Paper proposes 'checkpoint handoff' to separate REACH and SOLVE effects in agentic RL
The arXiv paper (2609.19636v1) introduces 'checkpoint handoff', an evaluation protocol that clones states reached by one checkpoint and runs another checkpoint from those identical states to decompose endpoint success into REACH (arriving at useful states) and SOLVE (finishing from identical states). Applied across two benchmarks and two released pipelines (including experiments on ALFWorld), the method shows positive interaction: RL histories help RL solvers more than SFT solvers, and independent REACH and SOLVE gaps predict aggregate gains.