diff --git a/backend/handlers/onlyoffice.go b/backend/handlers/onlyoffice.go
index ee2802b..e804a2d 100644
--- a/backend/handlers/onlyoffice.go
+++ b/backend/handlers/onlyoffice.go
@@ -302,14 +302,27 @@ func (h *OnlyOfficeHandler) ListOfficeFiles(c *fiber.Ctx) error {
 	}
 
 	type OfficeFile struct {
-		Name    string `json:"name"`
-		Path    string `json:"path"`
-		Size    int64  `json:"size"`
-		ModTime string `json:"mod_time"`
+		Name     string `json:"name"`
+		Path     string `json:"path"`
+		Size     int64  `json:"size"`
+		ModTime  string `json:"mod_time"`
+		Checksum string `json:"checksum,omitempty"`
 	}
 
 	var results []OfficeFile
 
+	checksums := make(map[string]string)
+	rows, err := h.DB.Query("SELECT path, checksum FROM files WHERE checksum != '' AND is_trashed = 0")
+	if err == nil {
+		defer rows.Close()
+		for rows.Next() {
+			var p, c string
+			if rows.Scan(&p, &c) == nil {
+				checksums[p] = c
+			}
+		}
+	}
+
 	filepath.Walk(h.Config.StorageDir, func(path string, info os.FileInfo, err error) error {
 		if err != nil {
 			return nil
@@ -325,11 +338,13 @@ func (h *OnlyOfficeHandler) ListOfficeFiles(c *fiber.Ctx) error {
 
 		if strings.HasSuffix(strings.ToLower(info.Name()), ext) {
 			relPath, _ := filepath.Rel(h.Config.StorageDir, path)
+			relPathSlash := filepath.ToSlash(relPath)
 			results = append(results, OfficeFile{
-				Name:    info.Name(),
-				Path:    filepath.ToSlash(relPath),
-				Size:    info.Size(),
-				ModTime: info.ModTime().UTC().Format("2006-01-02T15:04:05Z"),
+				Name:     info.Name(),
+				Path:     relPathSlash,
+				Size:     info.Size(),
+				ModTime:  info.ModTime().UTC().Format("2006-01-02T15:04:05Z"),
+				Checksum: checksums[relPathSlash],
 			})
 		}
 		return nil
diff --git a/frontend/src/components/FileExplorer.tsx b/frontend/src/components/FileExplorer.tsx
index b48d33e..0ad31fe 100644
--- a/frontend/src/components/FileExplorer.tsx
+++ b/frontend/src/components/FileExplorer.tsx
@@ -1403,7 +1403,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
       >
         <div className="flex flex-col gap-1 px-3 py-4 border-b" style={{ borderColor: 'var(--color-border-subtle)' }}>
           <button
-            onClick={() => { setAppMode('drive'); setEditingFile(null); }}
+            onClick={() => { setAppMode('drive'); setEditingFile(null); setActiveSection('files'); }}
             className="w-full flex items-center gap-3 px-3 py-2.5 rounded-xl text-sm font-bold transition-all duration-150"
             style={{
               backgroundColor: appMode === 'drive' ? 'var(--color-accent-subtle)' : 'transparent',
@@ -1417,7 +1417,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
           </button>
           
           <button
-            onClick={() => { setAppMode('docs'); setEditingFile(null); }}
+            onClick={() => { setAppMode('docs'); setEditingFile(null); setActiveSection('files'); }}
             className="w-full flex items-center gap-3 px-3 py-2.5 rounded-xl text-sm font-bold transition-all duration-150"
             style={{
               backgroundColor: appMode === 'docs' ? 'var(--color-accent-subtle)' : 'transparent',
@@ -1431,7 +1431,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
           </button>
           
           <button
-            onClick={() => { setAppMode('slides'); setEditingFile(null); }}
+            onClick={() => { setAppMode('slides'); setEditingFile(null); setActiveSection('files'); }}
             className="w-full flex items-center gap-3 px-3 py-2.5 rounded-xl text-sm font-bold transition-all duration-150"
             style={{
               backgroundColor: appMode === 'slides' ? 'var(--color-accent-subtle)' : 'transparent',
@@ -1445,7 +1445,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
           </button>
           
           <button
-            onClick={() => { setAppMode('sheets'); setEditingFile(null); }}
+            onClick={() => { setAppMode('sheets'); setEditingFile(null); setActiveSection('files'); }}
             className="w-full flex items-center gap-3 px-3 py-2.5 rounded-xl text-sm font-bold transition-all duration-150"
             style={{
               backgroundColor: appMode === 'sheets' ? 'var(--color-accent-subtle)' : 'transparent',
@@ -1766,7 +1766,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
                       )}
                     </AnimatePresence>
                   </div>
-                  {activeSection === 'files' && (
+                  {activeSection === 'files' && appMode === 'drive' && (
                     <div className="relative">
                       <button
                         onClick={() => setMobileFabOpen(!mobileFabOpen)}
@@ -1872,7 +1872,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
                         </>
                       )}
 
-                      {activeSection === 'files' && (
+                      {activeSection === 'files' && appMode === 'drive' && (
                         <button
                           id="new-folder-button"
                           onClick={() => setShowNewFolder(true)}
@@ -1884,7 +1884,7 @@ export default function FileExplorer({ onLogout }: FileExplorerProps) {
                         </button>
                       )}
 
-                      {activeSection === 'files' && (
+                      {activeSection === 'files' && appMode === 'drive' && (
                         <>
                           <button
                             id="upload-button"