For my personal use case, I use something that's known as “lossless context management.” I made a custom harness implementation that uses it. In short, it has a database with every message ever exchanged, and the model can access any of those messages using a simple search. On top of that, every exchange is summarized and stored separately as a level zero summary. Level zero summaries are then periodically summarized together into level one summaries that leave only the most important parts (lessons, knowledge).

The full context then looks something like: [intro prompt] + [old exhanges lvl 1 summaries] + [larger system prompt] + [more recent exchanges lvl 0 summaries] + [temporal context] + [recent messages with tool results stripped] + [recent messages including tool results]

Tool results are progressively stripped because they are generally only useful for a few turns. This allows to keep everything we've ever done in the context, and the model can easily look up more information by expanding each node. It's a single perpetual session that never compacts during active work.

I find it outperforming every other solution I tried for my use case (personal assistant).