Build a BigCommerce custom app using storefront API tokens to implement a headless B2B quote request workflow

Steps

1. Create a BigCommerce custom app in the Developer Portal and implement the OAuth install callback to store the access token and store hash for the merchant account
2. Generate a storefront API token with the appropriate customer impersonation scope using the Management API token endpoint, scoping it to the logged-in B2B customer's ID
3. Build a quote cart by cloning the customer's current cart via the Carts API, adding a custom line item note field for quote reference, and tagging the cart with a custom status via a script tag injection
4. Submit the quote by converting the cart to a draft order using the Orders API, setting the order status to a custom status that bypasses payment collection and triggers a sales rep notification webhook
5. Implement a quote approval flow where the sales rep updates the order's line item prices and custom discount via the Order Products endpoint and changes the status to pending_payment
6. Notify the B2B customer via the BigCommerce transactional email trigger or an external email provider that the quote is approved and ready for payment, linking them back to a payment URL generated by the Checkout API