Python client: port stream-alarms and acknowledge-alarm

Adds the session-less alarm CLI subcommands to mxgw-py. stream-alarms reads a
bounded slice of the gateway's central alarm feed (--filter-prefix,
--max-messages, --timeout, --json; aggregate `{messages: [...]}`);
acknowledge-alarm is a unary ack (--reference required, --comment, --operator).
GatewayClient.stream_alarms joins query_active_alarms via a
_canceling_alarm_feed_iterator helper mirroring the existing
_canceling_active_alarms_iterator pattern.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

clients/python/src/zb_mom_ww_mxgateway/client.py

@@ -172,6 +172,28 @@ class GatewayClient:
         call = self.raw_stub.QueryActiveAlarms(request, **kwargs)
         return _canceling_active_alarms_iterator(call)
 
+    def stream_alarms(
+        self,
+        request: pb.StreamAlarmsRequest,
+        *,
+        metadata: Sequence[tuple[str, str]] | None = None,
+    ) -> AsyncIterator[pb.AlarmFeedMessage]:
+        """Attach to the gateway's central alarm feed.
+
+        The stream opens with one ``AlarmFeedMessage`` per currently-active
+        alarm (the ConditionRefresh snapshot), then a single
+        ``snapshot_complete``, then a ``transition`` for every subsequent
+        raise / acknowledge / clear. Served by the gateway's always-on alarm
+        monitor — no worker session is opened — so any number of clients may
+        attach. Optionally scoped by alarm-reference prefix
+        (``request.alarm_filter_prefix``).
+        """
+        kwargs: dict[str, Any] = {"metadata": merge_metadata(self.options.api_key, metadata)}
+        if self.options.stream_timeout is not None:
+            kwargs["timeout"] = self.options.stream_timeout
+        call = self.raw_stub.StreamAlarms(request, **kwargs)
+        return _canceling_alarm_feed_iterator(call)
+
     async def _unary(
         self,
         operation: str,
@@ -223,3 +245,15 @@ async def _canceling_active_alarms_iterator(call: Any) -> AsyncIterator[pb.Activ
         cancel = getattr(call, "cancel", None)
         if cancel is not None:
             cancel()
+
+
+async def _canceling_alarm_feed_iterator(call: Any) -> AsyncIterator[pb.AlarmFeedMessage]:
+    try:
+        async for message in call:
+            yield message
+    except grpc.RpcError as error:
+        raise map_rpc_error("stream alarms", error) from error
+    finally:
+        cancel = getattr(call, "cancel", None)
+        if cancel is not None:
+            cancel()