ll(cellId),
                    'Alt-Enter': () => runCellAndInsertBelow(cellId),
                    'Esc': () => commandMode(),
                    'Tab': 'indentMore'
                }
            });
            
            editorInstances.set(cellId, editor);
            return editor;
        }
        
        // Cell execution
        async function runCell(cellId) {
            const cell = document.querySelector(`[data-cell-id="${cellId}"]`);
            if (!cell) return;
            
          