// reference

Ownership (chown / lchown)

You change who owns file over the mount. If it only lives in original location, PrismaFS copies it to session first, then changes owner there. Original owner stays.

macOS

stat -f '%Su %Sg' ~/pfs-base/hello.txt
chown "$(id -u):$(id -g)" ~/pfs-mnt/hello.txt
ls ~/pfs-session
stat -f '%Su %Sg' ~/pfs-base/hello.txt

Linux

stat -c '%U %G' ~/pfs-base/hello.txt
chown "$(id -u):$(id -g)" ~/pfs-mnt/hello.txt
ls ~/pfs-session
stat -c '%U %G' ~/pfs-base/hello.txt

hello.txt now exists in session layer (copy-on-write). Both stat lines for base layer print same owner and group.