@agent-relay/credential-proxy

JWT-authenticated credential proxy for upstream LLM providers. Lets sandboxed agents call provider APIs (OpenAI, Anthropic, OpenRouter) without being given raw provider credentials — the proxy holds the keys, agents present per-session JWTs, and the proxy enforces per-credential token budgets.

What it is

A Hono app plus a handful of helpers:

• createCredentialProxyApp(options) — mounts the HTTP router (/health, /usage, and a catch-all provider-forwarding route under *). Use it directly in Node (via @hono/node-server) or bind it inside a Cloudflare Worker.
• mintProxyToken(...) / verifyProxyToken(...) — JWT helpers built on jose. HS256 by default, audience relay-llm-proxy.
• MeteringCollector + checkBudget — in-memory usage accounting with pessimistic reservations so concurrent requests can't bypass the declared budget.
• Provider adapters under providers/ — translate incoming JWT claims to the correct upstream HTTP request for OpenAI / Anthropic / OpenRouter.

Environment variables

Required at runtime (the host of the proxy):

| Variable | Purpose | | ----------------------------------- | ------------------------------------------------------------ | | CREDENTIAL_PROXY_JWT_SECRET | HS256 secret the proxy uses to verify per-session JWTs. | | CREDENTIAL_PROXY_ADMIN_JWT_SECRET | Secret for admin-scoped tokens (e.g. the /usage endpoint). | | CREDENTIAL_PROXY_ADMIN_AUDIENCE | Audience claim the proxy requires on admin tokens. | | OPENAI_API_KEY | Upstream credential for the OpenAI provider adapter. | | ANTHROPIC_API_KEY | Upstream credential for the Anthropic provider adapter. | | OPENROUTER_API_KEY | Upstream credential for the OpenRouter provider adapter. |

Only the provider keys you actually forward to need to be set — missing keys surface as 502 credential_unavailable on the relevant route.

The agent side (whichever process mints tokens and launches the sandboxed CLI) uses CREDENTIAL_PROXY_JWT_SECRET to sign tokens and puts them into the agent's environment as CREDENTIAL_PROXY_TOKEN (alias: RELAY_LLM_PROXY_TOKEN) plus RELAY_LLM_PROXY / RELAY_LLM_PROXY_URL so the SDK's proxy-env helpers can wire up per-CLI OPENAI_BASE_URL / ANTHROPIC_BASE_URL overrides.

Usage

import { serve } from '@hono/node-server';
import { createCredentialProxyApp } from '@agent-relay/credential-proxy';

const app = createCredentialProxyApp({
  // Defaults to process.env.CREDENTIAL_PROXY_JWT_SECRET / ADMIN_JWT_SECRET.
});

serve({ fetch: app.fetch, port: Number(process.env.PORT ?? 3001) });

For the SDK-side wiring that lets workflow agents use the proxy transparently, see @agent-relay/sdk/workflows's proxy-env module and the credentialProxy field on SwarmConfig.

Development

npm run build      # tsc → dist/
npm run test       # vitest
npm run dev        # builds then runs the proxy on PORT (default 3001)