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OpenEnv is Hugging Face’s open protocol for RL environments: an environment is an HTTP service exposing reset / step (and optionally evaluate), so any environment speaking the protocol can serve any trainer. Miles integrates OpenEnv as an agent-function integration: a Miles-side agent function drives the agentic loop — reset(task_id), repeated steps, then scoring the episode with the task’s own tests — against an unmodified OpenEnv server, and the score becomes the sample’s reward through a custom reward hook.

Try it

The maintained end-to-end recipe is Terminal-Bench-2 GRPO in examples/experimental/openenv. It runs against a shared Docker env server (full per-task image fidelity) or per-episode Daytona cloud sandboxes built from each task’s official image (no resident infrastructure). Follow the recipe README for prompt-data preparation, env-server modes, launcher flags, and operational notes.