The paper introduces CANOPY (Coverage-ANchored On-PolicY RL), a protocol that addresses signal starvation and policy drift in long-horizon reinforcement learning for small open models. By scaling same-task exploration and keeping updates KL-anchored, the method allows agents to learn effectively from end-of-task verification alone.

  • CANOPY scales exploration until natural signal reappears, avoiding the silence of sparse rewards on hard tasks.
  • Updates are kept on-policy and confined to the agent's own action tokens to prevent policy drift.
  • A Qwen3-14B policy trained with CANOPY topped the AppWorld public leaderboard (Feb. 2026) with a Test-Normal TGC of 86.9.
  • The same principles lifted Qwen3.5-9B on SWE-bench Verified by 16.6 points without auxiliary credit signals or elaborate scaffolding.

The authors argue that agentic RL alone can internalize long-horizon capability directly into small open models, with the complete training stack planned for release.