Pure RL Trains a Strong 4B Continual-Learning LLM, No Distillation or SFT

aviral_kumar2 · x · 2026-11-13

aviralkumar2 reports training a very strong 4B LLM using only RL with proper rewards on the right curricula—no distillation or SFT—achieving a much better tradeoff between continual learning ability and performance.

On the Continual Learning Bench codebase adaptation task, the model outperforms all reported systems, trailing only the team's latest frontier models. The shared leaderboard shows their Qwen3.5-4B rising from 1.33 (untrained, ACT+WRITE loop) to 10.55 cumulative reward (+2.27 gain), rivaling GPT-5.4 ICL (10.14) but still below frontier systems like Claude Opus 5.5 (17.40) and GPT-6 Astra (17.25).

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