X and the toolbar's Construction no longer start a pick tool (Fusion has none): with a selection they convert it, with nothing selected they switch construction mode, outside a sketch they say so. Center Rectangle draws both diagonals as construction, the centre at their crossing, with only the first carrying the midpoint constraint (the second is implied), so a fresh one stays at 4 DOF. Scenarios s30 (pattern a hole) and s32 (cut in the active component) enabled now that b36b332 is on main

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

crates/engine/src/cmd/sketch.rs

@@ -552,10 +552,16 @@ fn rect_center(s: &mut Session, p: &Value) -> Result<Value> {
     let (out, info) = edit(s, p, cmd, false, |sk, _| {
         let (l, pts) = polygon_lines(sk, &[c - h, Vec2::new(c.x + h.x, c.y - h.y), c + h, Vec2::new(c.x - h.x, c.y + h.y)])?;
         let mut cons = rect_constraints(sk, &l)?;
-        if let (Some(p0), Some(p2)) = (pts.first(), pts.get(2)) {
+        // Both diagonals (construction), the centre at their crossing. Only the first carries
+        // the midpoint constraint: diagonals of a parallelogram bisect each other, so a second
+        // one would be redundant (over-constrained).
+        if let (Some(p0), Some(p1), Some(p2), Some(p3)) = (pts.first(), pts.get(1), pts.get(2), pts.get(3)) {
             let diag = sk.add_line_pts(*p0, *p2, None)?;
-            if let Some(cu) = sk.curves.get_mut(diag) {
-                cu.construction = true;
+            let diag2 = sk.add_line_pts(*p1, *p3, None)?;
+            for d in [diag, diag2] {
+                if let Some(cu) = sk.curves.get_mut(d) {
+                    cu.construction = true;
+                }
             }
             let cp = sk.add_point(c, None)?;
             cons.push(add_c(sk, ConstraintKind::Midpoint { p: cp, l: diag })?);

crates/engine/src/cmd/sketch_rect_tests.rs

@@ -101,3 +101,19 @@ fn dragging_corners_never_collapses_a_side() {
         }
     }
 }
+
+#[test]
+fn center_rectangle_draws_both_diagonals_like_fusion() {
+    let (mut s, _) = rect("center");
+    let si = run(&mut s, "sketch.inspect", json!({}));
+    let curves = si["curves"].as_array().cloned().unwrap_or_default();
+    // Four sides plus two construction diagonals; the other rectangles have no diagonals.
+    assert_eq!(curves.len(), 6, "{si}");
+    assert_eq!(curves.iter().filter(|c| c["construction"] == true).count(), 2, "{si}");
+    assert_eq!(healthy(&mut s, "center diagonals"), 4);
+    for k in ["two", "three"] {
+        let (mut s, _) = rect(k);
+        let si = run(&mut s, "sketch.inspect", json!({}));
+        assert_eq!(si["curves"].as_array().map(Vec::len), Some(4), "{k}: {si}");
+    }
+}

crates/ui-egui/src/lib.rs

@@ -420,8 +420,8 @@ impl SolveApp {
             }
         }
         // Construction toggle: selected sketch curves switch at once, otherwise pick them.
-        // Construction (X): convert the selection, or switch construction mode.
-        if id == "sketch.construction" && self.session.active_sketch.is_some() {
+        // Construction (X): convert the selection, or switch construction mode; no pick tool.
+        if id == "sketch.construction" {
             sketch_palette::toggle_construction(self);
             return;
         }

crates/ui-egui/src/sketch_palette.rs

@@ -75,7 +75,9 @@ pub fn set_mode(app: &mut SolveApp, m: u8) {
 /// switch construction mode on or off.
 pub fn toggle_construction(app: &mut SolveApp) {
     let curves = selected_curves(app);
-    if curves.is_empty() {
+    if curves.is_empty() && app.session.active_sketch.is_none() {
+        app.set_status("Construction mode is for drawing in a sketch: edit a sketch first", false);
+    } else if curves.is_empty() {
         let m = if mode(app) == 1 { 0 } else { 1 };
         set_mode(app, m);
     } else {

crates/ui-egui/src/tools.rs

@@ -65,7 +65,6 @@ impl Tool {
             "ConstraintCollinear" => ("ConstraintCollinear", Kind::Pick(2)),
             "ConstraintMidPoint" => ("ConstraintMidPoint", Kind::Pick(2)),
             "ConstraintSymmetry" => ("ConstraintSymmetry", Kind::Pick(3)),
-            "sketch.construction" => ("sketch.construction", Kind::Pick(1)),
             _ => return crate::sketch_tools::tool_for(id),
         };
         Some(Tool { cmd, kind, pts: Vec::new(), hover: None, picks: Vec::new(), dims: Vec::new(), dims_stage: usize::MAX, dims_focus: false })
@@ -280,7 +279,6 @@ fn run_pick(app: &mut SolveApp, t: &Tool) {
     let params = match t.cmd {
         "ConstraintHorizontalVertical" => json!({"line": k[0]}),
         "ConstraintFix" => json!({"entity": k[0]}),
-        "sketch.construction" => json!({"curves": [k[0]]}),
         "ConstraintCoincident" => json!({"a": k[0], "b": k[1]}),
         "ConstraintMidPoint" => json!({"point": k[0], "line": k[1]}),
         "ConstraintSymmetry" => json!({"a": k[0], "b": k[1], "line": k[2]}),

crates/ui-egui/tests/scenarios.rs

@@ -53,7 +53,9 @@ scenarios!(
     s33_move_x_arrow,
     s34_component_move_carries_sketches,
     s35_construction_mode,
-    s36_sketch_palette_visible
+    s36_sketch_palette_visible,
+    s32_cut_in_active_component,
+    s30_pattern_a_hole
 );
 
 /// Scenarios written ahead of their fixes or features (the user's open bugs): run with
@@ -70,6 +72,4 @@ macro_rules! pending {
 
 pending!(
     s31_sketch_on_face_projects: "user bug: a sketch on a face projects its loops as reference (solvecraft-sketch)",
-    s32_cut_in_active_component: "user bug: a cut in the active component leaves others alone (solvecraft-params)",
-    s30_pattern_a_hole: "the dialog sends the hole as a feature; the engine's pattern of a blind hole cuts too little (one hole short)",
 );