[BUG]: Multi-line edit only inserts newline on first cursor in Markdown files

[KSAdk]

Description:

When using multi-cursor editing in Markdown files with the Learn Markdown extension enabled, pressing Enter to insert a newline only inserts the newline at the first cursor position. All other cursors do not insert newlines, breaking the expected multi-cursor behavior.

Steps to Reproduce:

1. Open any Markdown (.md) file in VS Code
2. Create multiple cursors (e.g., using Alt+Click or Ctrl+Alt+Down)
3. Press Enter to insert a newline
4. Observe that only the first cursor inserts a newline; other cursors remain unchanged

Expected Behavior:

All cursors should insert a newline when Enter is pressed, consistent with standard VS Code multi-cursor behavior.

Actual Behavior:
Only the first cursor inserts a newline. Other cursors do not respond to the Enter key.

Environment:

• VS Code Version:
  • Version: 1.112.0 (user setup)
  • Commit: 07ff9d6178ede9a1bd12ad3399074d726ebe6e43
  • Date: 2026-03-17T18:09:23Z
  • Electron: 39.8.0
  • ElectronBuildId: 13470701
  • Chromium: 142.0.7444.265
  • Node.js: 22.22.0
  • V8: 14.2.231.22-electron.0
  • OS: Windows_NT x64 10.0.26200
• Learn Markdown Extension Version: 1.0.18
• OS: Windows

Additional Context:

• The issue does NOT occur when all extensions are disabled (verified using "Developer: Reload With Extensions Disabled")
• The issue is resolved when the Learn Markdown extension is disabled
• Multi-cursor editing works correctly in non-Markdown files with the extension enabled
• This suggests the extension is interfering with the default Enter key behavior specifically for Markdown files