feat(site-builder): multi-select with bulk styling and mixed-type actions

Shift/cmd/ctrl-click multi-select via DefaultEventHandlers, same-type bulk
styling as one undo step, mixed-type Delete/Duplicate/Move block, grouped
undo for array-aware edit.* commands.

Refs #50

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

craft/src/App.tsx

@@ -1,5 +1,5 @@
 import React from 'react';
-import { Editor } from '@craftjs/core';
+import { Editor, DefaultEventHandlers } from '@craftjs/core';
 import { EditorShell } from './editor/EditorShell';
 import { RenderNode } from './editor/RenderNode';
 import { componentResolver } from './components/resolver';
@@ -25,6 +25,14 @@ const SitesmithModalMount: React.FC = () => {
   return <SitesmithModal target={target} onClose={close} />;
 };
 
+// #50: shift / cmd / ctrl-click adds to the selection (Craft's default is cmd only).
+// In Craft 0.2.12 `isMultiSelectEnabled` is an option of DefaultEventHandlers, not
+// of <Editor>, so it is set by supplying the handlers; the other options keep
+// Craft's own defaults.
+export const isMultiSelectClick = (e: MouseEvent) => e.shiftKey || e.metaKey || e.ctrlKey;
+export const craftHandlers = (store: any) =>
+  new DefaultEventHandlers({ store, removeHoverOnMouseleave: false, isMultiSelectEnabled: isMultiSelectClick });
+
 // Craft fires onNodesChange only when the serialized node tree changes (not on
 // selection, hover or DOM registration), which is exactly "the canvas was edited".
 export const SaveAwareEditor: React.FC<{ children: React.ReactNode }> = ({ children }) => {
@@ -34,6 +42,7 @@ export const SaveAwareEditor: React.FC<{ children: React.ReactNode }> = ({ child
       resolver={componentResolver}
       enabled={true}
       onRender={RenderNode}
+      handlers={craftHandlers}
       onNodesChange={markDirty}
       indicator={{
         className: 'wsb-drop-line',

craft/src/editor/core-commands.ts

@@ -45,8 +45,19 @@ function insertTree(actions: any, tree: any, parentId: string, index?: number):
   return tree.rootNodeId;
 }
 
+/** Applies several structural edits as ONE undo step: the first is a normal
+ *  history entry, the rest fold into it via `history.merge()` (#50). */
+function groupedActions(actions: any) {
+  let first = true;
+  return () => {
+    if (first) { first = false; return actions; }
+    return actions.history.merge();
+  };
+}
+
 function duplicateAll({ query, actions, selectedIds }: CommandContext): void {
   const created: string[] = [];
+  const step = groupedActions(actions);
   for (const id of topLevelSelection(query, selectedIds)) {
     try {
       const sib = siblingsOf(query, id);
@@ -54,7 +65,7 @@ function duplicateAll({ query, actions, selectedIds }: CommandContext): void {
       // Linked nodes (columns, section inner) are not in `nodes` and cannot be copied alone.
       if (!sib || idx === -1) continue;
       const tree = regenerateTreeIds(query.node(id).toNodeTree());
-      created.push(insertTree(actions, tree, sib.parentId, idx + 1));
+      created.push(insertTree(step(), tree, sib.parentId, idx + 1));
     } catch (err) {
       console.error('Duplicate failed:', err);
     }
@@ -68,9 +79,10 @@ function deleteAll({ query, actions, selectedIds }: CommandContext): void {
     const t = findDeletableTarget(query, id);
     if (t) targets.add(t);
   }
+  const step = groupedActions(actions);
   targets.forEach((t) => {
     try {
-      actions.delete(t);
+      step().delete(t);
     } catch (err) {
       console.error('Delete failed:', err);
     }
@@ -100,15 +112,16 @@ function pasteClipboard({ query, actions, selectedIds }: CommandContext): void {
  *  adjacent nodes keeps its order; a node already at the edge stays put. */
 function moveAll({ query, actions, selectedIds }: CommandContext, dir: -1 | 1): void {
   const ids = topLevelSelection(query, selectedIds);
+  const step = groupedActions(actions);
   for (const id of dir === 1 ? [...ids].reverse() : ids) {
     try {
       const sib = siblingsOf(query, id);
       if (!sib) continue;
       const idx = sib.siblings.indexOf(id);
       if (idx === -1) continue;
-      if (dir === -1 && idx > 0) actions.move(id, sib.parentId, idx - 1);
+      if (dir === -1 && idx > 0) step().move(id, sib.parentId, idx - 1);
       // Craft's move index is the slot BEFORE removal, hence idx + 2.
-      if (dir === 1 && idx < sib.siblings.length - 1) actions.move(id, sib.parentId, idx + 2);
+      if (dir === 1 && idx < sib.siblings.length - 1) step().move(id, sib.parentId, idx + 2);
     } catch (err) {
       console.error('Move failed:', err);
     }

craft/src/panels/right/GuidedStyles.multi.test.tsx

@@ -0,0 +1,141 @@
+import { describe, test, expect, afterEach } from 'vitest';
+import React from 'react';
+import { renderEditorHarness, EditorHarness } from '../../test-utils/editorHarness';
+import { SiteDesignProvider } from '../../state/SiteDesignContext';
+import { PageProvider } from '../../state/PageContext';
+import { SitesmithProvider } from '../../state/SitesmithContext';
+import { DeviceProvider } from '../../state/DeviceContext';
+import { ButtonLink } from '../../components/basic/ButtonLink';
+import { Heading } from '../../components/basic/Heading';
+import { isMultiSelectClick, craftHandlers } from '../../App';
+import { GuidedStyles } from './GuidedStyles';
+import { useNodeProp } from './styles/shared';
+
+let h: EditorHarness;
+afterEach(() => h?.unmount());
+
+function mount(device: 'desktop' | 'tablet' = 'desktop') {
+  h = renderEditorHarness({
+    wrap: (tree) => <DeviceProvider initialDevice={device}>{tree}</DeviceProvider>,
+  });
+  h.mountChild(
+    <PageProvider><SiteDesignProvider><SitesmithProvider>
+      <GuidedStyles />
+    </SitesmithProvider></SiteDesignProvider></PageProvider>,
+  );
+  return h;
+}
+
+const add = (el: React.ReactElement): string => {
+  let id = '';
+  h.act(() => {
+    const tree = h.query.parseReactElement(el).toNodeTree();
+    h.actions.addNodeTree(tree, 'ROOT');
+    id = tree.rootNodeId;
+  });
+  return id;
+};
+const kids = () => h.query.node('ROOT').get().data.nodes as string[];
+const props = (id: string) => h.query.node(id).get().data.props;
+const select = (ids: string[]) => h.act(() => h.actions.selectNode(ids));
+const header = () => h.container.querySelector('[data-testid="type-header"]')?.textContent?.trim();
+
+describe('multi-select: same type', () => {
+  test('header counts the group; Button colour writes both; ONE undo reverts both', () => {
+    mount();
+    const b1 = add(<ButtonLink />);
+    const b2 = add(<ButtonLink />);
+    select([b1, b2]);
+    expect(header()).toContain('2 Buttons selected');
+
+    const before1 = props(b1).style?.backgroundColor;
+    const swatch = h.container.querySelector('.preset-swatch') as HTMLButtonElement;
+    h.act(() => swatch.click());
+    const color = props(b1).style.backgroundColor;
+    expect(color).toBeTruthy();
+    expect(color).not.toBe(before1);
+    expect(props(b2).style.backgroundColor).toBe(color);
+
+    h.act(() => h.actions.history.undo());
+    expect(props(b1).style?.backgroundColor).toBe(before1);
+    expect(props(b2).style?.backgroundColor).toBe(before1);
+  });
+
+  test('single selection is unchanged: only that node is written, header is the plain type', () => {
+    mount();
+    const b1 = add(<ButtonLink />);
+    const b2 = add(<ButtonLink />);
+    select([b1]);
+    expect(header()).toBe('Button');
+    const b2Before = props(b2).style?.backgroundColor;
+    const b1Before = props(b1).style?.backgroundColor;
+    h.act(() => (h.container.querySelector('.preset-swatch') as HTMLButtonElement).click());
+    expect(props(b1).style.backgroundColor).not.toBe(b1Before);
+    expect(props(b2).style?.backgroundColor).toBe(b2Before);
+  });
+
+  test('tablet device: bulk write goes to styleTablet on every node, never to style', () => {
+    mount('tablet');
+    const a = add(<Heading />);
+    const b = add(<Heading />);
+    const Probe: React.FC<{ ids: string[] }> = ({ ids }) => {
+      const { setPropStyle } = useNodeProp(ids);
+      return <button data-testid="go" onClick={() => setPropStyle('width', '50%')} />;
+    };
+    h.mountChild(<DeviceProvider initialDevice="tablet"><Probe ids={[a, b]} /></DeviceProvider>);
+    h.act(() => (h.container.querySelector('[data-testid="go"]') as HTMLButtonElement).click());
+    for (const id of [a, b]) {
+      expect(props(id).styleTablet?.width).toBe('50%');
+      expect(props(id).style?.width).toBeUndefined();
+    }
+    h.act(() => h.actions.history.undo());
+    for (const id of [a, b]) expect(props(id).styleTablet?.width).toBeUndefined();
+  });
+});
+
+describe('multi-select: mixed types', () => {
+  test('shows the actions block; Delete removes both in ONE undo step', () => {
+    mount();
+    const b = add(<ButtonLink />);
+    const t = add(<Heading />);
+    const keep = add(<Heading />);
+    select([b, t]);
+    expect(h.container.querySelector('[data-testid="multi-select-actions"]')).not.toBeNull();
+    h.act(() => (h.container.querySelector('[data-testid="multi-edit.delete"]') as HTMLButtonElement).click());
+    expect(kids()).toEqual([keep]);
+    h.act(() => h.actions.history.undo());
+    expect(kids()).toEqual([b, t, keep]);
+  });
+
+  test('Duplicate puts a copy after each original, in one undo step', () => {
+    mount();
+    const b = add(<ButtonLink />);
+    const t = add(<Heading />);
+    select([b, t]);
+    h.act(() => (h.container.querySelector('[data-testid="multi-edit.duplicate"]') as HTMLButtonElement).click());
+    const k = kids();
+    expect(k).toHaveLength(4);
+    expect(k[0]).toBe(b);
+    expect(k[2]).toBe(t);
+    expect(h.query.node(k[1]).get().data.displayName).toBe('Button');
+    expect(h.query.node(k[3]).get().data.displayName).toBe('Heading');
+    h.act(() => h.actions.history.undo());
+    expect(kids()).toEqual([b, t]);
+  });
+});
+
+describe('Editor multi-select option', () => {
+  test('shift / cmd / ctrl enable multi-select, a plain click does not', () => {
+    const ev = (init: MouseEventInit) => new MouseEvent('mousedown', init);
+    expect(isMultiSelectClick(ev({ shiftKey: true }))).toBe(true);
+    expect(isMultiSelectClick(ev({ metaKey: true }))).toBe(true);
+    expect(isMultiSelectClick(ev({ ctrlKey: true }))).toBe(true);
+    expect(isMultiSelectClick(ev({}))).toBe(false);
+  });
+
+  test('the Editor handlers carry the option', () => {
+    const handlers: any = craftHandlers({} as any);
+    expect(handlers.options.isMultiSelectEnabled(new MouseEvent('mousedown', { shiftKey: true }))).toBe(true);
+    expect(handlers.options.isMultiSelectEnabled(new MouseEvent('mousedown'))).toBe(false);
+  });
+});

craft/src/panels/right/GuidedStyles.tsx

@@ -1,4 +1,4 @@
-import React from 'react';
+import React, { useLayoutEffect } from 'react';
 import { useEditor } from '@craftjs/core';
 import { SiteDesignPanel } from './SiteDesignPanel';
 import { useSitesmithModal } from '../../state/SitesmithContext';
@@ -20,6 +20,37 @@ import {
   HtmlStylePanel,
 } from './styles';
 import { DeviceBanner } from './styles/responsive-panel';
+import { setBulkSelection } from './styles/shared';
+import { CORE_COMMANDS } from '../../editor/core-commands';
+
+const MULTI_ACTIONS = [
+  { id: 'edit.delete', label: 'Delete', icon: 'fa-trash-o' },
+  { id: 'edit.duplicate', label: 'Duplicate', icon: 'fa-clone' },
+  { id: 'edit.move-up', label: 'Move up', icon: 'fa-arrow-up' },
+  { id: 'edit.move-down', label: 'Move down', icon: 'fa-arrow-down' },
+] as const;
+
+/** Mixed-type multi-selection: no shared styles, only structural actions.
+ *  Runs the core `edit.*` commands (array-aware, one undo step each). */
+export const MultiSelectActions: React.FC<{ ids: string[] }> = ({ ids }) => {
+  const { query, actions } = useEditor();
+  const run = (id: string) => {
+    const cmd = CORE_COMMANDS.find((c) => c.id === id);
+    cmd?.run({ query, actions, selectedIds: ids } as any);
+  };
+  return (
+    <div className="guided-section multi-select-actions" data-testid="multi-select-actions">
+      <p className="multi-select-hint">{ids.length} elements of different types selected. Styles are edited one type at a time.</p>
+      <div className="multi-select-buttons">
+        {MULTI_ACTIONS.map((a) => (
+          <button key={a.id} type="button" className="multi-select-btn" data-testid={`multi-${a.id}`} onClick={() => run(a.id)}>
+            <i className={`fa ${a.icon}`} /> {a.label}
+          </button>
+        ))}
+      </div>
+    </div>
+  );
+};
 
 /* ================================================================
    IMPORTANT: None of these panels use useNode().
@@ -31,6 +62,11 @@ import { DeviceBanner } from './styles/responsive-panel';
    Main GuidedStyles component
    ================================================================ */
 
+function pluralType(name: string, n: number): string {
+  if (n === 1) return name;
+  return /(s|x)$/i.test(name) ? `${name}es` : `${name}s`;
+}
+
 export const GuidedStyles: React.FC<{
   /** What to render with nothing selected: the Site Design panel (default,
    *  used by the mobile sheet) or a placeholder (desktop RightPanel, which
@@ -40,10 +76,11 @@ export const GuidedStyles: React.FC<{
   const { open: openSitesmith } = useSitesmithModal();
   const { query } = useEditor();
 
-  const { selected, selectedType, nodeProps } = useEditor((state) => {
-    const currentNodeId = state.events.selected
-      ? Array.from(state.events.selected)[0]
-      : undefined;
+  const { selected, selectedType, nodeProps, selectedIds, mixedTypes } = useEditor((state) => {
+    const all = state.events.selected ? Array.from(state.events.selected) : [];
+    const currentNodeId = all[0];
+    const typeOf = (id: string) => state.nodes[id]?.data.displayName || state.nodes[id]?.data.name || null;
+    const mixedTypes = all.length > 1 && all.some((id) => typeOf(id) !== typeOf(all[0]));
     let selectedType: string | null = null;
     let nodeProps: Record<string, any> = {};
 
@@ -59,8 +96,19 @@ export const GuidedStyles: React.FC<{
       selected: currentNodeId || null,
       selectedType,
       nodeProps,
+      // string key so the collector only changes when the selection does
+      selectedIds: all.join('\n'),
+      mixedTypes,
     };
   });
+  const ids = selectedIds ? selectedIds.split('\n') : [];
+  const bulk = ids.length > 1 && !mixedTypes;
+
+  // Same-type group: writes addressed to the primary id fan out to every id (see shared.tsx).
+  useLayoutEffect(() => {
+    setBulkSelection(bulk ? ids : []);
+    return () => setBulkSelection([]);
+  }, [bulk, selectedIds]); // eslint-disable-line react-hooks/exhaustive-deps
 
   if (!selected) {
     if (emptyFallback === 'placeholder') {
@@ -76,6 +124,19 @@ export const GuidedStyles: React.FC<{
     return <SiteDesignPanel />;
   }
 
+  if (ids.length > 1 && mixedTypes) {
+    return (
+      <div className="guided-styles">
+        <div className="guided-section guided-type-header">
+          <span className="guided-type-badge" data-testid="multi-select-header">
+            <i className="fa fa-clone" /> {ids.length} elements selected
+          </span>
+        </div>
+        <MultiSelectActions ids={ids} />
+      </div>
+    );
+  }
+
   // Determine which panel to show based on displayName
   const typeName = selectedType || '';
 
@@ -123,9 +184,9 @@ export const GuidedStyles: React.FC<{
     <div className="guided-styles">
       {/* Component type badge + Sitesmith shortcut */}
       <div className="guided-section guided-type-header" style={{ display: 'flex', alignItems: 'center', gap: 8 }}>
-        <span className="guided-type-badge" style={{ flex: 1 }}>
+        <span className="guided-type-badge" data-testid="type-header" style={{ flex: 1 }}>
           <i className={`fa ${typeIcon}`} />
-          {' '}{typeName}
+          {' '}{bulk ? `${ids.length} ${pluralType(typeName, ids.length)} selected` : typeName}
         </span>
         <button
           onClick={handleAskSitesmith}

craft/src/panels/right/styles/multi-select.test.tsx

@@ -0,0 +1,64 @@
+import { describe, test, expect, afterEach } from 'vitest';
+import { renderEditorHarness, EditorHarness } from '../../../test-utils/editorHarness';
+import { ButtonLink } from '../../../components/basic/ButtonLink';
+import { discreteSetProp, continuousSetProp, closeContinuousBurst, setBulkSelection } from './shared';
+
+let h: EditorHarness;
+afterEach(() => { closeContinuousBurst(); setBulkSelection([]); h?.unmount(); });
+
+function setup() {
+  h = renderEditorHarness();
+  const ids: string[] = [];
+  for (let i = 0; i < 3; i++) {
+    h.act(() => {
+      const tree = h.query.parseReactElement(<ButtonLink />).toNodeTree();
+      h.actions.addNodeTree(tree, 'ROOT');
+      ids.push(tree.rootNodeId);
+    });
+  }
+  return ids;
+}
+const text = (id: string) => h.query.node(id).get().data.props.text;
+
+describe('discreteSetProp / continuousSetProp with several ids', () => {
+  test('explicit id array: all written, ONE undo step', () => {
+    const [a, b, c] = setup();
+    const orig = text(a);
+    h.act(() => discreteSetProp(h.actions, [a, b], (p: any) => { p.text = 'X'; }));
+    expect([text(a), text(b), text(c)]).toEqual(['X', 'X', orig]);
+    h.act(() => h.actions.history.undo());
+    expect([text(a), text(b)]).toEqual([orig, orig]);
+  });
+
+  test('a burst of continuous edits over a group is ONE undo step', () => {
+    const [a, b] = setup();
+    const orig = text(a);
+    for (const v of ['1', '12', '123']) {
+      h.act(() => continuousSetProp(h.actions, [a, b], 'text', (p: any) => { p.text = v; }));
+    }
+    expect([text(a), text(b)]).toEqual(['123', '123']);
+    h.act(() => h.actions.history.undo());
+    expect([text(a), text(b)]).toEqual([orig, orig]);
+  });
+
+  test('registered bulk selection expands the primary id only', () => {
+    const [a, b, c] = setup();
+    setBulkSelection([a, b]);
+    h.act(() => discreteSetProp(h.actions, a, (p: any) => { p.text = 'Y'; }));
+    expect([text(a), text(b)]).toEqual(['Y', 'Y']);
+    // a write to a non-primary id is never fanned out
+    h.act(() => discreteSetProp(h.actions, c, (p: any) => { p.text = 'Z'; }));
+    expect([text(a), text(b), text(c)]).toEqual(['Y', 'Y', 'Z']);
+  });
+
+  test('a no-op on the first node does not make the next write merge into an earlier edit', () => {
+    const [a, b] = setup();
+    h.act(() => discreteSetProp(h.actions, a, (p: any) => { p.text = 'Same'; }));
+    const origB = text(b);
+    // a already says 'Same' (no change, no history entry); b changes
+    h.act(() => discreteSetProp(h.actions, [a, b], (p: any) => { p.text = 'Same'; }));
+    h.act(() => h.actions.history.undo());
+    expect(text(b)).toBe(origB);
+    expect(text(a)).toBe('Same'); // the earlier edit survived: b's write was its own step
+  });
+});

craft/src/panels/right/styles/shared.tsx

@@ -1,4 +1,4 @@
-import React, { useState, useCallback, useEffect, useRef, CSSProperties } from 'react';
+import React, { useState, useCallback, useEffect, useMemo, useRef, CSSProperties } from 'react';
 import { useEditor } from '@craftjs/core';
 import {
   GRADIENTS,
@@ -489,11 +489,46 @@ if (typeof document !== 'undefined') {
   document.addEventListener('keydown', (e) => { if (e.ctrlKey || e.metaKey) closeContinuousBurst(); }, true);
 }
 
+/* ---------- Bulk (multi-select) writes (#50) ----------
+   GuidedStyles registers the multi-selection here while a same-type group is
+   selected. A write addressed to the PRIMARY id (what every panel receives as
+   `selectedId`) fans out to all ids, so panels need no change. Writes to any
+   other node are never expanded. */
+let bulkIds: string[] = [];
+
+export function setBulkSelection(ids: string[]) {
+  bulkIds = ids.length > 1 ? [...ids] : [];
+}
+
+function expandIds(nodeId: string | string[]): string[] {
+  if (Array.isArray(nodeId)) return nodeId;
+  return bulkIds.length > 1 && bulkIds[0] === nodeId ? bulkIds : [nodeId];
+}
+
+/** Runs `updater` on every id as ONE undo step: the first id that records a
+ *  history entry is a plain setProp, later ones fold into it via
+ *  `history.merge()`. `mergeFirst` makes even the first fold into the
+ *  previous entry (a continuing burst). */
+function setPropAll(actions: any, ids: string[], updater: (p: any) => void, mergeFirst = false) {
+  let merge = mergeFirst;
+  for (const id of ids) {
+    let changed = false;
+    const tracked = (p: any) => {
+      const before = JSON.stringify(p);
+      updater(p);
+      changed = JSON.stringify(p) !== before;
+    };
+    (merge ? actions.history.merge() : actions).setProp(id, tracked);
+    if (changed) merge = true;
+  }
+}
+
 /** setProp for a continuous input. `controlKey` identifies the control within
  *  the node (e.g. "style.color"); a change from any other control closes the
  *  open burst and starts its own history entry. */
-export function continuousSetProp(actions: any, nodeId: string, controlKey: string, updater: (p: any) => void) {
-  const key = `${nodeId}:${controlKey}`;
+export function continuousSetProp(actions: any, nodeId: string | string[], controlKey: string, updater: (p: any) => void) {
+  const ids = expandIds(nodeId);
+  const key = `${ids.join(',')}:${controlKey}`;
   const continuing = openBurst?.key === key;
   if (!continuing) closeContinuousBurst();
   else clearTimeout(openBurst!.timer);
@@ -505,18 +540,19 @@ export function continuousSetProp(actions: any, nodeId: string, controlKey: stri
   const tracked = (p: any) => {
     const before = JSON.stringify(p);
     updater(p);
-    changed = JSON.stringify(p) !== before;
+    if (JSON.stringify(p) !== before) changed = true;
   };
-  (continuing ? actions.history.merge() : actions).setProp(nodeId, tracked);
+  setPropAll(actions, ids, tracked, continuing);
   if (continuing || changed) {
     openBurst = { key, timer: setTimeout(closeContinuousBurst, CONTINUOUS_EDIT_IDLE_MS) };
   }
 }
 
-/** Plain setProp for a discrete edit: always its own undo step. */
-export function discreteSetProp(actions: any, nodeId: string, updater: (p: any) => void) {
+/** Plain setProp for a discrete edit: always its own undo step (one step for
+ *  the whole group when a bulk selection is active). */
+export function discreteSetProp(actions: any, nodeId: string | string[], updater: (p: any) => void) {
   closeContinuousBurst();
-  actions.setProp(nodeId, updater);
+  setPropAll(actions, expandIds(nodeId), updater);
 }
 
 /* ---------- Per-device style writes (#45) ----------
@@ -563,7 +599,7 @@ const styleControlKey = (device: DeviceMode, controlKey: string) => `${device}:$
  *  (default `style.<key>`). */
 export function setResponsiveStyleProp(
   actions: any,
-  nodeId: string,
+  nodeId: string | string[],
   device: DeviceMode,
   key: string,
   value: unknown,
@@ -577,7 +613,7 @@ export function setResponsiveStyleProp(
 /** Removes `device`'s override of `key` (or of every key in a group, e.g. the
  *  four padding sides) in ONE discrete setProp = one undo step. No-op on
  *  desktop: the desktop value is the base, there is nothing to reset to. */
-export function clearResponsiveStyleProp(actions: any, nodeId: string, device: DeviceMode, key: string | readonly string[]) {
+export function clearResponsiveStyleProp(actions: any, nodeId: string | string[], device: DeviceMode, key: string | readonly string[]) {
   if (device === 'desktop') return;
   const field = OVERRIDE_FIELD[device];
   const keys = typeof key === 'string' ? [key] : key;
@@ -594,7 +630,11 @@ export function clearResponsiveStyleProp(actions: any, nodeId: string, device: D
    to this (some panels use different param names or extra logic and keep
    their own local versions). The style setters are device-aware (#45): see
    applyStylePatch above. */
-export function useNodeProp(selectedId: string) {
+export function useNodeProp(selectedIdArg: string | string[]) {
+  // Stable dependency for the useCallbacks below (an array literal changes identity per render).
+  const idKey = Array.isArray(selectedIdArg) ? selectedIdArg.join('\u0000') : selectedIdArg;
+  // eslint-disable-next-line react-hooks/exhaustive-deps
+  const selectedId = useMemo(() => selectedIdArg, [idKey]);
   const { actions } = useEditor();
   const { device } = useDevice();
   // Default setters are plain: one call = one undo step. Continuous inputs

craft/src/styles/editor.css

@@ -2731,3 +2731,25 @@ body {
   color: var(--color-text);
   cursor: pointer;
 }
+
+/* #50 multi-select: mixed-type selection actions */
+.multi-select-hint {
+  margin: 0 0 8px;
+  font-size: 11px;
+  color: var(--color-text-muted, #a1a1aa);
+}
+.multi-select-buttons {
+  display: grid;
+  grid-template-columns: 1fr 1fr;
+  gap: 6px;
+}
+.multi-select-btn {
+  padding: 6px 8px;
+  font-size: 11px;
+  color: var(--color-text);
+  background: var(--color-surface-2, #27272a);
+  border: 1px solid var(--color-border, #3f3f46);
+  border-radius: var(--radius-sm);
+  cursor: pointer;
+}
+.multi-select-btn:hover { border-color: var(--color-accent); }