Merge pull request #4482 from Felixoid/fix-wezterm-kitty-esc

Address edge-case with kitty protocol in wezterm

packages/tui/src/stdin-buffer.ts

@@ -205,6 +205,29 @@ function extractCompleteSequences(buffer: string): { sequences: string[]; remain
 				const status = isCompleteSequence(candidate);
 
 				if (status === "complete") {
+					// WezTerm with enable_kitty_keyboard sends the Escape key press as a
+					// raw '\x1b' byte (simple text path in encode_kitty, ignoring
+					// DISAMBIGUATE_ESCAPE_CODES) and the release as a full Kitty CSI-u
+					// sequence. These arrive concatenated as '\x1b\x1b[27;...u'.
+					// The buffer would normally treat '\x1b\x1b' as a complete meta-key
+					// sequence (ESC + single char), leaving '[27;...u' to be typed as
+					// plain text. If the character immediately following '\x1b\x1b'
+					// would begin a new escape sequence, emit only the first ESC and
+					// restart from the second.
+					if (candidate === "\x1b\x1b") {
+						const nextChar = remaining[seqEnd];
+						if (
+							nextChar === "[" || // CSI
+							nextChar === "]" || // OSC
+							nextChar === "O" || // SS3
+							nextChar === "P" || // DCS
+							nextChar === "_" // APC
+						) {
+							sequences.push(ESC);
+							pos += 1;
+							break;
+						}
+					}
 					sequences.push(candidate);
 					pos += seqEnd;
 					break;

packages/tui/test/stdin-buffer.test.ts

@@ -198,6 +198,26 @@ describe("StdinBuffer", () => {
 			assert.deepStrictEqual(emittedSequences, ["\x1b[3;1:3~"]);
 		});
 
+		it("should split ESC+ESC+CSI into standalone ESC and the CSI sequence (WezTerm Escape key regression)", () => {
+			// WezTerm with enable_kitty_keyboard sends Escape key press as raw \x1b
+			// and the release as a full Kitty CSI-u sequence, concatenated.
+			// The buffer must not treat \x1b\x1b as a complete meta-key when the
+			// following byte starts a new escape sequence.
+			processInput("\x1b\x1b[27;129:3u");
+			assert.deepStrictEqual(emittedSequences, ["\x1b", "\x1b[27;129:3u"]);
+		});
+
+		it("should split ESC+ESC+CSI with no modifier (no num_lock)", () => {
+			processInput("\x1b\x1b[27;1:3u");
+			assert.deepStrictEqual(emittedSequences, ["\x1b", "\x1b[27;1:3u"]);
+		});
+
+		it("should still emit ESC+ESC as a single sequence when not followed by a new escape", () => {
+			// \x1b\x1b alone (no following CSI) stays as-is — e.g. ctrl+alt+[
+			processInput("\x1b\x1b");
+			assert.deepStrictEqual(emittedSequences, ["\x1b\x1b"]);
+		});
+
 		it("should handle plain characters mixed with Kitty sequences", () => {
 			// Plain 'a' followed by Kitty release
 			processInput("a\x1b[97;1:3u");