Ctrl+C and Ctrl+D are not recognized with a Cyrillic layout under Kitty keyboard enhancement

What version of Codex CLI is running?

codex-cli 0.145.0

What subscription do you have?

Not relevant to terminal input handling.

Which model were you using?

Not model-dependent.

What platform is your computer?

Linux 6.17.0-122035-tuxedo x86_64 x86_64

What terminal emulator and version are you using (if applicable)?

A terminal implementing Kitty keyboard enhancement with alternate-key reporting. The original runtime observation was captured with Shitty 2026.07.23, but the failure can be reproduced directly from the CSI-u input below and does not depend on terminal-specific behavior.

No terminal multiplexer is involved.

Codex doctor report

Not collected; the failure is reproducible in the keyboard-event parser pinned by Codex.

What issue are you seeing?

With a Cyrillic keyboard layout active, physical Ctrl+C and Ctrl+D are not recognized by the Codex TUI when the terminal reports Kitty base-layout keys.

The protocol-level inputs are:

• physical Ctrl+C under the Russian layout: ESC[1089::99;5:1u
• physical Ctrl+D under the Russian layout: ESC[1074::100;5:1u

In these packets, 1089 and 1074 are the active-layout characters с and в; 99 and 100 are the base-layout characters c and d.

Codex 0.145.0 pins Crossterm 0.28.1 from nornagon/crossterm revision 87db8bfa6dc99427fd3b071681b07fc31c6ce995. Its CSI-u parser reads the primary codepoint but does not retain the third base-layout component. The resulting events are Ctrl+с and Ctrl+в, while Codex matches the shortcuts against ASCII Ctrl+c and Ctrl+d.

The same physical keys work through legacy keyboard encoding when keyboard enhancement is disabled.

What steps can reproduce the bug?

Parser-level reproduction against the Crossterm revision pinned by Codex:

1. Pass b"\x1b[1089::99;5:1u" to parse_csi_u_encoded_key_code.
2. Observe a Ctrl+с key event; base-layout codepoint 99 is not represented in the result.
3. Pass b"\x1b[1074::100;5:1u" through the same parser.
4. Observe a Ctrl+в key event; base-layout codepoint 100 is not represented in the result.

Runtime reproduction:

1. Run Codex in a terminal that implements Kitty alternate-key reporting.
2. Switch to a Russian keyboard layout.
3. Press the physical Ctrl+C or Ctrl+D key.
4. Observe that the corresponding Codex action is not triggered.
5. Start Codex with CODEX_TUI_DISABLE_KEYBOARD_ENHANCEMENT=1 codex and repeat. The shortcuts are recognized through legacy keyboard encoding.

What is the expected behavior?

Ctrl+C and Ctrl+D shortcuts should remain usable when a non-Latin keyboard layout is active and the terminal supplies the corresponding base-layout key.

Additional information

The missing base-layout support is tracked upstream in Crossterm:

https://github.com/crossterm-rs/crossterm/issues/968

Kitty defines unicode-key-code::base-layout-key and explicitly describes Cyrillic Ctrl+C as a use case:

https://sw.kovidgoyal.net/kitty/keyboard-protocol/#key-codes

Pinned parser implementation:

https://github.com/nornagon/crossterm/blob/87db8bfa6dc99427fd3b071681b07fc31c6ce995/src/event/sys/unix/parse.rs#L548-L667