fix(paste) incorrect handling of \\\n in pastes (#6532)

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

@@ -1211,6 +1211,43 @@ describe('InputPrompt', () => {
     });
   });
 
+  describe('multiline paste', () => {
+    it.each([
+      {
+        description: 'with \n newlines',
+        pastedText: 'This \n is \n a \n multiline \n paste.',
+      },
+      {
+        description: 'with extra slashes before \n newlines',
+        pastedText: 'This \\\n is \\\n a \\\n multiline \\\n paste.',
+      },
+      {
+        description: 'with \r\n newlines',
+        pastedText: 'This\r\nis\r\na\r\nmultiline\r\npaste.',
+      },
+    ])('should handle multiline paste $description', async ({ pastedText }) => {
+      const { stdin, unmount } = renderWithProviders(
+        <InputPrompt {...props} />,
+      );
+      await wait();
+
+      // Simulate a bracketed paste event from the terminal
+      stdin.write(`\x1b[200~${pastedText}\x1b[201~`);
+      await wait();
+
+      // Verify that the buffer's handleInput was called once with the full text
+      expect(props.buffer.handleInput).toHaveBeenCalledTimes(1);
+      expect(props.buffer.handleInput).toHaveBeenCalledWith(
+        expect.objectContaining({
+          paste: true,
+          sequence: pastedText,
+        }),
+      );
+
+      unmount();
+    });
+  });
+
   describe('enhanced input UX - double ESC clear functionality', () => {
     it('should clear buffer on second ESC press', async () => {
       const onEscapePromptChange = vi.fn();

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

@@ -239,6 +239,12 @@ export const InputPrompt: React.FC<InputPromptProps> = ({
         return;
       }
 
+      if (key.paste) {
+        // Ensure we never accidentally interpret paste as regular input.
+        buffer.handleInput(key);
+        return;
+      }
+
       if (vimHandleInput && vimHandleInput(key)) {
         return;
       }

packages/cli/src/ui/components/shared/text-buffer.ts

@@ -1833,6 +1833,13 @@ export function useTextBuffer({
     }): void => {
       const { sequence: input } = key;
 
+      if (key.paste) {
+        // Do not do any other processing on pastes so ensure we handle them
+        // before all other cases.
+        insert(input, { paste: key.paste });
+        return;
+      }
+
       if (
         key.name === 'return' ||
         input === '\r' ||