fix(tui): add Kitty CSI-u printable decoding to Input component, closes #1857

packages/tui/CHANGELOG.md

@@ -2,8 +2,13 @@
 
 ## [Unreleased]
 
+### Added
+
+- Exported `decodeKittyPrintable()` from `keys.ts` for decoding Kitty CSI-u sequences into printable characters
+
 ### Fixed
 
+- Fixed `Input` component not accepting typed characters when Kitty keyboard protocol is active (e.g., VS Code 1.110+), causing model selector filter to ignore keystrokes ([#1857](https://github.com/badlogic/pi-mono/issues/1857))
 - Fixed editor/footer visibility drift during terminal resize by forcing full redraws when terminal width or height changes ([#1844](https://github.com/badlogic/pi-mono/pull/1844) by [@ghoulr](https://github.com/ghoulr)).
 
 ## [0.56.1] - 2026-03-05

packages/tui/src/components/editor.ts

@@ -1,6 +1,6 @@
 import type { AutocompleteProvider, CombinedAutocompleteProvider } from "../autocomplete.js";
 import { getEditorKeybindings } from "../keybindings.js";
-import { matchesKey } from "../keys.js";
+import { decodeKittyPrintable, matchesKey } from "../keys.js";
 import { KillRing } from "../kill-ring.js";
 import { type Component, CURSOR_MARKER, type Focusable, type TUI } from "../tui.js";
 import { UndoStack } from "../undo-stack.js";
@@ -92,48 +92,6 @@ export function wordWrapLine(line: string, maxWidth: number): TextChunk[] {
 }
 
 // Kitty CSI-u sequences for printable keys, including optional shifted/base codepoints.
-const KITTY_CSI_U_REGEX = /^\x1b\[(\d+)(?::(\d*))?(?::(\d+))?(?:;(\d+))?(?::(\d+))?u$/;
-const KITTY_MOD_SHIFT = 1;
-const KITTY_MOD_ALT = 2;
-const KITTY_MOD_CTRL = 4;
-const KITTY_LOCK_MASK = 64 + 128; // Caps Lock + Num Lock
-const KITTY_ALLOWED_MODIFIERS = KITTY_MOD_SHIFT | KITTY_LOCK_MASK;
-
-// Decode a printable CSI-u sequence, preferring the shifted key when present.
-function decodeKittyPrintable(data: string): string | undefined {
-	const match = data.match(KITTY_CSI_U_REGEX);
-	if (!match) return undefined;
-
-	// CSI-u groups: <codepoint>[:<shifted>[:<base>]];<mod>u
-	const codepoint = Number.parseInt(match[1] ?? "", 10);
-	if (!Number.isFinite(codepoint)) return undefined;
-
-	const shiftedKey = match[2] && match[2].length > 0 ? Number.parseInt(match[2], 10) : undefined;
-	const modValue = match[4] ? Number.parseInt(match[4], 10) : 1;
-	// Modifiers are 1-indexed in CSI-u; normalize to our bitmask.
-	const modifier = Number.isFinite(modValue) ? modValue - 1 : 0;
-
-	// Only accept printable CSI-u input for plain or Shift-modified text keys.
-	// Reject unsupported modifier bits (e.g. Super/Meta) to avoid inserting
-	// characters from modifier-only terminal events.
-	if ((modifier & ~KITTY_ALLOWED_MODIFIERS) !== 0) return undefined;
-	if (modifier & (KITTY_MOD_ALT | KITTY_MOD_CTRL)) return undefined;
-
-	// Prefer the shifted keycode when Shift is held.
-	let effectiveCodepoint = codepoint;
-	if (modifier & KITTY_MOD_SHIFT && typeof shiftedKey === "number") {
-		effectiveCodepoint = shiftedKey;
-	}
-	// Drop control characters or invalid codepoints.
-	if (!Number.isFinite(effectiveCodepoint) || effectiveCodepoint < 32) return undefined;
-
-	try {
-		return String.fromCodePoint(effectiveCodepoint);
-	} catch {
-		return undefined;
-	}
-}
-
 interface EditorState {
 	lines: string[];
 	cursorLine: number;

packages/tui/src/components/input.ts

@@ -1,4 +1,5 @@
 import { getEditorKeybindings } from "../keybindings.js";
+import { decodeKittyPrintable } from "../keys.js";
 import { KillRing } from "../kill-ring.js";
 import { type Component, CURSOR_MARKER, type Focusable } from "../tui.js";
 import { UndoStack } from "../undo-stack.js";
@@ -187,6 +188,16 @@ export class Input implements Component, Focusable {
 			return;
 		}
 
+		// Kitty CSI-u printable character (e.g. \x1b[97u for 'a').
+		// Terminals with Kitty protocol flag 1 (disambiguate) send CSI-u for all keys,
+		// including plain printable characters. Decode before the control-char check
+		// since CSI-u sequences contain \x1b which would be rejected.
+		const kittyPrintable = decodeKittyPrintable(data);
+		if (kittyPrintable !== undefined) {
+			this.insertCharacter(kittyPrintable);
+			return;
+		}
+
 		// Regular character input - accept printable characters including Unicode,
 		// but reject control characters (C0: 0x00-0x1F, DEL: 0x7F, C1: 0x80-0x9F)
 		const hasControlChars = [...data].some((ch) => {

packages/tui/src/index.ts

@@ -35,6 +35,7 @@ export {
 } from "./keybindings.js";
 // Keyboard input handling
 export {
+	decodeKittyPrintable,
 	isKeyRelease,
 	isKeyRepeat,
 	isKittyProtocolActive,

packages/tui/src/keys.ts

@@ -1152,3 +1152,58 @@ export function parseKey(data: string): string | undefined {
 
 	return undefined;
 }
+
+// =============================================================================
+// Kitty CSI-u Printable Decoding
+// =============================================================================
+
+const KITTY_CSI_U_REGEX = /^\x1b\[(\d+)(?::(\d*))?(?::(\d+))?(?:;(\d+))?(?::(\d+))?u$/;
+const KITTY_PRINTABLE_ALLOWED_MODIFIERS = MODIFIERS.shift | LOCK_MASK;
+
+/**
+ * Decode a Kitty CSI-u sequence into a printable character, if applicable.
+ *
+ * When Kitty keyboard protocol flag 1 (disambiguate) is active, terminals send
+ * CSI-u sequences for all keys, including plain printable characters. This
+ * function extracts the printable character from such sequences.
+ *
+ * Only accepts plain or Shift-modified keys. Rejects Ctrl, Alt, and unsupported
+ * modifier combinations (those are handled by keybinding matching instead).
+ * Prefers the shifted keycode when Shift is held and a shifted key is reported.
+ *
+ * @param data - Raw input data from terminal
+ * @returns The printable character, or undefined if not a printable CSI-u sequence
+ */
+export function decodeKittyPrintable(data: string): string | undefined {
+	const match = data.match(KITTY_CSI_U_REGEX);
+	if (!match) return undefined;
+
+	// CSI-u groups: <codepoint>[:<shifted>[:<base>]];<mod>[:<event>]u
+	const codepoint = Number.parseInt(match[1] ?? "", 10);
+	if (!Number.isFinite(codepoint)) return undefined;
+
+	const shiftedKey = match[2] && match[2].length > 0 ? Number.parseInt(match[2], 10) : undefined;
+	const modValue = match[4] ? Number.parseInt(match[4], 10) : 1;
+	// Modifiers are 1-indexed in CSI-u; normalize to our bitmask.
+	const modifier = Number.isFinite(modValue) ? modValue - 1 : 0;
+
+	// Only accept printable CSI-u input for plain or Shift-modified text keys.
+	// Reject unsupported modifier bits (e.g. Super/Meta) to avoid inserting
+	// characters from modifier-only terminal events.
+	if ((modifier & ~KITTY_PRINTABLE_ALLOWED_MODIFIERS) !== 0) return undefined;
+	if (modifier & (MODIFIERS.alt | MODIFIERS.ctrl)) return undefined;
+
+	// Prefer the shifted keycode when Shift is held.
+	let effectiveCodepoint = codepoint;
+	if (modifier & MODIFIERS.shift && typeof shiftedKey === "number") {
+		effectiveCodepoint = shiftedKey;
+	}
+	// Drop control characters or invalid codepoints.
+	if (!Number.isFinite(effectiveCodepoint) || effectiveCodepoint < 32) return undefined;
+
+	try {
+		return String.fromCodePoint(effectiveCodepoint);
+	} catch {
+		return undefined;
+	}
+}