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Kitty keyboard: DISAMBIGUATE (flag 1)
Flag 1 of the Kitty keyboard protocol's progressive enhancement. When set, the terminal uses CSI u encoding for keys that would otherwise be ambiguous — e.g., Escape vs Alt, Tab vs Ctrl+I, Enter vs Ctrl+M. This is the minimum flag most applications need. Without it, decades-old terminal ambiguities persist. All terminals claiming kitty keyboard support must implement this flag.
How this is testedautomated
Push keyboard mode with flag 1 (
Push keyboard mode with flag 1 (
CSI > 1 u), query flags (CSI ? u), verify bit 1 is set in response, then pop (CSI < u).The same probe runs against headless backends (via Termless) and real terminal apps (via a daemon launched in each terminal). This lets us distinguish parser correctness from rendering correctness.
Analysis2026-04-06
Supported by 7 of 12 terminals (58%). Not supported by: Kitty, Terminal.app, Cursor, vt100.js, xterm.js. Part of the Rich TUI baseline. Notes: vt100.js: Not implemented — pure TypeScript emulator; xterm.js: Kitty keyboard protocol not implemented in xterm.js.
Supported by 9 of 14 backends (64%)
Terminal Applications
| Terminal | Version | Support | Notes |
|---|---|---|---|
| iTerm2 | 3.6.9 | ✓ yes | |
| Ghostty | 1.3.1 | ✓ yes | |
| VS Code | ✓ yes | ||
| Warp | ✓ yes | ||
| Cursor | ✗ no | ||
| Terminal.app | ✗ no |
Headless Backends
Parser correctness only — a ✓ means the parser accepts the sequence.
| Backend | Version | Support | Notes |
|---|---|---|---|
| Alacritty | 0.26.0 | ✓ yes | |
| Kitty | 0.40.0 | ✓ yes | |
| vterm | 0.2.0 | ✓ yes | |
| WezTerm | 0.1.0-fork.5 | ✓ yes | |
| vt100.js | 0.2.1 | ✗ no | Not implemented — pure TypeScript emulator |
| xterm.js | 5.5.0 | ✗ no | Kitty keyboard protocol not implemented in xterm.js |