How One Developer Built a Fraud-Resistant Guest AI Image Generation Flow

A developer building PicEditor, a browser-based AI image editor, designed a controlled guest flow to let visitors try AI image generation without creating an account while preventing abuse and runaway costs. Rather than using a simple boolean flag to track free usage, the system treats each guest request as a small distributed job with defined states: reserved, pending, processing, completed, and failed. Before any request reaches the model provider, the server runs sequential checks covering anti-bot verification, identity allowance limits, duplicate active jobs, and daily cost budgets to prevent race conditions from double-spending. A two-step reservation protocol handles identity slots and cost budgets separately, with an explicit rollback if either step fails. Access tiers — paid, free_first, and free_slow — are assigned per request so that workflow logic stays clean and guest history is preserved even after a user signs in.