Proposal: URML, substrate-neutral intent vocabulary above openpi policies (RFC for maintainer comment)

[idoco2003]

Hello Physical Intelligence (openpi) maintainers,

URML is an open-source, vendor-neutral language for describing robot intent (Apache 2.0). Spec, validator, and reference runtimes at https://github.com/URML-MARS/URML.

RFC-0045 proposes a urml-openpi-bridge package that follows openpi's documented Inputs/Outputs extension pattern. The bridge wraps a pi-zero / pi-zero-FAST / pi-zero.5 policy and translates its action output into URML primitive calls before any motion reaches the substrate adapter. Same goal as our LeRobot integration (RFC-0040), targeting openpi's policy API specifically: policy = policy_config.create_trained_policy(...); action = policy.infer(example)['actions'].

The bridge is proposal-only; no plugin code lands until your team weighs in. No ROS dependency.

Full RFC:
https://github.com/URML-MARS/URML/blob/main/docs/rfcs/0045-physical-intelligence-openpi.md

Specific questions in the RFC focus on the URMLOutputs extension class shape, the right hosting (URML PyPI org vs community plugin vs openpi-side reference), and any conventions URML should respect when wrapping the Inputs/Outputs surface.

URML is independent open-source work; nothing on our side is gated by your response.

Thanks for any time you can spare.

Ido Yahalomi
URML maintainer
greenvh@gmail.com

[idoco2003]

Closing as a duplicate of #954, filed earlier today on the same proposal. Please direct any maintainer feedback to the canonical thread. Apologies for the cross-post.