What actually happens to your context window after 6 hours of continuous agent runtime

The documentation answer to context windows management in long running agents is: summarize old turns, use RAG for retrieval, truncate from the front. In practice all three of those have failure modes that ONLY show up after extended runtime. Summarization compresses what the model can see at the cost of implicit state. By hour six or seven of a continuous run, the summary is factually accurate about what happened but the agent is making decisions that would have been obviously wrong to anyone who saw the full context. The facts are there, the judgment context no longer is. RAG retrieval assumes the agent knows what to retrieve. Long running agents often don't know what they don't know. The failure pattern keeps repeating: the agent stops asking the right question because it doesn't have the context to know that question should exist to begin with. Truncating from the front is the worst default. You lose the task framing and the agent starts optimizing for recent signals without the original constraint. What implementation is working for those of you running agents past the four/five hour mark?