face.delete heal: false leaves an open surface body (#861)

Delete Face takes heal (default true, as before). With heal: false the picked faces are removed and the gap stays open, leaving the remaining faces as a surface body (kernel remove_faces); deleting every face is refused. Saved only when false, noted under format 18.

crates/doc/src/document.rs

@@ -607,6 +607,10 @@ pub enum FeatureKind {
         faces: Vec<Vec3>,
         #[serde(default, skip_serializing_if = "Option::is_none")]
         body: Option<String>,
+        /// Close the gap by extending the neighbouring faces (the default); `false` leaves it
+        /// open, the faces left a surface body.
+        #[serde(default = "yes", skip_serializing_if = "is_yes")]
+        heal: bool,
     },
     /// A box around bodies, grown by a margin.
     BoundingSolid {
@@ -1745,6 +1749,14 @@ fn all_profiles() -> ProfileSel {
     ProfileSel::All
 }
 
+fn yes() -> bool {
+    true
+}
+
+fn is_yes(b: &bool) -> bool {
+    *b
+}
+
 fn zero_expr() -> String {
     "0".into()
 }

crates/doc/src/eval.rs

@@ -4134,7 +4134,7 @@ fn eval_feature(doc: &Document, vals: &BTreeMap<String, Value>, f: &Feature, st:
             }
             Ok(())
         }
-        FeatureKind::DeleteFace { faces, body } => {
+        FeatureKind::DeleteFace { faces, body, heal } => {
             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();
@@ -4146,7 +4146,8 @@ fn eval_feature(doc: &Document, vals: &BTreeMap<String, Value>, f: &Feature, st:
                 }
             }
             let all = kernel::with_same_surface(&mb.body, &picked);
-            let nb = Traced::step(kernel::delete_faces(&mb.body, &all)?, &[&mb.traced()]);
+            let left = if *heal { kernel::delete_faces(&mb.body, &all)? } else { kernel::remove_faces(&mb.body, &all)? };
+            let nb = Traced::step(left, &[&mb.traced()]);
             if let Some(slot) = st.bodies.get_mut(i) {
                 *slot = ModelBody::traced_new(mb.name, nb, mb.feature);
             }

crates/doc/src/format.rs

@@ -113,6 +113,9 @@
 //!   `letter_spacing` (mm), `line_spacing` (times the font's line distance), `path` (the id of a
 //!   curve of the same sketch the baseline follows) and `reverse`. A text without `style` is set
 //!   as it always was; 0.9.0 would drop the style and set the text plain, off its curve.
+//!   Under the same version, Delete Face can leave the gap open (`heal: false` on the feature:
+//!   the faces left are a surface body); a Delete Face without it heals, as it always did, and
+//!   saves as before. 0.9.0 would heal a gap the design leaves open.
 
 use serde_json::Value;