From 648f0ff76840d42d85d2dc921e41ba2c8e152563 Mon Sep 17 00:00:00 2001
From: bherbruck <brennen.herbruck@gmail.com>
Date: Tue, 13 Oct 2026 19:44:46 -0400
Subject: [PATCH] Open large designs faster: count the cache budget without
 cloning wires (#911)

Body::retained_bytes counts face and edge uses on the borrowed boundaries (the same numbers, checked by a test), and each model body keeps the footprint measured when a feature made or changed it, so the evaluation cache's budget no longer walks every body's topology after every feature.
---
 crates/doc/src/eval.rs     |  8 +++++++-
 crates/kernel/src/body.rs  | 11 ++++++++++-
 crates/kernel/src/tests.rs | 14 ++++++++++++++
 3 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/crates/doc/src/eval.rs b/crates/doc/src/eval.rs
index c09d6253..8a5ca8c5 100644
--- a/crates/doc/src/eval.rs
+++ b/crates/doc/src/eval.rs
@@ -44,6 +44,9 @@ pub struct ModelBody {
     pub transferred: bool,
     /// The look it was imported with, carried through later features.
     pub imported: Option<Arc<crate::appearance::ImportedLook>>,
+    /// [`Body::retained_bytes`] of `body`, measured when a feature made or changed it (0: not
+    /// measured), so the evaluation cache's budget does not walk every body after every feature.
+    bytes: usize,
 }
 
 impl ModelBody {
@@ -62,6 +65,7 @@ impl ModelBody {
             component: 0,
             transferred: false,
             imported: None,
+            bytes: 0,
         }
     }
     pub fn definition_name(&self) -> &str {
@@ -486,6 +490,7 @@ impl ModelState {
                 Some(x) => {
                     b.key = x.key;
                     b.names = x.names.clone();
+                    b.bytes = if x.bytes > 0 { x.bytes } else { b.body.retained_bytes() };
                 }
                 None => {
                     let mut h = std::collections::hash_map::DefaultHasher::new();
@@ -507,6 +512,7 @@ impl ModelState {
                     {
                         b.imported = crate::appearance::ImportedLook::of(old);
                     }
+                    b.bytes = b.body.retained_bytes();
                 }
             }
         }
@@ -597,7 +603,7 @@ impl ModelState {
     /// topology is what makes a kept timeline snapshot expensive, so it dominates; sketches
     /// and the rest are counted from their entity counts.
     pub fn retained_bytes(&self) -> usize {
-        let bodies: usize = self.bodies.iter().map(|b| b.body.retained_bytes()).sum();
+        let bodies: usize = self.bodies.iter().map(|b| if b.bytes > 0 { b.bytes } else { b.body.retained_bytes() }).sum();
         let sketches: usize = self.sketches.iter().map(|s| s.retained_bytes()).sum();
         bodies + sketches + self.sheets.len() * 4096 + self.threads.len() * 192 + self.construct.len() * 192
     }
diff --git a/crates/kernel/src/body.rs b/crates/kernel/src/body.rs
index 211cfcd8..a0e9710f 100644
--- a/crates/kernel/src/body.rs
+++ b/crates/kernel/src/body.rs
@@ -939,7 +939,16 @@ impl Body {
         if let Some(m) = &self.mesh {
             return m.positions.len() * 24 + m.triangles.len() * 12;
         }
-        self.solid.face_iter().count() * 2048 + self.solid.edge_iter().count() * 512 + self.solid.vertex_iter().count() * 96
+        // Counted on the borrowed boundaries: `Solid::edge_iter` and `vertex_iter` clone every
+        // face's wires to walk them, which made this estimate (taken after every feature, over
+        // every body) cost more than evaluating most features. Each edge use is one edge and
+        // one vertex in those iterators, so the counts are the same.
+        let (mut faces, mut uses) = (0usize, 0usize);
+        for face in self.solid.face_iter() {
+            faces += 1;
+            uses += face.absolute_boundaries().iter().map(|w| w.len()).sum::<usize>();
+        }
+        faces * 2048 + uses * (512 + 96)
     }
 
     /// Distinct edges in a stable order (the order of `edges()` and `tessellate().edges`).
diff --git a/crates/kernel/src/tests.rs b/crates/kernel/src/tests.rs
index abd2a89a..6d180db6 100644
--- a/crates/kernel/src/tests.rs
+++ b/crates/kernel/src/tests.rs
@@ -2312,3 +2312,17 @@ fn shell_of_a_disc_rounded_smaller_than_the_wall() {
         }
     }
 }
+
+/// The cache-budget estimate counts edge and vertex uses on the borrowed boundaries; it must
+/// equal what walking the cloned wires (`Solid::edge_iter`, `vertex_iter`) counts.
+#[test]
+fn retained_bytes_matches_the_iterator_counts() {
+    let block = box_solid(Vec3::ZERO, Vec3::new(40.0, 30.0, 10.0)).unwrap();
+    let hole = cylinder(Vec3::new(20.0, 15.0, -5.0), Vec3::Z, 5.0, 30.0).unwrap();
+    let drilled = boolean(&block, &hole, BoolOp::Cut).unwrap().unwrap();
+    for body in [&block, &hole, &drilled] {
+        let s = &body.solid;
+        let walked = s.face_iter().count() * 2048 + s.edge_iter().count() * 512 + s.vertex_iter().count() * 96;
+        assert_eq!(body.retained_bytes(), walked);
+    }
+}