Add AI SDK Provider

[selander-stripe]

Add Stripe AI SDK packages for Vercel AI SDK integration

This PR adds three new packages under llm/ for integrating Stripe billing with AI applications.

Packages Added

@stripe/ai-sdk/provider

A custom Vercel AI SDK provider that routes requests through Stripe's llm.stripe.com proxy for automatic usage tracking and billing. Provides a unified interface to OpenAI, Google Gemini, and Anthropic Claude models.

import { createStripe } from '@stripe/ai-sdk/provider';
import { generateText } from 'ai';

const stripe = createStripe({
  apiKey: process.env.STRIPE_API_KEY,
  customerId: 'cus_xxxxx',
});

const result = await generateText({
  model: stripe('openai/gpt-5'),
  prompt: 'Hello world',
});

@stripe/ai-sdk/meter

A wrapper that adds Stripe billing tracking to any AI SDK v2 language model. Allows developers to continue using their existing provider setup while gaining billing capabilities.

import { meteredModel } from '@stripe/ai-sdk/meter';
import { openai } from '@ai-sdk/openai';

const model = meteredModel(
  openai('gpt-4o-mini'),
  process.env.STRIPE_API_KEY,
  'cus_xxxxx'
);

@stripe/token-billing

A generic token metering library for native AI SDKs (OpenAI, Anthropic, Google Gemini) without framework dependencies. Automatically detects provider types and tracks token usage for billing.

import OpenAI from 'openai';
import { createTokenMeter } from '@stripe/token-billing';

const openai = new OpenAI({ apiKey: process.env.OPENAI_API_KEY });
const meter = createTokenMeter(process.env.STRIPE_API_KEY);

const response = await openai.chat.completions.create({
  model: 'gpt-4o-mini',
  messages: [{ role: 'user', content: 'Hello!' }],
});

meter.trackUsage(response, 'cus_xxxxx');

Notes

• All packages support streaming, non-streaming responses, and automatic token tracking
• The AI SDK provider currently does not support tool calling, text embeddings, or image generation (graceful error handling included)
• Comprehensive test coverage and documentation included
• Requires access to Stripe's Billing for LLM Tokens Private Preview

[matv-stripe]

quick skim 1

[nm-stripe]

did a quick review as requested!

https://stripe.slack.com/archives/C08VDSYV666/p1761676405298589?thread_ts=1761606128.745229&cid=C08VDSYV666

[mpbagwell-stripe]

A mix of widely applicable suggestions!

[stevekaliski-stripe]

token-billing or token-meter/