Shape Builder: double-clicking the tool opens Shape Builder Tool Options

Double-clicking the Shape Builder tool reported that the tool has no
options. The reference app opens Shape Builder Tool Options there.

The dialog sets Consider Open Filled Paths as Closed, Pick Color From
(Artwork or Color Swatches), Cursor Swatch Preview, Selection (Freeform
or Straight Line) and Highlight Fill. The defaults keep today's
behavior. With Consider Open Filled Paths as Closed off, a filled open
path cuts regions as an unfilled one does. With Color Swatches, a merge
fills the new shape with the current fill, and the Left and Right arrow
keys step the current fill through the document's color swatches.
Cursor Swatch Preview shows the current fill and the swatches before
and after it above the pointer. With Straight Line, a drag merges what
the line from its first point to its last crosses. With Highlight Fill
off, merge mode shades no regions.

The options persist like other tools' options. shapeBuilder.merge
takes openFilledAsClosed and pickColorFrom, and shapeBuilder.regions
takes openFilledAsClosed. Gap Detection, "In Merge Mode, Clicking
Stroke Splits the Path" and Highlight Stroke When Editable are not part
of this change.

Docs: docs/mcp.md, docs/target-app-parity.md.

crates/engine/src/cmd/buildcmds.rs

@@ -39,7 +39,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Shape Builder",
             [],
             None,
-            "{ids?|id?: [id…] (default: selection), points: [[x,y]…] (drag path; one point = click), erase?: bool (erase mode, Alt: deletes the regions touched, and the pieces of unfilled open paths and the edges (outline pieces between the points where paths meet; see shapeBuilder.regions) within tolerance; a deleted edge opens its path there, and edges bounding a deleted region go with it), tolerance?: pt (2, erase only), fill?: \"#rrggbb\" | {color|swatch|gradient|none} (default: the fill of the object under the first point; the current fill for an area only lines enclose)} → {ids, merged, regions, lines, edges} (counts deleted or merged)",
+            "{ids?|id?: [id…] (default: selection), points: [[x,y]…] (drag path; one point = click), erase?: bool (erase mode, Alt: deletes the regions touched, and the pieces of open paths that cut regions and the edges (outline pieces between the points where paths meet; see shapeBuilder.regions) within tolerance; a deleted edge opens its path there, and edges bounding a deleted region go with it), tolerance?: pt (2, erase only), openFilledAsClosed?: true (Consider Open Filled Paths as Closed: a filled open path bounds a region as if an invisible edge closed it; false: it cuts the regions it crosses like an unfilled one), pickColorFrom?: \"artwork\" (default: the merged shape takes the fill of the front-most object over the first region the drag touches that an object covers; the current fill when only lines enclose every region touched) | \"swatches\" (the current fill), fill?: \"#rrggbb\" | {color|swatch|gradient|none} (overrides pickColorFrom)} → {ids, merged, regions, lines, edges} (counts deleted or merged)",
             has_selection_or_ids,
             sb_merge
         ),
@@ -48,7 +48,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Shape Builder Regions",
             [],
             None,
-            "{ids?|id?} → {regions: [{bounds: [x0,y0,x1,y1], area, sources: [id…]}], lines: [{bounds, source: id}], edges: [{bounds, source: id}]} faces of the planar arrangement (unfilled open paths cut them; sources is empty for an area only they enclose), the pieces of those open paths and the edges (the other paths' outlines cut where paths meet; source: the front-most path along it), which erasing deletes",
+            "{ids?|id?, openFilledAsClosed?: true (as shapeBuilder.merge)} → {regions: [{bounds: [x0,y0,x1,y1], area, sources: [id…]}], lines: [{bounds, source: id}], edges: [{bounds, source: id}]} faces of the planar arrangement (unfilled open paths cut them, and filled ones too with openFilledAsClosed false; sources is empty for an area only they enclose), the pieces of those open paths and the edges (the other paths' outlines cut where paths meet; source: the front-most path along it), which erasing deletes",
             has_selection_or_ids,
             sb_regions
         ),
@@ -245,12 +245,24 @@ fn sb_merge(s: &mut Session, p: &Value) -> Result<Value> {
     let erase = bool_or(p, "erase", false);
     // Line pieces and edges are only deleted (erase mode), never merged.
     let piece_tol = erase.then(|| f64_or(p, "tolerance", 2.0).clamp(0.0, 1000.0));
-    let fill = fill_param(s, p, C)?;
+    let open_filled_as_closed = bool_or(p, "openFilledAsClosed", true);
+    let swatches = match p.get("pickColorFrom") {
+        None | Some(Value::Null) => false,
+        Some(v) => match v.as_str() {
+            Some("artwork") => false,
+            Some("swatches") => true,
+            _ => return Err(bad(C, format!("pickColorFrom is \"artwork\" or \"swatches\", not {v}"))),
+        },
+    };
     let current_fill = s.paint.fill.clone();
+    let fill = match fill_param(s, p, C)? {
+        None if swatches => Some(current_fill.clone()),
+        f => f,
+    };
     let roots = root_ids(s, p)?;
     let label = if erase { "Shape Builder Delete" } else { "Shape Builder" };
     let (ids, merged, touched) = s.edit(label, |d, sel| {
-        let (map, leaves) = BuilderMap::new(d, &roots, erase);
+        let (map, leaves) = BuilderMap::new(d, &roots, erase, open_filled_as_closed);
         let leaves: Vec<Node> = leaves.into_iter().cloned().collect();
         if map.shapes.is_empty() {
             return Err(EngineError::Other("Shape Builder: select paths or compound paths".into()));
@@ -311,7 +323,7 @@ fn sb_merge(s: &mut Session, p: &Value) -> Result<Value> {
                 } else {
                     b::node_outline(leaf).map_or_else(|| sh.path.clone(), |o| o.0)
                 };
-                let fill_closes = !leaf.appearance.fill_paint().is_none();
+                let fill_closes = open_filled_as_closed && !leaf.appearance.fill_paint().is_none();
                 let mut cut = false;
                 for piece in &cuts {
                     if let Some(r) = po::cut_out(&rest, piece, fill_closes, cut_tol) {
@@ -366,7 +378,7 @@ fn replace_roots(d: &mut Document, roots: &[NodeId], nodes: Vec<Node>) -> Result
 fn sb_regions(s: &mut Session, p: &Value) -> Result<Value> {
     let roots = root_ids(s, p)?;
     let d = &s.doc()?.doc;
-    let (map, leaves) = BuilderMap::new(d, &roots, true);
+    let (map, leaves) = BuilderMap::new(d, &roots, true, bool_or(p, "openFilledAsClosed", true));
     let id_of = |i: usize| leaves.get(i).map(|n| n.id.0);
     let regions: Vec<Value> = map
         .regions