Is your feature request related to a problem? Please describe.

• I save artifacts to tool context using tool_context.save_artifact() when within a tool
• Then retrieve it back in the agent using artifact service with session
• The retrieval filters only artifacts for the current session (which is equivalent to conversation)
• But not for the current invocation (which is equivalent to current message within conversation)

# save artifact from a tool
await tool_context.save_artifact(FILENAME, some_data)

# retrieve in agent (e.g. within agent stream fn)
await artifact_service.load_artifact(
    app_name=app_name,
    user_id=user_id,
    session_id=session_id,
    filename=FILENAME,
)

Describe the solution you'd like
tool context have invocation id when inside a particular invocation

Describe alternatives you've considered

• I can retrieve and save invocation id to state (using an session event update)
• Use this invocation id from tool call and add to metadata
• Then filter each retrieved artifact using metadata
• A better way would be have invocation id within the tool context

Additional context
N/A