Rusty Backup

July 23, 2026 · View on GitHub

The single source of truth for what Rusty Backup can do with every filesystem, container, and partition table today — a living support checklist (Browse / Create / Edit / Shrink-Grow / fsck per filesystem in §1) plus the notable formats it cannot yet handle (§6). First generated 2026-07-07 by reading the src/fs/mod.rs dispatch hub, src/partition/, src/rbformats/, src/model/file_types.rs, and every driver's trait impls directly (not the prose docs, which had drifted — see §7); kept current as capabilities land (last: 2026-07-10 — PFS3 + SFS fsck, El Torito boot-image extract/replace).

Companion docs: full_MiSTer_support_status.md grades each MiSTer computer core; ../README.md is the user-facing feature list; filesystem_completion_plan.md turns the gaps in §6 into a sequenced work-list. This file is the exhaustive engine-level view.

How to read the support columns

Column	Meaning
Detect	`Auto` = recognized from on-disk signature/geometry; `String` = caller must declare the format (no on-disk signature); `via X` = reached only through another path
Browse	Read + list + extract files (Inspect tab, `rb-cli ls` / `get`)
Edit	Create / delete / write files (Edit Mode, `rb-cli put` / `rm` / `mkdir`) — implements `EditableFilesystem` and is wired into the edit dispatch
Create	Format a blank volume (`rb-cli new --fs`)
Shrink/Grow	Compact to minimum for backup and/or re-expand on restore. `compaction` = backup-side size reduction only; `in-place` = true volume resize
fsck	`check+repair` = detects and fixes; `check` = detects/reports only; `validate` = restore-time integrity gate, no interactive check

GUI Check/Repair access. Every filesystem whose driver implements fsck() is reachable from rb-cli fsck (+ --repair). In the GUI there are two Check buttons: the Inspect-grid one (gated by is_checkable_type / is_checkable_fs_name / is_checkable_retro_fs, runs fsck async through fsck_runner over the block factory) covers everything factory-reachable — the big FS, Amiga OFS/FFS/PFS3/SFS, and the retro superfloppies (CBM, DragonDOS, RS-DOS, Acorn DFS, Human68k). The browse-view one covers HFS and Alto BFS/TFS (Alto packs open through the open_pack container path, not the factory).

Everything below is a disk image or physical disk; backup/restore itself works on any filesystem at the raw sector level — these columns describe the filesystem-aware value-adds (browse, edit, shrink, fsck) on top of that.

1. Supported filesystems

PC / DOS / Windows

Filesystem	Detect	Browse	Edit	Create	Shrink/Grow	fsck	Systems / era
FAT12 / FAT16 / FAT32	Auto	Yes	Yes	Yes	Yes (in-place + defrag)	Yes (check + repair)	DOS, Windows 3.x/9x, MSX, universal
exFAT	Auto	Yes	Yes	Yes	Yes (in-place + defrag clone)	Yes (check + repair)	Modern removable media, large SD/CF
NTFS	Auto	Yes	Yes	Yes	Yes (in-place + defrag clone)	Yes (check + repair)	Windows NT / 2000 / XP+

Classic Mac & Apple

Filesystem	Detect	Browse	Edit	Create	Shrink/Grow	fsck	Systems / era
MFS (Macintosh File System)	Auto	Yes	Yes	Yes (`--fs mfs`)	N/A (fixed floppy)	check+repair	Mac 128K / 512K / Plus, 400 / 800 KB floppies (1984–86)
HFS (Mac OS Standard)	Auto	Yes	Yes	Yes	Yes (block-size clone)	check+repair	Classic Mac OS (System 7–9), 68k / early PPC
HFS+ / HFSX	Auto	Yes	Yes	Yes	Yes (defrag clone)	check+repair	Mac OS 8.1 → macOS; embedded + wrapped variants
HFV (flat HFS)	via HFS	Yes	Yes	Yes (`--fs hfv`)	Yes	check+repair	BasiliskII / SheepShaver — flat classic HFS ≤ 2047 MB, no APM wrapper
ProDOS	Auto / MBR 0xA8 / APM	Yes	Yes	Yes (`--fs prodos`)	Yes (in-place)	check+repair	Apple II / IIgs
Apple DOS 3.3	Auto (140 KB only)	Yes	Yes	Yes (`--fs apple-dos`)	No	check+repair	Apple II 5.25" (`.dsk` / `.do` / `.po`, sector-order auto)
UCSD p-System	Auto	Yes	Yes	Yes (`--fs ucsd`)	—	check+repair	UCSD Pascal — Apple II/III, PC (contiguous flat FS); full quartet, clean-room-oracle-validated
Apple Lisa FS	Auto (tag-bearing DC42/DART)	Yes	No	No	No	No	Apple Lisa — reconstructed from 12-byte sector tags

HFV is the write side of classic HFS for BasiliskII / SheepShaver: a flat HFS volume with no APM wrapper, created via rb-cli new --fs hfv. Reads/edits/fscks flow through the HFS path; only creation is HFV-specific, capped at classic HFS ≤ 2047 MB.

Linux / Unix / BSD

Filesystem	Detect	Browse	Edit	Create	Shrink/Grow	fsck	Systems / era
ext2 / ext3 / ext4	Auto	Yes	Yes	Yes	Yes (in-place)	Yes (check + repair, incl. ext4 metadata_csum crc32c)	Linux
btrfs	Auto	Yes	No (read-only)	No	Yes (volume resize)	validate	Modern Linux
XFS (v4 / v5)	Auto	Yes (v4 edit)	Yes (v4)	No	Grow only (disk-layout + `xfs_growfs`)	check+repair	SGI IRIX 6.x, Linux
JFS (JFS2)	Auto	Yes	No (read-only)	No	compaction	check+repair	IBM OS/2 Warp Server, AIX 5+, Linux JFS2
ReiserFS (v3.5 / v3.6)	Auto	Yes	No (read-only)	No	compaction	No	Linux, late-1990s → mid-2000s
Minix (V1 / V2 / V3)	Auto	Yes	Yes	Yes	—	check+repair	Minix, early Linux (pre-ext); full quartet, fsck.minix-validated
UFS / FFS (UFS1 / UFS2)	Auto	Yes	Yes	No	compaction	check+repair	4.2/4.4BSD, FreeBSD, SunOS / Solaris, NeXTSTEP

UFS is browse + edit (create / delete / rename) + fsck with repair (replica superblock, block bitmap, orphan → lost+found). Its edit path was wired into the dispatch as part of this sweep — see §7.

SGI

Filesystem	Detect	Browse	Edit	Create	Shrink/Grow	fsck	Systems / era
SGI EFS	Auto	Yes	Yes	Yes	Yes (in-place + aggressive shrink)	check+repair	SGI IRIX < 6.0
SGI XFS	(see Linux/Unix row above — same driver)

Amiga

Filesystem	Detect	Browse	Edit	Create	Shrink/Grow	fsck	Systems / era
AFFS (OFS / FFS, Intl, DirCache)	Auto `DOS\0`..`DOS\7`	Yes	Yes	Yes	Yes (in-place)	check+repair (Disk Validator)	Commodore Amiga
PFS3 / PDS3 / muFS	String	Yes	Yes	Yes	Yes (in-place + defrag clone)	Yes	Amiga Professional File System 3
SFS (Smart File System)	String	Yes	Yes (single-leaf btree)	Yes	Yes (in-place)	Yes	Amiga `SFS\0` / `SFS\2`

8-bit & home micros

Filesystem	Detect	Browse	Edit	Create	Shrink/Grow	fsck	Systems / era
CBM DOS (1541 / 1571 / 1581 / 8050 / 8250)	Auto	Yes	Yes	Yes	— (fixed geometry)	Yes	Commodore C64 / 128 / VIC-20 / C16 / PET. fsck = VALIDATE (BAM reconciliation), rewrite byte-verified vs `c1541 validate`
Atari DOS 2 (2.0S / 2.5)	Auto	Yes	Yes	Yes (`--fs atari`, SD)	— (fixed geometry)	check+repair	Atari 8-bit (400/800/XL/XE)
RS-DOS / Disk BASIC	Auto	Yes	Yes	Yes	— (fixed geometry)	Yes	Tandy CoCo 1 / 2 / 3. fsck = granule-table reconciliation vs the directory file chains (VALIDATE model): reclaims leaked granules, surfaces cross-links / broken chains
OS-9 / NitrOS-9 RBF	Auto	Yes	Yes	Yes (`--fs os9`)	— (fixed geometry)	check+repair	Tandy CoCo, Dragon, 6809 systems
DragonDOS	Auto	Yes	Yes	Yes	— (fixed geometry)	Yes	Dragon 32 / 64. fsck = bitmap reconciliation vs the directory extent chains (VALIDATE model), rewrites both dir-track copies
Acorn DFS	Auto	Yes	Yes	Yes	— (fixed geometry)	Yes	BBC Micro / Master, Acorn Electron. fsck = contiguous-file consistency (overlap + out-of-bounds detection; canonical descending-catalogue reorder as the repair)
TR-DOS	Auto	Yes	Yes	Yes (`--fs trdos`)	— (fixed geometry)	check+repair	ZX Spectrum Beta Disk (`.trd`, 80-/40-track SS/DS). Flat 128-entry catalogue of contiguous files, append at a first-free high-water mark. fsck = catalogue-packing check + disk-info-counter reconciliation (repair withheld on structural damage); full quartet, clean-room-oracle-validated
TI-99/4A	Auto	Yes	Yes	Yes (`--fs ti99`)	— (fixed geometry)	check+repair	TI-99/4A (flat V9T9 `.dsk`, SSSD/DSSD/DSDD). VIB allocation bitmap + sorted FDIR of extent-based FDRs, big-endian. fsck = VIB-bitmap-vs-directory-walk reconciliation + cross-link detection (repair withheld on structural damage); full quartet, validated against BOTH MAME's `imgtool` and a clean-room oracle
Acorn ADFS / FileCore	Auto / String	Yes	Yes (new-map E/F/HD + old-map D)	Yes (`--fs adfs`, E-format)	N/A (fixed floppy)	check+repair (new-map)	Acorn Archimedes, BBC Master, RISC OS. Old-map D-format read+write validated vs real Repton 3 / Lemmings
CP/M (2.2 / 3 / Plus)	String	Yes	Yes	Yes (`--fs cpm --cpm-preset`)	No	check+repair	Amstrad CPC/PCW, Einstein, SV-328, Altair, MultiComp, ZX +3 (9 DPBs — see §2)
Human68k (FAT12 / FAT16)	Auto / String	Yes	Yes	Yes	Yes (HDD in-place + defrag repack)	Yes	Sharp X68000 (big-endian FAT dialect). fsck = FAT allocation reconciliation vs the directory tree (VALIDATE model): reclaims lost clusters, resyncs the backup FAT copy, surfaces cross-links / broken chains
QDOS (QXL.WIN)	Auto / String	Yes	Yes	No	Yes (in-place resize)	No	Sinclair QL hard-disk container

Xerox research systems

Filesystem	Detect	Browse	Edit	Create	Shrink/Grow	fsck	Systems / era
Alto BFS / TFS	Auto	Yes	Yes	Yes	Yes (resize)	Yes (CLI)	Xerox Alto (Diablo 31/44), Trident T-80/T-300. fsck = label/bitmap reconciliation vs the file page-chains (VALIDATE model): flags overlaps / broken chains read-only, rebuilds the DiskDescriptor free-page bitmap + count as the repair. Reached via `rb-cli fsck` — which has its own Alto branch because packs open through the `open_pack` container path, not the block-reader factory. `--repair` is allowed in place only for a `.pdi` input (it rebuilds + writes back as a PARC Disk Image; other containers would have their format changed). In the GUI, Check/Repair is on the browse-view toolbar (gated on `fs_type == "Alto BFS"`), since Alto packs open through `BrowseSession`/`open_pack` and repair self-persists as PDI — the block-factory inspect-grid path can't reach them.
Pilot / Cedar	Auto	Yes	No (read-only in GUI)	(test infra)	No	No	Xerox D-machines (Dolphin / Dorado / Dandelion)

Detect-only scaffolds & fallback

Filesystem	Detect	Browse	Notes
QDOS Microdrive (`.mdv`)	Auto	Detect only	Cartridge name surfaced; directory walk not implemented (`Unsupported`)
ANDOS	Auto / String	Detect only	Signature probe surfaces "ANDOS"; browse returns `Unsupported`. Soviet BK0011M / Elektronika BK
Carve (raw recovery)	Fallback	Yes (synthetic)	Last-resort for unmountable / NDOS images: whole-disk blob + carved text/JSON runs + Amiga bootblock

Totals: ~30 filesystem drivers — 27 editable+wired, 8 with an interactive fsck (AFFS, EFS, HFS, HFS+, JFS, Minix, UFS, XFS — all repair; JFS and Minix repair by adopting orphaned inodes into /lost+found), 18 create-blank, 2 detect-only scaffolds, 1 recovery fallback.

2. CP/M disk-parameter blocks (DPBs)

CP/M has no on-disk signature, so the format is declared explicitly (--fs cpm:<preset>). Nine presets ship (src/fs/cpm_diskdefs.rs):

Preset	Machine / format
`amstrad_data`	Amstrad CPC 6128 data format (no reserved tracks)
`amstrad_sys`	Amstrad CPC 6128 system format (2 boot tracks)
`amstrad_pcw`	Amstrad PCW 8256/8512 Format A (3" CF2, 180 KB SS)
`einstein`	Tatung Einstein 80T DS 10×512
`svi328_cpm`	Spectravideo SV-328 CP/M (80 KB SS, 40-track)
`altair_8in`	MITS Altair 8800 8" SSSD (26×128, 77 track)
`altair_cf`	Altair-Z80 CF / IDE image (8 MB chunks)
`multicomp`	Grant Searle MultiComp SD (80×10×512 SS)
`zxplus3`	ZX Spectrum +3 / +3DOS (Amstrad-data compatible)

The DPB registry is the extension point for any other CP/M machine (Kaypro, Osborne, Epson, TRS-80 CP/M, …) — a new format is a table entry, not a new driver.

3. Optical-disc filesystems

Read through the opticaldiscs crate (v0.10, optical feature). Browse + extract only — no edit / resize / fsck on the disc filesystem itself. Container formats opened: ISO 9660 (.iso / .toast), BIN/CUE, CHD-CD, MDF/MDS, NRG, CCD, MDX, DiscJuggler .cdi (raw 2352-byte-sector images auto-detected inside a bare .iso). rb-cli optical info --format json reports the volume metadata leniently (PVD identity, RR / Joliet / UDF flags, El Torito boot catalog, HFS/APM). El Torito boot images are a first-class exception to "read-only": optical boot extract pulls a boot image out as a nested disk image — then the filesystem drivers above browse / edit / fsck it — and optical boot replace writes an edited image back into the catalog (raw .iso).

Filesystem	Typical discs
ISO 9660 (+ Joliet, Rock Ridge)	PC / Unix / mixed data CDs & DVDs
High Sierra	Pre-ISO 9660 CD-ROMs (early Microsoft / IBM titles)
UDF (1.02–2.01)	DVDs, data discs
HFS / HFS+	Classic Mac & Mac OS X CDs / DVDs, "Mac/PC" hybrids
SGI EFS	IRIX install / distribution CDs
UFS / FFS	Tru64 / Solaris CDs, NeXT / OpenStep / Rhapsody discs
VMS ODS-2 / Files-11	OpenVMS (VAX / Alpha) discs

Gap: UDF 2.50+ metadata-partition discs (Blu-ray) are detected only.

4. Container / image formats

Whole-disk wrappers (src/rbformats/):

Format	Read	Write	Notes
Raw (`.img/.raw/.bin/.dd/.hda/.hdv/.hdf/.hds`)	Yes	Yes	Passthrough, sparse zero-skip
VHD fixed / dynamic	Yes	Yes	+ VHD export
QCOW2 v2/v3	Yes	Yes	+ in-place edit; `qemu-img`-clean
VMDK flat / sparse	Yes	Yes	Allocate-on-write edit
MAME CHD (disk + CD-cooked)	Yes	Yes	In-process libchdman-rs; expand
2MG	Yes	Yes	Apple II
DiskCopy 4.2 (+ Twiggy)	Yes	Yes	Twiggy read-only
WOZ 1 / 2	Yes	Yes	Apple nibble/bitstream
DART	Yes	No	Compressed Apple/Lisa (LZH/RLE)
UDIF DMG / NDIF	Yes	No	Compressed Apple images
WinImage IMZ	Yes	No	ZIP-wrapped (incl. encrypted)
Norton Ghost (`.gho/.ghs`)	Yes	No	File-aware + password + span sets
cb-dos (`.cbk`)	Yes	Yes	Native single-file backup
gzip (`.gz/.adz/.hdz`), `.zip` disk	Yes	`.adz/.hdz`	Transparent decompress

Floppy-container decoders (src/rbformats/containers/):

Kind	Read	Write	Machines
MSA	Yes	Yes	Atari ST
D88	Yes	Yes	X68000, PC-88/98, MSX, FM-7
XDF / HDM / DIM	Yes	Yes	X68000 / PC-98 / DiskExplorer
ATR	Yes	Yes	Atari 8-bit
G64 / G71	Yes	Yes (from d64)	Commodore GCR
EDSK / DSK (CPCEMU)	Yes	No	Amstrad CPC/PCW, Einstein, Oric

Gaps here: EDSK write, and the flux/track container family (TD0, IMD, HFE, 86F, IPF, SCP, NIB) — the fluxfox crate is the candidate infrastructure (see MiSTer status doc §"Prior art").

5. Partition tables

Scheme	Parse	Edit	Build	Notes
MBR	Yes	Yes	Yes	Incl. extended/logical, CHS patch
GPT	Yes	Yes	Yes	Protective-MBR paired, CRC refresh
APM (Apple)	Yes	Yes	Yes	68k / PowerPC Macs
RDB (Amiga)	Yes	Bootable-flag only	—	RDSK + PART chain; carries `DosType`
SGI Volume Header	Yes	Yes	Yes	IRIX; 16 slots + volume dir
AHDI (Atari ST/TT/Falcon)	Yes	No	Yes	Big-endian, XGM chains
X68000 / Sharp	Yes	No	Yes	256/512/1024-B sectors
None (superfloppy)	Yes (~30 fs hints)	—	—	FS auto-detected at sector 0

Gaps: AHDI and X68000 partition editing (build works, in-place edit bails); BSD disklabels and Solaris VTOC slices as first-class partition schemes.

6. Gap analysis — what is not supported

No canonical "every filesystem ever made" list exists, but cross-referencing Wikipedia's list of file systems against the mission — backup / restore / inspect of vintage-computer disk images, with a MiSTer-FPGA lean — the gaps sort into four bands.

High value (retro, disk-image, plausible demand)

Filesystem	Systems	Why it matters	Prior art
UCSD p-System	Apple II/III, IBM PC, many	Cross-platform Pascal environment; common on Apple II archival disks	a2kit has partial p-System
HPFS	OS/2	The defining OS/2 filesystem; PC-preservation gap	TotalImage (C#, portable)
Minix FS	Minix, early Linux	Small, well-documented; the FS Linux booted on in 1991	Linux kernel `fs/minix`
~~TR-DOS~~ (done)	ZX Spectrum (Beta Disk)	MiSTer ZX-Spectrum core; native Spectrum disk FS	full quartet shipped — see §1
TRSDOS / LDOS / NEWDOS	TRS-80	MiSTer TRS-80 core	—
~~TI-99 FS (VIB / FDIR)~~ (done)	TI-99/4A	MiSTer TI-99_4A core	full quartet shipped — see §1
Sedoric / Oric DOS	Oric	MiSTer Oric core	—
N88-BASIC	NEC PC-8801	MiSTer PC88 core	—
SpartaDOS / MyDOS / DOS 3	Atari 8-bit	Alternative Atari DOSes beyond the supported DOS 2	—
APFS (read)	Modern macOS	Rising relevance for later Mac SSD images	Apple spec public
ZFS (read)	Solaris, FreeBSD, Linux	Workstation & NAS preservation	OpenZFS

Medium value (niche machine or workstation)

SquashFS write (browse / extract shipped — src/fs/squashfs.rs) — the one modern-Linux filesystem that reaches our users: AppImages (we ship one), Raspberry Pi OS / DietPi / Buildroot images, live-media filesystem.squashfs, OpenWrt, SteamOS. Read landed; the remaining gap is edit, which is rebuild-only by construction — read the scoping note below before planning it, the caveats are not the usual ones
ADFS write completion + double-sided .dsd (upgrade the existing Partial)
SAM DOS / MasterDOS (SAM Coupé), Sharp MZ FD, Coleco EOS, Atom DOS — each a MiSTer core in the floppy long-tail
AIX JFS1 — the pre-JFS2 format; currently detected then rejected
Veritas VxFS, Tru64 AdvFS, Solaris QFS/ZFS — commercial-Unix workstation filesystems (we cover SGI EFS/XFS; the rest are gaps)
OpenVMS ODS-2 on a raw disk — we read ODS-2 on optical only
Apple SOS (Apple III), Apple DOS 3.2 (13-sector), Apple Pascal
CD-i / Video-CD structure, El Torito boot-catalog emulation-image extraction, UDF 2.50+ metadata partition (optical extras)

Low value (Soviet / hobby / research)

Finish the ANDOS and QL Microdrive scaffolds; CSIDOS, MicroDOS (Vector-06C), Specialist-MX
Reiser4, NILFS, F2FS, bcachefs, HAMMER/HAMMER2 (modern/experimental Linux & BSD — detected-not-read where they collide with supported magics)

Explicitly out of scope

Not disk images of vintage machines — no plan to support:

Modern flash translation FS — JFFS2, YAFFS, UBIFS, F2FS
cramfs — superseded by SquashFS everywhere it mattered; no demand. (SquashFS itself is no longer in this list — the Buildroot-appliance exception it anticipated. Read-only support shipped: see src/fs/squashfs.rs — v4.0, gzip/XZ/LZMA/LZ4/zstd, browse + read; LZO images are refused by name. Write is not in-place under any implementation — see the scoping note below.)
Network / distributed / clustered — NFS, SMB/CIFS, AFS, Ceph, Lustre, GlusterFS, GFS2, OCFS2, ZFS-as-pool
Pseudo / virtual — procfs, sysfs, tmpfs, overlayfs, FUSE shims
Mainframe — z/OS VTOC/VSAM, VM/CMS, and other non-sector-image stores
Windows Server modern — ReFS

Scoping note — SquashFS

SquashFS sat in "explicitly out of scope" until read-only support shipped (src/fs/squashfs.rs). It's the only modern-Linux filesystem our users routinely hit. But "full support" does not decompose the way it does for every other driver in the tree, so the four README columns are answered separately here.

Browse / extract / backup — shipped. v4.0, stable since 2009 and completely specified. Four of the five compressors were already in-tree deps: gzip (flate2), zstd, lz4 (lz4_flex), xz/lzma (lzma-rs). LZO is the gap — rare outside old OpenWrt firmware, refused by name; lzokay (MIT, Rust 1.81) or lzo (MIT, 1.85) would close it. Backup works via the raw whole-partition path; smart compaction is a no-op win (the image is already compressed).

Edit — rebuild-only, never in place. This is inherent to the format, not an implementation shortcut: there is no free-space bitmap, no allocation metadata, and everything is densely packed and sorted. mksquashfs rewrites the whole image even to append one file. The pattern already exists here (ContainerEditSession decode-to-temp / re-encode-on-commit, plus archive_fs / mem_archive presenting archives as Filesystem), so EditableFilesystem is reachable — with caveats that have no analogue elsewhere in the tree:

commit is O(image size), not O(edit);
a rebuilt image is not byte-identical to the original even with zero edits — block packing, fragment packing, dedup and compressor tuning all differ per mksquashfs version. For a tool whose pitch is fidelity that is a real behavioural break from every other filesystem here;
the rebuilt image's size is not knowable before the rebuild runs, because everything is compressed. That is what forces the size prompt described in docs/squashfs_edit.md — unlike every other editable filesystem here, we cannot answer "will this file fit?" from a free-space counter.

fsck — a verifier, not a repairer. There is no upstream squashfs fsck; a read-only filesystem can't go inconsistent through normal use. And squashfs carries no checksums anywhere, so corruption surfaces only as a decompression failure and there is no redundancy to repair from. What's buildable is a structural validator ("does every metadata block, inode, dirent and data block decompress and cross-reference"). Useful; not repair.

Shrink / expand — not meaningful in the in-place sense. The image already is its minimum size, so defragmented_minimum_size ≈ total_size; growing means rebuilding.

7. Known code gaps & drift (fixed in this sweep)

Discrepancies between the code and the prose docs, found while auditing. The doc-side items were corrected in the same commit as this file; the code-side items are logged for follow-up.

Doc drift (fixed):

JFS, ReiserFS, UFS shipped full read drivers but were missing from the README Filesystems table — now listed.
README Filesystems table was also missing MFS, Apple DOS 3.3, CP/M, ADFS, QDOS (all implemented) — now listed.
MiSTer status doc understated QDOS as "read" — it is read + write + in-place resize.

Code gaps (one fixed here, rest logged for follow-up):

UFS edit — FIXED in this sweep. impl EditableFilesystem for UfsFilesystem was complete and fixture-tested but unreachable — no arm of open_editable_filesystem routed "ufs". It is now wired into the 0x00 and 0x83 arms (mirroring the read dispatch), guarded by a dispatch-level regression test. UFS is read + edit + fsck-with-repair.
XFS has no shrink or backup compaction — a known, accepted limitation. It edits (v4) and fscks/repairs, but has no CompactXfsReader or in-place resize, so XFS backups are written full-size. Grow is disk-layout-level only (xfs_growfs); clone-into-fresh shrink is the planned path (OPEN-WORK §2.2).
JFS fsck repair — FIXED. repair() now adopts orphaned (allocated-but-unreachable) fileset inodes into /lost+found/ino_<inum>, creating /lost+found when absent. This pulled forward the JFS edit primitives (inode allocator + inline dtree insert + dinode write-back) behind EditableFilesystem; general create/delete/rename remain Unsupported. Every structural write is oracle-verified against real fsck.jfs (scripts/jfs-oracle.sh). Now on par with the other repairing fscks: AFFS, EFS, HFS, HFS+, UFS (replica SB / bitmap / orphan), XFS (R1–R8).
AIX JFS1 and Reiser4 are detected then rejected — magic recognized, read not implemented.
fsck reach exceeded the Inspect-tab "Check" button — FIXED. The button gate (is_checkable_type) enabled only classic HFS + AmigaDOS, but browse-view and rb-cli fsck call fs.fsck() directly, so AFFS, EFS, HFS, HFS+, JFS, UFS, and XFS all actually run. The gate now also consults is_checkable_fs_name(type_name) — the resolved family the inspect grid shows after content-probing — so the Unix filesystems (SGI EFS, UFS/FFS, XFS, JFS) and HFS+ get the "Check" button too. The button lives inside the partition_is_browsable block, and fsck reuses the same open_filesystem factory as Browse, so routing is guaranteed to match. Guarded by checkable_fs_name_covers_probed_unix_families.

Maintenance

When you add or change a filesystem / container / partition driver, update this file alongside the three surfaces in ../CLAUDE.md's "Pre-commit documentation sync" checklist (README tables, full_MiSTer_support_status.md, DISK_IMAGE_EXTS). This audit is the superset view; the others are the user- and core-facing slices of it.