Booleans stay in their component: a join, cut or intersect without explicit targets changes only its own component's bodies (and what it made), auto join/cut looks only at the active component; any feature takes participants: [bodies] to reach other components ("*" = every body); file format 5 gives older features in designs with components participants ["*"] so they keep their shape

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/engine/src/cmd/features.rs

@@ -139,7 +139,14 @@ pub fn auto_operation(s: &Session, p: &Value) -> Option<&'static str> {
     if st.bodies.is_empty() || !d.is_finite() {
         return Some("new");
     }
-    let inside = |q: Vec3| st.bodies.iter().any(|b| b.mesh().contains(q));
+    // Only the active component's bodies take part (or the ones named as participants).
+    let parts = string_list(p, "participants");
+    let inside = |q: Vec3| {
+        st.bodies
+            .iter()
+            .filter(|b| if parts.is_empty() { s.doc.body_component(&b.name, b.feature) == s.active_component } else { parts.contains(&b.name) })
+            .any(|b| b.mesh().contains(q))
+    };
     let eps = (d.abs() * 1e-3).max(1e-3);
     let sign = if d < 0.0 { -1.0 } else { 1.0 };
     if symmetric {
@@ -262,8 +269,13 @@ pub(super) fn add_feature(s: &mut Session, p: &Value, kind: FeatureKind) -> Resu
         let pts = kind.face_points();
         if pts.is_empty() { Vec::new() } else { solvecraft_doc::naming::face_names_at(&s.model.state(), &pts) }
     };
+    let participants = string_list(p, "participants");
+    if participants.len() > 10_000 || participants.iter().any(|b| b != "*" && s.model.state().body(b).is_none()) {
+        return Err(EngineError::Other("`participants` must list existing bodies".into()));
+    }
     let id = s.doc_mut().add_feature(kind, name)?;
     if let Some(f) = s.doc_mut().feature_mut(id) {
+        f.participants = participants;
         f.edge_refs = refs;
         f.edge_names = names;
         f.face_names = face_names;

crates/engine/src/tests.rs

@@ -1387,6 +1387,8 @@ fn tapped_and_clearance_holes() {
     assert!(rel(v2 - volume(&mut s), PI * 2.15 * 2.15 * 10.0) < 1e-3);
     assert!(s.execute("FusionHoleCommand", &json!({"position": [20, 25, 10], "clearance": "M7"})).is_err());
     assert!(s.execute("FusionHoleCommand", &json!({"position": [20, 25, 10]})).is_err());
+}
+
 /// In an inch design, a bare length typed into a feature means inches (stored with the unit);
 /// lengths with units and angles are left alone.
 #[test]
@@ -1427,3 +1429,30 @@ fn press_pull_on_curved_faces() {
     let v1 = volume(&mut s);
     assert!(rel(v1 - v0, PI * (25.0 - 16.0) * 20.0) < 1e-3, "{v0} {v1}");
 }
+
+/// A cut in one component leaves other components' bodies alone unless they are named as
+/// participants; auto join/cut looks at the active component only.
+#[test]
+fn booleans_stay_in_their_component() {
+    let mut s = Session::default();
+    for (name, x) in [("A", 0), ("B", 20)] {
+        run(&mut s, "component.activate", json!({"component": "root"}));
+        run(&mut s, "FusionCreateNewComponentCommand", json!({"name": name}));
+        run(&mut s, "PrimitiveBox", json!({"length": 20, "width": 10, "height": 10, "corner": [x, 0, 0], "body_name": format!("{name}Box")}));
+    }
+    // A's box spans x 0…20, B's x 20…40 (in their own frames, both occurrences in place).
+    run(&mut s, "component.activate", json!({"component": "A"}));
+    run(&mut s, "SketchCreate", json!({"plane": "XY", "name": "Slot"}));
+    run(&mut s, "ShapeRectangleTwoPoint", json!({"p0": [8, 2], "p1": [28, 8]}));
+    run(&mut s, "SketchStop", json!({}));
+    let vol = |s: &mut Session, b: &str| run(s, "MeasureCommand", json!({"bodies": [b]}))["total"]["volume_mm3"].as_f64().unwrap_or(0.0);
+    assert_eq!(auto_operation(&s, &json!({"sketch": "Slot", "distance": 10})), Some("cut"));
+    run(&mut s, "Extrude", json!({"sketch": "Slot", "distance": 10, "operation": "cut", "name": "Cut"}));
+    assert!((vol(&mut s, "ABox") - (2000.0 - 12.0 * 6.0 * 10.0)).abs() < 1e-6, "{}", vol(&mut s, "ABox"));
+    assert!((vol(&mut s, "BBox") - 2000.0).abs() < 1e-6, "B untouched: {}", vol(&mut s, "BBox"));
+    // Named as a participant, B is cut too.
+    run(&mut s, "UndoCommand", json!({}));
+    run(&mut s, "Extrude", json!({"sketch": "Slot", "distance": 10, "operation": "cut", "participants": ["ABox", "BBox"]}));
+    assert!((vol(&mut s, "BBox") - (2000.0 - 8.0 * 6.0 * 10.0)).abs() < 1e-6, "{}", vol(&mut s, "BBox"));
+    assert!(s.execute("Extrude", &json!({"sketch": "Slot", "distance": 1, "operation": "cut", "participants": ["Nope"]})).is_err());
+}