docs(requirements): sync SiteRuntime + DCL specs with hardening changes (C3/C4/C5 + S1-S6, P2/P4/P6, UA1/UA4 behavior notes)

docs/requirements/Component-DataConnectionLayer.md

@@ -255,6 +255,7 @@ The `DataConnectionActor` opens **one alarm feed per connection** (not per subsc
 - **State gating**: `SubscribeAlarmsRequest` is handled only in the **Connected** state; requests arriving while **Connecting**/**Reconnecting** are stashed (standard Become/Stash) and processed on entering Connected.
 - **Capability check**: if `_adapter is not IAlarmSubscribableConnection`, the actor replies `SubscribeAlarmsResponse(Success = false, ...)`.
 - **Reconnect handling**: on entering **Reconnecting**, the actor pushes a `NativeAlarmSourceUnavailable` to every alarm subscriber (consumers mark mirrored alarms uncertain rather than clearing them). On successful reconnection it re-subscribes the feed; the adapter re-emits a snapshot, reconciling state.
+- **Shared condition filter (last-subscriber-wins)**: because the feed is opened once per source, it carries a single condition filter. A second subscriber that registers a *different* filter for the same source overwrites it (last writer wins) and the actor logs a warning — co-subscribers to one source are expected to agree on the filter.
 
 ### Protocol-Neutral Types & Messages
 
@@ -299,10 +300,11 @@ This pattern ensures no messages are lost during connection transitions and is t
 
 The DCL manages connection lifecycle automatically:
 
-1. **Connection drop detection**: When a connection to a data source is lost, the DCL immediately pushes a value update with quality `bad` for **every tag subscribed on that connection**. Instance Actors and their downstream consumers (alarms, scripts checking quality) see the staleness immediately.
-2. **Auto-reconnect with fixed interval**: The DCL retries the connection at a configurable fixed interval (e.g., every 5 seconds). The retry interval is defined **per data connection**. This is consistent with the fixed-interval retry philosophy used throughout the system. Individual gRPC/OPC UA operations (reads, writes) fail immediately to the caller on error; there is no operation-level retry within the adapter.
+1. **Connection drop detection**: When a connection to a data source is lost, the DCL immediately pushes a value update with quality `bad` for **every tag subscribed on that connection**. Instance Actors see the staleness immediately and publish it to the site stream / debug view; **script and alarm actors are deliberately NOT re-notified on a quality-only change** (no value changed — re-evaluating triggers would cause spurious firings). Scripts observe quality on their next attribute read; a computed alarm holds its last-known state until fresh values arrive.
+2. **Auto-reconnect with fixed interval**: The DCL retries the connection at a configurable fixed interval (e.g., every 5 seconds). The retry interval is a **shared setting for all data connections** (`ReconnectInterval` in the Shared Settings table). This is consistent with the fixed-interval retry philosophy used throughout the system. Individual gRPC/OPC UA operations (reads, writes) fail immediately to the caller on error; there is no operation-level retry within the adapter.
 3. **Connection state transitions**: The DCL tracks each connection's state as `connected`, `disconnected`, or `reconnecting`. All transitions are logged to Site Event Logging.
 4. **Transparent re-subscribe**: On successful reconnection, the DCL automatically re-establishes all previously active subscriptions for that connection. Instance Actors require no action — they simply see quality return to `good` as fresh values arrive from restored subscriptions.
+5. **Clean client replacement on (re)connect**: On every (re)connect the adapter detaches and disposes the previous protocol client (session, keep-alive timers, event loop) before creating a new one — a stale client can neither leak nor signal a disconnect against the new session.
 
 ### Disconnect Detection Pattern