[dependabot]

Bumps filelock from 4.0.1 to 4.2.1.

Release notes

Sourced from filelock's releases.

4.2.1

• On a singleton wrapper, close> and close> end only the holds that tasks acquired through that wrapper. A reader that arrives during close() gets the closed error instead of joining the ending hold. After synchronous code closes or force-releases the shared lock, the wrappers refuse to admit readers into the ended hold, and close() on such a wrapper returns. Closing one wrapper no longer ends a task's nested hold taken through another wrapper on the same path. #832
• ReadWriteLock locks again after a release() that an exception from a signal handler interrupted. The async read-write wrappers stop admitting readers into such a level. The async read-write locks forget a hold whose backend release failed after the backend let go, and they free the memory of each acquire that times out or is canceled. AsyncFileLock returns from release() after a few hundred acquires gave up behind a waiting one. An exception from a signal handler delivered while an AsyncFileLock call joins its queue no longer blocks every later call on that lock. #833
• Fix ReadWriteLock acting on -journal, -wal or -shm files another process puts beside its database: a write could land in another file, a reader could get in beside a writer, and an acquire could fail. SQLite now opens the database by name only in a directory no other account can write, and through a private hard link elsewhere. On Windows the directory's access control list decides. Where hard links are unavailable, keep the database in a directory other accounts cannot write, such as one under %LOCALAPPDATA%. The lock removes link directories through a checked descriptor rather than by name, reads a link directory's name only when the locking account owns it, and leaves alone a directory with other content renamed onto a link directory's name. A database whose schema takes more than a few kilobytes to load raises ValueError instead of running past the acquire timeout. #834
• Fix five bugs in opening the lock file. UnixFileLock no longer truncates a file it did not create, such as one renamed to the lock path, and no longer applies mode to it. An on_acquired hook that writes holder metadata now truncates the file itself. A lease (Linux) or an oplock (Windows) on the lock file or a soft lock's marker no longer holds acquire() past its timeout or blocking=False, and an oplock no longer holds release(); ReadWriteLock on Windows waits for its timeout and raises Timeout. On Windows, a mode without group and other bits, such as 0o600, now creates the lock file with an owner-only permission list; the ReadWriteLock database gets the same. The soft locks' writability check no longer follows a symlink swapped in at the lock path. On a filesystem without flock, a contender from another account now waits on a marker it cannot write instead of raising PermissionError. #835
• Fix SoftFileLock, MarkerSoftFileLock and SoftFileLease removing a live holder's marker in three cases: the holder and the contender run in Linux time namespaces with different boottime offsets; only one of them can read the boot id; a process other than the owner rewrote the marker. Soft markers no longer carry group or other write bits. A process name containing a carriage return or another line separator no longer makes the stale check raise ValueError. When /proc/self/ns/time exists but cannot be read, the stale check no longer compares start times and keeps the marker. #836
• The async read-write locks record their hold under a task owner, so synchronous code on the executor thread that took the hold can no longer re-enter or release it. AsyncSoftReadWriteLock gives back one level on release, so synchronous readers of a shared singleton keep theirs. SoftReadWriteLock tracks read levels per thread: release() from a thread that holds none raises RuntimeError. After its heartbeat recorded a lost hold, it refuses new acquires until that hold is released. #838
• StrictSoftFileLock creates <path>.filelock and its claims directory with the lock's mode and sets the sticky bit (a directory flag that lets only a file's owner remove it) on both. On the next acquisition it narrows a directory it owns that an earlier release created wider; it leaves a directory of another account as it is, so remove such leftovers by hand. It reaches claims through a descriptor opened without following symlinks; on Windows it holds both directories open and refuses a junction (a directory that points at another directory). Under a sticky parent such as /tmp it refuses a coordination directory of another account, as SoftReadWriteLock does for <path>.rw. One read grace now covers a whole claim scan, a failed claim cleanup no longer leaves the sentinel descriptor open, and a non-regular node at a sentinel private-record name raises SoftFileLockProtocolError. On Windows, contenders read claims without blocking their owner's unlink. #839

... (truncated)

Changelog

Sourced from filelock's changelog.

########### Changelog ###########

.. towncrier-draft-entries:: Unreleased

.. towncrier release notes start

---

4.2.4 (2026-10-19)

---

• Keep GitHub Release notes free of extra blank lines while retaining the PyPI and version comparison links. :pr:863

---

4.2.3 (2026-10-19)

---

• Creating a lock on a Python 3.15 interpreter without types.LazyImportType no longer triggers AttributeError at exit. :pr:860
• Handle EFTYPE when a no-follow open refuses a symlink in a soft reader/writer lock's protocol tree, so heartbeat reports lost ownership rather than a transient refresh error.

---

4.2.2 (2026-10-18)

---

• Fix a lock on a relative path that stayed held after a later with lock: ended, when an earlier acquire() had failed because the working directory no longer exists. That call still raises :class:FileNotFoundError, and it now leaves the lock's hold count unchanged. :pr:856

---

4.2.1 (2026-10-17)

---

• On a singleton wrapper, :meth:AsyncReadWriteLock.close() <filelock.AsyncReadWriteLock.close> and :meth:AsyncSoftReadWriteLock.close() <filelock.AsyncSoftReadWriteLock.close> end only the holds that tasks acquired through that wrapper. A reader that arrives during close() gets the closed error instead of joining the ending hold. After synchronous code closes or force-releases the shared lock, the wrappers refuse to admit readers into the ended hold, and close() on such a wrapper returns. Closing one wrapper no longer ends a task's nested hold taken through another wrapper on the same path. :pr:832
• :class:~filelock.ReadWriteLock locks again after a release() that an exception from a signal handler interrupted. The async read-write wrappers stop admitting readers into such a level. The async read-write locks forget a hold whose backend release failed after the backend let go, and they free the memory of each acquire that times out or is canceled. :class:~filelock.AsyncFileLock returns from release() after a few hundred acquires gave up behind a waiting one. An exception from a signal handler delivered while an :class:~filelock.AsyncFileLock call joins its queue no longer blocks every later call on that lock. :pr:833
• Fix :class:~filelock.ReadWriteLock acting on -journal, -wal or -shm files another process puts beside its database: a write could land in another file, a reader could get in beside a writer, and an acquire could fail. SQLite now opens the database by name only in a directory no other account can write, and through a private hard link elsewhere. On Windows the directory's access control list decides. Where hard links are unavailable, keep the database

... (truncated)

Commits

• 60331bb Release 4.2.1
• 834bf13 🧪 test(soft): skip Unix pin test on Windows
• 9d15e38 fix(soft-rw): isolate subclass singleton registries (#855)
• e1e825b 🐛 fix(open): keep lock files intact, honor deadlines and mode (#835)
• 5e3f2ec 🐛 fix(read-write): keep SQLite off shared names, bound schema (#834)
• bfa066d 🐛 fix(strict): keep claim directories private to the lock (#839)
• 977d2c3 🐛 fix(soft): wait on an empty marker instead of evicting (#846)
• 740ff66 🐛 fix(soft): break stale markers without emptying the lock path (#843)
• 86c6d5f 🐛 fix(async): honor cancellation and per-thread gates (#844)
• eeceaa8 🐛 fix(soft): keep live holders when owner identity differs (#836)
• Additional commits viewable in compare view

Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.

---

Dependabot commands and options

You can trigger Dependabot actions by commenting on this PR:

• @dependabot rebase will rebase this PR
• @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
• @dependabot show <dependency name> ignore conditions will show all of the ignore conditions of the specified dependency
• @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
• @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
  You can disable automated security fix PRs for this repo from the Security Alerts page.

[github-actions]

AI review: no P0-P2 findings

Reviewed 7436ebc. Run log

Dependabot bumps the transitive dependency filelock from 4.0.1 to 4.2.1 in uv.lock. The tool that writes the lockfile also moved its format revision from 3 to 5. Only development tools reach filelock (pip-audit through cachecontrol[filecache], tox, virtualenv, python-discovery), so the published package is unaffected and the risk is low. Two metadata issues remain: the fix(deps) title will trigger a release, and the revision bump goes unmentioned.

⚪ P3

• uv.lock:567 fix(deps) title on a development-only dependency will cut an unneeded SDK release
• uv.lock:2 Lockfile format revision jumps from 3 to 5 with no explanation, while CI and the project minimum stay on uv 0.12.17

Not checked: The AI review read the diff, the code, and the PR's text; it ran no tests or builds and read nothing outside this repository.

• Whether uv 0.12.17, as pinned in CI and the publish workflow, accepts a lockfile with revision = 5 under uv sync --locked and uv run --locked, and whether it would rewrite that field.
• Whether filelock 4.2.1's changes to lock-file opening, soft locks and directory permissions alter how tox, virtualenv or pip-audit behave during poe checks in CI.

Human review: not needed

[github-actions]

⚪ P3: fix(deps) title on a development-only dependency will cut an unneeded SDK release

In uv.lock, only pip-audit (via cachecontrol[filecache]), tox, virtualenv and python-discovery depend on filelock. All of them come from the dev dependency group, and nothing in [project] dependencies or the durable extra pulls it in. maintainers/releasing.md says development dependency updates use chore, which does not release. With release-please-config.json, a squash-merge under this fix(deps): title makes Release Please open a 0.15.2 release. That release would list a filelock bump under "Bug Fixes", even though the published package does not depend on filelock. Change the squash commit title to chore(deps): bump filelock from 4.0.1 to 4.2.1 when merging. Dependabot seems to have treated this indirect dependency as production.

_{Found by claude-opus-5-5}

[github-actions]

⚪ P3: Lockfile format revision jumps from 3 to 5 with no explanation, while CI and the project minimum stay on uv 0.12.17

The diff changes revision = 3 to revision = 5. That means Dependabot's own, newer uv wrote this lock, not the uv 0.12.17 that ci.yml, publish.yml and mutation-audit.yml pin and that tool.uv.required-version names as the minimum. If 0.12.17 writes a lower revision, a maintainer who runs uv lock on the pinned toolchain will rewrite the field. Dependabot will then flip it back, so the lock churns between versions. If 0.12.17 cannot handle revision 5, uv sync --locked in CI and in the release job will fail. Confirm the CI run on this head passes uv sync --locked. Consider moving the CI pin and required-version to a uv release that writes revision 5, so local, CI and Dependabot locks agree.

_{Found by claude-opus-5-5}