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src/components/category/CategoryNameDialog.jsx

@@ -113,8 +113,9 @@ class CategoryNameDialog extends Component {
     const { open, mode = 'create' } = this.props;
     const { mode: formMode, name, bulkText, busy, error } = this.state;
     const isBulk = formMode === BULK_MODE;
-    const canBulk = mode === 'create';
-    const canSubmitSingle = name.trim() !== '';
+    const canSubmitSingle =
+      name.trim() !== '' &&
+      (mode !== 'edit' || name.trim() !== (this.props.initialName ?? '').trim());
     const bulkNames = parseBulkNames(bulkText);
     const canSubmitBulk = bulkNames.length > 0;
 
@@ -157,7 +158,13 @@ class CategoryNameDialog extends Component {
               <Button
                 type="submit"
                 variant="contained"
+                color={canSubmitSingle ? 'success' : 'inherit'}
                 disabled={busy || !canSubmitSingle}
+                sx={
+                  canSubmitSingle
+                    ? { bgcolor: 'success.main', color: '#fff', '&:hover': { bgcolor: 'success.dark' } }
+                    : undefined
+                }
               >
                 {SUBMIT_LABELS[mode]}
               </Button>

src/components/category/CategoryTree.jsx

@@ -749,13 +749,27 @@ export default class CategoryTree extends PureComponent {
             >
               Abbrechen
             </Button>
-            <Button
-              onClick={this.handleConfirmRename}
-              variant="contained"
-              disabled={!renameValue.trim() || isSubmitting}
-            >
-              Speichern
-            </Button>
+            {(() => {
+              const canSave =
+                Boolean(renameValue.trim()) &&
+                !isSubmitting &&
+                renameValue.trim() !== (renameTarget?.name ?? '').trim();
+              return (
+                <Button
+                  onClick={this.handleConfirmRename}
+                  variant="contained"
+                  color={canSave ? 'success' : 'inherit'}
+                  disabled={!canSave}
+                  sx={
+                    canSave
+                      ? { bgcolor: 'success.main', color: '#fff', '&:hover': { bgcolor: 'success.dark' } }
+                      : undefined
+                  }
+                >
+                  Speichern
+                </Button>
+              );
+            })()}
           </DialogActions>
         </AppDialog>