Preserve document path for fragment and query URLs

experiments/WebScene.NativeEngine.Probe/native/webscene_native_resource_url.h

@@ -70,6 +70,16 @@ inline std::string resolve_url(std::string value, const std::string& base)
         const auto origin = authority_end == std::string::npos ? base : base.substr(0U, authority_end);
         if (value.starts_with('/')) return origin + value;
 
+        // A query or fragment changes this document's URL, not its path.
+        // Rebuilding from the containing directory drops the final segment
+        // (and breaks same-document iframe history traversal).
+        if (value.starts_with('#')) {
+            return base.substr(0U, base.find('#')) + value;
+        }
+        if (value.starts_with('?')) {
+            return base.substr(0U, base.find_first_of("?#")) + value;
+        }
+
         const auto value_suffix_offset = value.find_first_of("?#");
         const auto value_suffix = value_suffix_offset == std::string::npos
             ? std::string{}

experiments/WebScene.NativeEngine.Probe/tests/native_v8_runtime_resource_tests.inc

@@ -122,6 +122,18 @@ struct contextual_resource_server final {
 
 void test_same_origin_iframe_navigation_document_replacement()
 {
+    using webscene_native::resources::resolve_url;
+    constexpr std::string_view base{
+        "https://iframe-navigation.test/nested/fake.html?id=history-reload#old"};
+    require(resolve_url("#one", std::string{base})
+            == "https://iframe-navigation.test/nested/fake.html?id=history-reload#one",
+        "fragment-only URL discarded document path or query");
+    require(resolve_url("?next=1#two", std::string{base})
+            == "https://iframe-navigation.test/nested/fake.html?next=1#two",
+        "query-only URL discarded document path or retained stale query");
+    require(resolve_url("../sibling.html", std::string{base})
+            == "https://iframe-navigation.test/sibling.html",
+        "ordinary relative URL resolution regressed");
     constexpr std::string_view address{
         "https://iframe-navigation.test/index.html"};
     constexpr std::string_view history_reload_page = R"HTML(<!doctype html><body>

experiments/WebScene.NativeEngine.Probe/tests/native_v8_runtime_tests.cpp

@@ -2,6 +2,7 @@
 #include "webscene_native_dom.h"
 #include "webscene_embed_fallback.h"
 #include "webscene_native_websocket.h"
+#include "webscene_native_resource_url.h"
 
 #include <ixwebsocket/IXGetFreePort.h>
 #include <ixwebsocket/IXNetSystem.h>