fix: drop trailing empty segment before appending FDv2 path

Author: beekld

libs/server-sdk/src/data_systems/fdv2/fdv2_polling_impl.cpp

@@ -54,10 +54,14 @@ network::HttpRequest MakeFDv2PollRequest(
     }
 
     boost::urls::url u = parsed.value();
-    // Use segments to join the path; string concatenation would produce a
-    // double slash when the base URL ends in '/'.
-    u.segments().push_back("sdk");
-    u.segments().push_back("poll");
+    // A trailing '/' on the base URL appears as an empty final segment;
+    // remove it so subsequent push_backs don't produce a double slash.
+    auto segs = u.segments();
+    if (!segs.empty() && segs.back().empty()) {
+        segs.pop_back();
+    }
+    segs.push_back("sdk");
+    segs.push_back("poll");
     if (selector.value) {
         u.params().append({"basis", selector.value->state});
     }

libs/server-sdk/src/data_systems/fdv2/streaming_synchronizer.cpp

@@ -75,10 +75,14 @@ void FDv2StreamingSynchronizer::State::EnsureStarted(
 
     boost::urls::url u = parsed.value();
 
-    // Safer way of appending /sdk/stream than string concatenation: avoids
-    // double slashes if the base URL has a trailing slash.
-    u.segments().push_back("sdk");
-    u.segments().push_back("stream");
+    // A trailing '/' on the base URL appears as an empty final segment;
+    // remove it so subsequent push_backs don't produce a double slash.
+    auto segs = u.segments();
+    if (!segs.empty() && segs.back().empty()) {
+        segs.pop_back();
+    }
+    segs.push_back("sdk");
+    segs.push_back("stream");
 
     // basis and filter are not added here — they are appended per-connect by
     // the on_connect hook (OnConnect), so that each (re)connection uses the
@@ -184,6 +188,10 @@ void FDv2StreamingSynchronizer::State::OnResponse(
 }
 
 void FDv2StreamingSynchronizer::State::OnEvent(sse::Event const& event) {
+    if (!FDv2ProtocolHandler::IsKnownEvent(event.type())) {
+        return;
+    }
+
     boost::system::error_code ec;
     auto data = boost::json::parse(event.data(), ec);
     if (ec) {

libs/server-sdk/tests/fdv2_polling_impl_test.cpp

@@ -119,6 +119,16 @@ TEST(MakeFDv2PollRequestTest, BaseWithTrailingSlashDoesNotProduceDoubleSlash) {
     EXPECT_EQ(req.Url(), "http://example.com/sdk/poll");
 }
 
+TEST(MakeFDv2PollRequestTest, BaseWithSubpathTrailingSlashJoinsCleanly) {
+    config::shared::built::ServiceEndpoints endpoints{
+        "http://example.com/relay/", "", ""};
+    auto props =
+        config::shared::Defaults<config::shared::ServerSDK>::HttpProperties();
+    auto req = MakeFDv2PollRequest(endpoints, props, data_model::Selector{},
+                                   std::nullopt);
+    EXPECT_EQ(req.Url(), "http://example.com/relay/sdk/poll");
+}
+
 TEST(MakeFDv2PollRequestTest, ValidFilterKeyIsIncluded) {
     config::shared::built::ServiceEndpoints endpoints{"http://example.com", "",
                                                       ""};