Switching from Anthropic direct: migrating the SDK

The wire format is already the right one

Claude models answer on POST https://token-share.app/v1/messages, authenticated with x-api-key and carrying anthropic-version: 2023-06-01. Those are the header names and the path the Anthropic SDK already sends, so pointing its base URL here is the entire transport change.

Request bodies port over unchanged: messages, system, max_tokens, tools, tool_choice, stop_sequences, temperature, stream. Responses come back from Anthropic upstream, so content blocks, stop_reason and the usage object are theirs, not a reconstruction.

The catalog also answers GET /v1/models. Send anthropic-version and the listing comes back in the Anthropic shape, which means a client that discovers models the Anthropic way keeps working.

import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  baseURL: 'https://token-share.app',
  apiKey: process.env.TOKEN_SHARE_KEY,
});

const message = await client.messages.create({
  model: 'claude-sonnet-5',
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'Explain this stack trace.' }],
});

for (const block of message.content) {
  if (block.type === 'text') console.log(block.text);
}

Model ids, and the retired ones

Twelve Claude ids are routed here. Five are pool ids — claude-opus-5, claude-opus-4-8, claude-opus-4-6, claude-sonnet-5, claude-sonnet-4-6 — billed at 0.1×, and the other seven are stable-* lanes at 0.4×. The ids are ours, so copy them from the catalog rather than from an upstream release note.

A few ids were retired in favour of a dedicated lane, and calling one is refused with 400 rather than quietly redirected. The message names the replacement: send claude-haiku-4-5 and you are told to use stable-claude-haiku-4-5. That is deliberate — the replacement is billed at 0.4× instead of 0.1×, so opting into it has to be your decision rather than a silent upgrade that costs more.

Claude requests draw only on the recharge balance. An empty recharge balance, or holding only earned or promotional balance, returns 402 with code claude_minimum_balance before anything is forwarded.

Claude Code and the decorated ids

Claude Code appends decorations to a model name: [1m] to ask for the long-context variant, and a trailing (budget) to carry a thinking budget, sometimes both as name[1m](1024). The allowlist parses those off and judges the base id, so a decorated id whose base is in the catalog is accepted.

It is a base-id comparison, not a substring match, so a variant that is not in the catalog is still refused. That keeps a real typo from being silently promoted to a model you did not intend to pay for.

Set the SDK's base URL through ANTHROPIC_BASE_URL and its key through ANTHROPIC_API_KEY, and any tool built on the Anthropic SDK follows. There is no separate integration path for CLI tools.

Common questions