Sort cell metadata to avoid unnecessary scm diffs

src/helper.ts

@@ -13,17 +13,50 @@ export async function updateCellTags(cell: vscode.NotebookCell, tags: string[])
     const metadata = JSON.parse(JSON.stringify(cell.metadata));
     if (useCustomMetadata()) {
         metadata.custom = metadata.custom || {};
-        metadata.custom.tags = tags;
+        metadata.custom.metadata = metadata.custom.metadata || {};
+        metadata.custom.metadata.tags = tags;
+        if (tags.length === 0) {
+            delete metadata.custom.metadata.tags;
+        }
     } else {
         metadata.metadata = metadata.metadata || {};
         metadata.metadata.tags = tags;
+        if (tags.length === 0) {
+            delete metadata.metadata.tags;
+        }
     }
     const edit = new vscode.WorkspaceEdit();
-    const nbEdit = vscode.NotebookEdit.updateCellMetadata(cell.index, metadata);
+    const nbEdit = vscode.NotebookEdit.updateCellMetadata(cell.index, sortObjectPropertiesRecursively(metadata));
     edit.set(cell.notebook.uri, [nbEdit]);
     await vscode.workspace.applyEdit(edit);
 }
 
 function useCustomMetadata() {
-    return !vscode.workspace.getConfiguration('jupyter').get<boolean>('experimental.dropCustomMetadata', false);
+    if (vscode.extensions.getExtension('vscode.ipynb')?.exports.dropCustomMetadata) {
+        return false;
+    }
+    return true;
+}
+
+
+/**
+ * Sort the JSON to minimize unnecessary SCM changes.
+ * Jupyter notbeooks/labs sorts the JSON keys in alphabetical order.
+ * https://github.com/microsoft/vscode/issues/208137
+ */
+function sortObjectPropertiesRecursively(obj: any): any {
+	if (Array.isArray(obj)) {
+		return obj.map(sortObjectPropertiesRecursively);
+	}
+	if (obj !== undefined && obj !== null && typeof obj === 'object' && Object.keys(obj).length > 0) {
+		return (
+			Object.keys(obj)
+				.sort()
+				.reduce<Record<string, any>>((sortedObj, prop) => {
+					sortedObj[prop] = sortObjectPropertiesRecursively(obj[prop]);
+					return sortedObj;
+				}, {}) as any
+		);
+	}
+	return obj;
 }