diff --git a/x-pack/packages/ml/response_stream/server/index.ts b/x-pack/packages/ml/response_stream/server/index.ts
index 2beb7223026174..ae337aa99898f2 100644
--- a/x-pack/packages/ml/response_stream/server/index.ts
+++ b/x-pack/packages/ml/response_stream/server/index.ts
@@ -8,5 +8,6 @@
 export {
   streamFactory,
   type StreamFactoryReturnType,
+  type StreamResponseWithHeaders,
   type UncompressedResponseStream,
 } from './stream_factory';
diff --git a/x-pack/packages/ml/response_stream/server/stream_factory.ts b/x-pack/packages/ml/response_stream/server/stream_factory.ts
index 79895525ba40ce..779e3457c7dac3 100644
--- a/x-pack/packages/ml/response_stream/server/stream_factory.ts
+++ b/x-pack/packages/ml/response_stream/server/stream_factory.ts
@@ -33,15 +33,16 @@ type StreamType<T extends StreamTypeUnion> = T extends string
   ? T
   : never;
 
-// Fallback to never is there for backwards compatibility.
-export interface StreamFactoryReturnType<T extends StreamTypeUnion = never> {
+export interface StreamResponseWithHeaders {
+  body: zlib.Gzip | UncompressedResponseStream;
+  headers?: ResponseHeaders;
+}
+
+export interface StreamFactoryReturnType<T extends StreamTypeUnion> {
   DELIMITER: string;
   end: () => void;
   push: (d: StreamType<T>, drain?: boolean) => void;
-  responseWithHeaders: {
-    body: zlib.Gzip | UncompressedResponseStream;
-    headers?: ResponseHeaders;
-  };
+  responseWithHeaders: StreamResponseWithHeaders;
 }
 
 /**
@@ -133,7 +134,7 @@ export function streamFactory<T extends StreamTypeUnion>(
         function repeat() {
           if (!tryToEnd) {
             if (responseSizeSinceLastKeepAlive < FLUSH_PAYLOAD_SIZE) {
-              push({ flushPayload, type: 'flushPayload' } as unknown as StreamType<T>);
+              push({ flushPayload, type: 'flushPayload' } as StreamType<T>);
             }
             responseSizeSinceLastKeepAlive = 0;
             setTimeout(repeat, FLUSH_KEEP_ALIVE_INTERVAL_MS);
@@ -211,7 +212,7 @@ export function streamFactory<T extends StreamTypeUnion>(
     }
   }
 
-  const responseWithHeaders: StreamFactoryReturnType<T>['responseWithHeaders'] = {
+  const responseWithHeaders: StreamResponseWithHeaders = {
     body: stream,
     headers: {
       ...(isCompressed ? { 'content-encoding': 'gzip' } : {}),
diff --git a/x-pack/plugins/elastic_assistant/server/lib/langchain/executors/types.ts b/x-pack/plugins/elastic_assistant/server/lib/langchain/executors/types.ts
index 0e7925df202811..ce2833fa144804 100644
--- a/x-pack/plugins/elastic_assistant/server/lib/langchain/executors/types.ts
+++ b/x-pack/plugins/elastic_assistant/server/lib/langchain/executors/types.ts
@@ -13,7 +13,7 @@ import { KibanaRequest, ResponseHeaders } from '@kbn/core-http-server';
 import type { LangChainTracer } from '@langchain/core/tracers/tracer_langchain';
 import type { AnalyticsServiceSetup } from '@kbn/core-analytics-server';
 import { ExecuteConnectorRequestBody, Message, Replacements } from '@kbn/elastic-assistant-common';
-import { StreamFactoryReturnType } from '@kbn/ml-response-stream/server';
+import { StreamResponseWithHeaders } from '@kbn/ml-response-stream/server';
 import { AnonymizationFieldResponse } from '@kbn/elastic-assistant-common/impl/schemas/anonymization_fields/bulk_crud_anonymization_fields_route.gen';
 import { ResponseBody } from '../types';
 import type { AssistantTool } from '../../../types';
@@ -51,7 +51,7 @@ export interface StaticReturnType {
   headers: ResponseHeaders;
 }
 export type AgentExecutorResponse<T extends boolean> = T extends true
-  ? StreamFactoryReturnType['responseWithHeaders']
+  ? StreamResponseWithHeaders
   : StaticReturnType;
 
 export type AgentExecutor<T extends boolean> = (
diff --git a/x-pack/plugins/elastic_assistant/server/routes/post_actions_connector_execute.ts b/x-pack/plugins/elastic_assistant/server/routes/post_actions_connector_execute.ts
index e579996eb13d19..e76b7cd3377835 100644
--- a/x-pack/plugins/elastic_assistant/server/routes/post_actions_connector_execute.ts
+++ b/x-pack/plugins/elastic_assistant/server/routes/post_actions_connector_execute.ts
@@ -8,7 +8,7 @@
 import { IRouter, Logger } from '@kbn/core/server';
 import { transformError } from '@kbn/securitysolution-es-utils';
 import { getRequestAbortedSignal } from '@kbn/data-plugin/server';
-import { StreamFactoryReturnType } from '@kbn/ml-response-stream/server';
+import { StreamResponseWithHeaders } from '@kbn/ml-response-stream/server';
 
 import { schema } from '@kbn/config-schema';
 import {
@@ -323,42 +323,41 @@ export const postActionsConnectorExecuteRoute = (
               page: 1,
             });
 
-          const result: StreamFactoryReturnType['responseWithHeaders'] | StaticReturnType =
-            await callAgentExecutor({
-              abortSignal,
-              alertsIndexPattern: request.body.alertsIndexPattern,
-              anonymizationFields: anonymizationFieldsRes
-                ? transformESSearchToAnonymizationFields(anonymizationFieldsRes.data)
-                : undefined,
-              actions,
-              isEnabledKnowledgeBase: request.body.isEnabledKnowledgeBase ?? false,
-              assistantTools,
-              connectorId,
-              elserId,
-              esClient,
-              isStream:
-                // TODO implement llmClass for bedrock streaming
-                // tracked here: https://github.com/elastic/security-team/issues/7363
-                request.body.subAction !== 'invokeAI' && actionTypeId === '.gen-ai',
-              llmType: getLlmType(actionTypeId),
-              kbResource: ESQL_RESOURCE,
-              langChainMessages,
-              logger,
-              onNewReplacements,
-              onLlmResponse,
-              request,
-              replacements: request.body.replacements,
-              size: request.body.size,
-              telemetry,
-              traceOptions: {
+          const result: StreamResponseWithHeaders | StaticReturnType = await callAgentExecutor({
+            abortSignal,
+            alertsIndexPattern: request.body.alertsIndexPattern,
+            anonymizationFields: anonymizationFieldsRes
+              ? transformESSearchToAnonymizationFields(anonymizationFieldsRes.data)
+              : undefined,
+            actions,
+            isEnabledKnowledgeBase: request.body.isEnabledKnowledgeBase ?? false,
+            assistantTools,
+            connectorId,
+            elserId,
+            esClient,
+            isStream:
+              // TODO implement llmClass for bedrock streaming
+              // tracked here: https://github.com/elastic/security-team/issues/7363
+              request.body.subAction !== 'invokeAI' && actionTypeId === '.gen-ai',
+            llmType: getLlmType(actionTypeId),
+            kbResource: ESQL_RESOURCE,
+            langChainMessages,
+            logger,
+            onNewReplacements,
+            onLlmResponse,
+            request,
+            replacements: request.body.replacements,
+            size: request.body.size,
+            telemetry,
+            traceOptions: {
+              projectName: langSmithProject,
+              tracers: getLangSmithTracer({
+                apiKey: langSmithApiKey,
                 projectName: langSmithProject,
-                tracers: getLangSmithTracer({
-                  apiKey: langSmithApiKey,
-                  projectName: langSmithProject,
-                  logger,
-                }),
-              },
-            });
+                logger,
+              }),
+            },
+          });
 
           telemetry.reportEvent(INVOKE_ASSISTANT_SUCCESS_EVENT.eventType, {
             actionTypeId,
@@ -371,9 +370,7 @@ export const postActionsConnectorExecuteRoute = (
               request.body.subAction !== 'invokeAI' && actionTypeId === '.gen-ai',
           });
 
-          return response.ok<
-            StreamFactoryReturnType['responseWithHeaders']['body'] | StaticReturnType['body']
-          >(result);
+          return response.ok<StreamResponseWithHeaders['body'] | StaticReturnType['body']>(result);
         } catch (err) {
           logger.error(err);
           const error = transformError(err);