Task 2 of the Phase 2 plan, plus the clean re-run of Task 1's cut-short
sampling that Task 2 was waiting on.
Gate doc: status NOT STARTED -> CLOSED. All five §5 open questions answered
inline. The questions are kept, not deleted — several of the answers overturn
a premise the gate itself stated, and that reasoning is the value:
- Oplog sizing is not the binding constraint. Cap overrun prunes and flags
needs_snapshot (graceful resync), so the caps need no defensive sizing; the
real ceiling is D6's 4 MB gRPC cap, binding on MaxBatchSize x row-bytes.
- LWW-vs-in-flight-send cannot arise on a correct pair (only the active node
sweeps). The honest cost is D2's semantic change: the standby is convergent,
no longer byte-identical.
- Migration-under-load is designed out, not managed — both mechanisms are
deleted in the same commit and D5 forecloses rolling upgrades.
- Rollback is genuinely "revert the commit": the migration is additive and
leaves the legacy files intact. Bounded cost is the post-cutover delta.
- One DB per process stays; every write axis is bounded.
§2's requirement to state CDC's duplicate-delivery bound is routed explicitly
to Task 21 rather than left implicit.
Task 1 re-run (safe copy-based snap(), both nodes restarted first, six 60s
intervals): sf_messages 0.80 rows/sec insert, 0/sec retry-UPDATE, oplog 0,
alarms 0, max payload_json 76 B, zero SQLite errors across 30 min, both site-a
nodes converged at 3564 rows. Independently confirms the disk-I/O storm was
observer-induced. Recorded with its limits stated: 0.80/s is ~1.6% of the 50/s
ceiling and the retry path was never exercised — acceptable only because that
ceiling is structural rather than empirical, and the rig's 721 B config rows
are explicitly NOT representative.
GATE VERDICT: PROCEED to Task 3. Binding output is MaxBatchSize 500 -> 16.
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
The Phase 2 soak's "LocalDb fails under load" blocker is NOT a product defect.
Root cause: host-side (macOS) sqlite3 reads of the live, bind-mounted WAL
databases. POSIX advisory locks do not propagate across the virtiofs boundary,
so the host reader believes it is the only connection, checkpoints on close and
resets the WAL to 0 bytes under the container. The container's still-mapped
WAL index then references frames that no longer exist and every subsequent
statement fails SQLITE_IOERR_SHORT_READ (522) -> primary code 10, permanently
until the process reopens the database.
Reproduced on demand both on the rig (one sqlite3 SELECT reset a 4.6 MiB WAL and
produced the first error one second later) and in a minimal python:3.12-alpine
repro with no LocalDb or .NET involved. Refuted the converse: a freshly-reopened
node sustained the full soak load 10+ minutes with zero errors.
The original brief's isolation was confounded - both nodes had been poisoned by
the same sampling pass, and a poisoned standby looks healthy only because it
issues almost no statements. Corrections annotated in place.
Hardening shipped alongside:
- SqliteErrorCodes.Describe: log SQLite primary AND extended codes at the
LocalDb-adjacent catch sites (the missing extended code is what made the
original diagnosis so slow).
- SiteAuditTelemetryActor: stop touching ActorContext across an await
(NotSupportedException), with regression coverage.
- infra/reseed.sh: apply the MSSQL init scripts explicitly. The official
mssql/server image does not implement /docker-entrypoint-initdb.d, so a fresh
volume hung the reseed forever; compose mounts annotated as informational.
Deliberately NOT done: detect-and-reopen self-heal in SqliteLocalDb. It defends
only against external interference, which is now prevented at the source, and
same-kernel production readers see the locks correctly.
Build 0 warnings; SiteAuditTelemetryActorTests 9/9, SiteEventLogging 70/70.
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
Task 1 of the Phase 2 plan. The gate stops the plan, but not for the reason it
anticipated: oplog sizing is fine and D6 is resolved.
BLOCKER: the Phase 1 consolidated LocalDb (site-localdb.db) throws SQLite
Error 10 'disk I/O error' on essentially every write on the ACTIVE node under
sustained load — site_events, OperationTracking and the audit telemetry paths
all fail, and site event logging silently drops events. Isolated to the load
(not the node, not host-side observation) by failing over between nodes, and to
LocalDb specifically (legacy store-and-forward.db / scadabridge.db in the same
bind-mounted directory take zero errors under identical load).
Phase 2 would register 8 more tables into that database — including the two
highest-volume ones — while deleting the bespoke mechanisms that currently
carry them. Must be root-caused first.
Also recorded: D6's premise corrected (largest known production config_json is
~60-70 KB, not >128 KB — but MaxBatchSize 500 is still unsafe, use 16); D4's
premise corrected (alarm writes are bounded by per-SourceReference coalescing at
a 100 ms flush); sf_messages has a hard 50 rows/sec structural ceiling; and
exceeding the oplog caps is a graceful snapshot-resync, not a failure.
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
Joseph Doherty