Focus cell editor if there is only one code cell in the document.

src/vs/workbench/contrib/notebook/browser/notebookBrowser.ts

@@ -110,6 +110,7 @@ export interface ICellViewModel {
 	currentTokenSource: CancellationTokenSource | undefined;
 	focusMode: CellFocusMode;
 	getText(): string;
+	getTextLength(): number;
 	metadata: NotebookCellMetadata | undefined;
 	textModel: ITextModel | undefined;
 	hasModel(): this is IEditableCellViewModel;

src/vs/workbench/contrib/notebook/browser/notebookEditorWidget.ts

@@ -440,6 +440,18 @@ export class NotebookEditorWidget extends Disposable implements INotebookEditor
 					}
 				}
 			}
+		} else if (this.notebookViewModel!.viewCells.length === 1 && this.notebookViewModel!.viewCells[0].cellKind === CellKind.Code) {
+			// there is only one code cell in the document
+			const cell = this.notebookViewModel!.viewCells[0];
+			if (cell.getTextLength() === 0) {
+				// the cell is empty, very likely a template cell, focus it
+				this.selectElement(cell);
+				await this.revealLineInCenterAsync(cell, 1);
+				const editor = this.renderedEditors.get(cell)!;
+				if (editor) {
+					editor.focus();
+				}
+			}
 		}
 	}
 

src/vs/workbench/contrib/notebook/browser/viewModel/baseCellViewModel.ts

@@ -197,6 +197,10 @@ export abstract class BaseCellViewModel extends Disposable {
 		return this.model.getValue();
 	}
 
+	getTextLength(): number {
+		return this.model.getTextLength();
+	}
+
 	private saveViewState(): void {
 		if (!this._textEditor) {
 			return;

src/vs/workbench/contrib/notebook/common/model/notebookCellTextModel.ts

@@ -93,6 +93,10 @@ export class NotebookCellTextModel extends Disposable implements ICell {
 		}
 	}
 
+	getTextLength(): number {
+		return this.textBuffer.getLength();
+	}
+
 	getFullModelRange() {
 		const lineCount = this.textBuffer.getLineCount();
 		return new Range(1, 1, lineCount, this.textBuffer.getLineLength(lineCount) + 1);