feat: add XTVERSION response (CSI > q)

Register a sendXtVersion CSI handler that responds with
DCS > | xterm-go(0.1.0) ST when queried with CSI > q.

Fixes #2

Co-authored-by: Ona <no-reply@ona.com>

Author: ona-automations

inputhandler.go

@@ -215,6 +215,7 @@ func NewInputHandler(
 	p.RegisterCsiHandler(FunctionIdentifier{Final: 'b'}, h.repeatPrecedingCharacter)
 	p.RegisterCsiHandler(FunctionIdentifier{Final: 'c'}, h.sendDeviceAttributesPrimary)
 	p.RegisterCsiHandler(FunctionIdentifier{Prefix: '>', Final: 'c'}, h.sendDeviceAttributesSecondary)
+	p.RegisterCsiHandler(FunctionIdentifier{Prefix: '>', Final: 'q'}, h.sendXtVersion)
 	p.RegisterCsiHandler(FunctionIdentifier{Final: 'g'}, h.tabClear)
 	p.RegisterCsiHandler(FunctionIdentifier{Final: 'm'}, h.charAttributes)
 	p.RegisterCsiHandler(FunctionIdentifier{Final: 'n'}, h.deviceStatus)

inputhandler_csi.go

@@ -458,6 +458,15 @@ func (h *InputHandler) sendDeviceAttributesSecondary(params *Params) bool {
 	return true
 }
 
+// sendXtVersion responds to XTVERSION (CSI > q) with a DCS response.
+func (h *InputHandler) sendXtVersion(params *Params) bool {
+	if params.Params[0] > 0 {
+		return true
+	}
+	h.coreService.TriggerDataEvent("\x1bP>|xterm-go(0.1.0)\x1b\\", false, false)
+	return true
+}
+
 func (h *InputHandler) deviceStatus(params *Params) bool {
 	buf := h.activeBuffer()
 	switch params.Params[0] {

inputhandler_csi_test.go

@@ -588,6 +588,43 @@ func TestDeviceAttributes(t *testing.T) {
 	}
 }
 
+func TestXtVersion(t *testing.T) {
+	t.Parallel()
+	type Expectation struct {
+		Response string
+	}
+
+	t.Run("default param responds with DCS version", func(t *testing.T) {
+		t.Parallel()
+		h := newTestInputHandler(80, 24)
+		var response string
+		h.coreService.OnDataEmitter.Event(func(data string) {
+			response = data
+		})
+		h.ParseString("\x1b[>q")
+		got := Expectation{Response: response}
+		expected := Expectation{Response: "\x1bP>|xterm-go(0.1.0)\x1b\\"}
+		if diff := cmp.Diff(expected, got); diff != "" {
+			t.Errorf("mismatch (-want +got):\n%s", diff)
+		}
+	})
+
+	t.Run("non-zero param produces no response", func(t *testing.T) {
+		t.Parallel()
+		h := newTestInputHandler(80, 24)
+		var response string
+		h.coreService.OnDataEmitter.Event(func(data string) {
+			response = data
+		})
+		h.ParseString("\x1b[>1q")
+		got := Expectation{Response: response}
+		expected := Expectation{Response: ""}
+		if diff := cmp.Diff(expected, got); diff != "" {
+			t.Errorf("mismatch (-want +got):\n%s", diff)
+		}
+	})
+}
+
 func TestEraseChars(t *testing.T) {
 	t.Parallel()
 	type Expectation struct {