Add back support for escaping newline with a \ character (#4064)

packages/cli/src/ui/components/InputPrompt.test.tsx

@@ -90,6 +90,7 @@ describe('InputPrompt', () => {
       killLineLeft: vi.fn(),
       openInExternalEditor: vi.fn(),
       newline: vi.fn(),
+      backspace: vi.fn(),
     } as unknown as TextBuffer;
 
     mockShellHistory = {
@@ -527,4 +528,19 @@ describe('InputPrompt', () => {
     expect(props.onSubmit).not.toHaveBeenCalled();
     unmount();
   });
+
+  it('should add a newline on enter when the line ends with a backslash', async () => {
+    props.buffer.setText('first line\\');
+
+    const { stdin, unmount } = render(<InputPrompt {...props} />);
+    await wait();
+
+    stdin.write('\r');
+    await wait();
+
+    expect(props.onSubmit).not.toHaveBeenCalled();
+    expect(props.buffer.backspace).toHaveBeenCalled();
+    expect(props.buffer.newline).toHaveBeenCalled();
+    unmount();
+  });
 });

packages/cli/src/ui/components/InputPrompt.tsx

@@ -329,7 +329,15 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
 
         if (key.name === 'return' && !key.ctrl && !key.meta && !key.paste) {
           if (buffer.text.trim()) {
-            handleSubmitAndClear(buffer.text);
+            const [row, col] = buffer.cursor;
+            const line = buffer.lines[row];
+            const charBefore = col > 0 ? cpSlice(line, col - 1, col) : '';
+            if (charBefore === '\\') {
+              buffer.backspace();
+              buffer.newline();
+            } else {
+              handleSubmitAndClear(buffer.text);
+            }
           }
           return;
         }