Adi S

While building LangSwap, I kept the financial rule deliberately simple: reserve the worst-case provider cost before execution, settle the actual returned usage, refund the unused reserve, and refuse the call before upstream spend when the balance is insufficient.

The difficult parts are not the checkout button. They are retry-safe meter events, signed and idempotent webhooks, reconciliation, failed-request releases, explainable ledgers and preventing a pricing rule from turning heavy usage into a negative margin.

I have packaged that work as fixed-scope Stripe and AI billing audits and implementations performed in the customer's own environment. No secrets are required before scope confirmation, and the engagement is paid upfront at a fixed price.

If you run token-, credit- or event-based billing, which edge case is currently costing your team the most time?