Xiaomi's CodeMidas builds 5,545 coding RL environments from raw source code

XiaomiMiMo · hf · 2026-09-21

Xiaomi's MiMo team presents CodeMidas, an agentic pipeline that turns implemented functionality in existing codebases into executable RL environments using only source code—no issues or commits needed. Agents explore functionality to write behavioral specs, build tests grounded in the original code's execution, and filter tasks via execution checks and repeated solution rollouts. The dataset spans 5,545 tasks from 3,185 repos across 23 languages and 15 domains. GRPO training on it lifts MiMo-V2.5 by +11.7% on DeepSWE, +17% on ProgramBench and +8.5% on Terminal-Bench v2.1; ablations show more high-quality tasks keep improving performance.

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