From 40238a1dbf3e73aca6d29dcbe6a60b5fc8f91249 Mon Sep 17 00:00:00 2001
From: wnduqrla <juyeop03@gmail.com>
Date: Mon, 25 May 2026 17:58:22 +0900
Subject: [PATCH] fix(terminal): forward Ctrl+<letter> to PTY under non-Latin
 IME
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Korean (and other non-Latin) IME maps physical letter keys to non-ASCII
glyphs: pressing O while Korean 2-set is active yields event.key="ㅐ"
instead of "o". xterm derives the Ctrl+<letter> control byte from
event.key, so it silently drops every Ctrl+<letter> chord typed while
such an IME is active — breaking TUI app shortcuts like Claude Code's
Ctrl+O (toggle transcript) and Ctrl+K (clear input).

The fix intercepts these chords in createTerminalKeyEventHandler before
xterm runs: when ctrlKey is set, no other modifier is held, event.code
is a letter key, and event.key is non-ASCII (charCode > 127), compute
the control byte from the physical key position (event.code) and write
it directly to the PTY via terminal.input(). event.code is always
layout- and IME-agnostic, so the correct byte is sent regardless of
which input source is active.

Relates to #3365, extends the event.code approach from #3391 to the
xterm key-encoder path.
---
 .../terminal-key-event-handler.test.ts        | 70 +++++++++++++++++++
 .../terminal/terminal-key-event-handler.ts    | 23 ++++++
 2 files changed, 93 insertions(+)

diff --git a/apps/desktop/src/renderer/lib/terminal/terminal-key-event-handler.test.ts b/apps/desktop/src/renderer/lib/terminal/terminal-key-event-handler.test.ts
index a8b5a65c06a..6b14675e366 100644
--- a/apps/desktop/src/renderer/lib/terminal/terminal-key-event-handler.test.ts
+++ b/apps/desktop/src/renderer/lib/terminal/terminal-key-event-handler.test.ts
@@ -113,4 +113,74 @@ describe("createTerminalKeyEventHandler", () => {
 		expect(handler(event)).toBe(true);
 		expect(xterm.input).not.toHaveBeenCalled();
 	});
+
+	describe("non-Latin IME Ctrl+<letter> fix", () => {
+		it("sends Ctrl+O to PTY when Korean IME maps KeyO to a non-ASCII glyph", () => {
+			const xterm = terminal();
+			// Korean 2-set: O key → "ㅐ" (U+1150, charCode 4432)
+			const event = keyboardEvent({
+				key: "ㅐ",
+				code: "KeyO",
+				ctrlKey: true,
+			});
+			const handler = createTerminalKeyEventHandler(xterm, {
+				platform: "MacIntel",
+			});
+
+			expect(handler(event)).toBe(false);
+			expect(event.preventDefault).toHaveBeenCalled();
+			// Ctrl+O = ASCII 15 = \x0f
+			expect(xterm.input).toHaveBeenCalledWith("\x0f", false);
+		});
+
+		it("sends Ctrl+K to PTY when Korean IME maps KeyK to a non-ASCII glyph", () => {
+			const xterm = terminal();
+			// Korean 2-set: K key → "ㅏ"
+			const event = keyboardEvent({
+				key: "ㅏ",
+				code: "KeyK",
+				ctrlKey: true,
+			});
+			const handler = createTerminalKeyEventHandler(xterm, {
+				platform: "MacIntel",
+			});
+
+			expect(handler(event)).toBe(false);
+			expect(event.preventDefault).toHaveBeenCalled();
+			// Ctrl+K = ASCII 11 = \x0b
+			expect(xterm.input).toHaveBeenCalledWith("\x0b", false);
+		});
+
+		it("does not intercept Ctrl+<letter> when Latin IME is active (event.key is ASCII)", () => {
+			const xterm = terminal();
+			const event = keyboardEvent({
+				key: "o",
+				code: "KeyO",
+				ctrlKey: true,
+			});
+			const handler = createTerminalKeyEventHandler(xterm, {
+				platform: "MacIntel",
+			});
+
+			// Let xterm handle it normally
+			expect(handler(event)).toBe(true);
+			expect(xterm.input).not.toHaveBeenCalled();
+		});
+
+		it("does not intercept Ctrl+Shift or Ctrl+Alt combos (only bare Ctrl)", () => {
+			const xterm = terminal();
+			const event = keyboardEvent({
+				key: "ㅐ",
+				code: "KeyO",
+				ctrlKey: true,
+				shiftKey: true,
+			});
+			const handler = createTerminalKeyEventHandler(xterm, {
+				platform: "MacIntel",
+			});
+
+			expect(handler(event)).toBe(true);
+			expect(xterm.input).not.toHaveBeenCalled();
+		});
+	});
 });
diff --git a/apps/desktop/src/renderer/lib/terminal/terminal-key-event-handler.ts b/apps/desktop/src/renderer/lib/terminal/terminal-key-event-handler.ts
index 1b7edf8f10f..39c20606f92 100644
--- a/apps/desktop/src/renderer/lib/terminal/terminal-key-event-handler.ts
+++ b/apps/desktop/src/renderer/lib/terminal/terminal-key-event-handler.ts
@@ -76,6 +76,29 @@ export function createTerminalKeyEventHandler(
 			return false;
 		}
 
+		// Non-Latin IME (e.g. Korean 2-set) maps physical letter keys to
+		// non-ASCII glyphs: pressing O while Korean is active yields
+		// event.key="ㅐ" instead of "o". xterm derives the Ctrl+<letter>
+		// control byte from event.key, so it silently drops Ctrl+O, Ctrl+K,
+		// and every other Ctrl+<letter> chord typed while such an IME is
+		// active. Compute the byte from the physical key position
+		// (event.code) instead — that value is always layout-agnostic.
+		if (
+			event.type === "keydown" &&
+			event.ctrlKey &&
+			!event.metaKey &&
+			!event.altKey &&
+			!event.shiftKey
+		) {
+			const codeMatch = event.code.match(/^Key([A-Z])$/);
+			if (codeMatch && event.key.charCodeAt(0) > 127) {
+				event.preventDefault();
+				const charCode = codeMatch[1].charCodeAt(0) - 64; // A→1 … Z→26
+				terminal.input(String.fromCharCode(charCode), false);
+				return false;
+			}
+		}
+
 		return true;
 	};
 }