Beyond Broken Billing: The Three Hidden Pitfalls That Destroy AI App Margins

Building a credit system for AI applications presents a deceptively complex challenge that most developers fail to solve correctly. The article identifies three critical mistakes—balance overdrawing from race conditions, double-granting from webhook retries, and forgotten refunds—that silently drain revenue and erode user trust. By moving validation from application code to database-level atomic operations and idempotency keys, these vulnerabilities can be permanently eliminated at the infrastructure level.