# IsGPTNerfed

A macOS menu-bar tool that checks whether Codex is actually using the model you selected, by reading Codex's own per-turn model records and periodically fingerprinting the live model with a bias test on random-number generation.

IsGPTNerfed watches Codex sessions for silent changes: a swapped model, a lowered reasoning effort, a hidden internal model, or a smaller context window, all read from the records Codex itself writes after each turn, at no extra token cost.

On a schedule it also forks the current session three times through the same app-server call Codex's desktop app uses for a side chat, asks each fork for about 300 "random" numbers, and compares the statistical bias of the answers against a calibrated fingerprint bank to identify which model actually answered. The verdict reports a match, an unconfident suspicious result, or a confident downgrade, upgrade or reroute.

A mismatch triggers a macOS notification, an in-session message and a menu-bar indicator. It runs entirely on the local machine, installs from a shell script or a downloaded disk image, and requires macOS 15 or newer.

Website: https://github.com/kiyoakii/is-gpt-nerfed