Reconciles the two parallel evolutions of PR #996 with this session's
publication design as authoritative:
- internal/upgrade, internal/app: ours — mkdir-claim identity witness
(dev:ino on POSIX, volume file ID on Windows), three-state ownership,
ErrSkillPathPublicationUncertain, copy-fallback short-circuits. Drops
the remote line's xattr publication-mark design and its six follow-up
fixes (retract contracts, Statx token); skill_publication_mark_*.go
removed accordingly.
- scripts/, build/npm/, test/scripts/, docs/rfc: theirs — same replayed
install hardening plus main's evolution and the npm no-clobber child
moves; no xattr dependency, consistent with the claim model.
- .changes: their npm/Shell/PowerShell narrative with the Go-design
sentences rewritten for the uncertain-publication contract.
Verified: go build, go vet (tests compiled), gofmt, and package tests
for internal/upgrade, internal/app, test/scripts all green on this tree.
Linux overlayfs recycles device+inode, so SameFile and a lone inode
token treated a replacement as owned and retracted it. Stamp staged
inodes with an xattr mark, prove Linux/Darwin identity with birth
time, and make shell copied-set rollback check dest first with inode
plus child names.
Match the Go dest-first identity check so a concurrent replacement is
never moved into .rollback-*; only a post-quarantine mismatch is
restored with no-replace. Cover both races in the npm smoke suite.
Record dest on occupy and retract it when confirmation, verify, or
staging cleanup fails. Restore unmatched quarantine with a no-replace
publish. Event/devapp copy uses mkdir-claim; shell rollback claims dest
before delete. Release copy now says npm/PowerShell create junctions and
Go uses os.Symlink, with copy fallback when linking is unavailable.
Cross-filesystem Skill moves now record publication identity as soon
as the staging path is renamed onto dest. A later mode-restore, copy
verification, or staging-cleanup failure retracts that proven dest so
retries are not blocked by an untracked leftover. A failed retract
reports an uncertain state naming both retained locations.
The shell mono/multi set publishers staged each Skill directory and
published it with a plain mv after the backup; anything another process
created at the destination between the backup and the move was silently
replaced, and restore_multi_skill_set then blind-deleted manifest paths,
so a concurrently replaced object could also be destroyed during
rollback. Publish through an atomic mkdir claim instead — EEXIST refuses
any occupant, staged children move into the claim one by one, and a
failed child move relocates them and removes only the claim. The
published manifest now records <dest>:<inode>, and rollback deletes a
destination only when its inode still matches the publication, skipping
concurrently replaced paths with a warning. Also fixes a latent
unbound-variable expansion where a shell variable was followed directly
by a full-width parenthesis in a message. Regression tests publish a
first Skill, replace it with a foreign directory, fail the second
publication, and assert rollback retains the foreign object untouched
while restoring the rest from backups.
The POSIX shell installers staged shared Skill links and published them
with mv after an existence check; a file or symlink another process
created at the destination between the check and the move was silently
replaced, and the inode confirmation could not detect the loss. Publish
by creating each link directly at its destination instead — symlink(2)
refuses an occupied path with EEXIST, so the creation itself is the
atomic no-replace check. A directory that appears at the destination
turns ln -s into a container; the nested link is removed after an
identity check and the transaction rolls back, leaving the foreign
directory untouched. Applied to install.sh, install-skills.sh,
install-event.sh, and install-devapp.sh. Also covers the remaining
retraction branches of the Go shell-removal fallback so changed-code
coverage is complete. Regression tests inject a concurrent occupant at
the publish instant for regular-file and directory cases and assert the
foreign object and its contents stay completely unchanged.
On filesystems without atomic no-replace rename, the degraded
publication moves the source children into a fresh claim and leaves an
emptied source shell for the caller to remove once the move is
confirmed. If that removal failed, moveSkillPathRecoverably reported a
plain failure claiming both locations were preserved while the data
existed only at the destination, so backupAndRemoveSkillDir never
recorded the backup and the original path was left empty. Move the
children back into the shell and withdraw the destination instead; a
failed retraction reports the data location explicitly. Restores the
contract that a failed move keeps the source intact.
publishCanonicalLinkNoReplace checked the destination with lstat and
then published, leaving a window the comment claimed did not exist: on
Windows renameSync replaces a concurrent object outright (libuv passes
MOVEFILE_REPLACE_EXISTING), and on POSIX ln -P source target links INTO
a directory that appeared at the target, leaving a stray link inside
foreign data that the rollback list never recorded. Create the symlink
or junction directly at the destination instead — link creation fails
with EEXIST when anything occupies the path and never treats the target
as a container, so the publication itself is the atomic no-replace
check. Identity confirmation re-reads the live link before the
publication enters the rollback list. Covered by injected concurrent
creators at the publish instant on POSIX and simulated Windows,
asserting the foreign object and its contents stay completely
unchanged.
The mono and multi set copy publishers checked destination existence
with lstat and then called Node's rename, which replaces the target on
every platform (libuv passes MOVEFILE_REPLACE_EXISTING on Windows). A
file, symlink, or empty directory created between the check and the
rename was silently overwritten, and the identity confirmation could not
recover it because the publication record only proved the staged object
arrived. Claim the destination with mkdir — which fails with EEXIST if
anything occupies the path, so the claim itself is the existence check —
and move the staged children into the claim, restoring the source mode
on it. A failed child move relocates the children back and removes only
the claim. Covered for mono, multi, and simulated Windows, including an
injected concurrent creator at the claim instant.
The no-replace file fallback links the destination and then removes the
source. If the removal fails, the caller treats the publish as failed,
but no publication record exists to roll the new destination back, and
a backup restore would refuse the occupied path. Remove the destination
behind an identity check — only the proven linked object may be deleted
— and report when the retraction itself fails or the destination was
concurrently replaced.
The degraded directory publication claimed the destination with mkdir, then
— on platforms whose rename refuses to replace a directory (macOS refuses
even an empty target, verified empirically) — removed the claim and retried
a plain rename. Between the unlink and the retry a foreign directory could
appear at the destination and be silently overwritten, breaking the
no-replace contract the fallback exists to provide.
Hold the claim for the whole transaction instead: rename over the claim
where the platform permits it (Linux), otherwise move the source children
into the claim one by one. The destination is never unlinked, so a
concurrent creator can only ever lose the mkdir race; every child rename
targets a nonexistent path inside the empty claim, and a failed move
restores the children and removes only the claim.
The child move legitimately changes the publication's identity, which the
confirmation now handles: a rename that consumed the staged path is still
proven by identity, while a child move is proven by the pre-rename content
fingerprint. The emptied source shell doubles as the signal distinguishing
the two shapes; moveSkillPathRecoverably removes it to keep move semantics.
Dennis4477