diff --git a/docs/AlarmHistorian.md b/docs/AlarmHistorian.md
index d437a2f4..164a6b16 100644
--- a/docs/AlarmHistorian.md
+++ b/docs/AlarmHistorian.md
@@ -145,13 +145,53 @@ fresh backoff.
 
 ## Runtime wiring
 
-Production routes alarm transitions through the Akka cluster. The
 `HistorianAdapterActor`
 ([`Runtime/Historian/HistorianAdapterActor.cs`](../src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/HistorianAdapterActor.cs))
-bridges messages from the scripted-alarm actor into the sink's `EnqueueAsync`,
-fire-and-forget so the actor loop is never blocked on historian reachability.
-The `WonderwareHistorianClient` is the `IAlarmHistorianWriter` the drain worker
-delegates to. See [ServiceHosting.md](ServiceHosting.md) for the sidecar setup.
+subscribes to the cluster **`alerts` DPS topic** and translates each
+`AlarmTransitionEvent` into an `AlarmHistorianEvent`, then calls
+`IAlarmHistorianSink.EnqueueAsync` fire-and-forget so the actor loop is never
+blocked on historian reachability. The actor is **Primary-gated**: only the
+node whose `RedundancyRole` is `Primary` historizes, giving exactly-once
+writes across a redundant pair. `AlarmTransitionEvent` carries `AlarmTypeName`
+(the Part 9 subtype string) and `Comment` (the operator comment from the
+originating ack/shelve command) that populate the corresponding fields of
+`AlarmHistorianEvent`. `WonderwareHistorianClient` is the `IAlarmHistorianWriter`
+the drain worker delegates to. See [ServiceHosting.md](ServiceHosting.md) for
+the sidecar setup.
+
+**Scope:** scripted alarms only. Galaxy-native alarms historize via System
+Platform's `HistorizeToAveva` toggle (not this actor); AB CIP ALMD is not on
+the `alerts` topic (future).
+
+## Configuration
+
+The real sink is opt-in via the `AlarmHistorian` section of `appsettings.json`.
+When `Enabled` is `false` (the default), `AddAlarmHistorian` registers
+`NullAlarmHistorianSink` and the feature is dormant. When `Enabled` is `true`,
+`AddAlarmHistorian` constructs `SqliteStoreAndForwardSink` and registers
+`WonderwareHistorianClient` as the `IAlarmHistorianWriter`.
+
+```json
+{
+  "AlarmHistorian": {
+    "Enabled": true,
+    "DatabasePath": "C:\\ProgramData\\OtOpcUa\\alarmhistorian.db",
+    "PipeName": "\\\\.\\pipe\\wonderware-historian",
+    "SharedSecret": "<token from historian sidecar config>",
+    "BatchSize": 100
+  }
+}
+```
+
+| Key | Type | Default | Description |
+|---|---|---|---|
+| `Enabled` | bool | `false` | Enable the real SQLite + Wonderware sink. `false` → `NullAlarmHistorianSink`. |
+| `DatabasePath` | string | — | Absolute path to the SQLite queue file. Created on first use (WAL mode). Required when `Enabled`. |
+| `PipeName` | string | — | Named-pipe path for the Wonderware Historian sidecar IPC channel. Required when `Enabled`. |
+| `SharedSecret` | string | — | Shared secret token the sidecar expects on every connection. Required when `Enabled`. |
+| `BatchSize` | int | `100` | Max rows per drain cycle handed to `IAlarmHistorianWriter.WriteBatchAsync`. |
+
+> Dev and docker-dev deployments leave `Enabled` unset (defaults to `false`) so alarm transitions historize to nowhere unless a historian sidecar is present.
 
 ---
 
diff --git a/docs/AlarmTracking.md b/docs/AlarmTracking.md
index 7c8731b6..53e392f6 100644
--- a/docs/AlarmTracking.md
+++ b/docs/AlarmTracking.md
@@ -178,9 +178,12 @@ AB CIP ALMD) route to AVEVA Historian via the Wonderware sidecar:
   silent data loss without log scraping.
 - `HistorianAdapterActor`
   (`src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Historian/HistorianAdapterActor.cs`)
-  bridges Akka cluster messages from `ScriptedAlarmActor` into the
-  sink's `EnqueueAsync`; fire-and-forget so the actor loop is never
-  blocked on historian reachability.
+  subscribes to the cluster `alerts` DPS topic, translates each
+  `AlarmTransitionEvent` → `AlarmHistorianEvent`, and calls
+  `EnqueueAsync` fire-and-forget. Primary-gated — only the Primary node
+  historizes, giving exactly-once writes across a redundant pair. See
+  [AlarmHistorian.md §Configuration](AlarmHistorian.md#configuration)
+  for the `AlarmHistorian` appsettings section that enables the real sink.
 
 Galaxy-native alarms with `$Alarm*` extensions reach AVEVA Historian
 directly via System Platform's `HistorizeToAveva` toggle on the
diff --git a/docs/Redundancy.md b/docs/Redundancy.md
index e27e9a23..69ccf39f 100644
--- a/docs/Redundancy.md
+++ b/docs/Redundancy.md
@@ -140,7 +140,7 @@ There is no operator-driven role swap during a partition. Failover is what the c
 Under warm/hot redundancy both cluster nodes run `ScriptedAlarmHostActor` and evaluate scripted alarms, keeping each node's address space and engine state warm for instant failover. However, to avoid duplicate rows on `/alerts` and duplicate historian writes, only the Primary node publishes externally:
 
 - **`alerts` topic emission** — `ScriptedAlarmHostActor` subscribes to the `redundancy-state` DPS topic and caches the local node's `RedundancyRole`. Each alarm transition is published to the cluster `alerts` topic **only when the node's role is `Primary`**. The default behaviour before any `redundancy-state` message arrives is to emit, so single-node deployments and the boot window never drop transitions. The OPC UA condition-node write and inbound ack/shelve command processing remain **ungated** on both nodes so the secondary is always ready to serve clients after a failover.
-- **`HistorianAdapterActor` historization** — likewise Primary-gated so alarm historization is exactly-once across all alarm sources. (This actor currently has no production feeder; the gate is a forward-looking guard.)
+- **`HistorianAdapterActor` historization** — likewise Primary-gated so alarm historization is exactly-once across all alarm sources. The actor subscribes to the `alerts` DPS topic and translates each `AlarmTransitionEvent` → `AlarmHistorianEvent` before enqueuing it on the sink; scripted alarms therefore historize exactly once regardless of cluster size.
 
 Net effect: each alarm transition appears **once** on `/alerts` and would historize once, not once per node.