bug: legacy (no slot) save files are synced to the wrong location

[2manyvcos]

What happened

For one of my retroarch-mgba games, I have a legacy (no-slot) save file.
The save is stored on the RomM server at …/assets/users/xyz/saves/gba/16/Game1.srm.

Since upgrading from 0.25.0 to 0.27.0, when playing the game in Steam and saving, the new save file is being synced (RomM 5.0.0) to the wrong location: …/assets/users/xyz/saves/gba/16/retroarch-mgba/Game1.srm (note the retroarch-mgba subdirectory).

Because of this, the new save is not available from the web (emulator.js) or from other clients.
Also, when switching save slots in Steam or clicking „Sync All Saves Now“ in the plugin menu, the new state is being lost, too. The file exists on the server, but is completely being ignored; the old save at the original location is used instead.

This effectively breaks saving, because the original save is always used instead of the new one.

Plugin version

0.27.0

Repro steps

1. Start with a game without any saves
2. Upload a save to the RomM server (using the web interface)
3. Go to Steam, sync saves, keep the save as legacy
4. Create an empty „default“ slot but do not use it; select the legacy slot instead (this was done automatically in my case)
5. Start the game, play a bit, save
6. The new save is successfully being synced to the server, but in the wrong location:
   • when starting the game in Steam again, the new save still works
   • on the RomM server, it looks like the new save was uploaded, but when loading the save using emulator.js, the old save is being used instead
   • when switching to the default save slot in Steam and switching back to legacy, the new save is being lost
   • when clicking „Sync All Saves Now“ in RomM Sync > Settings, the new save is also being lost

Expected behavior

The save should be stored at the correct location.
After syncing, the new save state should be available for all clients instead of the old one.

RetroDECK version

0.10.9b

Decky Loader version

3.2.6

Log excerpt

[2manyvcos]

Gerade getestet: Das Problem tritt auch auf, wenn der zusätzliche default slot nicht existiert.

[danielcopper]

hi.
i'll look into it later in detail.

the deprecation of legacy slots was introduced here:
https://github.com/danielcopper/decky-romm-sync/releases/tag/decky-romm-sync-v0.25.0

the sync wizard should have appeared for you. Did this not happen?

[2manyvcos]

Thanks!

I think I saw a migration wizard once, but after it finished, I was left with an empty „default“ slot, so I reuploaded the file to RomM directly.

[danielcopper]

ok good to know that part worked.
so for know you could put the file in the correct location on your deck and let the plugin sync it to the default slot on romm.

i'll reconsider the re-integration of the legacy slot. Afaik other clients for romm are also not using the 'legacy' slot.
i have to see how conflicts it might bring. I try to bring it back as an opt-in.

[danielcopper]

I've root-caused this. It's three separate defects — I'll file individual issues and link them here:

1. The legacy switch is still half-open. The v0.25.0 retirement removed the legacy (no-slot) mode from the setup wizard, but the slot switcher still accepts an empty slot name and silently puts a game into legacy mode. That's most likely how your device ended up actively syncing against the legacy bucket in the first place. This path gets closed.

2. The migration wizard didn't migrate. In your case it left default empty instead of moving the legacy save into it — and per your comment it also happens when default doesn't exist yet. I need to reproduce and fix that.

3. The actual wrong-location bug: the emulator tag. When the plugin uploads in legacy mode it attaches an emulator tag, and RomM stores tagged saves under an emulator subfolder — that's the second copy you saw at the "wrong" path. The web player only reads the untagged one, and the plugin's own Sync All then picked the older untagged save too. That's the lost-progress behavior you hit. The newer tagged copy should still be on the server — it won't load in the web player, but it should be visible in the ROM's saves list in the web UI, so nothing from that session is unrecoverable.

One correction to my earlier comment: other clients do use the no-slot bucket. Grout reads it as its default bucket, and the RomM web player lives exclusively in it — browser uploads can't target named slots at all. So as long as this plugin can't address the no-slot bucket, browser play and Deck play can't share saves.

Plan: the three bugs get fixed regardless. Separately, I'm working out the design to bring the no-slot bucket back as an explicit opt-in — a real setting, not the old "leave the slot name empty" behavior — so saves can flow between the web player and the Deck again. That one needs care: RomM has no server-side conflict protection for slot-less saves (the write-conflict gate and the sync negotiation only cover named slots), so the plugin has to carry that safety client-side. I'll open a tracking issue for it and link it here.