`/heid-bug-hunt` on U2's diff, four arms, artifact-only. Eight findings were
real against live code; a ninth was already closed by v0.2.1 and is recorded as
declined. Full triage in persistent-memory.d/2026-09-22-bug-hunt-panel.md.
THE LOCK LIFECYCLE (4/4 convergent, and two defects in one place)
`_Locked.__exit__` unlinked `.marks.lock` on the no-op path so a booth that had
never been marked was left exactly as it was found. `flock` binds to an INODE:
unlinking it under a blocked waiter leaves that waiter holding an exclusive
lock on a deleted file while the next writer creates a fresh lock and takes it
immediately. Two processes then run the read-modify-write concurrently, the
later os.replace drops the earlier one's mark, and both obeyed the protocol.
The cleanup existed to protect the booth's TTL, and was failing at that too:
creating or removing a directory entry bumps the DIRECTORY's mtime, which is
what `_newest_mtime` seeds from. The guard's comment reasons about the lock
file's own mtime and misses that the directory moved underneath it.
One fix: never unlink the lock, exempt `.<name>.lock` dotfiles from
`_newest_mtime`, and restore the directory's mtime after creating one.
THE READ PATH'S BLAST RADIUS
`_clean_text` did `(text or "").replace(...)` and `marks_for` sorts on
`(created, id)`, so a stored `text` that was a dict or a `created` that was a
number raised out of the read path. `list_booths` reads every booth's marks on
every index load, so one hand-edited file returned 500 for `/` and `/healthz`
across all 25 booths. Guarded in two layers — a named type check and a
`_hydrate_safe` backstop that cannot raise — and an unreadable mark now renders
as ⚠ broken rather than as an empty note.
ALSO
- import_legacy_asks stamped `created` at whole-second resolution, so two
sidecars from the same second lost the ordering the importer had just
established and re-sorted alphabetically. Microseconds, per the stated
`(mtime, name)` rule.
- The five mark-write routes ran a blocking flock on the event loop; they now
dispatch through run_in_threadpool, asserted structurally like INV-1.
- `/answer` 500'd on a non-string `notes` form value where `/note` handled it.
- The inline-doc tile had a flag control and no note field.
- The marks panel was suppressed on any booth carrying a links.md.
- The viewer's arrow keys and Escape threw away a note being typed.
CLI
`booth marks` printed a traceback and exited 0 on a failed read, and `--wait`
emitted a whole JSON document per poll. `booth answer --wait` read a damaged
file as "not yet" and spun the full hour. Both now use real exit codes —
0 ok, 1 unanswered/timed-out, 2 no such pick, 3 unreadable — and `--wait`
prints once. `marks.read_error()` lets the CLI ask what the page must not: the
browser stays lenient, the machine consumer gets the truth.
`scripts/booth` had no tests; it has five now, run against the real script
under the system python3, which also makes them a live check on INV-1.
275 tests (253 before). Live service restarted, 25/25 booth pages verified 200.
