[MartinMajewski]

Fix or feature

• Fix
• Feature

What and why

Problem. The library folder patch, now 0031-mac-library-folder.patch (0010 and 0112 from #920 and #1097, squashed together) keeps a game's save in ~/Library when its game library is on a drive that can't hold saves. @thehobbit85's review of #920 found three cases where it still loses progress, and the fixes for them never reached main, because #920 was closed before I could push them.

Cause. 0031 only copies a save into an empty folder, so an older copy can win after a library moves between drives. Its copy doesn't report failures, so the game can start on half a save. And HFS+ doesn't report the clone and swap bits, so 0031 treats it as able to hold saves.

Change. New patch 0046-mac-launcher-bring-the-last-played-save-along-al.patch on top of 0031, in dm/mac/launcher.c:

• The launcher records the folder it last started the game from (save-location in the game's Application Support folder). When that changes, it brings the whole save along. Without a record, the library's save counts as current.
• The copy is all or nothing: it goes into <save>.migrating and is renamed into place only when every file arrived. An older save in the destination is kept as <save>.replaced-<time>. If the copy fails, an alert says why, the game doesn't start, and the next start tries again.
• When a volume doesn't report the clone and swap bits, the filesystem type from statfs decides, and only APFS keeps saves next to the game.

Two things main gained since #920 are covered too. The device save (<save>_device) moves together with the save. And a save folder the launcher passes in DM_SAVE (the per-game and global save folders from #1097) is used as it is, and only recorded.

Checked

• Tests: python3 tools/engine.py check passes (on 0c078130). python3 -m unittest test_nsp_mac_app in engine/dm/tools/tests passes, 83 tests. frontend/ and frontend-qt/ aren't changed.
• Test for a fix: six new or changed tests in test_nsp_mac_app.App, and each one fails on the old 0112 behavior that 0031 still has:
  • test_library_folder_on_hfs: a library on an HFS+ disk image
  • test_library_save_beats_older_home_save: a newer library save wins over an older ~/Library copy
  • test_library_back_on_apfs: progress made in ~/Library, device save included, follows the library to APFS
  • test_library_save_copy_fails: a copy cut short by a file-size limit doesn't start the game, and the next start finishes it
  • test_library_save_chosen_by_the_front_end: DM_SAVE from the launch environment is used and recorded
  • test_library_folder_on_apfs: now also checks the record
• Run on a device or Mac: Mac Studio, M4 Max, macOS 27.2. On the earlier base, Link's Awakening (01006BB00C6F0000, 1.0.1) in an exFAT library started with this launcher on its ~/Library save, and recorded it. I didn't run it again on today's main.

Screenshots

None, no visible change in the launcher. The one new piece of UI is the game app's own alert when a save can't be copied.

Scope

• No engine file (dm/, scripts/, docs/, ref/) is added to the repository: a change there is a patch in patches/ (a commit in engine/, then tools/engine.py export, and tools/engine.py check passes), with its Upstream-Status
• A fix to the engine or a game profile also goes to seedds/nxnative as a PR in parallel. Not applicable: this patch fixes 0031, which only this fork has. Upstream's version of the feature is Mac app: a dataFolder key keeps a game's save, caches and log in one folder a front end chooses seedds/nxnative#460, so the patch says pending.
• A change to a launcher view has before and after screenshots above. Not applicable, no launcher view changes.
• No keys, game files or data extracted from a game in the change or the attachments

One thing I left out: VolumeSaves.holdsSaves in frontend/Sources/NXCore/SaveLocation.swift (from #1097) has the same HFS+ gap, so the launcher's save settings would show an HFS+ library as fine while the game falls back to ~/Library. I can add that in this PR or a separate one if you'd like.

🤖 Co-authored with Claude Code

[LNPANDY]

Heads up @MartinMajewski: #1120 just merged into main and took slot 0123 (patches/0123-splatoon-raiders-shader-tables-are-split-again-w.patch). Please rebase onto main and renumber this patch to 0124-mac-launcher-bring-the-last-played-save-along-al.patch in patches/ and patches/series.

[MartinMajewski]

Thanks for the heads-up, @LNPANDY. It's rebased onto the current main now, and the patch is renamed to 0124-mac-launcher-bring-the-last-played-save-along-al.patch in patches/ and patches/series. The patch queue check passes with all 88 patches, and the Mac app tests still pass on the new base.

🤖 Co-authored with Claude Code