diff --git a/runtime/include/host_file_identity.h b/runtime/include/host_file_identity.h
index 2cb5e193..9b190257 100644
--- a/runtime/include/host_file_identity.h
+++ b/runtime/include/host_file_identity.h
@@ -29,9 +29,24 @@ inline bool host_file_identity(const std::filesystem::path& path, std::string& i
     const bool is_remote = GetFileInformationByHandleEx(file, FileRemoteProtocolInfo,
         &remote, sizeof remote) != FALSE;
     const DWORD protocol_error = is_remote ? ERROR_SUCCESS : GetLastError();
+    bool local_handle = false;
+    if (!is_remote) {
+        // A failed protocol query proves nothing about locality. Resolve the
+        // handle itself: mapped drives become UNC paths here and cannot take
+        // the local fallback when a remote provider omits protocol metadata.
+        WCHAR final_path[32768]{};
+        const DWORD length = GetFinalPathNameByHandleW(file, final_path, 32768, FILE_NAME_NORMALIZED);
+        if (length >= 7 && length < 32768 && final_path[0] == L'\\' &&
+            final_path[1] == L'\\' && final_path[2] == L'?' && final_path[3] == L'\\' &&
+            final_path[5] == L':' && final_path[6] == L'\\') {
+            WCHAR drive_root[] = {final_path[4], L':', L'\\', L'\0'};
+            const UINT drive_type = GetDriveTypeW(drive_root);
+            local_handle = drive_type == DRIVE_FIXED || drive_type == DRIVE_REMOVABLE;
+        }
+    }
     const bool reliable_protocol = is_remote
         ? remote.Protocol == 0x00020000 && remote.ProtocolMajorVersion >= 3 // WNNC_NET_LANMAN
-        : protocol_error == ERROR_INVALID_PARAMETER || protocol_error == ERROR_NOT_SUPPORTED;
+        : local_handle && (protocol_error == ERROR_INVALID_PARAMETER || protocol_error == ERROR_NOT_SUPPORTED);
     const bool reliable_fs = reliable_protocol &&
         GetVolumeInformationByHandleW(file, nullptr, 0, nullptr, nullptr, nullptr,
                                      filesystem_name, 32) &&
diff --git a/runtime/src/mod_runtime.cpp b/runtime/src/mod_runtime.cpp
index f9c1e433..ca21db8b 100644
--- a/runtime/src/mod_runtime.cpp
+++ b/runtime/src/mod_runtime.cpp
@@ -1873,14 +1873,21 @@ bool mod_runtime_prepare_for_launcher(const std::filesystem::path& disc_path, st
 
 bool mod_runtime_try_prepare_cached(const std::filesystem::path& disc_path) {
 #if defined(PSX_LAUNCHER_MOD_COMMIT_WORKER_SAFE)
-    auto& s = state();
-    if (!s.initialized || s.main_applied || !session_plan_fp().empty()) return false;
-    auto probe = s.manager;
-    if (!probe.prepare_resources(s.game_id, disc_path, media_cache_root(), nullptr, true)) return false;
-    ScopedFlag flag(s.cached_prepare);
-    const bool ok = mod_runtime_commit(disc_path, nullptr, true);
-    if (ok && s.ticket_ready) psx_mod_counter_add("startup.preload_hit", 1);
-    return ok && s.ticket_ready;
+    try {
+        auto& s = state();
+        if (!s.initialized || s.main_applied || !session_plan_fp().empty()) return false;
+        auto probe = s.manager;
+        if (!probe.prepare_resources(s.game_id, disc_path, media_cache_root(), nullptr, true)) return false;
+        ScopedFlag flag(s.cached_prepare);
+        const bool ok = mod_runtime_commit(disc_path, nullptr, true);
+        if (ok && s.ticket_ready) psx_mod_counter_add("startup.preload_hit", 1);
+        return ok && s.ticket_ready;
+    } catch (...) {
+        // Preload is best effort before the launcher exists. The ordinary
+        // provider path reports full-preparation errors once UI is available.
+        state().ticket_ready = false;
+        return false;
+    }
 #else
     (void)disc_path;
     return false;
diff --git a/runtime/tests/test_mod_runtime.cpp b/runtime/tests/test_mod_runtime.cpp
index 9304872b..20a5373b 100644
--- a/runtime/tests/test_mod_runtime.cpp
+++ b/runtime/tests/test_mod_runtime.cpp
@@ -301,7 +301,19 @@ static uint64_t startup_counter(const char* requested) {
 }
 
 int main() {
+#if defined(PSX_LAUNCHER_MOD_COMMIT_WORKER_SAFE)
+    const fs::path root = fs::temp_directory_path() / "psxrecomp-mod-runtime-cache-test";
+    const auto isolated_cache = root / "test-cache";
+#if defined(_WIN32)
+    check(SetEnvironmentVariableW(L"LOCALAPPDATA", isolated_cache.c_str()) != FALSE,
+          "isolate audited digest receipts from owner cache");
+#else
+    check(setenv("XDG_CACHE_HOME", isolated_cache.c_str(), 1) == 0,
+          "isolate audited digest receipts from owner cache");
+#endif
+#else
     const fs::path root = fs::temp_directory_path() / "psxrecomp-mod-runtime-test";
+#endif
     std::error_code ec;
     fs::remove_all(root, ec);
     const std::vector<uint8_t> stock(8 * 2352, 0);
@@ -1453,11 +1465,9 @@ int main() {
         // A throw inside resolve must restore cached-only/provider modes.
         check(PSXRecompV4::mod_runtime_initialize(cached_root, "READER", 0, {}, &error), "invalidate ticket for resolver exception fixture");
         throw_resolver = true;
-        bool threw = false;
-        try { PSXRecompV4::mod_runtime_try_prepare_cached(disc); }
-        catch (const std::runtime_error&) { threw = true; }
+        check(!PSXRecompV4::mod_runtime_try_prepare_cached(disc),
+              "best-effort preload contains resolver exceptions before launcher UI");
         throw_resolver = false;
-        check(threw, "resolver exception reaches caller for unwind fixture");
         fs::remove(output_path);
         const auto before_unwind = prepare_calls;
         check(PSXRecompV4::mod_runtime_prepare_for_launcher(disc, &error) && prepare_calls == before_unwind + 1,