From 9fda54bd06d37cd8f8f71056bf4f59e158cd8112 Mon Sep 17 00:00:00 2001
From: paul <paul-nothaft@hotmail.de>
Date: Sun, 14 Sep 2025 17:02:03 +0200
Subject: [PATCH] feat(select): add per-tile checkbox selection in Admin grid
 and all gallery layouts; tile click opens viewer; checkbox toggles selection;
 auto-enable selection mode; add testids

---
 .../src/components/admin/AdminPhotoGrid.tsx   | 46 ++++++-----
 .../gallery/PhotoGridWithLayouts.tsx          | 10 ++-
 .../gallery/layouts/GridGalleryLayout.tsx     | 34 ++++----
 .../gallery/layouts/HeroGalleryLayout.tsx     | 31 ++++----
 .../gallery/layouts/MasonryGalleryLayout.tsx  | 34 ++++----
 .../gallery/layouts/MosaicGalleryLayout.tsx   | 78 ++++++++++++-------
 .../gallery/layouts/TimelineGalleryLayout.tsx | 31 ++++----
 7 files changed, 159 insertions(+), 105 deletions(-)

diff --git a/frontend/src/components/admin/AdminPhotoGrid.tsx b/frontend/src/components/admin/AdminPhotoGrid.tsx
index 0831661..2714b70 100644
--- a/frontend/src/components/admin/AdminPhotoGrid.tsx
+++ b/frontend/src/components/admin/AdminPhotoGrid.tsx
@@ -29,7 +29,10 @@ export const AdminPhotoGrid: React.FC<AdminPhotoGridProps> = ({
     if (e) {
       e.stopPropagation();
     }
-    
+    // Auto-enable selection mode when selecting via checkbox
+    if (!isSelectionMode) {
+      setIsSelectionMode(true);
+    }
     const newSelected = new Set(selectedPhotos);
     if (newSelected.has(photoId)) {
       newSelected.delete(photoId);
@@ -126,7 +129,7 @@ export const AdminPhotoGrid: React.FC<AdminPhotoGridProps> = ({
             {isSelectionMode ? 'Cancel Selection' : 'Select Photos'}
           </Button>
           
-          {isSelectionMode && (
+          {(isSelectionMode || selectedPhotos.size > 0) && (
             <>
               <Button
                 variant="ghost"
@@ -167,25 +170,32 @@ export const AdminPhotoGrid: React.FC<AdminPhotoGridProps> = ({
           return (
             <div
               key={photo.id}
+              data-testid={`admin-photo-tile-${photo.id}`}
               className={`relative group cursor-pointer rounded-lg overflow-hidden bg-neutral-100 transition-opacity ${
                 isSelectionMode ? 'ring-2 ring-offset-2 ' + (selectedPhotos.has(photo.id) ? 'ring-primary-500' : 'ring-transparent') : ''
               } ${isDeleting ? 'opacity-50' : ''}`}
-              onClick={() => !isDeleting && (isSelectionMode ? handlePhotoSelect(photo.id) : onPhotoClick(photo, index))}
+              onClick={() => !isDeleting && onPhotoClick(photo, index)}
           >
-            {/* Selection Checkbox */}
-            {isSelectionMode && (
-              <div className="absolute top-2 left-2 z-10">
-                <div className={`w-6 h-6 rounded border-2 flex items-center justify-center ${
-                  selectedPhotos.has(photo.id) 
-                    ? 'bg-primary-500 border-primary-500' 
-                    : 'bg-white/80 border-neutral-300'
-                }`}>
-                  {selectedPhotos.has(photo.id) && (
-                    <Check className="w-4 h-4 text-white" />
-                  )}
-                </div>
+            {/* Selection Checkbox (top-right) */}
+            <button
+              type="button"
+              aria-label={`Select ${photo.filename}`}
+              role="checkbox"
+              aria-checked={selectedPhotos.has(photo.id)}
+              data-testid={`admin-photo-checkbox-${photo.id}`}
+              className={`absolute top-2 right-2 z-20 transition-opacity ${
+                selectedPhotos.has(photo.id) ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'
+              }`}
+              onClick={(e) => handlePhotoSelect(photo.id, e)}
+            >
+              <div className={`w-6 h-6 rounded border-2 flex items-center justify-center ${
+                selectedPhotos.has(photo.id)
+                  ? 'bg-primary-600 border-primary-600'
+                  : 'bg-white/90 border-white'
+              }`}>
+                {selectedPhotos.has(photo.id) && <Check className="w-4 h-4 text-white" />}
               </div>
-            )}
+            </button>
 
             {/* Thumbnail */}
             <div className="aspect-square">
@@ -240,7 +250,7 @@ export const AdminPhotoGrid: React.FC<AdminPhotoGridProps> = ({
 
             {/* Category Badge */}
             {photo.category_name && (
-              <div className="absolute top-2 right-2">
+              <div className="absolute right-2" style={{ top: (selectedPhotos.has(photo.id) || isSelectionMode) ? '40px' : '8px' }}>
                 <span className="px-2 py-1 text-xs font-medium bg-white/90 text-neutral-700 rounded">
                   {photo.category_name}
                 </span>
@@ -276,4 +286,4 @@ export const AdminPhotoGrid: React.FC<AdminPhotoGridProps> = ({
       )}
     </div>
   );
-};
\ No newline at end of file
+};
diff --git a/frontend/src/components/gallery/PhotoGridWithLayouts.tsx b/frontend/src/components/gallery/PhotoGridWithLayouts.tsx
index 37e1564..cbf9558 100644
--- a/frontend/src/components/gallery/PhotoGridWithLayouts.tsx
+++ b/frontend/src/components/gallery/PhotoGridWithLayouts.tsx
@@ -81,6 +81,14 @@ export const PhotoGridWithLayouts: React.FC<PhotoGridWithLayoutsProps> = ({
   };
 
   const handlePhotoSelect = (photoId: number) => {
+    // Auto-enable selection mode when selecting via checkbox
+    if (!isSelectionMode) {
+      if (parentToggleSelectionMode) {
+        parentToggleSelectionMode();
+      } else {
+        setLocalSelectionMode(true);
+      }
+    }
     const newSelected = new Set(selectedPhotos);
     if (newSelected.has(photoId)) {
       newSelected.delete(photoId);
@@ -279,4 +287,4 @@ export const PhotoGridWithLayouts: React.FC<PhotoGridWithLayoutsProps> = ({
       )}
     </>
   );
-};
\ No newline at end of file
+};
diff --git a/frontend/src/components/gallery/layouts/GridGalleryLayout.tsx b/frontend/src/components/gallery/layouts/GridGalleryLayout.tsx
index 217dd99..ea06553 100644
--- a/frontend/src/components/gallery/layouts/GridGalleryLayout.tsx
+++ b/frontend/src/components/gallery/layouts/GridGalleryLayout.tsx
@@ -12,6 +12,7 @@ interface GridPhotoProps {
   isSelectionMode: boolean;
   onClick: (e: React.MouseEvent) => void;
   onDownload: (e: React.MouseEvent) => void;
+  onToggleSelect: () => void;
   animationType?: string;
   allowDownloads?: boolean;
   slug?: string;
@@ -26,6 +27,7 @@ const GridPhoto: React.FC<GridPhotoProps> = ({
   isSelectionMode,
   onClick,
   onDownload,
+  onToggleSelect,
   animationType = 'fade',
   allowDownloads = true,
   slug,
@@ -105,13 +107,22 @@ const GridPhoto: React.FC<GridPhotoProps> = ({
             )}
           </div>
 
-          {isSelectionMode && (
-            <div className={`absolute top-2 right-2 ${isSelected ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'} transition-opacity`}>
-              <div className={`w-6 h-6 rounded-full border-2 ${isSelected ? 'bg-primary-600 border-primary-600' : 'bg-white/80 border-white'} flex items-center justify-center transition-colors`}>
-                {isSelected && <Check className="w-4 h-4 text-white" />}
-              </div>
+          {/* Selection Checkbox (visible on hover or when selected) */}
+          <button
+            type="button"
+            aria-label={`Select ${photo.filename}`}
+            role="checkbox"
+            aria-checked={isSelected}
+            data-testid={`gallery-photo-checkbox-${photo.id}`}
+            className={`absolute top-2 right-2 z-20 transition-opacity ${
+              isSelected ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'
+            }`}
+            onClick={(e) => { e.stopPropagation(); onToggleSelect(); }}
+          >
+            <div className={`w-6 h-6 rounded-full border-2 ${isSelected ? 'bg-primary-600 border-primary-600' : 'bg-white/90 border-white'} flex items-center justify-center transition-colors`}>
+              {isSelected && <Check className="w-4 h-4 text-white" />}
             </div>
-          )}
+          </button>
 
           {/* Feedback Indicators */}
           {feedbackEnabled && (photo.comment_count > 0 || photo.average_rating > 0 || photo.like_count > 0) && (
@@ -187,13 +198,8 @@ export const GridGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
           photo={photo}
           isSelected={selectedPhotos.has(photo.id)}
           isSelectionMode={isSelectionMode}
-          onClick={() => {
-            if (isSelectionMode && onPhotoSelect) {
-              onPhotoSelect(photo.id);
-            } else {
-              onPhotoClick(index);
-            }
-          }}
+          onClick={() => onPhotoClick(index)}
+          onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo.id)}
           onDownload={(e) => onDownload(photo, e)}
           animationType={animation}
           allowDownloads={allowDownloads}
@@ -205,4 +211,4 @@ export const GridGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
       ))}
     </div>
   );
-};
\ No newline at end of file
+};
diff --git a/frontend/src/components/gallery/layouts/HeroGalleryLayout.tsx b/frontend/src/components/gallery/layouts/HeroGalleryLayout.tsx
index d22e970..c4e0c54 100644
--- a/frontend/src/components/gallery/layouts/HeroGalleryLayout.tsx
+++ b/frontend/src/components/gallery/layouts/HeroGalleryLayout.tsx
@@ -152,13 +152,7 @@ export const HeroGalleryLayout: React.FC<HeroGalleryLayoutProps> = ({
             <div
               key={photo.id}
               className="relative group cursor-pointer aspect-square"
-              onClick={() => {
-                if (isSelectionMode && onPhotoSelect) {
-                  onPhotoSelect(photo.id);
-                } else {
-                  onPhotoClick(actualIndex);
-                }
-              }}
+              onClick={() => onPhotoClick(actualIndex)}
             >
               <AuthenticatedImage
                 src={photo.thumbnail_url || photo.url}
@@ -198,17 +192,26 @@ export const HeroGalleryLayout: React.FC<HeroGalleryLayoutProps> = ({
                 )}
               </div>
 
-              {isSelectionMode && (
-                <div className={`absolute top-2 right-2 ${selectedPhotos.has(photo.id) ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'} transition-opacity`}>
-                  <div className={`w-6 h-6 rounded-full border-2 ${selectedPhotos.has(photo.id) ? 'bg-primary-600 border-primary-600' : 'bg-white/80 border-white'} flex items-center justify-center transition-colors`}>
-                    {selectedPhotos.has(photo.id) && <Check className="w-4 h-4 text-white" />}
-                  </div>
+              {/* Selection Checkbox (visible on hover or when selected) */}
+              <button
+                type="button"
+                aria-label={`Select ${photo.filename}`}
+                role="checkbox"
+                aria-checked={selectedPhotos.has(photo.id)}
+                data-testid={`gallery-photo-checkbox-${photo.id}`}
+                className={`absolute top-2 right-2 z-20 transition-opacity ${
+                  selectedPhotos.has(photo.id) ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'
+                }`}
+                onClick={(e) => { e.stopPropagation(); onPhotoSelect && onPhotoSelect(photo.id); }}
+              >
+                <div className={`w-6 h-6 rounded-full border-2 ${selectedPhotos.has(photo.id) ? 'bg-primary-600 border-primary-600' : 'bg-white/90 border-white'} flex items-center justify-center transition-colors`}>
+                  {selectedPhotos.has(photo.id) && <Check className="w-4 h-4 text-white" />}
                 </div>
-              )}
+              </button>
             </div>
           );
         })}
       </div>
     </div>
   );
-};
\ No newline at end of file
+};
diff --git a/frontend/src/components/gallery/layouts/MasonryGalleryLayout.tsx b/frontend/src/components/gallery/layouts/MasonryGalleryLayout.tsx
index be7e3e2..6741910 100644
--- a/frontend/src/components/gallery/layouts/MasonryGalleryLayout.tsx
+++ b/frontend/src/components/gallery/layouts/MasonryGalleryLayout.tsx
@@ -11,6 +11,7 @@ interface MasonryPhotoProps {
   isSelectionMode: boolean;
   onClick: (e: React.MouseEvent) => void;
   onDownload: (e: React.MouseEvent) => void;
+  onToggleSelect: () => void;
   style?: React.CSSProperties;
   allowDownloads?: boolean;
   feedbackEnabled?: boolean;
@@ -22,6 +23,7 @@ const MasonryPhoto: React.FC<MasonryPhotoProps> = ({
   isSelectionMode,
   onClick,
   onDownload,
+  onToggleSelect,
   style,
   allowDownloads = true,
   feedbackEnabled = false
@@ -104,13 +106,22 @@ const MasonryPhoto: React.FC<MasonryPhotoProps> = ({
         )}
       </div>
 
-      {isSelectionMode && (
-        <div className={`absolute top-2 right-2 ${isSelected ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'} transition-opacity`}>
-          <div className={`w-6 h-6 rounded-full border-2 ${isSelected ? 'bg-primary-600 border-primary-600' : 'bg-white/80 border-white'} flex items-center justify-center transition-colors`}>
-            {isSelected && <Check className="w-4 h-4 text-white" />}
-          </div>
+      {/* Selection Checkbox (visible on hover or when selected) */}
+      <button
+        type="button"
+        aria-label={`Select ${photo.filename}`}
+        role="checkbox"
+        aria-checked={isSelected}
+        data-testid={`gallery-photo-checkbox-${photo.id}`}
+        className={`absolute top-2 right-2 z-20 transition-opacity ${
+          isSelected ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'
+        }`}
+        onClick={(e) => { e.stopPropagation(); onToggleSelect(); }}
+      >
+        <div className={`w-6 h-6 rounded-full border-2 ${isSelected ? 'bg-primary-600 border-primary-600' : 'bg-white/90 border-white'} flex items-center justify-center transition-colors`}>
+          {isSelected && <Check className="w-4 h-4 text-white" />}
         </div>
-      )}
+      </button>
 
       {photo.type === 'collage' && (
         <div className="absolute bottom-2 left-2">
@@ -182,14 +193,9 @@ export const MasonryGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
                 photo={photo}
                 isSelected={selectedPhotos.has(photo.id)}
                 isSelectionMode={isSelectionMode}
-                onClick={() => {
-                  if (isSelectionMode && onPhotoSelect) {
-                    onPhotoSelect(photo.id);
-                  } else {
-                    onPhotoClick(originalIndex);
-                  }
-                }}
+                onClick={() => onPhotoClick(originalIndex)}
                 onDownload={(e) => onDownload(photo, e)}
+                onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo.id)}
                 allowDownloads={allowDownloads}
                 feedbackEnabled={feedbackEnabled}
               />
@@ -199,4 +205,4 @@ export const MasonryGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
       ))}
     </div>
   );
-};
\ No newline at end of file
+};
diff --git a/frontend/src/components/gallery/layouts/MosaicGalleryLayout.tsx b/frontend/src/components/gallery/layouts/MosaicGalleryLayout.tsx
index 1bd672f..40de30a 100644
--- a/frontend/src/components/gallery/layouts/MosaicGalleryLayout.tsx
+++ b/frontend/src/components/gallery/layouts/MosaicGalleryLayout.tsx
@@ -11,6 +11,7 @@ interface MosaicPhotoProps {
   isSelectionMode: boolean;
   onClick: (e: React.MouseEvent) => void;
   onDownload: (e: React.MouseEvent) => void;
+  onToggleSelect: () => void;
   className?: string;
   allowDownloads?: boolean;
 }
@@ -21,6 +22,7 @@ const MosaicPhoto: React.FC<MosaicPhotoProps> = ({
   isSelectionMode,
   onClick,
   onDownload,
+  onToggleSelect,
   className = '',
   allowDownloads = true
 }) => {
@@ -69,13 +71,22 @@ const MosaicPhoto: React.FC<MosaicPhotoProps> = ({
         )}
       </div>
 
-      {isSelectionMode && (
-        <div className={`absolute top-2 right-2 ${isSelected ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'} transition-opacity`}>
-          <div className={`w-6 h-6 rounded-full border-2 ${isSelected ? 'bg-primary-600 border-primary-600' : 'bg-white/80 border-white'} flex items-center justify-center transition-colors`}>
-            {isSelected && <Check className="w-4 h-4 text-white" />}
-          </div>
+      {/* Selection Checkbox (visible on hover or when selected) */}
+      <button
+        type="button"
+        aria-label={`Select ${photo.filename}`}
+        role="checkbox"
+        aria-checked={isSelected}
+        data-testid={`gallery-photo-checkbox-${photo.id}`}
+        className={`absolute top-2 right-2 z-20 transition-opacity ${
+          isSelected ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'
+        }`}
+        onClick={(e) => { e.stopPropagation(); onToggleSelect(); }}
+      >
+        <div className={`w-6 h-6 rounded-full border-2 ${isSelected ? 'bg-primary-600 border-primary-600' : 'bg-white/90 border-white'} flex items-center justify-center transition-colors`}>
+          {isSelected && <Check className="w-4 h-4 text-white" />}
         </div>
-      )}
+      </button>
 
       {photo.type === 'collage' && (
         <div className="absolute bottom-2 left-2">
@@ -136,8 +147,9 @@ export const MosaicGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
                 photo={photo0}
                 isSelected={selectedPhotos.has(photo0.id)}
                 isSelectionMode={isSelectionMode}
-                onClick={() => handlePhotoClick(idx0, photo0.id)}
+                onClick={() => onPhotoClick(idx0)}
                 onDownload={(e) => onDownload(photo0, e)}
+                onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo0.id)}
                 className="col-span-1"
                 allowDownloads={allowDownloads}
               />
@@ -148,22 +160,24 @@ export const MosaicGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
                   photo={photo1}
                   isSelected={selectedPhotos.has(photo1.id)}
                   isSelectionMode={isSelectionMode}
-                  onClick={() => handlePhotoClick(idx1, photo1.id)}
-                  onDownload={(e) => onDownload(photo1, e)}
-                  className=""
-                  allowDownloads={allowDownloads}
-                />
+                onClick={() => onPhotoClick(idx1)}
+                onDownload={(e) => onDownload(photo1, e)}
+                onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo1.id)}
+                className=""
+                allowDownloads={allowDownloads}
+              />
               )}
               {photo2 && (
                 <MosaicPhoto
                   photo={photo2}
                   isSelected={selectedPhotos.has(photo2.id)}
                   isSelectionMode={isSelectionMode}
-                  onClick={() => handlePhotoClick(idx2, photo2.id)}
-                  onDownload={(e) => onDownload(photo2, e)}
-                  className=""
-                  allowDownloads={allowDownloads}
-                />
+                onClick={() => onPhotoClick(idx2)}
+                onDownload={(e) => onDownload(photo2, e)}
+                onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo2.id)}
+                className=""
+                allowDownloads={allowDownloads}
+              />
               )}
             </div>
           </div>
@@ -209,8 +223,9 @@ export const MosaicGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
                 photo={photo0}
                 isSelected={selectedPhotos.has(photo0.id)}
                 isSelectionMode={isSelectionMode}
-                onClick={() => handlePhotoClick(idx0, photo0.id)}
+                onClick={() => onPhotoClick(idx0)}
                 onDownload={(e) => onDownload(photo0, e)}
+                onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo0.id)}
                 className="col-span-2"
                 allowDownloads={allowDownloads}
               />
@@ -221,22 +236,24 @@ export const MosaicGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
                   photo={photo1}
                   isSelected={selectedPhotos.has(photo1.id)}
                   isSelectionMode={isSelectionMode}
-                  onClick={() => handlePhotoClick(idx1, photo1.id)}
-                  onDownload={(e) => onDownload(photo1, e)}
-                  className=""
-                  allowDownloads={allowDownloads}
-                />
+                onClick={() => onPhotoClick(idx1)}
+                onDownload={(e) => onDownload(photo1, e)}
+                onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo1.id)}
+                className=""
+                allowDownloads={allowDownloads}
+              />
               )}
               {photo2 && (
                 <MosaicPhoto
                   photo={photo2}
                   isSelected={selectedPhotos.has(photo2.id)}
                   isSelectionMode={isSelectionMode}
-                  onClick={() => handlePhotoClick(idx2, photo2.id)}
-                  onDownload={(e) => onDownload(photo2, e)}
-                  className=""
-                  allowDownloads={allowDownloads}
-                />
+                onClick={() => onPhotoClick(idx2)}
+                onDownload={(e) => onDownload(photo2, e)}
+                onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo2.id)}
+                className=""
+                allowDownloads={allowDownloads}
+              />
               )}
             </div>
           </div>
@@ -263,8 +280,9 @@ export const MosaicGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
                 photo={photo}
                 isSelected={selectedPhotos.has(photo.id)}
                 isSelectionMode={isSelectionMode}
-                onClick={() => handlePhotoClick(index, photo.id)}
+                onClick={() => onPhotoClick(index)}
                 onDownload={(e) => onDownload(photo, e)}
+                onToggleSelect={() => onPhotoSelect && onPhotoSelect(photo.id)}
                 className="aspect-square"
                 allowDownloads={allowDownloads}
               />
@@ -282,4 +300,4 @@ export const MosaicGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
       {renderMosaicLayout()}
     </div>
   );
-};
\ No newline at end of file
+};
diff --git a/frontend/src/components/gallery/layouts/TimelineGalleryLayout.tsx b/frontend/src/components/gallery/layouts/TimelineGalleryLayout.tsx
index c34cb4b..098a204 100644
--- a/frontend/src/components/gallery/layouts/TimelineGalleryLayout.tsx
+++ b/frontend/src/components/gallery/layouts/TimelineGalleryLayout.tsx
@@ -90,13 +90,7 @@ export const TimelineGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
                   <div
                     key={photo.id}
                     className="relative group cursor-pointer aspect-square"
-                    onClick={() => {
-                      if (isSelectionMode && onPhotoSelect) {
-                        onPhotoSelect(photo.id);
-                      } else {
-                        onPhotoClick(actualIndex);
-                      }
-                    }}
+                    onClick={() => onPhotoClick(actualIndex)}
                   >
                     <AuthenticatedImage
                       src={photo.thumbnail_url || photo.url}
@@ -141,13 +135,22 @@ export const TimelineGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
                       )}
                     </div>
 
-                    {isSelectionMode && (
-                      <div className={`absolute top-2 right-2 ${selectedPhotos.has(photo.id) ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'} transition-opacity`}>
-                        <div className={`w-6 h-6 rounded-full border-2 ${selectedPhotos.has(photo.id) ? 'bg-primary-600 border-primary-600' : 'bg-white/80 border-white'} flex items-center justify-center transition-colors`}>
-                          {selectedPhotos.has(photo.id) && <Check className="w-4 h-4 text-white" />}
-                        </div>
+                    {/* Selection Checkbox (visible on hover or when selected) */}
+                    <button
+                      type="button"
+                      aria-label={`Select ${photo.filename}`}
+                      role="checkbox"
+                      aria-checked={selectedPhotos.has(photo.id)}
+                      data-testid={`gallery-photo-checkbox-${photo.id}`}
+                      className={`absolute top-2 right-2 z-20 transition-opacity ${
+                        selectedPhotos.has(photo.id) ? 'opacity-100' : 'opacity-0 group-hover:opacity-100'
+                      }`}
+                      onClick={(e) => { e.stopPropagation(); onPhotoSelect && onPhotoSelect(photo.id); }}
+                    >
+                      <div className={`w-6 h-6 rounded-full border-2 ${selectedPhotos.has(photo.id) ? 'bg-primary-600 border-primary-600' : 'bg-white/90 border-white'} flex items-center justify-center transition-colors`}>
+                        {selectedPhotos.has(photo.id) && <Check className="w-4 h-4 text-white" />}
                       </div>
-                    )}
+                    </button>
                   </div>
                 );
               })}
@@ -157,4 +160,4 @@ export const TimelineGalleryLayout: React.FC<BaseGalleryLayoutProps> = ({
       </div>
     </div>
   );
-};
\ No newline at end of file
+};