From fdb7346f3a15c5a5e0df32367fd1ffd455549e26 Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 10 Mar 2026 00:27:27 -0700
Subject: [PATCH 1/2] Fix kitty keyboard disambiguate mode for space, enter,
 tab, backspace

---
 src/common/input/KittyKeyboard.test.ts | 31 +++++++++++++++++++-------
 src/common/input/KittyKeyboard.ts      | 13 +++++++----
 2 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/src/common/input/KittyKeyboard.test.ts b/src/common/input/KittyKeyboard.test.ts
index e495ac591..a0422ecb1 100644
--- a/src/common/input/KittyKeyboard.test.ts
+++ b/src/common/input/KittyKeyboard.test.ts
@@ -100,24 +100,24 @@ describe('KittyKeyboard', () => {
         assert.strictEqual(result.key, '\x1b[27u');
       });
 
-      it('Enter → CSI 13 u', () => {
+      it('Enter → legacy \\r', () => {
         const result = kitty.evaluate(createEvent({ key: 'Enter' }), flags);
-        assert.strictEqual(result.key, '\x1b[13u');
+        assert.strictEqual(result.key, '\r');
       });
 
-      it('Tab → CSI 9 u', () => {
+      it('Tab → legacy \\t', () => {
         const result = kitty.evaluate(createEvent({ key: 'Tab' }), flags);
-        assert.strictEqual(result.key, '\x1b[9u');
+        assert.strictEqual(result.key, '\t');
       });
 
-      it('Backspace → CSI 127 u', () => {
+      it('Backspace → legacy \\x7f', () => {
         const result = kitty.evaluate(createEvent({ key: 'Backspace' }), flags);
-        assert.strictEqual(result.key, '\x1b[127u');
+        assert.strictEqual(result.key, '\x7f');
       });
 
-      it('Space → CSI 32 u', () => {
+      it('Space → plain space (text-generating key)', () => {
         const result = kitty.evaluate(createEvent({ key: ' ' }), flags);
-        assert.strictEqual(result.key, '\x1b[32u');
+        assert.strictEqual(result.key, ' ');
       });
 
       it('Shift+Tab → CSI 9;2 u', () => {
@@ -134,6 +134,21 @@ describe('KittyKeyboard', () => {
         const result = kitty.evaluate(createEvent({ key: 'Escape', altKey: true }), flags);
         assert.strictEqual(result.key, '\x1b[27;3u');
       });
+
+      it('Ctrl+Backspace → CSI 127;5 u', () => {
+        const result = kitty.evaluate(createEvent({ key: 'Backspace', ctrlKey: true }), flags);
+        assert.strictEqual(result.key, '\x1b[127;5u');
+      });
+
+      it('Ctrl+Space → CSI 32;5 u', () => {
+        const result = kitty.evaluate(createEvent({ key: ' ', ctrlKey: true }), flags);
+        assert.strictEqual(result.key, '\x1b[32;5u');
+      });
+
+      it('Alt+Space → CSI 32;3 u', () => {
+        const result = kitty.evaluate(createEvent({ key: ' ', altKey: true }), flags);
+        assert.strictEqual(result.key, '\x1b[32;3u');
+      });
     });
 
     describe('navigation keys', () => {
diff --git a/src/common/input/KittyKeyboard.ts b/src/common/input/KittyKeyboard.ts
index b296695c5..606b121c3 100644
--- a/src/common/input/KittyKeyboard.ts
+++ b/src/common/input/KittyKeyboard.ts
@@ -457,9 +457,11 @@ export class KittyKeyboard {
     } else if (reportEventTypes) {
       useCsiU = true;
     } else if (flags & KittyKeyboardFlags.DISAMBIGUATE_ESCAPE_CODES) {
-      if (keyCode === 27 || keyCode === 127 || keyCode === 13 || keyCode === 9 || keyCode === 32) {
-        useCsiU = true;
-      } else if (isFunc) {
+      // Per spec, Enter/Tab/Backspace "still generate the same bytes as in legacy
+      // mode" and Space is a text-generating key, so these skip the isFunc fast-path
+      // and only get CSI u when modifiers are present (handled below).
+      const isDisambiguateLegacy = keyCode === 13 || keyCode === 9 || keyCode === 127;
+      if (isFunc && !isDisambiguateLegacy) {
         useCsiU = true;
       } else if (modifiers > 0) {
         if (ev.shiftKey && !ev.ctrlKey && !ev.altKey && !ev.metaKey && ev.key.length === 1) {
@@ -474,7 +476,10 @@ export class KittyKeyboard {
       result.key = this._buildCsiUSequence(ev, keyCode, modifiers, eventType, flags, isFunc, isMod);
       result.cancel = true;
     } else {
-      if (ev.key.length === 1 && !ev.ctrlKey && !ev.altKey && !ev.metaKey) {
+      const legacyByte = keyCode === 13 ? '\r' : keyCode === 9 ? '\t' : keyCode === 127 ? '\x7f' : undefined;
+      if (legacyByte) {
+        result.key = legacyByte;
+      } else if (ev.key.length === 1 && !ev.ctrlKey && !ev.altKey && !ev.metaKey) {
         result.key = ev.key;
       }
     }

From 6f3ce7b0febf2de350174ffd5e9bd4fe75e13acc Mon Sep 17 00:00:00 2001
From: Anthony Kim <anthonykim@microsoft.com>
Date: Tue, 10 Mar 2026 00:30:29 -0700
Subject: [PATCH 2/2] comment

---
 src/common/input/KittyKeyboard.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/common/input/KittyKeyboard.ts b/src/common/input/KittyKeyboard.ts
index 606b121c3..76c468cc4 100644
--- a/src/common/input/KittyKeyboard.ts
+++ b/src/common/input/KittyKeyboard.ts
@@ -458,7 +458,7 @@ export class KittyKeyboard {
       useCsiU = true;
     } else if (flags & KittyKeyboardFlags.DISAMBIGUATE_ESCAPE_CODES) {
       // Per spec, Enter/Tab/Backspace "still generate the same bytes as in legacy
-      // mode" and Space is a text-generating key, so these skip the isFunc fast-path
+      // mode" and consider space to be a text-generating key, so these skip the isFunc fast-path
       // and only get CSI u when modifiers are present (handled below).
       const isDisambiguateLegacy = keyCode === 13 || keyCode === 9 || keyCode === 127;
       if (isFunc && !isDisambiguateLegacy) {