These are the current limits of Mountee 0.2.0. None of them are silent: unsupported operations return ENOTSUP rather than a false success.

Filesystem behavior

POSIX permissions are not mapped from NTFS security descriptors yet. Uniform mode bits are reported, and ownership is ignored (noowners).
Symlinks, hard links, and extended attributes/resource forks are unsupported. Windows junctions appear as plain entries.
RENAME_SWAP cannot be refused. FSKit passes no rename flags (Apple bug FB24419773), so a swap request is performed as a destination replace.
fsync delivery is not independently verified end to end. Writes use the resource’s direct I/O path and the volume syncs on unmount. Crash consistency under power loss has not been fault-injection tested.
One volume per resource. This follows FSKit’s unary design and NTFS semantics.

Mount behavior

Mount location: through Disk Arbitration, the system picks /Volumes/<name>. When Mountee falls back to the mount -F path, it uses ~/Library/MacNTFS/Volumes/<name>.
Dirty and hibernated volumes are never mounted read/write. They mount read-only with the reason logged.
No format, repair, or erase. Mountee does not check or repair NTFS integrity. Use Windows tools for that.
Per-user extension enablement. Each macOS account must enable the file system extension once.

Platform

macOS 26 or later, Apple Silicon only. Built and tested against the macOS 27 SDK and runtime on Apple Silicon. Verified on macOS 26.6.2 and macOS 27.0.1.
No Intel support. The release is arm64.
FSKit itself requires macOS 15.4+, but Mountee claims no support before macOS 26. The 26.0 deployment target and validated mount paths are the supported baseline. macOS 15.x is not supported even though FSKit exists there; the project’s validation notes document failures in the system mount paths.

Development and packaging

Stale extension processes can linger after unmounts during development. The project’s diagnostics guide documents the pkill workaround.
The 0.2.0 DMG still uses the MacNTFS name and installs MacNTFS.app.
macOS 26 had a system bug where the System Settings toggle could not enable third-party FSKit modules; the app’s enable button and macOS 27 avoid it.

What this means for your data

Mountee’s safety gates protect against the common NTFS corruption cases, but this is a 0.2.0 release. Keep backups, test read/write on disposable or non-critical data first, and eject volumes before unplugging them.

See the upstream LIMITATIONS.md for the canonical list.