OpenHands RL post-training on Cortex Training

The trainer and the sampler run on Cortex Training GPUs (4 training + 4 sampling H200s). Your machine runs a CPU-only driver that executes OpenHands rollouts against a local OpenAI-compatible proxy (ChatCompletionsProxy) and sends the exact sampled token IDs (loss_mask = 1 on assistant turns, 0 on prompts and tool outputs) plus verifier rewards back to Cortex for a GSPO/GRPO update.

Two recipes ship in Arctic Platform:

1. Harbor RL (recipes/rl/harbor + arctic_platform/integrations/harbor, PR #294): Takes any Harbor training and eval task directories (TRAIN_HARBOR_TASKS and EVAL_HARBOR_TASKS, each task containing instruction.md, environment/, and tests/test.sh) and any target OpenHands agent (HARBOR_SKILL, OPENHANDS_TOOLS, OPENHANDS_SYSTEM_PROMPT_FILE, or HARBOR_AGENT). Each rollout is orchestrated by Harbor's Trial and scored by Harbor's Verifier (tests/test.sh $\to$ /logs/verifier/reward.txt or reward.json).
2. Code localization (recipes/rl/openhands/code_localization): Direct SWE-smith code localization (file + module + function F1, max 3.0).

• Cortex Training guides: docs/integrations/openhands.md · docs/integrations/bring-your-own-agent.md
• Harbor recipe guide: recipes/rl/harbor/README.md. Its Snowflake sandbox environment (HARBOR_ENV=snowflake) ships in Arctic Platform.

Rules