Choosing an AI Agent¶

FermiLink delegates reasoning to an external AI agent provider. The global setting of the default agent for FermiLink is done with fermilink agent <provider>.

Supported providers¶

Provider	CLI tool	Install	Notes
Codex	`codex`	`npm i -g @openai/codex` or `brew install codex`	OpenAI’s coding agent.
Claude	`claude`	See Claude CLI docs	Anthropic’s Claude Code.
Gemini	`gemini`	See Gemini CLI docs	Google’s Gemini CLI.
OpenCode	`opencode`	See OpenCode docs	Model-agnostic OpenCode CLI. Authenticate providers with `opencode auth login` and use model names in `provider/model` form.

Setting up your agent¶

# 1. Install the provider CLI (example: Codex)
npm i -g @openai/codex

# 2. Authenticate
codex login

# 3. Register with FermiLink
fermilink agent codex

# Switch providers later
fermilink agent claude
fermilink agent gemini
fermilink agent opencode --model openai/gpt-5.5

How to choose¶

All providers work with the main FermiLink workflows (exec, chat, loop, research, reproduce, and optimize). The exploop Windows workflow is documented separately and remains Codex-tested. The best provider choice depends on your priorities:

If you want the broadest compatibility: Codex and Claude are the most tested providers, which give the richest interactive experience.

If you want flexible model/provider routing: OpenCode lets FermiLink use any provider/model profile configured in OpenCode.

If you use Google Cloud: Gemini is a natural fit if you’re already in the Google ecosystem.

Note

We are actively adding support for more providers. If you have a preferred agent provider that you want to see integrated, please let us know in the GitHub discussions.

Advanced configuration¶

By default, agents run in a sandbox that restricts file-system and network access. Some scientific simulations (e.g., MPI jobs, access to external data) require bypassing the sandbox. You can do this per-provider:

# show current policy
fermilink agent --json

# enforce sandbox mode (default), codex provider
fermilink agent codex --sandbox --model gpt-5.3-codex --reasoning-effort xhigh

# bypass sandbox (which might be needed for local MPI jobs)
fermilink agent codex --bypass-sandbox --model gpt-5.3-codex --reasoning-effort xhigh

# bypass sandbox for claude
fermilink agent claude --bypass-sandbox --model sonnet --reasoning-effort high

# bypass sandbox for gemini
fermilink agent gemini --bypass-sandbox --model auto-gemini-3 --reasoning-effort high

# bypass sandbox for opencode
fermilink agent opencode --bypass-sandbox --model openai/gpt-5.5 --reasoning-effort xhigh

Warning

When fermilink agent --bypass-sandbox is needed for maximal functionality, NEVER run it as a root user.

By default, FermiLink normalizes the reasoning effort setting for agents to the codex provider’s reasoning effort levels (low, medium, high, xhigh). For OpenCode, use model identifiers in provider/model form; FermiLink maps xhigh reasoning effort to OpenCode’s max variant.