adding Vercel Labs fx (PR #590) and auth-check guidance

[bqx619]

Hello maintainers 👋

I’d like to kindly request a review of PR #590, which adds fx (Vercel Labs) to the ACP Registry.

What’s in the PR

• Agent id: fx
• Version: v0.0.8 (current official GitHub Release)
• Distribution: binary archives from releases/download with pinned SHA-256
• Launch: ./fx acp
• Icon: official fx.sh logo glyph, adapted to registry rules (16×16, currentColor)

Why I’m opening this issue

While preparing the entry I noticed that fx acp may not currently pass CI --auth-check as written:

1. Without saved credentials / AI_GATEWAY_API_KEY, initialize can return a JSON-RPC error asking the user to run fx login / fx setup.
2. In the successful-initialize path, fx’s source currently emits "authMethods": [] (see writeInitializeResponse in the fx codebase).

Per AUTHENTICATION.md and CONTRIBUTING, the registry expects at least one authMethods entry with type: "agent" or "terminal".

I opened the PR intentionally without inventing auth behavior on fx’s behalf, out of respect for fx’s existing login UX (fx login / fx setup / env key). At the same time, I don’t want to create busywork for reviewers or leave a permanently red CI job without a clear path.

What I’d appreciate guidance on

Could you please advise which path you’d prefer for this entry?

1. Land Add fx (Vercel Labs) v0.0.8 #590 as-is and temporarily quarantine fx (similar to other agents whose initialize currently fails), or
2. Hold the registry PR until fx advertises a proper Terminal/Agent Auth method on initialize, or
3. Any other process you recommend for experimental agents in this situation.

Happy to update the PR, open a companion issue on vercel-labs/fx, or adjust docs/notes however you prefer.

Thank you very much for maintaining this registry — and for any time you can spare to review #590.

cc @Rizzen @benbrandt @EugeneTheDev @Ololoshechkin