ADK Context Manager

Philosophy & Architecture

InvocationContext provides the "bundle" of information (session state, events, services) for a single request-response cycle (invocation).

Context Flavors

• •InvocationContext: Comprehensive internal container; used directly in _run_async_impl.
• •CallbackContext: Shared across agent and model callbacks.
• •ToolContext: Subclass of CallbackContext for tool callbacks; adds function_call_id.
• •ReadonlyContext: Safe access for toolsets/services that don't modify state.

State Management

• •Access: context.state (dict-like object).
• •Modification: context.state['key'] = 'value'. Changes are tracked as state_delta in events.
• •Prefixes:
  • •user:*: User-level preferences (persistent).
  • •app:*: Application-wide settings (persistent).
  • •temp:*: Short-lived invocation-level data.
  • •(No prefix): Session-specific data.

Identity & Tracking

• •invocation_id: Unique identifier for the current run.
• •agent.name: Identify the currently running agent.
• •Read references/context.md for full attribute definitions.

Success Criteria

• •Correct state scope usage (e.g., user: for preferences).
• •Proper access to services (e.g., context.artifact_service).
• •Effective use of InvocationContext for early termination (ctx.end_invocation = True).