Generally, I keep the context. If I'm one shotting then I invoke a new agent. All calls and responses append to the agent's chat history. Agent's are relatively short lived, so the context length isn't typically an issue. With the pricing agent the initial data has been longer than the context window sometimes, but that just means it needs more preprocessing. Now if there is a real reason that I would want to manage it more actively, I can reach out to the agent internals. I have a tool call emulation layer, because some models have poor native tool support, and in those cases it's sometimes necessary to retry calls if the response fails validation. In those cases, I will only keep the last successful try in the conversation history.
There is one special case where I manage it more actively. I wrote an REPL process analyst, to help build the pricing agent and refine the policy document. In that case I would have long threads with an artifact attachment. So I added a facility to redact old versions of the artifact replacing them with [attachment: filename] and just keep the last one. It works better that way because multiple versions in the same conversation history confuse the model, and I don't like to burn tokens.
For longer lived state, I give the agent memory tools. For example the pricing agent's initial state includes the most recent decision batch and reasoning notes, and the agent can request older copies. The agent also keeps a notebook which they are required to update, allowing agents to develop long running strategies and experiments. And they use it to do just that. Honestly the whole system works much better than I anticipated. The latest crop of models are awesome, especially Gemini 2.5 flash.