Class App

src/google/adk/apps/app.py:53–109

Represents an LLM-backed agentic application. An `App` is the top-level container for an agentic system powered by LLMs. It manages either a root agent (`root_agent`) or a root node (`root_node`), which serves as the entry point for execution. Exactly one of `root_agent` or `root_node` mus

class App(BaseModel):
  """Represents an LLM-backed agentic application.

  An `App` is the top-level container for an agentic system powered by LLMs.
  It manages either a root agent (`root_agent`) or a root node (`root_node`),
  which serves as the entry point for execution.

  Exactly one of `root_agent` or `root_node` must be provided.

  The `plugins` are application-wide components that provide shared capabilities
  and services to the entire system.
  """

  model_config = ConfigDict(
      arbitrary_types_allowed=True,
      extra="forbid",
  )

  name: str
  """The name of the application."""

  # Change to Union[BaseAgent, BaseNode, None] after dependency is fixed.
  root_agent: Union[BaseAgent, Any, None] = None
  """The root agent or node in the application.

  Accepts either a BaseAgent or a BaseNode instance.
  """

  plugins: list[BasePlugin] = Field(default_factory=list)
  """The plugins in the application."""

  events_compaction_config: Optional[EventsCompactionConfig] = None
  """The config of event compaction for the application."""

  context_cache_config: Optional[ContextCacheConfig] = None
  """Context cache configuration that applies to all LLM agents in the app."""

  resumability_config: Optional[ResumabilityConfig] = None
  """
  The config of the resumability for the application.
  If configured, will be applied to all agents in the app.
  """

  @model_validator(mode="after")
  def _validate(self) -> App:
    validate_app_name(self.name)
    if self.root_agent is None:
      raise ValueError("root_agent must be provided.")

    from ..workflow._base_node import BaseNode

    if not isinstance(self.root_agent, (BaseAgent, BaseNode)):
      raise TypeError(
          "root_agent must be a BaseAgent or BaseNode instance, got"
          f" {type(self.root_agent).__name__}"
      )
    return self