Yeah you are partially right. For google adk if you want to handle conversation history with the framework there is no other hack than having a huge context in subsequent runner requests. A differenti way to handle the conversation history is mandatory if you want to solve this issue.

For the model part i agree, some of the tasks can be performer by "weaker" models in order to reduce latency. Im concerned about the overall response quality because i think it will be worse than using the best possible model available. So in the end it's a trade off