v1.3.6

Concurrency, measured instead of argued — and three defects that only showed up
when four real processes met on one index.

A second verification of a capture no longer destroys the first. A caller
that verified a prepared nonce and finished could have its result deleted by the
next caller to arrive: the store refuses every phase but prepared, and the
refusal was answered by discarding the transaction. Once the first caller has
released its lock and exited, a deliberate replay and a concurrent caller that
arrived late are byte-identical from inside — so a verification whose caller had
been told it passed was thrown away. It is now refused before anything is
recomputed, and the refusal is reported: every drafted record comes back
rejected, naming the phase and what to do about it. The guarantee that mattered
is unchanged — a result nobody stored is still never reported as accepted.

Opening the index while another process opens it no longer throws.
PRAGMA journal_mode = WAL raised SQLITE_IOERR — "disk I/O error" — out of
openIndex when several writers arrived together, which is a crash on the path
the edit hook takes per edit. And the write transaction opened with a deferred
BEGIN, which SQLite will not apply busy_timeout to: the timeout was set and
had no effect on the case it was set for. Both fixed, and the journal-mode guard
tests SQLite's own result code rather than the wording of a message — it
re-raises the two codes that mean the file needs rebuilding and absorbs the rest.

Contention itself still reaches the caller, and deliberately so. A version of
this release absorbed it and reported a pass that had done nothing; review found
that a notes refresh which lost its write lock then returned normally with the
old rows in place, and a query served that stale index as complete where it had
previously fallen back to a full scan. A derived cache must not answer "I am
authoritative" when it means "I am behind".

doctor and validate --range stopped re-reading the same messages.
doctor parsed each candidate branch separately, and validate --range parsed
every message twice because its shape pass and its reference pass held separate
caches. Both now read a range once. On this repository: doctor goes from 70
interpret-trailers to 30 and from 592 git processes to 531, with all 22 rows
identical; a 79-commit validate --range goes from 179 to 14 and from 445
processes to 281, with the report identical.

The test suite can be believed locally again. npm run test:local bounds
the workers, and the two files that scan real history carry timeouts sized from
a measurement rather than from a default. Under full parallelism this suite was
reporting failures that were not failures — eleven of fifteen were the 20-second
default expiring on work that takes six.