Increase Sandbox Default Thread Worker Count

[DamianB-BitFlipper]

Description

When running an env with very high concurrency, the sanbox_client's asyncio threadpool executor gets clogged up. The default value of 10 is quite low and hardware can comfortably support 50.

This took down the "sandbox is ready" time for a swe benchmark from 250s down to about 75s.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Test improvement

Testing

• All existing tests pass when running uv run pytest locally.
• New tests have been added to cover the changes

Checklist

• [I couldnt find the style guidelines] My code follows the style guidelines of this project as outlined in AGENTS.md
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Additional Notes

refactor: Increase max workers for sandbox client setup

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Note

Low Risk
Concurrency tuning only; behavior changes are limited to resource usage (more threads/connections) and could surface rate-limit or saturation issues in constrained runtimes.

Overview
Increases the default sandbox_client_max_workers from 10 to 50 across sandbox-backed environments (including SandboxEnv, RLMEnv, and the math_python environment) to prevent the sandbox client threadpool from becoming a bottleneck at high concurrency.

Also configures AsyncSandboxClient instances in experimental envs (CliAgentEnv, HarborEnv) with explicit higher HTTP connection/keepalive limits (max_connections=100, max_keepalive_connections=50) to better support parallel sandbox operations.

^{Written by Cursor Bugbot for commit 1e60b52. This will update automatically on new commits. Configure here.}

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[mikasenghaas]

can go even higher? usually set to 128 for any stuff i do

[willccbb]

@cursoragent update CliAgentEnv / HarborEnv limits accordingly

[cursor]

• Updated both CliAgentEnv and HarborEnv to align sandbox client limits with the new defaults:

  • AsyncSandboxClient(..., max_connections=100, max_keepalive_connections=50)
  • Applied in verifiers/envs/experimental/cli_agent_env.py (create/wait/delete paths) and verifiers/envs/experimental/harbor_env.py (reward compute path).

• Committed and pushed to more-sandbox-threads (commit 1e60b52). If you want these envs to also use the threaded client with an explicit worker pool, I can follow up with a switch to ThreadedAsyncSandboxClient and expose a sandbox_client_max_workers param.