Copybara import of the project:

--
ad923c2c8c503ba73c62db695e88f1a3ea1aeeea by YU MING HSU <abego452@gmail.com>:

docs: enhance Contribution process within CONTRIBUTING.md

--
8022924fb7e975ac278d38fce3b5fd593d874536 by YU MING HSU <abego452@gmail.com>:

fix: move _maybe_append_user_content from google_llm.py to base_llm.py,
so subclass can get benefit from it, call _maybe_append_user_content
from generate_content_async within lite_llm.py

--
cf891fb1a3bbccaaf9d0055b23f614ce52449977 by YU MING HSU <abego452@gmail.com>:

fix: modify install dependencies cmd, and use pyink to format codebase
COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/428 from hsuyuming:fix_litellm_error_issue_427 dbec4949798e6399a0410d1b8ba7cc6a7cad7bdd
PiperOrigin-RevId: 754124679

src/google/adk/sessions/base_session_service.py

@@ -26,6 +26,7 @@ from .state import State
 
 class GetSessionConfig(BaseModel):
   """The configuration of getting a session."""
+
   num_recent_events: Optional[int] = None
   after_timestamp: Optional[float] = None
 
@@ -35,11 +36,13 @@ class ListSessionsResponse(BaseModel):
 
   The events and states are not set within each Session object.
   """
+
   sessions: list[Session] = Field(default_factory=list)
 
 
 class ListEventsResponse(BaseModel):
   """The response of listing events in a session."""
+
   events: list[Event] = Field(default_factory=list)
   next_page_token: Optional[str] = None
 

src/google/adk/sessions/database_session_service.py

@@ -219,6 +219,7 @@ class StorageAppState(Base):
       DateTime(), default=func.now(), onupdate=func.now()
   )
 
+
 class StorageUserState(Base):
   """Represents a user state stored in the database."""
 
@@ -562,6 +563,7 @@ class DatabaseSessionService(BaseSessionService):
   ) -> ListEventsResponse:
     raise NotImplementedError()
 
+
 def convert_event(event: StorageEvent) -> Event:
   """Converts a storage event to an event."""
   return Event(