P3-4 — SiteAlarmAggregatorActor pinned _openInFlight forever on a stream open
that produced none of its three peer-driven outcomes. SiteStreamGrpcClient gives
up on response headers after ConnectedHeaderTimeout (10s) and then treats the
first received EVENT as its fallback connected signal, so an alarm-only site
that stays quiet supplies neither — leaving _streamDown=true AND _openInFlight=
true, which makes OnReconcileTick's reopen guard (_streamDown && !_openInFlight)
skip every tick until the site's 4h max stream lifetime ends the call.
Fix: bound one open attempt with a generation-fenced single-shot deadline
(GrpcAlarmStreamOpenTimedOut, ctor-injected, production default 30s — above the
10s header timeout, below the 60s reconcile interval). Firing it releases the
flag and nothing else: no retry-budget spend, no node flip, no liveness
republish, and the abandoned subscription is left running so a merely-slow
connect still comes up normally. Self-healing rather than reachability analysis.
The deadline is cancelled on connect / error / graceful completion.
P3-5 — SiteStreamGrpcServer cancelled the incumbent stream on a duplicate
correlation id and only THEN checked the concurrency cap. Checking Count >= max
after the removal is right at exactly the cap but wrong above it, and above it
is reachable because the cap check is documented check-then-act: two subscribes
that both clear it before either registers overshoot by one. In that window a
routine reconnect killed a healthy stream AND was refused with
ResourceExhausted, leaving the correlation with ZERO streams until its next
retry.
Fix: claim the removal, consult the cap only for a genuinely NEW correlation id,
then cancel. A replacement is net-neutral on the count so it never consults the
cap; a refused new subscriber cancelled nothing (TryRemove found nothing), so
the incumbent survives. Newest-wins is unchanged — a fresh authenticated
subscribe still displaces a dead/wedged incumbent.
Tests (both shown failing against the unfixed code):
- OpenAttemptThatNeverResolves_ReleasesTheInFlightGuard_SoTheTickCanReopen —
fails (reopen never happens) with the deadline arming disabled.
- OpenDeadline_DoesNotFire_OnAStreamThatConnects_NorFlipNodeOrBurnBudget —
inertness lock on every healthy path.
- AtCapOvershoot_DuplicateReconnect_IsNotRefused_AndLeavesExactlyOneLiveStream —
fails with ResourceExhausted against the old ordering; the overshoot is driven
deterministically by parking both openers on the ServerCallContext token read,
which sits between the cap check and the _activeStreams insert.
- AtCap_AGenuinelyNewSubscriber_IsStillRefused_AndTheIncumbentSurvives.
The P3-4 test's doc comment carries the honesty note: the aggregator-side
starvation reproduces exactly, but how often the >10s header delay that gets you
there occurs in production is NOT demonstrated — the site flushes headers
explicitly as soon as its relay is attached, so the budget has to be consumed by
connect + handshake + server scheduling instead.
F1 (HIGH) DebugStreamBridgeActor: the 5-minute orphan net measured the MAILBOX
(SetReceiveTimeout), and once stream events were correctly marked
INotInfluenceReceiveTimeout nothing recurring reset it — the snapshot lands once
and GrpcStreamStable once — so every healthy session self-terminated at ~6 min
with a false "Site disconnected". Replaced with a periodic self-tick
(ConsumerLivenessCheckInterval, 30s) over a consumer-last-seen stamp renewed only
by DebugStreamConsumerAlive, which DebugStreamService Tells on a shared timer to
every session still in its registry (holding a session there IS "a consumer is
attached" — both the Blazor view and the SignalR hub release it on
dispose/disconnect, and it works headless). Reverting the wrapper was rejected: it
would restore the quiet-instance orphan bug.
F2 (MED) SiteStreamGrpcClient: the RpcException(Cancelled) filter now requires
cts.IsCancellationRequested. A peer-originated / channel-dispose Cancelled fired
none of onError/onCompleted/onConnected, leaving SiteAlarmAggregatorActor with
_streamDown=false forever (IsLive stuck true, reconcile reopen guard never fired).
F3 (MED) SiteStreamGrpcClient: a header TIMEOUT is no longer reported as
connected — that shape is exactly what an unreachable site produces, and it
cleared _streamDown, consumed _seedOnConnect and launched a full snapshot fan-out
at a dead site. AwaitHeadersAsync returns bool; the first received event is the
fallback connected signal, fired at most once from headers OR first event.
F4 (LOW-MED) SqliteAuditWriter.MarkReconciledUpToAsync: the blanket below-cursor
UPDATE retired late-stamped inserts that were never served (then age-purged —
silent loss). The flip is now bounded by insertion order: a Pending row retires
only if its rowid is at or below the high-water mark of rows this instance has
served from ReadPendingSinceAsync (clamped on purge, since SQLite reuses rowids);
Forwarded rows are exempt (central ACKed them over the push path). At-least-once
is unchanged.
F5 (LOW) Documented the liveness dependency (a served row never covered by a later
cursor stays Pending forever; PurgeExpiredAsync never purges Pending) in
ISiteAuditQueue + Component-AuditLog.md, and added a cheap site-health signal:
SiteAuditBacklogReporter logs a rate-limited warning when the existing
oldest-pending metric exceeds 24h.
F6 (MED) SiteAlarmAggregatorActor: _fanoutSinceLastTick was armed by the
reconcile's OWN fan-out, so steady state ran fan-out→skip→fan-out→skip — one
reconcile per 2x interval (120s), halving the not-reporting refresh and the alarm
reconcile backstop. The skip is now armed only by connect/failover-driven seeds
(initial, _seedOnConnect, and a re-seed queued behind one).
Tests: Communication.Tests 691 passed (+13), AuditLog.Tests 382 passed (+5).
Adds the active-central-node, in-memory, reference-counted per-site live alarm
cache backing the operator Alarm Summary page. No persisted central alarm store
([PERM]) — no EF entity/table/migration/DbSet.
- ISiteAlarmLiveCache (new): singleton seam — Subscribe(siteId, onChanged) ->
IDisposable (ref-counted, linger stop on last-out), GetCurrentAlarms, IsLive.
- SiteAlarmAggregatorActor (new): one per site. Seed-then-stream ordering copied
from DebugStreamBridgeActor — open the site-wide alarm-only gRPC stream first,
buffer live deltas while the snapshot fan-out runs, flush with per-key dedup
(AlarmKey = InstanceUniqueName|AlarmName|SourceReference), then live pass-through
into an in-memory dict. Placeholder rows seeded from the snapshot and never
expected on the stream; a real-alarm delta (distinct key) never wipes them.
NodeA<->NodeB reconnect (retry budget + stability window), reconnect re-seeds,
periodic reconcile (authoritative clear-and-rebuild) corrects instance-set drift,
and a budget-exhausted stream self-heals on the next reconcile tick.
- SiteAlarmLiveCacheService (new): DI singleton facade — viewer reference-counting,
linger-delayed last-out stop (version + TryRemove(ref) race guards), the
snapshot fan-out seed (RequestDebugSnapshotAsync per Enabled instance, capped),
bounded start-retry self-heal on transient start failure, and the immutable
published-snapshot store the page reads. Cache mutated only on the actor thread;
viewer callbacks invoked outside the lock.
- CommunicationOptions: LiveAlarmCacheLinger (30s), LiveAlarmCacheReconcileInterval
(60s), LiveAlarmCacheSeedConcurrency (8), LiveAlarmCacheMaxSubscribersPerSite
(200). Task 6 formalizes eager validation + telemetry.
- DI registration + AkkaHostedService SetActorSystem wiring on the active central node.
- Tests: 14 actor (seed/stream ordering, dedup, native-alarm parity, placeholder
coherence, reconnect re-seed, reconcile replace, self-heal, stop) + 6 service
(shared start, linger stop, resubscribe cancels stop, idempotent dispose, unknown
site, transient-start self-heal). Code-reviewer pass: no persistence, no Critical;
both Important findings addressed.
Claude-Session: https://claude.ai/code/session_01MtdgwpEeCUn6cUA5f1LMPj
Joseph Doherty