fix: Resolve event delivery configuration header passing between frontend and backend (#7514)

Co-authored-by: Gabriel Luiz Freitas Almeida <gabriel@langflow.org>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>

src/backend/base/langflow/api/build.py

@@ -13,6 +13,7 @@ from sqlmodel import select
 from langflow.api.disconnect import DisconnectHandlerStreamingResponse
 from langflow.api.utils import (
     CurrentActiveUser,
+    EventDeliveryType,
     build_graph_from_data,
     build_graph_from_db,
     format_elapsed_time,
@@ -84,12 +85,12 @@ async def get_flow_events_response(
     *,
     job_id: str,
     queue_service: JobQueueService,
-    stream: bool = True,
+    event_delivery: EventDeliveryType,
 ):
     """Get events for a specific build job, either as a stream or single event."""
     try:
         main_queue, event_manager, event_task, _ = queue_service.get_queue_data(job_id)
-        if stream:
+        if event_delivery in (EventDeliveryType.STREAMING, EventDeliveryType.DIRECT):
             if event_task is None:
                 logger.error(f"No event task found for job {job_id}")
                 raise HTTPException(status_code=404, detail="No event task found for job")

src/backend/base/langflow/api/utils.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import uuid
 from datetime import timedelta
+from enum import Enum
 from typing import TYPE_CHECKING, Annotated, Any
 
 from fastapi import Depends, HTTPException, Query
@@ -34,6 +35,12 @@ CurrentActiveUser = Annotated[User, Depends(get_current_active_user)]
 DbSession = Annotated[AsyncSession, Depends(get_session)]
 
 
+class EventDeliveryType(str, Enum):
+    STREAMING = "streaming"
+    DIRECT = "direct"
+    POLLING = "polling"
+
+
 def has_api_terms(word: str):
     return "api" in word and ("key" in word or ("token" in word and "tokens" not in word))
 

src/backend/base/langflow/api/v1/chat.py

@@ -27,6 +27,7 @@ from langflow.api.limited_background_tasks import LimitVertexBuildBackgroundTask
 from langflow.api.utils import (
     CurrentActiveUser,
     DbSession,
+    EventDeliveryType,
     build_and_cache_graph_from_data,
     build_graph_from_db,
     format_elapsed_time,
@@ -55,12 +56,10 @@ from langflow.services.deps import (
     get_chat_service,
     get_queue_service,
     get_session,
-    get_settings_service,
     get_telemetry_service,
     session_scope,
 )
 from langflow.services.job_queue.service import JobQueueNotFoundError, JobQueueService
-from langflow.services.settings.service import SettingsService
 from langflow.services.telemetry.schema import ComponentPayload, PlaygroundPayload
 
 if TYPE_CHECKING:
@@ -154,7 +153,7 @@ async def build_flow(
     current_user: CurrentActiveUser,
     queue_service: Annotated[JobQueueService, Depends(get_queue_service)],
     flow_name: str | None = None,
-    settings_service: Annotated[SettingsService, Depends(get_settings_service)],
+    event_delivery: EventDeliveryType = EventDeliveryType.POLLING,
 ):
     """Build and process a flow, returning a job ID for event polling.
 
@@ -174,6 +173,7 @@ async def build_flow(
         queue_service: Queue service for job management
         flow_name: Optional name for the flow
         settings_service: Settings service
+        event_delivery: Optional event delivery type - default is streaming
 
     Returns:
         Dict with job_id that can be used to poll for build status
@@ -197,12 +197,14 @@ async def build_flow(
         queue_service=queue_service,
         flow_name=flow_name,
     )
-    if settings_service.settings.event_delivery != "direct":
+
+    # This is required to support FE tests - we need to be able to set the event delivery to direct
+    if event_delivery == EventDeliveryType.DIRECT:
         return {"job_id": job_id}
     return await get_flow_events_response(
         job_id=job_id,
         queue_service=queue_service,
-        stream=True,
+        event_delivery=event_delivery,
     )
 
 
@@ -211,13 +213,13 @@ async def get_build_events(
     job_id: str,
     queue_service: Annotated[JobQueueService, Depends(get_queue_service)],
     *,
-    stream: bool = True,
+    event_delivery: EventDeliveryType = EventDeliveryType.STREAMING,
 ):
     """Get events for a specific build job."""
     return await get_flow_events_response(
         job_id=job_id,
         queue_service=queue_service,
-        stream=stream,
+        event_delivery=event_delivery,
     )