Embed paid AI features in your SaaS

const billing = await sdk.spaces.endUserBilling.update("acme-prod", {
  stripeWebhookSecret: process.env.STRIPE_WEBHOOK_SECRET!Keystash verifies Stripe signatures before granting spend.,
  endUserIdSource: "metadata",
  endUserIdMetadataKey: "keystash_end_user_id"Stripe checkout metadata field that tells Keystash which SaaS user to fund.,
  spendAmountSource: "metadata",
  spendAmountMetadataKey: "keystash_spend_usd"Stripe metadata field that defines how much runtime spend to grant.
});

console.log(billing.webhookUrlResult: https://api.keystash.dev/api/spaces/acme-prod/end-user-billing/stripe/webhook);

{
  type: "checkout.session.completed"Keystash handles the completed payment once per Stripe event id.,
  data: {
    object: {
      metadata: {
        "keystash_end_user_id": "user_123"Match the same user id you pass when minting browser runtime sessions.,
        "keystash_spend_usd": "25"Result: Keystash creates or tops up that user's spend record with $25.
      }
    }
  }
}

const result = await sdk.runtime.invoke({
  operationId: "op_live_abc123"Use the same feature id that the publishable key and runtime session were scoped to.,
  input: {
    ticket: "Customer asks for refund after duplicate charge."
  }
}, session.token);

const summary = result.outputTextResult: "Duplicate charge. Refund likely. Escalate billing.";
const billedTokens = result.usage.totalTokensResult: 248 tokens. Usage is tracked against that user and deducted from remaining spend.;
const model = result.modelResult: openai/gpt-5.4-mini as configured in the hidden feature.;