feat: Add an internal function name 'adk_framework' to allow passing function response to the framework but not poluting the agent context

Co-authored-by: Shangjie Chen <deanchen@google.com>
PiperOrigin-RevId: 845933584

src/google/adk/flows/llm_flows/contents.py

@@ -270,6 +270,7 @@ def _should_include_event_in_context(
   return not (
       _contains_empty_content(event)
       or not _is_event_belongs_to_branch(current_branch, event)
+      or _is_adk_framework_event(event)
       or _is_auth_event(event)
       or _is_request_confirmation_event(event)
   )
@@ -656,6 +657,11 @@ def _is_request_confirmation_event(event: Event) -> bool:
   return _is_function_call_event(event, REQUEST_CONFIRMATION_FUNCTION_CALL_NAME)
 
 
+def _is_adk_framework_event(event: Event) -> bool:
+  """Checks if the event is an ADK framework event."""
+  return _is_function_call_event(event, 'adk_framework')
+
+
 def _is_live_model_audio_event_with_inline_data(event: Event) -> bool:
   """Check if the event is a live/bidi audio event with inline data.