we can’t deploy it until a bug is fixed in the Steam client that causes, when we enable SLR 3, all Steam Decks to run the Linux build. Yes, Steam Decks run the Proton version, solely because the save file has different letter casing
Sounds more like the bug is on your side caused by whoever had the genius idea to use different file names for Windows and Linux builds.
there’s no way to fix this without some folks losing their saves, and that is absolutely not an option.
For me the fix looks very easy: Use completely new file names. The old saves are only read and new saves get the new file names. Stay on the current SLR/Proton setup until the saves are migrated to the new naming format for the active user base. Make a dedicated “beta” branch for legacy saves in a year or so to not screw over inactive users. Make announcements and pinned forum posts.
Sounds more like the bug is on your side caused by whoever had the genius idea to use different file names for Windows and Linux builds.
For me the fix looks very easy: Use completely new file names. The old saves are only read and new saves get the new file names. Stay on the current SLR/Proton setup until the saves are migrated to the new naming format for the active user base. Make a dedicated “beta” branch for legacy saves in a year or so to not screw over inactive users. Make announcements and pinned forum posts.