M3.68: groups, layers and type have their own fills, strokes and effects, with Contents and Characters rows

A group's or layer's own fills and strokes paint every member's geometry, below or above the
members as the new contents slot (Appearance.contents_index) says; its geometry effects reshape
the members as one piece and its raster effects apply to the composite (one combined shadow),
respecting knockout groups. Type's own fills and strokes paint under or over its characters.
Render, SVG/PDF (via bake) and Expand Appearance evaluate them alike.

Commands: appearance.* / effect.* take target: "object"|"contents" and layer ids;
appearance.moveItem moves the Contents slot (from: "contents") or an item across it
(contents); appearance.targetContents selects a group's members. Graphic styles applied to a
group now style the group itself. The Appearance panel shows Contents/Characters rows that
drag, and double-click to target the members or edit the characters' paint.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/engine/src/cmd/effectcmd.rs

@@ -1,7 +1,9 @@
 //! Effect menu commands (live effects) and Object → Expand Appearance.
 //!
 //! Effects are stored on the object's appearance (`appearance.effects`) and evaluated at render
-//! time by `vectorcraft-effects` (re-exported by the renderer).
+//! time by `vectorcraft-effects` (re-exported by the renderer). The commands edit the objects'
+//! own stacks, groups and layers included (layers through `ids`), or with `target: "contents"`
+//! the objects inside them (see `appearance`).
 
 use std::sync::Arc;
 
@@ -20,8 +22,8 @@ pub fn specs() -> Vec<CommandSpec> {
             "Apply Effect",
             [],
             None,
-            "{effect: id (see effect.list, e.g. \"stylize.dropShadow\", \"distort.roughen\", \"warp.arc\"), params?: {…} (missing keys take the dialog defaults), item?: appearance item index|null (apply to that fill/stroke only; omitted: the Appearance panel's active item, else the whole object), ids?: [..]} append a live effect to each selected object's appearance → {ids, index, item}",
-            has_selection,
+            "{effect: id (see effect.list, e.g. \"stylize.dropShadow\", \"distort.roughen\", \"warp.arc\"), params?: {…} (missing keys take the dialog defaults), item?: appearance item index|null (apply to that fill/stroke only; omitted: the Appearance panel's active item, else the whole object), ids?: [..] (layers too), target?: \"object\"|\"contents\" (contents: the objects inside groups and layers)} append a live effect to each selected object's appearance (a group's or layer's apply to its members as one piece: one combined shadow) → {ids, index, item}",
+            has_doc,
             apply
         ),
         cmd!(
@@ -39,7 +41,7 @@ pub fn specs() -> Vec<CommandSpec> {
             [],
             None,
             "{index: int (position in the effect list), item?: appearance item index|null (that fill/stroke's effects; omitted: the active item, else the object's), ids?: [..]} → {ids}",
-            has_selection,
+            has_doc,
             remove
         ),
         cmd!(
@@ -48,7 +50,7 @@ pub fn specs() -> Vec<CommandSpec> {
             [],
             None,
             "{index: int, params?: {…} (merged into the current parameters), visible?: bool, item?: appearance item index|null (as effect.remove), ids?: [..]} → {ids}",
-            has_selection,
+            has_doc,
             set_params
         ),
         cmd!(
@@ -56,8 +58,8 @@ pub fn specs() -> Vec<CommandSpec> {
             "Expand Appearance",
             ["Object"],
             None,
-            "{ids?: [..]} bake geometry effects into the paths and drop them (raster effects stay live) → {ids}",
-            has_selection,
+            "{ids?: [..], target?} bake geometry effects into the paths and drop them (raster effects stay live); a group's or layer's own fills and strokes become paths among its members → {ids}",
+            has_doc,
             expand_appearance
         ),
         cmd!(
@@ -66,7 +68,7 @@ pub fn specs() -> Vec<CommandSpec> {
             [],
             None,
             "{index: int, item?: appearance item index|null (as effect.remove), ids?: [..]} insert a copy of the effect right after it → {ids}",
-            has_selection,
+            has_doc,
             duplicate
         ),
         cmd!(
@@ -75,7 +77,7 @@ pub fn specs() -> Vec<CommandSpec> {
             [],
             None,
             "{from: int (position in the source list), to: int (its position in the destination list afterwards), fromItem?: appearance item index|null (the source list: that fill/stroke's effects, null the object's; omitted: the active item, else the object's), toItem?: item index|null (the destination list; default: the source list), copy?: bool (copy instead of move, as Alt-dragging the row), ids?: [..]} reorder an effect or move it between the object and its fills/strokes, as one undo step → {ids, index, item}",
-            has_selection,
+            has_doc,
             move_effect
         ),
     ]
@@ -256,31 +258,22 @@ fn node_geometry(n: &Node) -> Option<(PathData, FillRule)> {
     }
 }
 
-/// Bake the object-level geometry effects of `id` (and, recursively, of group members).
+/// Bake the object-level geometry effects of `id` (and, recursively, of group members). A group's
+/// or layer's Pathfinder and geometry effects and its own fills and strokes become its members.
 fn expand_node(d: &mut vectorcraft_doc::Document, id: NodeId, out: &mut Vec<NodeId>) {
     let Some(n) = d.node(id).cloned() else { return };
-    // Effect → Pathfinder: the group's members become the Pathfinder result.
-    if let Some(result) = effects::pathfinder_children(&n, None) {
-        let children = result
-            .into_iter()
-            .map(|c| {
-                let mut c = Arc::unwrap_or_clone(c);
-                c.id = d.alloc_id();
-                Arc::new(c)
-            })
-            .collect();
-        let Some(m) = d.node_mut(id) else { return };
-        if let Some(ch) = m.children_mut() {
-            *ch = children;
+    if matches!(n.kind, NodeKind::Group { .. } | NodeKind::Layer { .. }) {
+        if let Some(mut m) = effects::evaluate_container(&n) {
+            let mut seen = std::collections::HashSet::from([m.id]);
+            for c in m.children_mut().into_iter().flatten() {
+                effects::fresh_ids(d, Arc::make_mut(c), &mut seen);
+            }
+            let Some(slot) = d.node_mut(id) else { return };
+            *slot = m;
+            out.push(id);
         }
-        m.appearance.effects.retain(|e| !effects::is_pathfinder(&e.id));
-        out.push(id);
-        return;
-    }
-    if let Some(children) = n.children()
-        && matches!(n.kind, NodeKind::Group { .. })
-    {
-        for c in children.iter().map(|c| c.id).collect::<Vec<_>>() {
+        let children: Vec<NodeId> = d.node(id).and_then(|n| n.children()).map(|c| c.iter().map(|c| c.id).collect()).unwrap_or_default();
+        for c in children {
             expand_node(d, c, out);
         }
         return;