Split Face (FusionSplitFaceCommand): a timeline feature dividing the picked faces where a plane, another body's face (its surface extended) or a sketch's curves meet them, through kernel::split_faces; the solid is unchanged and the pieces take the face's name with #k. Rebase fixes: duplicate Chamfer and Combine specs; the Delete selection's face test expects Delete Face's refusal

Co-Authored-By: Claude Opus 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/doc/src/assembly.rs

@@ -162,6 +162,13 @@ impl FeatureKind {
                     pt(&mut t.point);
                 }
             }
+            FeatureKind::SplitFace { faces, plane, tool, .. } => {
+                faces.iter_mut().for_each(pt);
+                map_plane_ref(m, plane);
+                if let Some(t) = tool {
+                    pt(&mut t.point);
+                }
+            }
             FeatureKind::Revolve { axis: AxisRef::Line { origin, dir: d }, .. } => {
                 pt(origin);
                 dir(d);

crates/doc/src/clipboard.rs

@@ -40,6 +40,12 @@ impl FeatureKind {
             FeatureKind::Sketch { plane, .. } | FeatureKind::ConstructionPlane { plane } | FeatureKind::Split { plane, .. } => {
                 plane_names(plane, names)
             }
+            FeatureKind::SplitFace { plane, sketch, .. } => {
+                plane_names(plane, names);
+                if let Some(s) = sketch {
+                    sk(s);
+                }
+            }
             FeatureKind::Extrude { sketch, .. }
             | FeatureKind::Revolve { sketch, .. }
             | FeatureKind::Emboss { sketch, .. }

crates/doc/src/document.rs

@@ -355,6 +355,19 @@ pub enum FeatureKind {
         #[serde(default, skip_serializing_if = "Option::is_none")]
         tool: Option<FaceAt>,
     },
+    /// Split faces (at the given points) where a tool meets them, the solid unchanged: a plane,
+    /// a face of a body (`tool`, its surface extended) or a sketch's curves (`sketch`, swept
+    /// along its normal). The pieces are named after the face (`#k`).
+    SplitFace {
+        faces: Vec<Vec3>,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        body: Option<String>,
+        plane: PlaneRef,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        tool: Option<FaceAt>,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        sketch: Option<u64>,
+    },
     /// Scale bodies about a point (uniform, or per axis).
     Scale {
         bodies: Vec<String>,
@@ -936,6 +949,7 @@ impl FeatureKind {
             FeatureKind::Shell { .. } => "ShellFeature",
             FeatureKind::Draft { .. } => "DraftFeature",
             FeatureKind::Split { .. } => "SplitBodyFeature",
+            FeatureKind::SplitFace { .. } => "SplitFaceFeature",
             FeatureKind::Move { .. } => "MoveFeature",
             FeatureKind::Scale { .. } => "ScaleFeature",
             FeatureKind::OffsetFace { .. } => "OffsetFacesFeature",
@@ -997,6 +1011,7 @@ impl FeatureKind {
             FeatureKind::Shell { .. } => "Shell",
             FeatureKind::Draft { .. } => "Draft",
             FeatureKind::Split { .. } => "Split",
+            FeatureKind::SplitFace { .. } => "SplitFace",
             FeatureKind::Move { .. } => "Move",
             FeatureKind::Scale { .. } => "Scale",
             FeatureKind::OffsetFace { .. } => "OffsetFace",
@@ -1042,6 +1057,7 @@ impl FeatureKind {
             | FeatureKind::Draft { faces, .. }
             | FeatureKind::OffsetFace { faces, .. }
             | FeatureKind::DeleteFace { faces, .. }
+            | FeatureKind::SplitFace { faces, .. }
             | FeatureKind::ReplaceFace { faces, .. } => faces.iter_mut().collect(),
             FeatureKind::Hole { position, points: None, to, .. } => std::iter::once(position).chain(to.iter_mut()).collect(),
             FeatureKind::Hole { to: Some(t), .. } => vec![t],
@@ -1060,9 +1076,10 @@ impl FeatureKind {
     pub fn expressions(&self) -> Vec<&str> {
         let mut v: Vec<&str> = Vec::new();
         match self {
-            FeatureKind::Sketch { plane, .. } | FeatureKind::ConstructionPlane { plane } | FeatureKind::Split { plane, .. } => {
-                plane_exprs(plane, &mut v)
-            }
+            FeatureKind::Sketch { plane, .. }
+            | FeatureKind::ConstructionPlane { plane }
+            | FeatureKind::Split { plane, .. }
+            | FeatureKind::SplitFace { plane, .. } => plane_exprs(plane, &mut v),
             FeatureKind::Extrude { extent, .. } => {
                 v.push(&extent.distance);
                 if let Some(d) = &extent.distance2 {
@@ -1551,7 +1568,7 @@ impl Document {
                 FeatureKind::Pattern { pattern: PatternKind::Path { path_sketch, .. }, .. } if *path_sketch == id => gone.push(f.id),
                 FeatureKind::Emboss { sketch, .. } | FeatureKind::Rib { sketch, .. } if *sketch == id => gone.push(f.id),
                 FeatureKind::SheetBase { sketch, .. } | FeatureKind::SheetContour { sketch, .. } if *sketch == id => gone.push(f.id),
-                FeatureKind::SheetFold { sketch: Some(s), .. } if *s == id => gone.push(f.id),
+                FeatureKind::SheetFold { sketch: Some(s), .. } | FeatureKind::SplitFace { sketch: Some(s), .. } if *s == id => gone.push(f.id),
                 _ => {}
             }
         }

crates/doc/src/eval.rs

@@ -2414,6 +2414,46 @@ fn eval_feature(doc: &Document, vals: &BTreeMap<String, Value>, f: &Feature, st:
             }
             apply_op(st, f, made, *operation, &[])
         }
+        FeatureKind::SplitFace { faces, body, plane, tool, sketch } => {
+            let i = body_at(st, body, faces)?;
+            let Some(mb) = st.bodies.get(i).cloned() else { return Err(DocError::Invalid("body".into())) };
+            let mut picked: Vec<usize> = Vec::new();
+            for p in faces {
+                let fi = crate::appearance::face_index_at(&mb, *p)
+                    .ok_or_else(|| DocError::Invalid(format!("Split Face: no face of {} at {p:?}", mb.name)))?;
+                if !picked.contains(&fi) {
+                    picked.push(fi);
+                }
+            }
+            let nb = match (tool, sketch) {
+                (Some(t), _) => {
+                    let tb = st.body(&t.body).ok_or_else(|| DocError::Unknown(format!("body `{}`", t.body)))?;
+                    let face = crate::appearance::face_index_at(tb, t.point)
+                        .ok_or_else(|| DocError::Invalid(format!("no face of `{}` at the tool point", t.body)))?;
+                    kernel::split_faces(&mb.body, &picked, &kernel::SplitTool::Face { body: &tb.body, face })?
+                }
+                (None, Some(sid)) => {
+                    let ss = st.sketch(*sid).ok_or_else(|| DocError::Unknown(format!("sketch {sid}")))?;
+                    let curves: Vec<Vec<Vec2>> = (0..ss.sketch.curves.len())
+                        .filter(|ci| ss.sketch.curves.get(*ci).is_some_and(|c| !c.construction))
+                        .map(|ci| ss.sketch.polyline(ci))
+                        .filter(|pl| pl.len() >= 2)
+                        .collect();
+                    if curves.is_empty() {
+                        return Err(DocError::Invalid(format!("sketch `{}` has no curves to split with", ss.name)));
+                    }
+                    kernel::split_faces(&mb.body, &picked, &kernel::SplitTool::Curves { plane: ss.plane, curves })?
+                }
+                (None, None) => {
+                    let pl = doc.resolve_plane(vals, plane, 0)?;
+                    kernel::split_faces(&mb.body, &picked, &kernel::SplitTool::Plane(pl))?
+                }
+            };
+            if let Some(slot) = st.bodies.get_mut(i) {
+                *slot = ModelBody::new(mb.name, nb, mb.feature);
+            }
+            Ok(())
+        }
         FeatureKind::Split { body, plane, tool } => {
             let i = st.bodies.iter().position(|b| &b.name == body).ok_or_else(|| DocError::Unknown(format!("body `{body}`")))?;
             let Some(mb) = st.bodies.get(i).cloned() else { return Err(DocError::Unknown(format!("body `{body}`"))) };

crates/doc/src/params.rs

@@ -34,6 +34,7 @@ impl FeatureKind {
             FeatureKind::Sketch { plane, .. }
             | FeatureKind::ConstructionPlane { plane }
             | FeatureKind::Split { plane, .. }
+            | FeatureKind::SplitFace { plane, .. }
             | FeatureKind::Mirror { plane, .. } => plane_inputs_mut(plane, &mut v),
             FeatureKind::Extrude { extent, .. } => {
                 v.push(("Distance", &mut extent.distance, L));

crates/engine/src/cmd/delete.rs

@@ -231,7 +231,8 @@ mod tests {
         let (mut s, _) = part();
         let b = s.model.state().bodies[0].name.clone();
         let e = s.execute("selection.delete", &json!({"items": [{"type": "face", "body": b, "index": 0, "point": [0, 0, 0]}]})).unwrap_err();
-        assert!(e.to_string().contains("not available yet"), "{e}");
+        // A side of the part its neighbours can't close: Delete Face refuses it.
+        assert!(e.to_string().contains("Delete Face"), "{e}");
         for p in [
             json!({}),
             json!({"items": "x"}),

crates/engine/src/cmd/features.rs

@@ -33,8 +33,6 @@ pub static COMMANDS: &[CommandSpec] = &[
         .key("F")
         .params("edges: [[x,y,z] point on edge | {body, index}]; radius: expr; body?; type?: constant|chord (radius is the width across)|variable (radius at the end nearest start, radius2 at the other); radius2?; start?: [x,y,z]"),
     CommandSpec::new("solid.chamfer", "Chamfer", chamfer).at("SOLID", "MODIFY").icon("chamfer").params("edges: [[x,y,z] | {body, index}]; distance: expr; distance2?: expr (along the second face) | angle?: expr (from the first face); flip?: bool (which face is first: by default the one facing up most); body?"),
-    CommandSpec::new("solid.combine", "Combine", combine).at("SOLID", "MODIFY").icon("combine").params("target: body; tools: [body]; operation?: join|cut|intersect; keep_tools?: bool"),
-    CommandSpec::new("solid.chamfer", "Chamfer", chamfer).at("SOLID", "MODIFY").icon("chamfer").params("edges: [[x,y,z] | {body, index}]; distance: expr; body?"),
     CommandSpec::new("solid.combine", "Combine", combine).at("SOLID", "MODIFY").icon("combine").params("target: body; tools: [body]; operation?: join|cut|intersect; keep_tools?: bool; new_component?: bool (the result goes into a new component; component_name?)"),
     CommandSpec::new("solid.pattern.rectangular", "Rectangular Pattern", pattern_rect)
         .at("SOLID", "CREATE")
@@ -94,6 +92,12 @@ pub static COMMANDS: &[CommandSpec] = &[
         .at("SOLID", "CONSTRUCT")
         .icon("plane")
         .params("base: XY|XZ|YZ|plane name; axis: X|Y|Z|{origin, dir}; angle: expr; name?"),
+    CommandSpec::new("solid.split_face", "Split Face", split_face)
+        .at("SOLID", "MODIFY")
+        .icon("split")
+        .params(
+            "faces: [[x,y,z] points on the faces to split]; body?; and the splitting tool: plane: XY|XZ|YZ|plane name|{origin, normal} — or tool: {body, point} (a face of a body, its surface extended) — or sketch: id or name (its curves, along the sketch's normal)",
+        ),
     CommandSpec::new("solid.split_body", "Split Body", split_body)
         .at("SOLID", "MODIFY")
         .icon("split")
@@ -835,6 +839,25 @@ fn plane_angle(s: &mut Session, p: &Value) -> Result<Value> {
     )
 }
 
+fn split_face(s: &mut Session, p: &Value) -> Result<Value> {
+    let cmd = "solid.split_face";
+    let faces = face_points(p, cmd)?;
+    let body = str_(p, "body").map(str::to_string);
+    let xy = || solvecraft_doc::PlaneRef::Origin { name: "XY".into() };
+    let kind = if let Some(t) = p.get("tool").filter(|t| !t.is_null()) {
+        let tb = t.get("body").and_then(Value::as_str).ok_or_else(|| bad(cmd, "`tool.body` must name a body"))?.to_string();
+        let point = t.get("point").and_then(crate::params::vec3).ok_or_else(|| bad(cmd, "`tool.point` must be [x, y, z] on the tool face"))?;
+        FeatureKind::SplitFace { faces, body, plane: xy(), tool: Some(solvecraft_doc::FaceAt { body: tb, point }), sketch: None }
+    } else if p.get("sketch").is_some_and(|v| !v.is_null()) {
+        let sketch = sketch_id(s, p.get("sketch"), cmd, "sketch")?;
+        FeatureKind::SplitFace { faces, body, plane: xy(), tool: None, sketch: Some(sketch) }
+    } else {
+        let plane = plane_param(s, p.get("plane"), cmd)?;
+        FeatureKind::SplitFace { faces, body, plane, tool: None, sketch: None }
+    };
+    add_feature(s, p, kind)
+}
+
 fn split_body(s: &mut Session, p: &Value) -> Result<Value> {
     let cmd = "solid.split_body";
     let body = str_(p, "body").ok_or_else(|| bad(cmd, "`body` is required"))?.to_string();

crates/engine/src/lib.rs

@@ -430,6 +430,8 @@ mod delete_face_tests;
 #[cfg(test)]
 mod extent_tests;
 #[cfg(test)]
+mod split_face_tests;
+#[cfg(test)]
 mod tests;
 #[cfg(test)]
 mod thread_tests;

crates/engine/src/split_face_tests.rs

@@ -0,0 +1,64 @@
+//! Split Face: the top of a box divided by a plane, by another body's face and by sketch curves.
+
+use serde_json::{Value, json};
+
+use crate::Session;
+
+fn run(s: &mut Session, id: &str, p: Value) -> Value {
+    match s.execute(id, &p) {
+        Ok(v) => v,
+        Err(e) => panic!("{id} {p}: {e}"),
+    }
+}
+
+/// (kernel faces, volume) of a body: the merged count joins pieces of one surface back up.
+fn faces_volume(s: &mut Session, b: &str) -> (u64, f64) {
+    let m = run(s, "inspect.measure", json!({ "bodies": [b] }))["bodies"][0].clone();
+    (m["kernel"]["faces"].as_u64().unwrap_or(0), m["volume_mm3"].as_f64().unwrap_or(0.0))
+}
+
+fn boxed() -> Session {
+    let mut s = Session::default();
+    run(&mut s, "solid.box", json!({"length": 40, "width": 30, "height": 20, "body_name": "B"}));
+    s
+}
+
+#[test]
+fn split_a_face_by_a_plane() {
+    let mut s = boxed();
+    run(&mut s, "solid.split_face", json!({"faces": [[10, 15, 20]], "plane": {"origin": [20, 0, 0], "normal": [1, 0, 0]}}));
+    let (f, v) = faces_volume(&mut s, "B");
+    assert_eq!(f, 7);
+    assert!((v - 24000.0).abs() < 1e-6 * 24000.0, "{v}");
+    assert_eq!(s.doc.features.last().unwrap().kind.type_name(), "SplitFaceFeature");
+}
+
+#[test]
+fn split_a_face_by_another_bodys_face() {
+    let mut s = boxed();
+    run(&mut s, "solid.box", json!({"corner": [-5, 10, 25], "length": 50, "width": 5, "height": 5, "body_name": "Tool"}));
+    // The tool's face at y = 10, extended down through the box's top.
+    run(&mut s, "solid.split_face", json!({"faces": [[20, 5, 20]], "body": "B", "tool": {"body": "Tool", "point": [20, 10, 27]}}));
+    assert_eq!(faces_volume(&mut s, "B").0, 7);
+}
+
+#[test]
+fn split_a_face_by_sketch_curves() {
+    let mut s = boxed();
+    run(&mut s, "sketch.create", json!({"plane": "XY", "name": "Cuts"}));
+    run(&mut s, "sketch.line", json!({"points": [[10, -5], [10, 35]]}));
+    run(&mut s, "sketch.line", json!({"points": [[30, -5], [30, 35]]}));
+    run(&mut s, "sketch.finish", json!({}));
+    run(&mut s, "solid.split_face", json!({"faces": [[20, 15, 20]], "body": "B", "sketch": "Cuts"}));
+    let (f, v) = faces_volume(&mut s, "B");
+    assert_eq!(f, 8, "two lines make three pieces of the top");
+    assert!((v - 24000.0).abs() < 1e-6 * 24000.0, "{v}");
+}
+
+#[test]
+fn a_tool_that_misses_is_refused() {
+    let mut s = boxed();
+    let n = s.doc.features.len();
+    assert!(s.execute("solid.split_face", &json!({"faces": [[10, 15, 20]], "plane": {"origin": [100, 0, 0], "normal": [1, 0, 0]}})).is_err());
+    assert_eq!(s.doc.features.len(), n);
+}