[Security Solution][Endpoint] Use a feature flag to use the new pending actions logic

x-pack/plugins/security_solution/common/experimental_features.ts

@@ -21,6 +21,7 @@ export const allowedExperimentalValues = Object.freeze({
   uebaEnabled: false,
   disableIsolationUIPendingStatuses: false,
   riskyHostsEnabled: false,
+  pendingActionResponsesWithAck: true,
 });
 
 type ExperimentalConfigKeys = Array<keyof ExperimentalFeatures>;

x-pack/plugins/security_solution/server/endpoint/routes/actions/status.ts

@@ -50,7 +50,8 @@ export const actionStatusRequestHandler = function (
     const response = await getPendingActionCounts(
       esClient,
       endpointContext.service.getEndpointMetadataService(),
-      agentIDs
+      agentIDs,
+      endpointContext.experimentalFeatures.pendingActionResponsesWithAck
     );
 
     return res.ok({

x-pack/plugins/security_solution/server/endpoint/services/actions.ts

@@ -186,7 +186,8 @@ export const getPendingActionCounts = async (
   esClient: ElasticsearchClient,
   metadataService: EndpointMetadataService,
   /** The Fleet Agent IDs to be checked */
-  agentIDs: string[]
+  agentIDs: string[],
+  isPendingActionResponsesWithAckEnabled: boolean
 ): Promise<EndpointPendingActions[]> => {
   // retrieve the unexpired actions for the given hosts
   const recentActions = await esClient
@@ -239,7 +240,8 @@ export const getPendingActionCounts = async (
     });
 
     const pendingActions: EndpointAction[] = recentActions.filter((action) => {
-      return ackResponseActionIdList.includes(action.action_id) // if has ack
+      return isPendingActionResponsesWithAckEnabled &&
+        ackResponseActionIdList.includes(action.action_id) // if has ack
         ? hasNoEndpointResponse({ action, agentId, indexedActionIds }) // then find responses in new index
         : hasNoFleetResponse({
             // else use the legacy way

x-pack/plugins/security_solution/server/search_strategy/security_solution/factory/hosts/details/helpers.ts

@@ -209,7 +209,8 @@ export const getHostEndpoint = async (
       ? getPendingActionCounts(
           esClient.asInternalUser,
           endpointContext.service.getEndpointMetadataService(),
-          [fleetAgentId]
+          [fleetAgentId],
+          endpointContext.experimentalFeatures.pendingActionResponsesWithAck
         )
           .then((results) => {
             return results[0].pending_actions;