout_bounds.vv(1.0);
         let (h_min, v_min, child_frame_w, child_frame_h) = child_frame_aabb(&child_bounds, hv, vv);
 
         // resize_matrix scales the child in the parent's local frame coordinate system
@@ -842,7 +841,8 @@ pub fn reflow_grid_layout(
 
         let position = child_position(
             child,
-            &layout_bounds,
+            hv,
+            vv,
             layout_data,
             &child_bounds,
             child.layout_item,