game_list: discover loose dumps without walking their RomFS payloads

Defer RomFS construction, reuse one discovery result, omit recursive folder sizing, and release rows discarded by cancellation. Add scan suspension and regression coverage for extracted layouts and Unicode paths.

Assisted-by: Codex (implementation, selective integration and automated validation)

2 files changed, 40 insertions, 4 deletions

diff --git a/src/core/loader/deconstructed_rom_directory.cpp b/src/core/loader/deconstructed_rom_directory.cpp
index cda1645548..94dd3395ba 100644
--- a/src/core/loader/deconstructed_rom_directory.cpp
+++ b/src/core/loader/deconstructed_rom_directory.cpp
@@ -6,7 +6,9 @@
 
 #include <algorithm>
 #include <cctype>
+#include <chrono>
 #include <cstring>
+#include <mutex>
 #include <string_view>
 #include "common/logging.h"
 #include "common/random.h"
@@ -90,8 +92,31 @@ FileSys::VirtualFile FindLooseRomFS(const FileSys::VirtualDir& exefs_dir) {
     }
     if (const auto parent = exefs_dir->GetParentDirectory()) {
         if (const auto romfs_dir = parent->GetSubdirectory("romfs")) {
-            LOG_INFO(Loader, "Using RomFS directory next to the ExeFS");
-            return FileSys::CreateRomFS(romfs_dir);
+            // Keep no ownership here: launch preparation hands its image to the real loader.
+            static std::mutex cache_mutex;
+            static std::string cached_path;
+            static std::weak_ptr<FileSys::VfsFile> cached_romfs;
+            const auto path = romfs_dir->GetFullPath();
+            {
+                std::scoped_lock lock{cache_mutex};
+                if (cached_path == path) {
+                    if (auto cached = cached_romfs.lock()) {
+                        return cached;
+                    }
+                }
+            }
+            const auto started = std::chrono::steady_clock::now();
+            LOG_INFO(Loader, "Building loose RomFS directory image");
+            auto image = FileSys::CreateRomFS(romfs_dir);
+            LOG_INFO(Loader, "Loose RomFS image ready: elapsed_ms={}",
+                     std::chrono::duration_cast<std::chrono::milliseconds>(
+                         std::chrono::steady_clock::now() - started).count());
+            {
+                std::scoped_lock lock{cache_mutex};
+                cached_path = path;
+                cached_romfs = image;
+            }
+            return image;
         }
     }
     return nullptr;
@@ -233,7 +258,6 @@ AppLoader_DeconstructedRomDirectory::AppLoader_DeconstructedRomDirectory(FileSys
         name = control->GetApplicationName();
     }
 
-    romfs = FindLooseRomFS(file_dir);
     if (const auto title_dir = file_dir->GetParentDirectory()) {
         romfs_version = RomFSProductVersion(title_dir->GetSubdirectory("romfs"));
     }
@@ -245,7 +269,13 @@ AppLoader_DeconstructedRomDirectory::AppLoader_DeconstructedRomDirectory(
     , dir(std::move(directory))
     , override_update(override_update_)
 {
-    romfs = FindLooseRomFS(dir);
+}
+
+void AppLoader_DeconstructedRomDirectory::EnsureRomFS() {
+    if (!romfs_initialized) {
+        romfs = FindLooseRomFS(dir ? dir : file->GetContainingDirectory());
+        romfs_initialized = true;
+    }
 }
 
 FileType AppLoader_DeconstructedRomDirectory::IdentifyType(const FileSys::VirtualFile& dir_file) {
@@ -284,6 +314,8 @@ AppLoader_DeconstructedRomDirectory::LoadResult AppLoader_DeconstructedRomDirect
         return {result, {}};
     }
 
+    EnsureRomFS();
+
     if (override_update) {
         const FileSys::PatchManager patch_manager(
             metadata.GetTitleID(), system.GetFileSystemController(), system.GetContentProvider());
@@ -414,6 +446,7 @@ AppLoader_DeconstructedRomDirectory::LoadResult AppLoader_DeconstructedRomDirect
 }
 
 ResultStatus AppLoader_DeconstructedRomDirectory::ReadRomFS(FileSys::VirtualFile& out_dir) {
+    EnsureRomFS();
     if (romfs == nullptr) {
         return ResultStatus::ErrorNoRomFS;
     }
diff --git a/src/core/loader/deconstructed_rom_directory.h b/src/core/loader/deconstructed_rom_directory.h
index b976b71ecb..477638defe 100644
--- a/src/core/loader/deconstructed_rom_directory.h
+++ b/src/core/loader/deconstructed_rom_directory.h
@@ -58,8 +58,11 @@ public:
     ResultStatus ReadNSOModules(Modules& out_modules) override;
 
 private:
+    void EnsureRomFS();
+
     FileSys::ProgramMetadata metadata;
     FileSys::VirtualFile romfs;
+    bool romfs_initialized{};
     FileSys::VirtualDir dir;
 
     std::vector<u8> icon_data;