Two release-blocking findings from the durability kill-matrix, both fixed
in the owning layer:
1. LOG-AUTHORITY REPLAY AT OPEN: durable-at-ack fsynced the fact before
the ack, but open() truncated every fact above the manifest — after a
power loss that takes the un-fsynced tmp+rename canonical bytes, the
acked write's ONLY durable copy was discarded. Now: under 'log'
authority, open() REPLAYS intact facts above the manifest into
canonical (FactLog.peekFactsAbove — CRC-gated, order-sorted) and
advances the manifest to cover them; tree-authority brains keep the
truncate contract they were promised. Pinned end to end: the power-loss
row constructs the exact disk state (fsynced log, vanished canonical
rename) and the acked write lives.
2. NO SILENT COMMIT: commitSingleOp buffered the generation BEFORE the
fact append; an append failure (ENOSPC) rejected the caller but the
next flush durably committed the generation with NO fact — a permanent
silent log gap. Now the failure path un-buffers and returns the counter
reservation: nothing commits, the log stays gap-free, and the canonical
execute-residue orphan is the documented crash-equivalent.
Plus: the kill-matrix itself (11 rows — every commit-path fault point ×
reopen-as-crash recovery contract, at-ack variants, disk-full row; five
new zero-cost faultPoint sites), the log-authority pin suite (oracle
green/red/state-differs, flip refusal, switch survives reopen, 9/9), and
the group-commit covering pins (5/5).
Gates: unit 2002/2002 (152 files) · integration 785 · conformance 27/27.
The storage-authority adoption path, guarded shape: the canonical tree
stays authoritative by default ('tree'); a brain flips to 'log' only
through the verification oracle, and the flip is stored, per-brain,
checked at open only.
- FactLog.ensureSynced(): classic group commit — concurrent writers
append, then join ONE covering fsync (running + queued slots give the
covering guarantee: the sync a caller awaits always starts after its
append landed). Solo writer = immediate sync.
- GenerationStore.logDurability 'deferred' (default, byte-identical to
today: fact durability rides the group-commit flush, ack latency
unchanged) | 'at-ack' (log-authority mode: every single-op ack awaits a
covering log fsync — an acked write's fact survives power loss, by
contract). transact() was already durable-at-return in both modes.
- src/db/logAuthority.ts: the stored switch artifact
(_system/log-authority.json, absent = tree), readLogAuthority, and the
VERIFICATION ORACLE — replay the fact log, fold latest state per id
(digests, never bodies — memory-bounded), diff against the canonical
tree paged; verdict green iff every canonical row is exactly reproduced
AND the log claims nothing canonical denies. Divergences are NAMED by
class (pre-log-record → needs baseline backfill; state-differs;
log-live-canonical-absent; log-tombstone-canonical-present). The flip
REFUSES on red with the first divergence and the cure in the message.
- Brainy: authority read at open (log → durable-at-ack enabled);
logAuthority() / verifyLogAuthority() / adoptLogAuthority() public API.
Nothing flips by itself; nothing changes for existing brains.
Stage-2 D1 contract item (co-frozen): a fact scan may be slow, never
silent. batches() now races its FIRST pull against
SCANFACTS_FIRST_BATCH_MS (10s, exported; test-overridable) — a wedged
or unreadably slow store produces a loud abort naming the contract
instead of a consumer hanging indistinguishably from progress (the
production shape: a heal against a generations-backlogged brain
wedged silently on the first segment read).
Only the first pull is raced: the bound is time-to-first-batch (proof
the producer is alive), not per-batch pacing, and it runs only while
a pull is pending — consumer think-time between pulls never counts
against the producer (pinned).
Three pins: wedged-store loud failure within the bound, healthy scan
untouched end-to-end, slow-consumer immunity.
- storage.committedGeneration(): the committed watermark exposed on the
fact-scan capability, so a provider compares its stamp's
sourceGeneration against the store's truth without parsing the
private manifest format (the capability source now carries both the
live fact log and the committed closure).
- Pinned contract tests: fsync-before-ack (transact passes today; the
single-op path is pinned via it.fails as the documented target —
group commit must become LATENCY batching, ack waiting on the shared
fsync, never durability skipping; the pin flips red when that lands
so there is no cliff to discover) and scan-stability-under-rotation
(a scan snapshot yields exactly its facts — no gaps, duplicates, or
bleed-in — while segments rotate beneath it; the reclaim-during-scan
variant lands with fact compaction, which does not exist yet).
- FactLog accepts a rotateBytes option so tests exercise real rotation.
Every committed generation now also appends a FACT — an after-image
commit record (what each touched entity/relationship became, or a
body-less tombstone for a removal) — to an append-only, crc32c-framed
segment log under _generations/facts/. The before-image history and the
canonical tree remain authoritative; the fact log gives consumers ONE
sequential, self-verifying stream (index heals, incremental replays)
in place of a per-entity directory walk.
- Wire format: positional msgpack facts [generation, timestamp, ops,
meta, blobHashes]; op = [kind u8, id bin16, record | nil tombstone];
32-byte segment header (magic, formatVersion, firstGeneration,
zeroed+verified reserved); length+crc32c frame per fact; zero-padded
segment names so lexicographic order == generation order; JSON
manifest with an atomic rename flip, manifest-first rotation.
- Commit protocol: facts append+fsync BEFORE the commit point inside
the existing durability window, so a crash can only leave the log
AHEAD of committed truth — open() truncates back (torn tails detected
by CRC). Absent generation = never committed; a scan can never see an
uncommitted fact. transact() facts are durable-on-return; single-op
facts ride the group-commit flush exactly like buffered history. A
fact-append failure fails the write, loudly — a silent gap would be a
lie a later replay discovers.
- New public surface: brain.scanFacts() (sequential batches with heal
telemetry: head/segments/approx up front, per-batch generation range
+ bytes + segment id, loud abort on gaps, summary cross-check) and
brain.factSegmentPaths() (immutable sealed segments for zero-copy
consumers; the mutable tail excluded). Exported types CommitFact,
FactOp, FactScanBatch, FactScanHandle.
- Storage: optional binary raw-byte primitives (appendRawBytes,
readRawBytes, writeRawBytes, rawByteSize) on StorageAdapter —
feature-detected; filesystem + memory adapters implement them; an
adapter without them hosts no fact log. Fact segments are byte-copied
(never hard-linked) into snapshots. The _generations/facts/ namespace
is registered as a protected family (rebuildable: false): no sweeper
or GC may delete under it.
- New crc32c (Castagnoli) utility with RFC known-answer tests.
