kousu · kousu · Feb 9, 2026 · Feb 10, 2026 · Feb 10, 2026 · Feb 11, 2026
diff --git a/xmpp.go b/xmpp.go
@@ -609,6 +609,10 @@ type Chat struct {
 	Oobdesc   string
 	ID        string
 	ReplaceID string
+	ReplyID   string // XEP-0461: id of the message being replied to (use stanza-id for groupchat)
+	ReplyTo   string // XEP-0461: JID of the author of the message being replied to
+	StanzaID  string // XEP-0359: refers to stanza-id but named Stanza for brevity
+	StanzaBy  string // XEP-0359: refers to stanza-id but named Stanza for brevity
 	Roster    Roster
 	Other     []string
 	OtherElem []XMLElement
@@ -684,6 +688,10 @@ func (c *Client) Recv() (stanza interface{}, err error) {
 				Thread:    v.Thread,
 				ID:        v.ID,
 				ReplaceID: v.ReplaceID.ID,
+				ReplyID:   v.Reply.ID,
+				ReplyTo:   v.Reply.To,
+				StanzaID:  v.StanzaID.ID,
+				StanzaBy:  v.StanzaID.By,
 				Other:     v.OtherStrings(),
 				OtherElem: v.Other,
 				Stamp:     stamp,
@@ -892,7 +900,16 @@ func (c *Client) Send(chat Chat) (n int, err error) {
 		msgcorrecttext = `<replace id='` + xmlEscape(chat.ReplaceID) + `' xmlns='urn:xmpp:message-correct:0'/>`
 	}
 
-	stanza := "<message to='%s' type='%s' " + msgidtext + " xml:lang='en'>" + subtext + "<body>%s</body>" + msgcorrecttext + oobtext + thdtext + "</message>"
+	var replytext string
+	if chat.ReplyID != `` {
+		replytext = `<reply id='` + xmlEscape(chat.ReplyID) + `'`
+		if chat.ReplyTo != `` {
+			replytext += ` to='` + xmlEscape(chat.ReplyTo) + `'`
+		}
+		replytext += ` xmlns='urn:xmpp:reply:0'/>`
+	}
+
+	stanza := "<message to='%s' type='%s' " + msgidtext + " xml:lang='en'>" + subtext + "<body>%s</body>" + replytext + msgcorrecttext + oobtext + thdtext + "</message>"
 
 	return fmt.Fprintf(c.conn, stanza, xmlEscape(chat.Remote), xmlEscape(chat.Type), xmlEscape(chat.Text))
 }
@@ -1014,6 +1031,18 @@ type clientMessageCorrect struct {
 	ID      string   `xml:"id,attr"`
 }
 
+type clientReply struct {
+	XMLName xml.Name `xml:"urn:xmpp:reply:0 reply"`
+	ID      string   `xml:"id,attr"`
+	To      string   `xml:"to,attr"`
+}
+
+type clientStanzaID struct {
+	XMLName xml.Name `xml:"urn:xmpp:sid:0 stanza-id"`
+	ID      string   `xml:"id,attr"`
+	By      string   `xml:"by,attr"`
+}
+
 // RFC 3921  B.1  jabber:client
 type clientMessage struct {
 	XMLName xml.Name `xml:"jabber:client message"`
@@ -1027,6 +1056,8 @@ type clientMessage struct {
 	Body      string `xml:"body"`
 	Thread    string `xml:"thread"`
 	ReplaceID clientMessageCorrect
+	Reply     clientReply
+	StanzaID  clientStanzaID
 
 	// Pubsub
 	Event clientPubsubEvent `xml:"event"`

diff --git a/xmpp_test.go b/xmpp_test.go
@@ -56,7 +56,7 @@ func (*testConn) SetWriteDeadline(time.Time) error {
 }
 
 var text = strings.TrimSpace(`
-<message xmlns="jabber:client" id="3" type="error" to="123456789@gcm.googleapis.com/ABC">
+<message xmlns="jabber:client" id="" type="error" to="123456789@gcm.googleapis.com/ABC">
 	<gcm xmlns="google:mobile:data">
 		{"random": "&lt;text&gt;"}
 	</gcm>
@@ -122,12 +122,13 @@ var emptyPubSub = strings.TrimSpace(`
   </pubsub>
 </iq>
 `)
+
 func TestEmptyPubsub(t *testing.T) {
 	var c Client
 	c.conn = tConnect(emptyPubSub)
 	c.p = xml.NewDecoder(c.conn)
 	m, err := c.Recv()
-	
+
 	switch m.(type) {
 	case AvatarData:
 		if err == nil {
@@ -138,3 +139,74 @@ func TestEmptyPubsub(t *testing.T) {
 		t.Errorf("Expected a return value of AvatarData")
 	}
 }
+
+func TestSendReply(t *testing.T) {
+	var c Client
+	buf := &bytes.Buffer{}
+	c.conn = &testConn{buf}
+
+	chat := Chat{
+		Remote:  "room@conference.example.com",
+		Type:    "groupchat",
+		Text:    "This is a reply",
+		ID:      "msg-123",
+		ReplyTo: "original-msg-456",
+		ReplyID: "reply-id-789",
+	}
+
+	_, err := c.Send(chat)
+	if err != nil {
+		t.Fatalf("Send() returned error: %v", err)
+	}
+
+	output := buf.String()
+
+	// Check that the reply element is present with correct namespace
+	expectedReply := `<reply id='reply-id-789' to='original-msg-456' xmlns='urn:xmpp:reply:0'/>`
+	if !strings.Contains(output, expectedReply) {
+		t.Errorf("Send() output missing XEP-0461 reply element.\nGot: %s\nExpected to contain: %s", output, expectedReply)
+	}
+
+	// Check that the body is present
+	if !strings.Contains(output, "<body>This is a reply</body>") {
+		t.Errorf("Send() output missing body element.\nGot: %s", output)
+	}
+
+	// Check message attributes
+	if !strings.Contains(output, "to='room@conference.example.com'") {
+		t.Errorf("Send() output missing 'to' attribute.\nGot: %s", output)
+	}
+	if !strings.Contains(output, "type='groupchat'") {
+		t.Errorf("Send() output missing 'type' attribute.\nGot: %s", output)
+	}
+}
+
+func TestSendWithoutReply(t *testing.T) {
+	var c Client
+	buf := &bytes.Buffer{}
+	c.conn = &testConn{buf}
+
+	chat := Chat{
+		Remote: "room@conference.example.com",
+		Type:   "groupchat",
+		Text:   "Regular message",
+		ID:     "msg-789",
+	}
+
+	_, err := c.Send(chat)
+	if err != nil {
+		t.Fatalf("Send() returned error: %v", err)
+	}
+
+	output := buf.String()
+
+	// Check that no reply element is present when ReplyTo is empty
+	if strings.Contains(output, "<reply") {
+		t.Errorf("Send() output should not contain reply element when ReplyTo is empty.\nGot: %s", output)
+	}
+
+	// Check that the body is still present
+	if !strings.Contains(output, "<body>Regular message</body>") {
+		t.Errorf("Send() output missing body element.\nGot: %s", output)
+	}
+}