From ef8ec984894408953cc6e0ea2e46cfeb9c272507 Mon Sep 17 00:00:00 2001
From: Billy Biggs <bbiggs@google.com>
Date: Mon, 14 Jul 2025 05:34:20 +0200
Subject: [PATCH] Add back support for escaping newline with a \ character
 (#4064)

---
 .../cli/src/ui/components/InputPrompt.test.tsx   | 16 ++++++++++++++++
 packages/cli/src/ui/components/InputPrompt.tsx   | 10 +++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/packages/cli/src/ui/components/InputPrompt.test.tsx b/packages/cli/src/ui/components/InputPrompt.test.tsx
index ad7a3985..53a2cb0e 100644
--- a/packages/cli/src/ui/components/InputPrompt.test.tsx
+++ b/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();
+  });
 });
diff --git a/packages/cli/src/ui/components/InputPrompt.tsx b/packages/cli/src/ui/components/InputPrompt.tsx
index 371fb48d..5edda273 100644
--- a/packages/cli/src/ui/components/InputPrompt.tsx
+++ b/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;
         }