Cosmos and Snowflake can actually be selected

Both alternative storage backends were fully built, tested and documented as selectable through Graph:Storage:Type — and neither one reached a shipped deployment. Nothing referenced them except their own test projects, and they were absent from the module publish layout, so the assemblies existed on no image and the documented selection could not be turned on at all.

They now ship under modules/, exactly as the AI provider packs and the other backends-by-listing do. Selecting one is an appsettings edit in the deployment that wants it: add the DLL to Modules:Assemblies and set Graph:Storage:Type. Nothing changes for anyone else — no portal lists them, and a module that is present but unlisted is never loaded.

They ship with the image rather than as an installable Store package on purpose: persistence selection happens during boot, so a storage backend is not something a running mesh can install for itself.