feat: add keyboard navigation for document views, externalize document preview handling, and include physics model documentation.

frontend/src/desktop/DesktopWorkspace.tsx

@@ -6,7 +6,6 @@ import React, {
   useState,
 } from 'react';
 import { LayoutStore, LayoutCard } from './LayoutSystem';
-import PreviewZoomOverlay from '../detail/PreviewZoomOverlay';
 import DesktopDocumentCard from './DesktopDocumentCard';
 import usePreviewMetadata from './hooks/usePreviewMetadata';
 import useDeskTagInteractions from './tags/useDeskTagInteractions';
@@ -31,12 +30,6 @@ export interface DeskDocument {
   [key: string]: unknown;
 }
 
-interface OverlayDisplay {
-  url: string;
-  alt?: string | null;
-  mimeType?: string | null;
-}
-
 interface DocumentSizeInfo {
   width: number;
   height: number;
@@ -57,6 +50,7 @@ export interface DesktopWorkspaceProps {
   onDocumentTagDrop?: (docId: Identifier, tag: any) => void;
   tenantId?: Identifier | null;
   viewId?: string | null;
+  onPreview?: (doc: DeskDocument) => void;
 }
 
 // Wrapper to handle hooks per card
@@ -90,6 +84,7 @@ const DesktopWorkspaceContent: React.FC<DesktopWorkspaceProps> = ({
   onDocumentTagDrop,
   tenantId,
   viewId,
+  onPreview,
 }) => {
   const { addPointer, removePointer } = usePointerTracking();
   const containerRef = useRef<HTMLDivElement>(null);
@@ -206,9 +201,22 @@ const DesktopWorkspaceContent: React.FC<DesktopWorkspaceProps> = ({
     requestCanvasFocus: focusShell,
   });
 
-  // Overlay State
-  const [overlayDisplay, setOverlayDisplay] = useState<OverlayDisplay | null>(null);
-  const closeOverlay = useCallback(() => setOverlayDisplay(null), []);
+  useEffect(() => {
+    const handleWindowKeyDown = (e: KeyboardEvent) => {
+      if (e.code === 'Space' && selectedDocumentIds.length > 0) {
+        // Preview the last selected document
+        const lastId = selectedDocumentIds[selectedDocumentIds.length - 1];
+        const doc = items.find(i => String(i.id) === lastId);
+        if (doc && onPreview) {
+          e.preventDefault();
+          onPreview(doc);
+        }
+      }
+    };
+
+    window.addEventListener('keydown', handleWindowKeyDown);
+    return () => window.removeEventListener('keydown', handleWindowKeyDown);
+  }, [selectedDocumentIds, items, onPreview]);
 
   return (
     <>
@@ -305,11 +313,6 @@ const DesktopWorkspaceContent: React.FC<DesktopWorkspaceProps> = ({
           })}
         </div>
       </div>
-      <PreviewZoomOverlay
-        open={Boolean(overlayDisplay?.url)}
-        onClose={closeOverlay}
-        document={null}
-      />
     </>
   );
 };