Fumadocs on TanStack Start

Install the SDK, configure a client, and make your first chat completion call in under a minute.

1. Install

npm install @qubittron/bastion-sdk
# or
pnpm add @qubittron/bastion-sdk
# or
bun add @qubittron/bastion-sdk
# or
yarn add @qubittron/bastion-sdk

Requirements:

Node ≥ 20 (uses global fetch and ReadableStream)
Bun, Deno (with Node compatibility), or any edge runtime exposing fetch
Browsers: any with global fetch — but see Environments before shipping a browser bundle (your API key would leak).

2. Get an API key

Sign up at qubittron.ai and verify your phone number.
Open the dashboard → API keys → Create key. Keys start with qbt_ and are shown only once.
Set the key in your environment:

export BASTION_API_KEY=qbt_your_key_here

The SDK reads BASTION_API_KEY automatically when you don't pass apiKey to the constructor.

3. Construct a client

import { Bastion } from "@qubittron/bastion-sdk";

const client = new Bastion(); // reads BASTION_API_KEY from env

// or, explicitly:
const client = new Bastion({
  apiKey: process.env.BASTION_API_KEY,
});

If apiKey is missing and BASTION_API_KEY is unset, the constructor throws synchronously. See Bastion API for all options.

4. Make your first call

const res = await client.chat.completions.create({
  model: "gpt-oss-120b",
  messages: [{ role: "user", content: "Reply with exactly: ok" }],
  max_tokens: 16,
});

console.log(res.choices[0]?.message.content);
console.log(res.usage); // { prompt_tokens, completion_tokens, total_tokens }

5. Stream tokens

Pass stream: true to get an AsyncIterable over ChatCompletionChunks:

const stream = await client.chat.completions.create({
  model: "gpt-oss-120b",
  messages: [{ role: "user", content: "Write a haiku about Canada." }],
  stream: true,
});

for await (const chunk of stream) {
  process.stdout.write(chunk.choices[0]?.delta.content ?? "");
}

See the streaming guide for cancellation, partial-tool-call handling, and reasoning tokens.

6. Handle errors

import {
  AuthenticationError,
  RateLimitError,
} from "@qubittron/bastion-sdk";

try {
  await client.chat.completions.create({
    model: "gpt-oss-120b",
    messages: [{ role: "user", content: "hi" }],
  });
} catch (err) {
  if (err instanceof RateLimitError) {
    // back off
  } else if (err instanceof AuthenticationError) {
    // refresh / rotate the key
  } else {
    throw err;
  }
}