refactor: make draggedDocIds a required property in PointerDownOptions and simplify handlePointerDown logic accordingly

frontend/src/desktop/DesktopWorkspace.tsx

@@ -10,7 +10,7 @@ import React, {
 import { resolveDocumentAssetUrl } from '../asset_manager';
 import type { GetAsset } from '../asset_manager';
 import { formatTransform } from '../utils/math';
-import useDocumentDrag from './useDocumentDrag';
+import useDocumentDrag, { PointerDownOptions } from './useDocumentDrag';
 import PreviewZoomOverlay from '../detail/PreviewZoomOverlay';
 import {
   WorkspaceEngine,
@@ -894,7 +894,7 @@ function DesktopWorkspaceView({
       onDocumentActivate: handleDeskDocumentActivate,
       markLayoutDirty,
     }) as {
-      handlePointerDown: React.PointerEventHandler<HTMLElement>;
+      handlePointerDown: (event: React.PointerEvent<HTMLElement>, docId: Identifier | null, options: PointerDownOptions) => void;
       handlePointerMove: React.PointerEventHandler<HTMLElement>;
       handlePointerUp: React.PointerEventHandler<HTMLElement>;
       handlePointerCancel: React.PointerEventHandler<HTMLElement>;

frontend/src/desktop/useDocumentDrag.ts

@@ -82,8 +82,8 @@ interface DragSettings {
   debugDrag?: boolean;
 }
 
-interface PointerDownOptions {
-  draggedDocIds?: string[];
+export interface PointerDownOptions {
+  draggedDocIds: string[];
   stackSelectionApplied?: boolean;
   modifierActive?: boolean;
 }
@@ -310,7 +310,7 @@ const useDocumentDrag = (options: UseDocumentDragOptions) => {
   );
 
   const handlePointerDown = useCallback(
-    (event: PointerEventLike, docIdInput?: Identifier | null, options: PointerDownOptions = {}) => {
+    (event: PointerEventLike, docIdInput: Identifier | null, options: PointerDownOptions) => {
       const targetElement = getEventTargetElement(event);
       if (targetElement?.closest && targetElement.closest('[data-desk-tag-chip="true"]')) {
         return;
@@ -330,22 +330,14 @@ const useDocumentDrag = (options: UseDocumentDragOptions) => {
         return;
       }
       const massGrams = computeDocumentMassGrams(doc);
-      const draggedDocIds = options?.draggedDocIds;
+      const draggedDocIds = options.draggedDocIds;
 
-      let selectionIds: string[] = [];
-
-      if (Array.isArray(draggedDocIds) && draggedDocIds.length > 0) {
-        // Use explicitly provided IDs for the drag operation
-        selectionIds = draggedDocIds;
-      } else {
-        // Fallback (should ideally not happen if useDeskPointer is correct)
-        selectionIds = [docKey];
-      }
+      let selectionIds: string[] = draggedDocIds;
 
       selectionIds = selectionIds.filter((id, index, array) => array.indexOf(id) === index && documentLookup.has(id));
 
       if (!selectionIds.length) {
-        selectionIds = [docKey];
+        return;
       }
 
       const isGroupDrag = selectionIds.length > 1;