fix(model): repair solid selection flows

src/modules/model/boolean_cmd.rs

@@ -1,6 +1,7 @@
-// Boolean operations on 3D solids. The actual CSG runs in
-// `App::solid_boolean` (src/app/model_ops.rs) using the kernel on the
-// cached B-reps; this module just names the operations.
+use acadrust::{EntityType, Handle};
+use glam::DVec3;
+
+use crate::command::{CadCommand, CmdResult, SelectionEntity};
 
 /// Which boolean operation to apply to selected solids.
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
@@ -21,6 +22,86 @@ impl BoolOp {
     }
 }
 
+enum SubtractStep {
+    Bases,
+    Cutters,
+}
+
+pub struct SubtractCommand {
+    step: SubtractStep,
+    bases: Vec<Handle>,
+    selected: Vec<Handle>,
+}
+
+impl SubtractCommand {
+    pub fn new(bases: Vec<Handle>) -> Self {
+        let step = if bases.is_empty() {
+            SubtractStep::Bases
+        } else {
+            SubtractStep::Cutters
+        };
+        Self {
+            step,
+            bases,
+            selected: Vec::new(),
+        }
+    }
+}
+
+impl CadCommand for SubtractCommand {
+    fn name(&self) -> &'static str {
+        "SUBTRACT"
+    }
+
+    fn prompt(&self) -> String {
+        match self.step {
+            SubtractStep::Bases => crate::t!("SUBTRACT  Select base solids, then press Enter:")
+                .into_owned(),
+            SubtractStep::Cutters => {
+                crate::t!("SUBTRACT  Select solids to subtract, then press Enter:").into_owned()
+            }
+        }
+    }
+
+    fn on_point(&mut self, _point: DVec3) -> CmdResult {
+        CmdResult::NeedPoint
+    }
+
+    fn on_enter(&mut self) -> CmdResult {
+        if self.selected.is_empty() {
+            return CmdResult::NeedPoint;
+        }
+        match self.step {
+            SubtractStep::Bases => {
+                self.bases = std::mem::take(&mut self.selected);
+                self.step = SubtractStep::Cutters;
+                CmdResult::DeselectAndContinue
+            }
+            SubtractStep::Cutters => CmdResult::SolidSubtract {
+                bases: std::mem::take(&mut self.bases),
+                cutters: std::mem::take(&mut self.selected),
+            },
+        }
+    }
+
+    fn is_selection_gathering(&self) -> bool {
+        true
+    }
+
+    fn inject_selection_entities(&mut self, entities: Vec<SelectionEntity>) {
+        self.selected = entities
+            .into_iter()
+            .filter_map(|entity| {
+                matches!(entity.entity, EntityType::Solid3D(_)).then_some(entity.handle)
+            })
+            .collect();
+    }
+
+    fn on_selection_complete(&mut self, _handles: Vec<Handle>) -> CmdResult {
+        CmdResult::NeedPoint
+    }
+}
+
 // ── Autocomplete registry ─────────────────────────────────
 inventory::submit!(crate::command::CommandRegistration {
     names: &["UNION", "SUBTRACT", "INTERSECT"]