Kitty keyboard protocol

Category: extensions · Tags: Kitty Extensions · Specification ↗

The Kitty keyboard protocol solves fundamental ambiguities in traditional terminal input handling. Legacy terminals cannot distinguish between Ctrl+I and Tab, Ctrl+M and Enter, or Escape and the start of an escape sequence — they all produce the same byte sequences. The protocol also enables key-release events and distinguishes between different modifier key presses (left vs. right Shift). Applications opt in with CSI > flags u, where flags is a bitmask selecting reporting modes: disambiguate keys (1), report event types (2), report alternate keys (4), report all keys as escape sequences (8), and report associated text (16). Keys are reported as CSI unicode-key-code : shifted-key : base-layout-key ; modifiers : event-type u. Adopted by Ghostty, WezTerm, foot, and rio. The protocol is progressive — applications can request only the features they need, and terminals report which flags they support.

Supported by 4 of 6 backends (67%)

Support Matrix

Backend	Version	Support	Notes
Alacritty	0.26.0	✓ yes
Ghostty	1.3.1	✓ yes
Kitty	0.40.0	✓ yes
WezTerm	0.1.0-fork.5	✓ yes
vt100	0.1.0	✗ no	Not implemented — pure TypeScript emulator
xterm.js	5.5.0	✗ no	Not implemented in xterm.js

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