Refuse fillets and chamfers that run past their faces or cross each other (#1080) (#1124)

* Refuse fillets and chamfers that run past their faces or cross each other (#1080)

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* Blend fit: chamfers keep their old acceptance of crossed loops; skip the volume bound along tangent chains

Co-Authored-By: Claude Opus 5.5 <[email protected]>

* Blend fit: one selection per check, a coarse volume pass first; record the refused oversize blends in the action matrix baseline

Co-Authored-By: Claude Opus 5.5 <[email protected]>

---------

Co-authored-by: Claude Opus 5.5 <[email protected]>

crates/engine/src/tests/blend_fit.rs

@@ -0,0 +1,46 @@
+//! #1080: a fillet or chamfer too large for the geometry beside its edge is refused, naming the
+//! largest size that fits, and one that fits still builds.
+
+use std::path::Path;
+
+use serde_json::json;
+
+use super::{run, volume};
+use crate::Session;
+
+fn open_fixture() -> Session {
+    let path = Path::new(env!("CARGO_MANIFEST_DIR")).join("src/tests/fixtures/cubeish-chamfer-too-large.solidcraft");
+    let mut s = Session::default();
+    run(&mut s, "doc.open", json!({"path": path.to_string_lossy()}));
+    s
+}
+
+fn chamfer_error(s: &Session) -> Option<String> {
+    s.model.results.iter().find(|r| r.name == "Chamfer1").and_then(|r| r.error.clone())
+}
+
+/// The report's design: a 20 mm cube with a 10 mm square opening into each of three faces,
+/// then a 9 mm chamfer on the top edge over one side opening. The openings are 5 mm from the
+/// edge, so the chamfer would cut through their rims. It is refused, naming 5 mm, and the part
+/// is left as it was.
+#[test]
+fn chamfer_through_the_openings_is_refused() {
+    let mut s = open_fixture();
+    let err = chamfer_error(&s).expect("the 9 mm chamfer cuts through two openings: it must be refused");
+    assert!(err.contains("runs past the faces beside the edge"), "{err}");
+    assert!(err.contains("the largest size that fits is 5 mm"), "{err}");
+    assert!((volume(&mut s) - 4000.0).abs() < 1e-6, "the part stays as it was without the chamfer");
+}
+
+/// Sizes that stop short of the openings build, and take away exactly the chamfer's triangle
+/// along the 20 mm edge.
+#[test]
+fn chamfer_that_fits_still_builds() {
+    let mut s = open_fixture();
+    for d in [4.0, 5.0] {
+        run(&mut s, "timeline.edit", json!({"feature": "Chamfer1", "set": {"distance": format!("{d} mm")}}));
+        assert_eq!(chamfer_error(&s), None, "{d} mm fits");
+        let want = 4000.0 - 0.5 * d * d * 20.0;
+        assert!((volume(&mut s) - want).abs() < 1e-6, "{d} mm: {} (want {want})", volume(&mut s));
+    }
+}