Highly recommended paper from NVIDIA.

(bookmark it)

There is a lot of debate about whether to use context compaction aggressively.

They show that with frequent compaction, frontier language models lose little to no accuracy on a broad range of long-horizon and long-input tasks while keeping their context short.

With one action per context, Claude Opus 4.5 scores 70.2 on SWE-bench Verified against 70.0 with the full history. Median peak context drops from 32K to 8K tokens.

The agent carries a short summary of its state between steps instead of the whole transcript. Simple compaction at the end of a conversation often does better than the full history, and Opus goes from 70.0 to 74.8 with it.

This also matters for cost. Later tokens cost more to generate than earlier ones, up to 7x on frontier open-weight models.

The pattern holds on Terminal-Bench, FRAMES, BFCLv3 and multilingual SWE-bench, with modest losses in some settings.

Before paying for million-token agent runs, it's worth testing aggressive compaction on your own tasks.

https://arxiv.org/abs/2611.05306

Chat with Paper: https://academy.dair.ai/papers/you-dont-need-long-context-2611.05306