Question: Could ARCropolis mods be loaded from LayeredFS (romfs) instead of only sd:/ultimate?

[codeman4033]

I've been looking into ways to make Smash mods easier to manage across tools and emulators, and I noticed that some ARCropolis-based mods (such as HDR) require files to be placed directly on the SD card under sd:/ultimate/... rather than being entirely contained within a game's romfs/exefs patch.

Is there a technical reason ARCropolis mods need to be stored on the SD card instead of being loadable through LayeredFS?

Would it be feasible for ARCropolis to support loading mods from romfs (or another location managed by LayeredFS), or would that conflict with how ARCropolis currently discovers, loads, or manages mods?

I'm mainly trying to understand the reasoning behind the current design and whether this is something that could be supported without compromising existing functionality.

EDIT: To clarify, I'm specifically referring to mod content files, not configuration files or other SD card resources.

[codeman4033]

I took a look through the source, and it appears that the mod root is centralized via paths::mods(), while writable data (logs, cache, config) is already stored separately. That made me wonder whether the mod content itself could be loaded from another source, such as LayeredFS, while leaving the writable directories on the SD card.

[ha1vorsen]

If loading mods for Smash via LayeredFS were possible then there would be no point to ARCropolis.

Smash does not contain files like "fighter/bayonetta/game.bin" within its romFS.
romFS of Smash instead contains an archive called data.arc.

ARCropolis, hence the name, exists to give Smash a layeredFS-like system for conveniently loading mods, otherwise you would have to repack data.arc, a 15+GB archive, into a static file every single time you wanted to add, change, or remove any modded asset within the game.

Atmosphere already provides LayeredFS functionality and is technically compatible with Smash given you choose to repack data.arc, this is not an ARCropolis issue. Redirecting ARCropolis to use the atmosphere directory is already implemented to an extent, as well. This issue is redundant.