RFC: Support external / non-distributable OpenEnv environments

[0xrushi]

Summary

I previously opened PR #353 to document a 0 A.D. RTS integration via an external bridge repo. The PR was closed because the env doesn’t live in this repo and can’t run in a typical Hugging Face Space (requires local 0 A.D. install and more resources).

However, there’s a real need for environments that:

• implement the OpenEnv interface,
• are too heavy / complex to be bundled here or on HF Hub,
• but are still valuable for the community to discover and use locally.

Proposed Solution

Introduce support for “external envs” by:

1. Allowing a small registry/section listing external OpenEnv-compatible envs with:
   ▫ name / id
   ▫ external repo link
   ▫ requirements (e.g., local game install, not runnable in HF Spaces)

2. Adding a docs section (e.g. “External / heavyweight environments”) that explains:
   ▫ these envs are not hosted here or on HF Hub,
   ▫ they are meant to be run locally,
   ▫ links to their installation / usage guides.

Alignment with Principles

Principles Addressed

• Minimize lifecycle deltas (training = production)
• Minimize human-agent divergence
• Be hands-on (working implementations)
• Design for LLMs

Impact

None

Files/Systems Affected

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