Banger report from Microsoft. (bookmark it) They show that it's possible to build competitive small coding agents without traditional distil…

Banger report from Microsoft. (bookmark it) They show that it's possible to build competitive small coding agents without traditional distillation from frontier models. This is a big deal! The work describes how they achieved this. They introduce a 4B coding agent trained on roughly 1,500 software engineering environments. The cool thing is that they use no distillation from a larger model at any point. FrogNano is post-trained purely with RL on synthetic tasks. The target is a coding agent that runs on minimal machines, which rules out both a frontier backbone and a frontier teacher. The ingredient the report credits the most is online task synthesis. The pipeline generates tasks calibrated to the frontier of learnability for the current checkpoint, so the agent always trains on problems it can just barely solve. The authors argue that calibration, rather than the volume of synthetic data, is what makes this work. This means that competitive small coding agents can be trained from synthetic tasks alone. And generating those tasks at the current agent's learnability frontier is what makes this particular training productive. The report covers training methodology, evaluations across diverse environments, and analyses of what the agent learned. Paper: https://academy.dair.ai/papers/frognano-training-a-4b-coding-agent-via-online-task-synthesis-2609.07925

Source: DAIR.AI (X) | 2026-09-09

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