It's sort of like LazyFS.
Paths
AppFS should normally be mounted on "/opt/appfs".
/opt/appfs/hostname Fetches: http://hostname/appfs/index Contains CSV file: type,extraData type == package; extraData = package,version,os,cpuArch,sha1 type == latest; extradata = package,version,os,cpuArch
/opt/appfs/hostname/package/os-cpuArch/version
/opt/appfs/hostname/sha1/
Fetches: http://hostname/appfs/
/opt/appfs/hostname/{sha1,package/os-cpuArch/version}/file
Fetches: http://hostname/appfs/