Perf/mesh collision (#1307)

Thanks @Ian-cmd-ops.

crates/kernel/Cargo.toml

@@ -25,4 +25,7 @@ spade = { workspace = true }
 rayon = { workspace = true }
 
 [dev-dependencies]
+# The vendored crate tests never build in CI, so its equivalence checks run from kernel tests.
+# Resolver 3 keeps this dev-only feature out of shipped builds.
+truck-meshalgo = { workspace = true, features = ["test-hooks"] }
 proptest = { version = "1", default-features = false, features = ["std"] }

crates/kernel/tests/mesh_collision_equivalence.rs

@@ -0,0 +1,24 @@
+//! Equivalence checks for SolidCraft's changes to the vendored truck crates.
+//!
+//! The vendored crates are outside the workspace, so their own tests never run in CI. Each
+//! change that replaces an algorithm keeps the old one behind the crate's `test-hooks` feature
+//! (on only for these tests) and these tests check the new one gives the same answers.
+
+use truck_meshalgo::analyzers::collision_test_hooks as collision;
+
+/// Mesh collision candidate search (sweep with per-triangle boxes): same collisions, same order.
+#[test]
+fn mesh_collision_same_as_before() {
+    match collision::same_collisions_in_the_same_order(0..200) {
+        Ok(n) => assert!(n > 0, "the random meshes produced no collisions to compare"),
+        Err(e) => panic!("{e}"),
+    }
+}
+
+/// NaN coordinates in a mesh: the collision search goes on without a panic.
+#[test]
+fn mesh_collision_nan_triangles_do_not_panic() {
+    if let Err(e) = collision::nan_triangles_do_not_panic() {
+        panic!("{e}");
+    }
+}