From 9c0ba357adc9034e7071302e83b9b79d054aec8d Mon Sep 17 00:00:00 2001
From: Mario Zechner <badlogicgames@gmail.com>
Date: Sat, 14 Mar 2026 03:58:28 +0100
Subject: [PATCH] fix(tui): distinguish ctrl+backspace from backspace on
 Windows Terminal

0x08 (BS) was treated as plain backspace alongside 0x7f (DEL). On
Windows Terminal, Backspace sends 0x7f and Ctrl+Backspace sends 0x08,
making ctrl+backspace bindings unreachable.

Now 0x08 matches ctrl+backspace (and ctrl+h, same byte) but not plain
backspace. 0x7f remains plain backspace.

fixes #2139
---
 packages/tui/CHANGELOG.md      |  4 ++++
 packages/tui/src/keys.ts       | 11 +++++++++--
 packages/tui/test/keys.test.ts | 14 ++++++++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/packages/tui/CHANGELOG.md b/packages/tui/CHANGELOG.md
index 62d9f6d7..0a3979cf 100644
--- a/packages/tui/CHANGELOG.md
+++ b/packages/tui/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Fixed
+
+- Fixed `ctrl+backspace` being indistinguishable from plain `backspace` on Windows Terminal. `0x08` is now recognized as `ctrl+backspace` instead of `backspace`, making `ctrl+backspace` bindable on terminals where it produces a distinct byte ([#2139](https://github.com/badlogic/pi-mono/issues/2139))
+
 ## [0.58.0] - 2026-03-14
 
 ### Added
diff --git a/packages/tui/src/keys.ts b/packages/tui/src/keys.ts
index 5d107d5a..dfd0e9bc 100644
--- a/packages/tui/src/keys.ts
+++ b/packages/tui/src/keys.ts
@@ -846,8 +846,14 @@ export function matchesKey(data: string, keyId: KeyId): boolean {
 				}
 				return matchesKittySequence(data, CODEPOINTS.backspace, MODIFIERS.alt);
 			}
+			if (ctrl && !alt && !shift) {
+				// Legacy: 0x08 (BS) is sent by Windows Terminal for Ctrl+Backspace.
+				// Also matches Ctrl+H (same byte, ambiguous in legacy terminals).
+				if (data === "\x08") return true;
+				return matchesKittySequence(data, CODEPOINTS.backspace, MODIFIERS.ctrl);
+			}
 			if (modifier === 0) {
-				return data === "\x7f" || data === "\x08" || matchesKittySequence(data, CODEPOINTS.backspace, 0);
+				return data === "\x7f" || matchesKittySequence(data, CODEPOINTS.backspace, 0);
 			}
 			return matchesKittySequence(data, CODEPOINTS.backspace, modifier);
 
@@ -1165,7 +1171,8 @@ export function parseKey(data: string): string | undefined {
 	if (data === "\r" || (!_kittyProtocolActive && data === "\n") || data === "\x1bOM") return "enter";
 	if (data === "\x00") return "ctrl+space";
 	if (data === " ") return "space";
-	if (data === "\x7f" || data === "\x08") return "backspace";
+	if (data === "\x7f") return "backspace";
+	if (data === "\x08") return "ctrl+backspace";
 	if (data === "\x1b[Z") return "shift+tab";
 	if (!_kittyProtocolActive && data === "\x1b\r") return "alt+enter";
 	if (!_kittyProtocolActive && data === "\x1b ") return "alt+space";
diff --git a/packages/tui/test/keys.test.ts b/packages/tui/test/keys.test.ts
index 87926728..6a7e53ca 100644
--- a/packages/tui/test/keys.test.ts
+++ b/packages/tui/test/keys.test.ts
@@ -252,6 +252,20 @@ describe("matchesKey", () => {
 			assert.strictEqual(parseKey("\x1b\x1f"), "ctrl+alt+-");
 		});
 
+		it("should distinguish backspace (0x7f) from ctrl+backspace (0x08)", () => {
+			setKittyProtocolActive(false);
+			// 0x7f is plain backspace
+			assert.strictEqual(matchesKey("\x7f", "backspace"), true);
+			assert.strictEqual(matchesKey("\x7f", "ctrl+backspace"), false);
+			assert.strictEqual(parseKey("\x7f"), "backspace");
+			// 0x08 is ctrl+backspace (Windows Terminal sends this for Ctrl+Backspace)
+			assert.strictEqual(matchesKey("\x08", "ctrl+backspace"), true);
+			assert.strictEqual(matchesKey("\x08", "backspace"), false);
+			assert.strictEqual(parseKey("\x08"), "ctrl+backspace");
+			// 0x08 also matches ctrl+h (same byte, ambiguous in legacy terminals)
+			assert.strictEqual(matchesKey("\x08", "ctrl+h"), true);
+		});
+
 		it("should parse legacy alt-prefixed sequences when kitty inactive", () => {
 			setKittyProtocolActive(false);
 			assert.strictEqual(matchesKey("\x1b ", "alt+space"), true);