fix: preserve group member user ids

server/im_http.go

@@ -6064,8 +6064,7 @@ func groupMemberSettingsPayload(sub *types.Subscription) map[string]any {
 
 func groupMemberPayload(sub types.Subscription, mentionable bool) map[string]any {
 	access := sub.ModeGiven & sub.ModeWant
-	userID := types.ParseUserId(sub.User)
-	user := &types.User{ObjHeader: types.ObjHeader{Id: userID.String()}, Public: sub.GetPublic(), Trusted: sub.GetTrusted()}
+	user := &types.User{ObjHeader: types.ObjHeader{Id: sub.User}, Public: sub.GetPublic(), Trusted: sub.GetTrusted()}
 	data := userSummaryPayload(user, "")
 	if private := groupPrivateMap(sub.Private); stringFromAny(private["nickname"]) != "" {
 		data["group_nickname"] = stringFromAny(private["nickname"])

server/im_http_test.go

@@ -2881,6 +2881,28 @@ func TestServeIMGroupMembers(t *testing.T) {
 	}
 }
 
+func TestGroupMemberPayloadUserIDFormats(t *testing.T) {
+	raw := types.Uid(101)
+	fromRaw := groupMemberPayload(types.Subscription{
+		User:      raw.String(),
+		ModeWant:  types.ModeJoin,
+		ModeGiven: types.ModeJoin,
+	}, true)
+	if fromRaw["user_id"] != raw.UserId() {
+		t.Fatalf("raw uid user_id: got %#v, want %s", fromRaw["user_id"], raw.UserId())
+	}
+
+	prefixed := types.Uid(102)
+	fromPrefixed := groupMemberPayload(types.Subscription{
+		User:      prefixed.UserId(),
+		ModeWant:  types.ModeJoin,
+		ModeGiven: types.ModeJoin,
+	}, true)
+	if fromPrefixed["user_id"] != prefixed.UserId() {
+		t.Fatalf("prefixed uid user_id: got %#v, want %s", fromPrefixed["user_id"], prefixed.UserId())
+	}
+}
+
 func TestServeIMGroupMemberProfile(t *testing.T) {
 	ctrl := gomock.NewController(t)
 	defer ctrl.Finish()