Invocation context attribute propagation

As per python-variant of the ADK library issue (https://github.com/google/adk-python/issues/1746) I would like to propagate request-scoped variable into agent and his tools (ToolContext) in order that tool used by agent would have this variable at its disposal for the given runAsync() run.
I suppose that instances of Runner, Agent and Tool(set) are meant to be long-lived singletons, so that leaves me only Session option, which also seem to live across many requests, so only hack-like solution with pushing and then removing the request variable through Session with before/afterToolCallback are available now.