How To Use A Subscription Claude Provider

Use a subscription-backed Claude provider when you want model access through an existing Claude subscription instead of a metered Anthropic API key. @inbrowser/model ships two factories you can register in the relay: claudeCodeModelClient (the Claude Agent SDK) and claudeCliModelClient (the claude command in print mode). Both run server-side, carry no API key on the wire, and bill against the logged-in subscription rather than per token.

If you want a metered API key instead, register the anthropicModelClient factory and supply a key (see How to wire a web app and the API reference for the BYOK and server-managed key modes).

Pick a provider

Both reach the same models without an API key. They differ in how they talk to Claude:

• claudeCodeModelClient drives the Claude Agent SDK (@anthropic-ai/claude-agent-sdk) in-process. Reach for it when you want a library dependency and no separate binary. The SDK is an optional peer dependency, so install it alongside.
• claudeCliModelClient shells out to the installed claude binary in print mode (claude -p). Reach for it when the CLI is already on the host and you would rather not add the SDK dependency.

Both factories take a config that extends { apiKey?, model } with their own options. Since the relay supplies only { apiKey, model } per request, register them as the bare factory when the defaults are fine, or wrap them to merge in extra options.

Use claudeCodeModelClient

Install the SDK peer dependency, then register the factory under whatever route key you like:

bun add @anthropic-ai/claude-agent-sdk

import { createRelay } from '@inbrowser/relay';
import { claudeCodeModelClient } from '@inbrowser/model/providers/claude-code';

const relay = createRelay({
  store,
  providers: {
    'claude-code': claudeCodeModelClient,
  },
});

The client authenticates from the ambient Claude Code login it finds at ~/.claude/.credentials.json. It strips ANTHROPIC_API_KEY from the subprocess environment so a stray key never switches the call back to per-token billing.

If you need to supply the token explicitly (for example in a container with no login on disk), wrap the factory so the relay-supplied { apiKey, model } is merged with your oauthToken:

providers: {
  'claude-code': (c) =>
    claudeCodeModelClient({ ...c, oauthToken: process.env.CLAUDE_CODE_OAUTH_TOKEN }),
}

Use claudeCliModelClient

The claude binary must be installed and logged in on the host. Register the factory:

import { createRelay } from '@inbrowser/relay';
import { claudeCliModelClient } from '@inbrowser/model/providers/claude-cli';

const relay = createRelay({
  store,
  providers: {
    'claude-cli': claudeCliModelClient,
  },
});

It spawns claude -p with a streaming-JSON output format and reads the NDJSON stream back as ModelEvents. By default it runs in a temporary working directory, so it ignores the host project’s CLAUDE.md and settings.

If the binary is not on PATH, or you need a longer timeout for long generations, wrap the factory and pass the ClaudeCliOptions:

providers: {
  'claude-cli': (c) =>
    claudeCliModelClient({ ...c, claudePath: '/usr/local/bin/claude', timeoutMs: 600_000 }),
}

Send a request

A client request looks the same as any other provider, with an empty apiKey because the subscription, not a key, authorizes the call:

await relay.handleStart(
  new Request('https://app.example/api/inference/job', {
    method: 'POST',
    body: JSON.stringify({
      provider: 'claude-code',
      model: 'claude-opus-4-8',
      messages: [{ role: 'user', text: 'Explain WebGPU in one paragraph.' }],
      tools: [],
      apiKey: '',
    }),
  }),
);

Set reasoningEffort to 'low', 'medium', or 'high' to request extended thinking; 'off' (the default) leaves the model’s own default in place.

Limits

• Both clients are Node-only and reject caller-defined tools: if a request carries a non-empty tools array they yield an error event. Leave tools empty.
• temperature, topP, and topK are not exposed by either path and are ignored.
• These clients authorize from a subscription on the host, so they belong on a trusted server, never in code you ship to a browser.

For the ModelClientFactory contract, request shape, and the ModelEvents these emit, see the API reference.