I've been reading BEACON from Zhejiang University's ZJU-REAL lab (arXiv:2605.06078), and the more I read it the more directly applicable it felt to the long-horizon agent work we're doing. So I'm turning that into a series.

The framing

To build a long-horizon agent that actually works, I think two things have to be right:

1. The agent keeps making progress toward the goal

Context compaction — what is safe to forget