Two-node keep-oldest could NEVER survive a crash of the oldest/active node:
Akka.NET 1.5.62 KeepOldest.OldestDecision only lets down-if-alone rescue a
side with >= 2 members, so the 1-vs-1 survivor takes DownReachable and downs
ITSELF — proven live on the rig ('SBR took decision ... including myself')
before this change. static-quorum(1) is worse (IsTooManyMembers -> DownAll);
keep-majority just re-keys the fatal crash to the lowest address.
SplitBrainResolverStrategy gains 'auto-down' (new default): BuildHocon emits
Akka's AutoDowning provider with auto-down-unreachable-after = StableAfter.
The leader among the REACHABLE members downs the unreachable peer, so the
survivor takes over singletons and /health/active in ~25s regardless of which
node died. Accepted trade (explicit owner decision): a real network partition
runs dual-active until an operator restarts one side. keep-oldest remains
supported; DownIfAlone validation is now scoped to it.
Live drill on the rebuilt rig: active-crash TAKEOVER in 28s (victim still
down; all 7 singletons Younger->Oldest), standby-crash removal 27s with 0
routing blips; victims rejoin as standby in 2s. New real-cluster tests pin
both directions (SbrFailoverTests.AutoDown_*); TwoNodeClusterFixture gains a
strategy knob. All 16 appsettings flipped (src, docker, docker-env2, and the
gitignored wonder-app-vd03 overlay on disk — owner must sync to the host).
Docs: decision record docs/plans/2026-07-21-auto-down-availability-decision.md,
Component-ClusterInfrastructure downing section rewritten, drill + README
reworked (active mode now asserts takeover), deferred-work SBR row resolved.
LocalDb Phase 2 deleted the bespoke replicators, so three config keys changed
meaning or died outright:
- ScadaBridge:StoreAndForward:ReplicationEnabled is fully dead. Deleted the
property, its 10 config entries, and the 5 test references.
- SqliteDbPath / SiteDbPath are now migration-only: they name the legacy files
SiteLocalDbLegacyMigrator drains at boot, not live databases. Both mandatory
rules are relaxed accordingly (StartupValidator's Site-only Require, and the
S&F validator's non-empty rule) — an absent value now means "nothing to
migrate", so an already-migrated node can drop the key. DatabaseOptions-
Validator still rejects a present-but-blank value.
- SiteRuntime:ConfigFetchRetryCount's only reader was SiteReplicationActor.
Deleted with its validator rule.
The two path keys stay present in every config, now with a comment explaining
why: removing them would strand un-migrated data on a node that has not yet
started once.
Both relaxations are pinned by the inverse of the test they replace
(Site_MissingSiteDbPath_IsAccepted..., EmptySqliteDbPath_IsAccepted...), each
verified to fail with the old rule restored.
Note: deploy/wonder-app-vd03/appsettings.Site.json is under a gitignored
deploy/ tree, so its edit is local-only and must be repeated on the box.
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
Task 3. Site nodes now open one ZB.MOM.WW.LocalDb-managed database holding
OperationTracking and site_events as replicated tables.
SiteLocalDbSetup.OnReady applies both schemas and then RegisterReplicated's them.
That order is load-bearing and easy to get silently wrong: capture is
trigger-based CDC, so rows written before registration are never captured or
snapshotted - they would be invisible to the peer forever, with no error anywhere.
Storage ships UNCONDITIONALLY, no feature flag. With no peer configured LocalDb is
just a local SQLite file, so this is behaviour-equivalent to what site nodes do
today. Replication is opt-in and lands in Program.cs (Task 7), which owns the gRPC
host the sync endpoint needs.
Config: LocalDb:Path added to all EIGHT site-node appsettings (the plan said six -
docker-env2's site-x pair exists too), plus the dev template and the wonder-app-vd03
production sample. All ten are required, not optional: LocalDbOptions.Path is
validated with ValidateOnStart, so a site node without it fails fast at startup.
That is the desired posture, and it is what caught ActorPathTests - the one Host
fixture that actually starts a host - whose config now sets the path too.
Note the path choice fixes an existing data-loss bug in passing: site-tracking.db
and site_events.db both defaulted to CWD-relative paths (/app/...), outside the
mounted volume, so they were silently lost on every container recreate. The
consolidated database lives on /app/data.
Tests are container-built against the REAL SiteServiceRegistration.Configure, not a
hand-assembled ServiceCollection - this family has shipped three wiring defects that
only a real graph would catch (inert Secrets replicator 0.2.0, singleton deadlock
0.2.2, Secrets.Ui missing IAuditWriter). They assert the library's own view of what
is registered rather than that we called the right method.
Verified (all after the change):
dotnet build ZB.MOM.WW.ScadaBridge.slnx -> 0 Error(s), 0 Warning(s)
Host.Tests -> 294 passed (5 new, red-first)
SiteRuntime.Tests -> 530 passed
CentralUI.Tests -> 925 passed
Commons.Tests -> 684 passed
Communication.Tests -> 312 passed
SiteEventLogging.Tests-> 70 passed
Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
Joseph Doherty