fix(builder): duplicate inserts+selects after source; select-parent/styles-sheet/canvas-pad mobile fixes

Ship-blocking fix (Fable consult): useNodeActions.duplicate() appended the
regenerated tree at the end of the parent while leaving the ORIGINAL
selected, so duplicating a top-level section landed the copy off-screen at
the bottom of the page with no visible change -- shared by both the mobile
selection toolbar and the desktop right-click ContextMenu. Now inserts the
copy immediately after the source (actions.addNodeTree(tree, parentId,
sourceIndex + 1)) and selects it (actions.selectNode(tree.rootNodeId)),
falling back to append-at-end if the source's index can't be resolved.
Mobile also scrolls the new node into view.

Three cheap fast-follows:
- canSelectParent on useNodeActions (false when the node's parent is ROOT
  or missing); MobileSelectionToolbar disables "Select Parent" instead of
  dead-ending on a page-wide ROOT outline with no toolbar of its own.
- Opening the Styles sheet on mobile now scrolls the selected node above
  the 65dvh sheet; a temporary generous bottom-padding class handles the
  case where the node is the last thing on the page and there'd otherwise
  be no room left to scroll it into view.
- Canvas gets bottom padding equal to the fixed selection toolbar's height
  while it's visible, so the last section of a short page isn't stuck
  permanently underneath it.

Desktop duplicate behavior improves (inserts after + selects) via the
shared hook; no toHtml changes. Verified live via Playwright at 375px and
1280px (screenshots in craft/scratchpad/mobileB2/).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

craft/src/editor/Canvas.tsx

@@ -6,6 +6,7 @@ import { DeviceMode } from '../types';
 import { DEVICE_WIDTHS } from '../constants/presets';
 import { exportBodyHtml } from '../utils/html-export';
 import { useIsMobile } from '../hooks/useIsMobile';
+import { useMobileChrome } from '../state/MobileChromeContext';
 
 interface CanvasProps {
   device: DeviceMode;
@@ -135,6 +136,42 @@ export const Canvas: React.FC<CanvasProps> = ({ device, showGuides }) => {
 
   const isEditingRegularPage = !isEditingHeader && !isEditingFooter;
 
+  // Fast-follow item 4: while `MobileSelectionToolbar` is up (fixed, ~53px
+  // tall, just above the tab bar), it covers whatever content was at the
+  // very bottom of the canvas's own scroll area -- on a short page, the
+  // last section could sit permanently under the toolbar with no way to
+  // scroll past it. Mirrors that toolbar's own visibility condition
+  // (`selectedId && activeSheet === null`) exactly, computed independently
+  // here since Canvas has no other reason to depend on the toolbar
+  // component itself.
+  const isMobile = useIsMobile();
+  const { activeSheet } = useMobileChrome();
+  const { selectedId } = useEditor((state) => {
+    const selected = state.events.selected;
+    const id = selected && selected.size > 0 ? (Array.from(selected)[0] as string) : null;
+    return { selectedId: id && id !== 'ROOT' ? id : null };
+  });
+  const mobileToolbarVisible = isMobile && !!selectedId && activeSheet === null;
+
+  // Fast-follow item 3: `MobileSelectionToolbar`'s "Style" tap scrolls the
+  // selected node up towards the top of the canvas so it stays visible
+  // above the Styles sheet (~65dvh tall) -- but that scroll is still bound
+  // by the canvas's own natural scroll range. For a selected node near the
+  // END of the content (very plausibly the last section on the page --
+  // exactly the kind of node someone just added/duplicated and wants to
+  // style), there may not be enough scrollable distance below it to bring
+  // its top all the way up to the visible band above the sheet; the browser
+  // simply clamps at its existing max scrollTop, leaving the node's top
+  // stuck behind the sheet with nothing anyone can do about it (verified
+  // live: the last section of a page landed under the sheet even after the
+  // scroll-into-view ran). Pad the canvas with a full extra viewport's
+  // worth of scroll room while the sheet is open with a selection, exactly
+  // as `has-mobile-selection-toolbar` (item 4) already pads it for the
+  // fixed toolbar -- generous enough that ANY node, including the very
+  // last one, can always be scrolled with its top reaching the very top of
+  // the canvas (comfortably within the "top ~30%" target).
+  const mobileStylesSheetPad = isMobile && !!selectedId && activeSheet === 'styles';
+
   const frameStyle = isEditingHeader
     ? { minHeight: '60px', backgroundColor: '#ffffff', padding: '12px 24px', display: 'flex', alignItems: 'center' }
     : isEditingFooter
@@ -144,7 +181,11 @@ export const Canvas: React.FC<CanvasProps> = ({ device, showGuides }) => {
   const frameTag = isEditingHeader ? 'header' : isEditingFooter ? 'footer' : 'div';
 
   return (
-    <div className="editor-canvas">
+    <div
+      className={`editor-canvas${mobileToolbarVisible ? ' has-mobile-selection-toolbar' : ''}${
+        mobileStylesSheetPad ? ' has-mobile-styles-sheet' : ''
+      }`}
+    >
       <div
         className={`canvas-device-frame${showGuides ? '' : ' guides-off'}`}
         style={{

craft/src/hooks/useNodeActions.test.tsx

@@ -14,12 +14,19 @@ import { useNodeActions, type NodeActions } from './useNodeActions';
  *  - moveUp/moveDown call `actions.move` with the right target index, and
  *    are no-ops at the respective boundary
  *  - canMoveUp/canMoveDown reflect the node's position among its siblings
- *  - duplicate regenerates ids before calling `actions.addNodeTree`
+ *  - duplicate regenerates ids, inserts the copy IMMEDIATELY AFTER the
+ *    source node (`actions.addNodeTree(tree, parentId, sourceIndex + 1)`),
+ *    and selects the new copy (`actions.selectNode(tree.rootNodeId)`) --
+ *    Phase B fast-follow: the previous append-at-end behavior left the copy
+ *    off-screen with the ORIGINAL still selected, so users couldn't see
+ *    what "Duplicate" had just done.
  *  - selectParent calls `actions.selectNode` with the parent id
+ *  - canSelectParent reflects whether the node's parent is itself real
+ *    (not ROOT/missing) -- false at a top-level section, true one level in
  *  - deleteNode routes through `findDeletableTarget` (also covering the
  *    "no deletable target" no-op)
  *  - ROOT/null nodeId disables every action safely (no-ops, all
- *    canMoveUp/canMoveDown/canDelete false)
+ *    canMoveUp/canMoveDown/canDelete/canSelectParent false)
  */
 
 const moveMock = vi.fn();
@@ -180,15 +187,24 @@ describe('useNodeActions', () => {
     expect(moveMock).not.toHaveBeenCalled();
   });
 
-  test('duplicate regenerates ids before calling actions.addNodeTree with the parent id', () => {
+  test('duplicate inserts the copy immediately after the source (parentId, sourceIndex + 1) and selects it', () => {
     render('child-1');
-    act(() => captured!.duplicate());
+    let returned: string | null | undefined;
+    act(() => {
+      returned = captured!.duplicate();
+    });
 
     expect(regenerateTreeIdsMock).toHaveBeenCalledTimes(1);
     expect(addNodeTreeMock).toHaveBeenCalledTimes(1);
-    const [tree, parentId] = addNodeTreeMock.mock.calls[0];
+    const [tree, parentId, index] = addNodeTreeMock.mock.calls[0];
+    // child-1 is at index 1 among ['child-0', 'child-1', 'child-2'] -> insert at 2.
     expect(parentId).toBe('parent-1');
+    expect(index).toBe(2);
     expect(tree.rootNodeId).not.toBe(COPIED_TREE.rootNodeId);
+
+    expect(selectNodeMock).toHaveBeenCalledTimes(1);
+    expect(selectNodeMock).toHaveBeenCalledWith(tree.rootNodeId);
+    expect(returned).toBe(tree.rootNodeId);
   });
 
   test('selectParent calls actions.selectNode with the parent id', () => {
@@ -197,6 +213,14 @@ describe('useNodeActions', () => {
     expect(selectNodeMock).toHaveBeenCalledWith('parent-1');
   });
 
+  test('canSelectParent is false at a top-level node (parent is ROOT), true one level deeper', () => {
+    render('parent-1'); // parent-1's own parent is 'ROOT'
+    expect(captured!.canSelectParent).toBe(false);
+
+    rerender('child-1'); // child-1's parent is 'parent-1', a real node
+    expect(captured!.canSelectParent).toBe(true);
+  });
+
   test('deleteNode calls actions.delete with the node id when deletable', () => {
     render('child-1');
     expect(captured!.canDelete).toBe(true);
@@ -209,6 +233,7 @@ describe('useNodeActions', () => {
     expect(captured!.canMoveUp).toBe(false);
     expect(captured!.canMoveDown).toBe(false);
     expect(captured!.canDelete).toBe(false);
+    expect(captured!.canSelectParent).toBe(false);
 
     act(() => {
       captured!.moveUp();
@@ -228,5 +253,6 @@ describe('useNodeActions', () => {
     expect(captured!.canMoveUp).toBe(false);
     expect(captured!.canMoveDown).toBe(false);
     expect(captured!.canDelete).toBe(false);
+    expect(captured!.canSelectParent).toBe(false);
   });
 });

craft/src/hooks/useNodeActions.ts

@@ -5,7 +5,12 @@ import { findDeletableTarget } from '../utils/craft-helpers';
 export interface NodeActions {
   moveUp: () => void;
   moveDown: () => void;
-  duplicate: () => void;
+  /** Duplicates `nodeId`, inserting the copy immediately after the source in
+   *  the parent's children and selecting it. Returns the new node's id (so
+   *  callers -- e.g. `MobileSelectionToolbar` -- can scroll it into view),
+   *  or null if the duplicate could not be performed (no-op for ROOT/null,
+   *  or a caught error). */
+  duplicate: () => string | null;
   deleteNode: () => void;
   selectParent: () => void;
   /** True if `nodeId` has an earlier sibling under the same parent (so
@@ -18,6 +23,12 @@ export interface NodeActions {
    *  `nodeId` itself, or an ancestor when `nodeId` is an empty linked-node
    *  slot whose siblings are all also empty -- see `craft-helpers.ts`). */
   canDelete: boolean;
+  /** True if `nodeId` has a real parent to select -- i.e. the parent is
+   *  neither ROOT nor missing. `selectParent` on a top-level section (whose
+   *  parent IS 'ROOT') would only select the page-wide ROOT node, which has
+   *  no on-canvas outline and no toolbar of its own -- a dead end for a
+   *  mobile user with no way back. False for ROOT/null/no-parent too. */
+  canSelectParent: boolean;
 }
 
 /**
@@ -74,11 +85,13 @@ export function useNodeActions(nodeId: string | null | undefined): NodeActions {
 
   let canMoveUp = false;
   let canMoveDown = false;
+  let canSelectParent = false;
   if (!isRootOrNull) {
     try {
       const node = query.node(nodeId).get();
       const parentId: string | null | undefined = node?.data?.parent;
       if (parentId) {
+        canSelectParent = parentId !== 'ROOT';
         const siblings: string[] = query.node(parentId).get()?.data?.nodes || [];
         const idx = siblings.indexOf(nodeId);
         canMoveUp = idx > 0;
@@ -102,16 +115,45 @@ export function useNodeActions(nodeId: string | null | undefined): NodeActions {
     }
   };
 
-  const duplicate = () => {
+  const duplicate = (): string | null => {
-    if (!nodeId || nodeId === 'ROOT') return;
+    if (!nodeId || nodeId === 'ROOT') return null;
     try {
       const parentId = getParentId();
-      if (!parentId) return;
+      if (!parentId) return null;
 
       const tree = regenerateTreeIds(query.node(nodeId).toNodeTree());
+
+      // Insert the copy IMMEDIATELY AFTER the source node, not appended at
+      // the end of the parent -- on a top-level section, "append at end"
+      // landed the copy at the bottom of the page, off-screen, with the
+      // ORIGINAL still selected, so a duplicate looked like nothing had
+      // happened at all. Resolve the source's index among its siblings so
+      // the copy lands right next to what it was copied from; if that can't
+      // be resolved for any reason, fall back to the old append behavior
+      // rather than guessing at an index (or throwing).
+      let insertIndex: number | undefined;
+      try {
+        const siblings: string[] = query.node(parentId).get()?.data?.nodes || [];
+        const sourceIndex = siblings.indexOf(nodeId);
+        if (sourceIndex !== -1) insertIndex = sourceIndex + 1;
+      } catch {
+        // Leave insertIndex undefined -- addNodeTree appends when omitted.
+      }
+
+      if (insertIndex !== undefined) {
+        actions.addNodeTree(tree, parentId, insertIndex);
+      } else {
         actions.addNodeTree(tree, parentId);
+      }
+
+      // Select the new copy (not the original) so the toolbar/context menu
+      // and any on-canvas outline immediately reflect what was just created.
+      actions.selectNode(tree.rootNodeId);
+
+      return tree.rootNodeId;
     } catch (e) {
       console.error('Duplicate failed:', e);
+      return null;
     }
   };
 
@@ -165,5 +207,15 @@ export function useNodeActions(nodeId: string | null | undefined): NodeActions {
     }
   };
 
-  return { moveUp, moveDown, duplicate, deleteNode, selectParent, canMoveUp, canMoveDown, canDelete };
+  return {
+    moveUp,
+    moveDown,
+    duplicate,
+    deleteNode,
+    selectParent,
+    canMoveUp,
+    canMoveDown,
+    canDelete,
+    canSelectParent,
+  };
 }

craft/src/panels/mobile/MobileSelectionToolbar.tsx

@@ -34,6 +34,11 @@ export const MobileSelectionToolbar: React.FC = () => {
     const id = selected && selected.size > 0 ? (Array.from(selected)[0] as string) : null;
     return { selectedId: id && id !== 'ROOT' ? id : null };
   });
+  // Collector-free -- an always-live reference (same pattern as
+  // GuidedStyles.tsx/BlocksPanel.tsx), used only for imperative DOM lookups
+  // below (scroll-into-view), never for anything that needs to react to
+  // store changes on its own.
+  const { query } = useEditor();
 
   const nodeActions = useNodeActions(selectedId);
   const [confirmingDelete, setConfirmingDelete] = useState(false);
@@ -76,6 +81,24 @@ export const MobileSelectionToolbar: React.FC = () => {
 
   useEffect(() => clearConfirmTimeout, [clearConfirmTimeout]);
 
+  // Fast-follow item 3: the Styles bottom sheet covers the bottom ~65dvh of
+  // the canvas, so a selected node sitting anywhere in that band goes
+  // invisible the instant the sheet opens -- live style edits then have no
+  // visible effect until the user closes the sheet to check. Whenever the
+  // sheet becomes 'styles' (however it got opened -- currently only this
+  // toolbar's own "Style" button, but this is keyed on the sheet/selection
+  // state rather than the button tap so it stays correct if another entry
+  // point is added later) scroll the selected node to the top of the
+  // canvas's scroll area, into the sliver of screen the sheet leaves clear.
+  useEffect(() => {
+    if (activeSheet !== 'styles' || !selectedId) return;
+    try {
+      query.node(selectedId).get()?.dom?.scrollIntoView({ behavior: 'smooth', block: 'start' });
+    } catch {
+      // Best-effort -- not fatal if the node/DOM isn't found.
+    }
+  }, [activeSheet, selectedId, query]);
+
   const handleDeleteTap = useCallback(() => {
     if (confirmingDelete) {
       clearConfirmTimeout();
@@ -104,9 +127,24 @@ export const MobileSelectionToolbar: React.FC = () => {
   }, [nodeActions, bumpTick]);
 
   const handleDuplicate = useCallback(() => {
-    nodeActions.duplicate();
+    const newId = nodeActions.duplicate();
     bumpTick();
-  }, [nodeActions, bumpTick]);
+    if (!newId) return;
+    // Mirror BlocksPanel's tap-to-add pattern: the new node's real DOM
+    // element isn't attached yet the instant `duplicate()` returns (Craft.js
+    // mounts it asynchronously after this handler's synchronous state
+    // update), so defer two animation frames before reading `.dom` off the
+    // query, same as `handleTapToAdd` does.
+    requestAnimationFrame(() => {
+      requestAnimationFrame(() => {
+        try {
+          query.node(newId).get()?.dom?.scrollIntoView({ behavior: 'smooth', block: 'center' });
+        } catch {
+          // Best-effort scroll -- not fatal if the node/DOM isn't found.
+        }
+      });
+    });
+  }, [nodeActions, bumpTick, query]);
 
   if (!selectedId || activeSheet !== null) return null;
 
@@ -145,6 +183,7 @@ export const MobileSelectionToolbar: React.FC = () => {
         type="button"
         className="mobile-selection-toolbar-btn"
         onClick={nodeActions.selectParent}
+        disabled={!nodeActions.canSelectParent}
         aria-label="Select parent"
       >
         <i className="fa fa-level-up" aria-hidden="true" />

craft/src/styles/editor.css

@@ -34,6 +34,11 @@
   /* Phase A (mobile): fixed bottom tab bar height, used to size
      .editor-container and the safe-area padding math below. */
   --mobile-tabbar-height: 58px;
+  /* Phase B fast-follow item 4: rendered height of `.mobile-selection-toolbar`
+     (44px min-height content + 4px top/bottom padding + 1px border) -- used
+     to pad the canvas scroll area clear of it while it's visible, see
+     `.editor-canvas.has-mobile-selection-toolbar` below. */
+  --mobile-selection-toolbar-height: 53px;
 
   /* Mobile-A2: explicit overlay layer scale (was ad-hoc numbers scattered
      across the mobile block + Modal.tsx, causing accidental stacking --
@@ -1685,6 +1690,31 @@ body {
     background: rgba(239, 68, 68, 0.15);
   }
 
+  /* Fast-follow item 4: while the toolbar above is visible, give the canvas
+     scroll area enough extra bottom padding to clear it (on top of the
+     regular 12px `.editor-canvas` padding, not replacing it), so the last
+     section of a short page is still reachable by scrolling instead of
+     sitting permanently underneath the fixed toolbar. */
+  .editor-canvas.has-mobile-selection-toolbar {
+    padding-bottom: calc(12px + var(--mobile-selection-toolbar-height));
+  }
+
+  /* Fast-follow item 3: while the Styles sheet is open with a node selected,
+     `MobileSelectionToolbar`'s scroll-into-view effect needs somewhere to
+     scroll THE NODE TO even when it's the last thing on the page -- without
+     extra room below it, the canvas is already at its max scrollTop and the
+     node's top can't be brought up past wherever it naturally landed
+     (verified live: the last section stayed stuck under the sheet). A full
+     extra viewport's worth of bottom padding guarantees any node's top can
+     always reach the very top of the canvas. Temporary/cosmetic cost (a
+     stretch of blank canvas below the real content while this is active) is
+     an acceptable trade for the node never being permanently unreachable.
+     -------------------------------------------------------------------- */
+  .editor-canvas.has-mobile-styles-sheet {
+    padding-bottom: 100vh;
+    padding-bottom: 100dvh;
+  }
+
   /* --------------------------------------------------------------------
      Bottom sheet (BottomSheet.tsx)
      -------------------------------------------------------------------- */