From 91be0eba77cd42ffe0148f7ca7eb0efae4e24709 Mon Sep 17 00:00:00 2001
From: Gergely Jutasi <28388707+0xGREG@users.noreply.github.com>
Date: Tue, 4 Aug 2026 02:03:45 +0200
Subject: [PATCH] fix(tui): use Kitty flag 1 on Windows to fix Shift+letter
 input

WezTerm/ConPTY on Windows drops Shift+letter keypresses entirely when
Kitty keyboard protocol flag 4 (report alternate keys) is set. Fall
back to flag 1 (disambiguate only) on Windows so shifted printable
keys are delivered as raw characters instead of being silently eaten.

Also adds a defensive SHIFT_MAP fallback in decodeKittyPrintable for
terminals that send CSI-u sequences with the shift modifier but omit
the shifted_key secondary codepoint.
---
 packages/tui/src/keys.ts     | 37 ++++++++++++++++++++++++++++++++++--
 packages/tui/src/terminal.ts |  6 ++++++
 2 files changed, 41 insertions(+), 2 deletions(-)

diff --git a/packages/tui/src/keys.ts b/packages/tui/src/keys.ts
index ba2cb46c2..8d556da48 100644
--- a/packages/tui/src/keys.ts
+++ b/packages/tui/src/keys.ts
@@ -307,6 +307,32 @@ const KITTY_MOD_CTRL = 4;
 const KITTY_MOD_SUPER = 8;
 const KITTY_MOD_NUM_LOCK = 128;
 const KITTY_LOCK_MASK = 64 + KITTY_MOD_NUM_LOCK; // Caps Lock + Num Lock
+const SHIFT_MAP: Record<number, number> = {
+	// US layout: unshifted codepoint → shifted codepoint
+	// digits
+	48: 41, // 0 → )
+	49: 33, // 1 → !
+	50: 64, // 2 → @
+	51: 35, // 3 → #
+	52: 36, // 4 → $
+	53: 37, // 5 → %
+	54: 94, // 6 → ^
+	55: 38, // 7 → &
+	56: 42, // 8 → *
+	57: 40, // 9 → (
+	// symbols
+	45: 95, // - → _
+	61: 43, // = → +
+	91: 123, // [ → {
+	93: 125, // ] → }
+	92: 124, // \ → |
+	59: 58, // ; → :
+	39: 34, // ' → "
+	96: 126, // ` → ~
+	44: 60, // , → <
+	46: 62, // . → >
+	47: 63, // / → ?
+};
 const MODIFY_OTHER_KEYS_PATTERN = /^\x1b\[27;(\d+);(\d+)~$/;
 const KITTY_KEYPAD_OPERATOR_TEXT: Record<number, string> = {
 	57410: "/",
@@ -430,8 +456,15 @@ function decodeKittyPrintable(data: string): string | undefined {
 	}
 
 	let effectiveCodepoint = codepoint;
-	if (effectiveMod & KITTY_MOD_SHIFT && typeof shiftedKey === "number") {
-		effectiveCodepoint = shiftedKey;
+	if (effectiveMod & KITTY_MOD_SHIFT) {
+		if (typeof shiftedKey === "number") {
+			effectiveCodepoint = shiftedKey;
+		} else if (codepoint >= 97 && codepoint <= 122) {
+			effectiveCodepoint = codepoint - 32;
+		} else {
+			const shifted = SHIFT_MAP[codepoint];
+			if (shifted !== undefined) effectiveCodepoint = shifted;
+		}
 	}
 
 	if (effectiveCodepoint >= 0xe000 && effectiveCodepoint <= 0xf8ff) {
diff --git a/packages/tui/src/terminal.ts b/packages/tui/src/terminal.ts
index d5204fe9c..c83e0adcd 100644
--- a/packages/tui/src/terminal.ts
+++ b/packages/tui/src/terminal.ts
@@ -1105,6 +1105,12 @@ export class ProcessTerminal implements Terminal {
 					// Push level-2 to keep its shortcuts reporting consistently.
 					this.#kittyEnableSeq = "\x1b[>7u";
 					this.#safeWrite(this.#kittyEnableSeq);
+				} else if (process.platform === "win32") {
+					// WezTerm/ConPTY on Windows drops Shift+letter keypresses entirely
+					// when flag 4 (report alternate keys) is set. Use flag 1
+					// (disambiguate only) to keep shifted printable keys working.
+					this.#kittyEnableSeq = "\x1b[>1u";
+					this.#safeWrite(this.#kittyEnableSeq);
 				} else {
 					// Disambiguate escape codes and report base-layout keys for physical
 					// shortcut matching, without event reporting that caused regression #3259.