THE DEFAULT FLIP (ruled on proven evidence — at-ack survived 301/301
acked-writes-through-power-cut in block-layer fault injection; deferred
tree authority demonstrably loses flush-covered acks): a brain with NO
stored authority artifact now ADOPTS LOG AUTHORITY AT OPEN. The oracle
gates the flip exactly as the guarded adoption path always did — curable
divergences baseline-backfilled, the flip lands ONLY on a green verdict —
and a brain that cannot verify STAYS tree-authoritative loudly, with the
refusal recorded on the switch artifact so subsequent opens are cheap.
config logAuthority: 'defer' is the explicit documented opt-out (no
automatic adoption; declared flush-window loss; adoptLogAuthority() flips
later). A stored artifact always wins. RELEASES.md carries the posture.
Two standing .fails debt pins FLIP TO HOLDING under the default: the
at-ack crash-survival gap and the ack-at-log durability target — both now
permanent asserted truths, not aspirations.
POWER-CUT THROW SITES (fault-injection findings, brainy-alone config):
- A manifest-listed-but-unloadable column segment QUARANTINES at
discovery (loud once, counted always, quarantinedSegments() exposed for
the heal) and the field serves its remaining segments DEGRADED — never
a raw throw killing every query on the field. Real storage faults still
propagate untouched.
- Torn generation artifacts (NaN/garbage in manifest or counter) DISCARD
with narration at the store's open and recovery re-derives — plus a
defensive finite-integer guard at the init consumer. Never a RangeError
killing an open.
THE LOUD TORN-RECORD CONTRACT: an existing-but-unparseable stored record
now surfaces as a typed, counted TornRecordError on every entity-read
surface (including fifteen previously-blind per-item batch catches);
ENOENT stays clean-absent; artifact readers with designed absent-recovery
keep null-tolerance behind the loud floor. Disk corruption can no longer
read as silent data invisibility.
Suite migration: the default's pins inverted deliberately, generation
baselines made relative, quarantine-contract pins rewritten to the ruled
behavior.
Gates: tsc 0 · unit 2065/2065 (159 files) · integration 826 (93 files) ·
conformance 31/31 · kill-matrix 15/15 · torn-open guards 2/2.
A committed transact() reported success while its canonical entity writes were
still only in the OS page cache (tmp+rename, not fsync'd), even though the
generation counter and manifest were fsync'd. A hard kill in that window could
leave the durable counter ahead of the persisted entity bytes — phantom
progress for any generation-based consumer resuming from the counter. Reported
from a downstream migration's crash-lifecycle forensics.
Add an optional transaction durability barrier to GenerationStorage
(beginWriteBarrier / flushWriteBarrier). FileSystemStorage implements it:
writeObjectToPath records each successful canonical write and
deleteObjectFromPath records each delete's parent dir, between begin and flush;
flush fsyncs every recorded write (contents + rename dir entries, via
syncRawObjects) and the parent dir of every delete. commitTransaction opens the
barrier before running the planned operations and flushes it after, BEFORE
persisting the counter and manifest — so the batch's entire canonical footprint
is durable before the generation stamp advances. The barrier is optional: the
generation store calls it through optional chaining, so in-memory and
durable-per-call (cloud object-PUT) adapters treat it as a no-op.
The single-op group-commit path is unchanged (deferred durability is the
Model-B design that avoids a 3-5x per-write fsync regression), but its
durability contract is now documented explicitly on commitSingleOp: transact =
durable on return; single-op = durable at the next flush()/close(), with the
counter buffered alongside the data so a crash loses both together (never a
torn counter-ahead-of-state store).
Regression (tests/integration/transact-durability-barrier.test.ts): the entity
writes fsync in an earlier syncRawObjects batch than the manifest for single-op
and multi-op (add+relate) transactions; a precommit-rejected batch opens no
barrier and advances nothing; MemoryStorage exposes no barrier (optional-chain
no-op).
