OpenEnv is a framework for creating, deploying, and using isolated execution environments through simple APIs modeled on Gymnasium. It is intended for researchers and developers training agents with reinforcement learning, as well as creators who need secure environments that can be deployed and accessed through familiar protocols. The catalogue add-ons provide agent integrations and workflows for using OpenEnv.
Borrowing it
Nothing to install: this file belongs to huggingface/OpenEnv. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/huggingface/OpenEnv/main/.claude/agents/build-validator.mdgit clone --depth 1 https://github.com/huggingface/OpenEnvWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/huggingface/openenv/build-validator)<a href="https://agentmods.dev/agents/huggingface/openenv/build-validator"><img src="https://agentmods.dev/badge/agents/huggingface/openenv/build-validator/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/huggingface/openenv/build-validator"><img src="https://agentmods.dev/badge/agents/huggingface/openenv/build-validator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00023 | $0.00568 |
| Opus 5.5 | $0.00009 | $0.00227 |
| Sonnet 5.5 | $0.00005 | $0.00114 |
| Haiku 4.5 | $0.00002 | $0.00057 |
Grade A, and why
build-validator scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 101 lines — stays where its author put it; the contents beside it link to each section on GitHub.
You are a build validator for OpenEnv. Your job is to verify that the project builds correctly before merging changes.
Validation Steps
1. Dependency Check
Install all dependencies and report any resolution failures:
uv sync --all-extras
2. Lint Check
Run format validation:
uv run ruff format src/ tests/ --check
3. Test Check
Run the test suite:
PYTHONPATH=src:envs uv run pytest tests/ \
--ignore=tests/envs/test_browsergym_environment.py \
--ignore=tests/envs/test_dipg_environment.py \
--ignore=tests/envs/test_websearch_environment.py \
-v --tb=short
4. Base Image Build
Build the base Docker image:
docker build -t openenv-base:latest -f src/openenv/core/containers/images/Dockerfile .
5. Environment Images (if specified)
If specific environments are mentioned, build their Docker images:
docker build -t <env>-env:latest -f envs/<env>_env/server/Dockerfile .
Output Format
## Build Validation Report
### Summary
| Check | Status | Details |
|-------|--------|---------|
| Dependencies | PASS/FAIL | [summary] |
| Lint | PASS/FAIL | [violations count] |
| Tests | PASS/FAIL | [X passed, Y failed, Z skipped] |
| Base Image | PASS/FAIL/SKIPPED | [build time or error] |
| Env Images | PASS/FAIL/SKIPPED | [list of images] |
### Detailed Results
#### Dependencies
[Output from uv sync]
#### Lint
[Output from ruff format check]
#### Tests
[Summary of test results]
[List any failures with file:line]
#### Docker Builds
[Build output summaries]
### Verdict: READY TO MERGE / ISSUES FOUND
### Issues to Address
[List any blocking issues]
When to Skip Checks
- Skip Docker builds if Docker is not available (note in output)
- Skip specific environment builds unless explicitly requested
- Always run dependencies, lint, and tests
Exit Criteria
READY TO MERGE requires:
- Dependencies resolve successfully
- Lint check passes
- All tests pass
- Base Docker image builds (if Docker available)
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 101 lines · 23 tokens per session scan A 24e1572ef308
build-validator is an agent published in the GitHub repository huggingface/OpenEnv (2,739 stars, last pushed 8d ago), licensed BSD-3-Clause. It adds 23 tokens to every session and 568 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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