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diff --git a/src/core/file_sys/nup_writer.h b/src/core/file_sys/nup_writer.h
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+++ b/src/core/file_sys/nup_writer.h
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+// SPDX-FileCopyrightText: Copyright 2026 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <atomic>
+#include <filesystem>
+#include <functional>
+#include <optional>
+#include <string>
+#include <vector>
+
+#include "common/common_types.h"
+
+// Packs a loose dump into a NUP container. Every package is kept: base/, each
+// updates/<version>/ and each dlc/<titleid>/<n>/.
+namespace FileSys::Nup {
+
+struct PackProgress {
+    u64 bytes_done{};
+    u64 bytes_total{};
+    u64 files_done{};
+    u64 files_total{};
+};
+
+enum class PackResult { Success, Cancelled, InvalidSource, IoError };
+
+// NupContainer keeps a zstd file in memory only while it fits half of its 512 MiB decompression
+// cache; a larger one is decompressed to a temporary file on first read, which costs time and
+// disk space. Files above this size are therefore stored raw.
+constexpr u64 DefaultRawThreshold = 256ULL * 1024 * 1024;
+
+// Application metadata written to the base package (or the first package when there is no base).
+// In PackOptions an empty field keeps what the dump supplies; ProbeMetadata fills all of them.
+struct Metadata {
+    std::string title_name;
+    // JPEG or PNG bytes; 256x256 JPEG as distributed on-console.
+    std::vector<u8> icon;
+    std::string display_version;
+    // Where ProbeMetadata found display_version, e.g. "update 458752" or "base".
+    std::string version_source;
+};
+
+struct PackOptions {
+    // Low-storage mode: delete each source file once its extent is synced and journaled.
+    bool delete_sources = false;
+    u64 chunk_bytes = 256ULL * 1024 * 1024;
+    int zstd_level = 3;
+    // Files larger than this are always stored raw.
+    u64 raw_threshold = DefaultRawThreshold;
+    // Overrides for the name, icon and display version found in the dump.
+    Metadata metadata;
+};
+
+// A loose dump holds exefs/main and main.npdm, directly or under base/ or updates/<version>/,
+// and a romfs folder. Folder names are matched case-insensitively.
+bool IsLooseDump(const std::filesystem::path& dir);
+// The dump folder a game list entry's exefs/main (or exefs folder) belongs to, if it is a loose
+// dump.
+std::optional<std::filesystem::path> DumpRootFromMain(const std::filesystem::path& main);
+// Reads the name, icon and display version a dump would be packed with. The version comes from
+// the newest update that reports one, else the base.
+Metadata ProbeMetadata(const std::filesystem::path& dump_root);
+std::filesystem::path DefaultArchivePath(const std::filesystem::path& dump_root);
+
+// Writes <archive>.part and renames it when done; an existing archive is never overwritten. A
+// cancelled or failed low-storage run keeps its .part and .journal, and calling this again with
+// the same arguments resumes it.
+PackResult PackDump(const std::filesystem::path& dump_root, const std::filesystem::path& archive,
+                    const PackOptions& options = {},
+                    const std::function<void(const PackProgress&)>& progress = {},
+                    const std::atomic_bool* cancel = nullptr, std::string* error_out = nullptr);
+
+bool HasResumableJournal(const std::filesystem::path& archive);
+
+} // namespace FileSys::Nup