In Neovim Shift+number keys produce digits instead of symbols with Kitty keyboard protocol

[wngtk]

Problem

In VS Code 1.116 integrated terminal, Shift+number keys (e.g., Shift+1 for !) produce digits instead of symbols when using Neovim. This only affects VS Code terminal; Ghostty, and other terminals work correctly.

Environment

• Neovim: nightly (post-2026-04-19)
• VS Code: 1.116 (released 2026-04)
• OS: macOS (Windows/Linux unconfirmed)
• Terminal: VS Code integrated terminal (xterm.js)

Steps to reproduce

1. Open VS Code integrated terminal
2. Launch nvim
3. Enter :
4. Press Shift+1 expecting !
5. Observe 1 appears instead

Root cause

VS Code added Kitty keyboard protocol support via xterm.js. Neovim detects this and sends CSI > 3 u to enable:

• bit0: Disambiguate escape codes
• bit1: Report event types