feat(localdb): alarm S&F on LocalDb with primary-gated drain (cutover)

Moves the alarm store-and-forward buffer out of its own alarm-historian.db
and into the node's consolidated LocalDb, where it replicates to the
redundant pair peer. A node that dies holding undelivered alarm history no
longer takes it to the grave.

Tasks 2 and 3 land together, as the plan anticipated. They are not separable:
the gate is a constructor argument of the rewritten sink, and a commit that
replicated the queue without gating the drain would be a commit in which both
nodes of a pair deliver every alarm event, continuously.

That drain gate is the load-bearing part of the change, and the recon
explains why it is new work rather than a refinement. Exactly-once delivery
across a pair is enforced today on the ENQUEUE side, by
HistorianAdapterActor: only the Primary enqueues, so the Secondary's queue is
empty and its ungated drain has nothing to send. Replicating the table
destroys that invariant.

The gate is a Func<bool> the caller supplies, because the drain runs on a
timer the sink owns rather than on a mailbox, and Core.AlarmHistorian cannot
reference PrimaryGatePolicy in Runtime. Runtime supplies it via a new
IRedundancyRoleView singleton that DriverHostActor publishes its Primary-gate
verdict to -- the same verdict the inbound-write and native-ack gates use, so
there is no second notion of am-I-the-Primary to drift.

Two failure modes are deliberately closed:

- The view is seeded OPEN, matching the policy's own answer for an unknown
  role with no driver peer. A deployment that runs no redundancy never
  publishes to it, and defaulting closed would silently stop its alarm
  history forever.

- A gate that throws is read as not-now, never as permission, and a closed
  gate reports the new HistorianDrainState.NotPrimary rather than Idle. A
  Secondary's rising queue is supposed to look different from a stalled
  drain, and if BOTH nodes report NotPrimary the pair is misconfigured and
  says so instead of quietly filling toward the capacity ceiling.

Row ids are a hash of the payload rather than fresh GUIDs. Both adapters
accept the same fanned transition in the window before the first redundancy
snapshot arrives, and under last-writer-wins an equal key converges those two
accepts into one row instead of duplicating them.

Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
This commit is contained in:
Joseph Doherty
2026-07-21 04:13:00 -04:00
parent 8a9cb40a72
commit 71379816e7
14 changed files with 804 additions and 365 deletions
@@ -19,18 +19,20 @@
{
"id": 2,
"subject": "Task 2: Rewire sink onto ILocalDb + delete bespoke file management (cutover 1/2)",
"status": "pending",
"status": "completed",
"blockedBy": [
1
]
],
"note": "Sink rewritten as LocalDbStoreAndForwardSink over ILocalDb; bespoke file/pragma/schema management deleted with the old class. AlarmHistorian:DatabasePath removed (breaking config key). Ids are a deterministic payload hash (D-1), not GUIDs."
},
{
"id": 3,
"subject": "Task 3: Primary-gated drain via PrimaryGatePolicy (cutover 2/2 \u2014 may co-commit with Task 2)",
"status": "pending",
"status": "completed",
"blockedBy": [
2
]
],
"note": "Drain gated on IRedundancyRoleView, a singleton DriverHostActor publishes PrimaryGatePolicy's verdict to on every snapshot. Fails closed on a throwing gate; seeded OPEN so a non-redundant deployment is never silently stopped. New HistorianDrainState.NotPrimary + transition-logged (D-2). Landed with Task 2 as one commit (D-3)."
},
{
"id": 4,