Keep directory discovery metadata in temporary jobs

Directory folder and file-list indices are only needed while initializing
descriptions and their cache. Replace the persistent lcPieceData fields
with local jobs holding the selected file info, source folder and change
flag. Workers update independent jobs, and cache writing uses their
timestamps after all workers finish.

Pass the discovered paths to alias classification so it opens the selected
source directly without reconstructing paths from asset bookkeeping.
Move include-free piece member defaults into the header and zero-initialize
the filename and description arrays there.

Validated with a warning-free Qt 6.10 Debug build, 58 offscreen lifecycle
groups covering directory/archive caches and cross-source aliases, and
clean diff whitespace checks.

common/lc_library.cpp

@@ -799,7 +799,7 @@ void lcPiecesLibrary::ReadArchiveDescriptions(const QString& OfficialFileName, c
 			}
 		}
 
-		ClassifyPieces();
+		ClassifyPieces(DirectoryFilePaths());
 		SaveArchiveCacheIndex(IndexFileName);
 	}
 }
@@ -923,6 +923,16 @@ void lcPiecesLibrary::ReadDirectoryDescriptions(const QFileInfoList (&FileLists)
 		}
 	}
 
+	struct DescriptionJob
+	{
+		lcPieceData* PieceData;
+		QFileInfo FileInfo;
+		lcLibraryFolderType FolderType;
+		bool Modified = false;
+	};
+
+	std::vector<DescriptionJob> Jobs;
+
 	for (int FolderIdx = 0; FolderIdx < static_cast<int>(lcLibraryFolderType::Count); FolderIdx++)
 	{
 		const QFileInfoList& FileList = FileLists[FolderIdx];
@@ -937,29 +947,34 @@ void lcPiecesLibrary::ReadDirectoryDescriptions(const QFileInfoList (&FileLists)
 
 			lcPieceData* PieceData = mPieceManager->CreateLibraryPieceData(Name, FileString.constData());
 
-			PieceData->mFolderType = FolderIdx;
-			PieceData->mFolderIndex = FileIdx;
+			Jobs.push_back({ PieceData, FileList[FileIdx], static_cast<lcLibraryFolderType>(FolderIdx) });
 		}
 	}
 
+	// Only process entries retained by the normalized registry after discovery.
+	Jobs.erase(std::remove_if(Jobs.begin(), Jobs.end(), [this](const DescriptionJob& Job)
+	{
+		return FindPieceData(Job.FileInfo.fileName().toLatin1().constData(), nullptr) != Job.PieceData;
+	}), Jobs.end());
+
 	QAtomicInt FilesLoaded;
-	std::atomic_bool Modified(false);
 
-	auto ReadDescriptions = [&FileLists, &CachedDescriptions, &FilesLoaded, &Modified](lcPieceData* PieceData)
+	auto ReadDescriptions = [&CachedDescriptions, &FilesLoaded](DescriptionJob& Job)
 	{
 		FilesLoaded.ref();
 
-		lcDiskFile PieceFile(FileLists[PieceData->mFolderType][PieceData->mFolderIndex].absoluteFilePath());
+		lcPieceData* PieceData = Job.PieceData;
+		lcDiskFile PieceFile(Job.FileInfo.absoluteFilePath());
 		char Line[1024];
 
 		const auto CachedIt = CachedDescriptions.find(PieceData->mFileName);
-		const quint64 FileTime = FileLists[PieceData->mFolderType][PieceData->mFolderIndex].lastModified().toMSecsSinceEpoch();
+		const quint64 FileTime = Job.FileInfo.lastModified().toMSecsSinceEpoch();
 
-		if (CachedIt != CachedDescriptions.end() && CachedIt->second.FileTime == FileTime && CachedIt->second.FolderType == PieceData->mFolderType &&
+		if (CachedIt != CachedDescriptions.end() && CachedIt->second.FileTime == FileTime && CachedIt->second.FolderType == static_cast<quint8>(Job.FolderType) &&
 			PieceData->InitializeFromCache(CachedIt->second.CacheData))
 			return;
 
-		Modified.store(true);
+		Job.Modified = true;
 
 		if (!PieceFile.Open(QIODevice::ReadOnly) || !PieceFile.ReadLine(Line, sizeof(Line)))
 		{
@@ -987,7 +1002,7 @@ void lcPiecesLibrary::ReadDirectoryDescriptions(const QFileInfoList (&FileLists)
 	ProgressDialog->setWindowFlags(ProgressDialog->windowFlags() & ~Qt::WindowCloseButtonHint);
 	ProgressDialog->setWindowTitle(tr("Initializing"));
 	ProgressDialog->setLabelText(tr("Loading Parts Library"));
-	ProgressDialog->setMaximum((int)mPieceManager->GetLibraryPieceDataCount());
+	ProgressDialog->setMaximum(static_cast<int>(Jobs.size()));
 	ProgressDialog->setMinimum(0);
 	ProgressDialog->setValue(0);
 	ProgressDialog->setCancelButton(nullptr);
@@ -995,8 +1010,7 @@ void lcPiecesLibrary::ReadDirectoryDescriptions(const QFileInfoList (&FileLists)
 	if (ShowProgress)
 		ProgressDialog->show();
 
-	std::vector<lcPieceData*> LibraryPieceData = mPieceManager->GetLibraryPieceData();
-	QFuture<void> LoadFuture = QtConcurrent::map(LibraryPieceData, ReadDescriptions);
+	QFuture<void> LoadFuture = QtConcurrent::map(Jobs, ReadDescriptions);
 
 	while (!LoadFuture.isFinished())
 	{
@@ -1010,17 +1024,28 @@ void lcPiecesLibrary::ReadDirectoryDescriptions(const QFileInfoList (&FileLists)
 	ProgressDialog->deleteLater();
 
 	// A target's change, addition or removal can invalidate otherwise unchanged aliases.
-	if (Modified.load() || CachedDescriptions.size() != LibraryPieceData.size())
+	const bool Modified = std::any_of(Jobs.begin(), Jobs.end(), [](const DescriptionJob& Job)
 	{
-		ClassifyPieces();
+		return Job.Modified;
+	});
+
+	if (Modified || CachedDescriptions.size() != Jobs.size())
+	{
+		DirectoryFilePaths FilePaths;
+
+		for (const DescriptionJob& Job : Jobs)
+			FilePaths.emplace(Job.PieceData, Job.FileInfo.absoluteFilePath());
+
+		ClassifyPieces(FilePaths);
 
 		lcMemFile NewIndexFile;
 
 		NewIndexFile.WriteQString(mLibraryDir.absolutePath());
-		NewIndexFile.WriteU32(static_cast<quint32>(LibraryPieceData.size()));
+		NewIndexFile.WriteU32(static_cast<quint32>(Jobs.size()));
 
-		for (const lcPieceData* PieceData : LibraryPieceData)
+		for (const DescriptionJob& Job : Jobs)
 		{
+			const lcPieceData* PieceData = Job.PieceData;
 			const lcPieceData::CacheData CacheData = PieceData->GetCacheData();
 
 			if (!WriteIndexString(NewIndexFile, PieceData->mFileName) ||
@@ -1028,8 +1053,8 @@ void lcPiecesLibrary::ReadDirectoryDescriptions(const QFileInfoList (&FileLists)
 				return;
 
 			NewIndexFile.WriteU8(CacheData.Flags);
-			NewIndexFile.WriteU8(static_cast<quint8>(PieceData->mFolderType));
-			const quint64 FileTime = FileLists[PieceData->mFolderType][PieceData->mFolderIndex].lastModified().toMSecsSinceEpoch();
+			NewIndexFile.WriteU8(static_cast<quint8>(Job.FolderType));
+			const quint64 FileTime = Job.FileInfo.lastModified().toMSecsSinceEpoch();
 			NewIndexFile.WriteU64(FileTime);
 		}
 
@@ -1358,7 +1383,7 @@ std::string lcPiecesLibrary::ReadAliasTarget(lcFile& File)
 	return Target;
 }
 
-void lcPiecesLibrary::ClassifyPieces()
+void lcPiecesLibrary::ClassifyPieces(const DirectoryFilePaths& FilePaths)
 {
 	const std::vector<lcPieceData*> Parts = mPieceManager->GetLibraryPieceData();
 	std::unordered_map<lcPieceData*, lcPieceData*> AliasTargets;
@@ -1379,8 +1404,15 @@ void lcPiecesLibrary::ClassifyPieces()
 			}
 			else
 			{
-				const QString Folder = PieceData->mFolderType == static_cast<int>(lcLibraryFolderType::Unofficial) ? QStringLiteral("unofficial/parts/") : QStringLiteral("parts/");
-				Source.FilePath = mLibraryDir.absoluteFilePath(Folder + QString::fromLatin1(PieceData->mFileName));
+				const auto FileIt = FilePaths.find(PieceData);
+
+				if (FileIt == FilePaths.end())
+				{
+					AliasTargets.emplace(PieceData, nullptr);
+					continue;
+				}
+
+				Source.FilePath = FileIt->second;
 			}
 
 			const lcResult<std::unique_ptr<lcFile>> File = OpenFile(Source);
@@ -2536,7 +2568,7 @@ bool lcPiecesLibrary::LoadBuiltinPieceLibrary()
 		}
 	}
 
-	ClassifyPieces();
+	ClassifyPieces(DirectoryFilePaths());
 
 	lcLoadDefaultColors(mStudStyle);
 	UpdateLoadingMeshColors();

common/lc_library.h

@@ -390,8 +390,11 @@ protected:
 	void ReleaseBuffers();
 
 private:
+	using DirectoryFilePaths = std::unordered_map<const lcPieceData*, QString>;
+
 	// Classifies descriptions, decorations and alias parents after all parts are registered.
-	void ClassifyPieces();
+	// Directory paths are temporary discovery metadata; archive entries use their stored indices.
+	void ClassifyPieces(const DirectoryFilePaths& FilePaths);
 	static std::string ReadAliasTarget(lcFile& File);
 
 	// Description cache strings are bounded to the piece name/description length limit.

common/lc_piecedata.cpp

@@ -16,13 +16,7 @@ lcPieceData::lcPieceData(bool IsLibraryPiece)
 	: mIsLibraryPiece(IsLibraryPiece)
 {
 	mZipFileType = lcZipFileType::Count;
-	mZipFileIndex = -1;
-	mFolderType = -1;
-	mFolderIndex = -1;
-	mState = lcAssetState::Unloaded;
 	SetLoadingBoundingBox();
-	mFileName[0] = 0;
-	m_strDescription[0] = 0;
 }
 
 bool lcPieceData::HasDecorationDescription(const char* Description)

common/lc_piecedata.h

@@ -194,13 +194,11 @@ public:
 	void Unload();
 
 public:
-	char mFileName[LC_PIECE_NAME_LEN];
-	char m_strDescription[256];
+	char mFileName[LC_PIECE_NAME_LEN] = {};
+	char m_strDescription[256] = {};
 	lcZipFileType mZipFileType;
-	int mZipFileIndex;
-	lcAssetState mState;
-	int mFolderType;
-	int mFolderIndex;
+	int mZipFileIndex = -1;
+	lcAssetState mState = lcAssetState::Unloaded;
 
 protected:
 	enum class Flag