At noon PDT on October 14, OpenAI removed GPT-5.5 from Codex for anyone accessing it through a ChatGPT sign-in, according to the company's changelog. The API version of GPT-5.5 was not touched. Codex is OpenAI's coding tool, and the split means the model did not disappear so much as it became unavailable through one specific login path while remaining fully reachable through another.
The decision that changes here is not whether GPT-5.5 exists, but which purchasing and authentication route keeps it working. Teams that wired Codex into their workflow through a ChatGPT account now have a model that simply stopped responding one afternoon. Teams that called GPT-5.5 through the API, billed on usage rather than a ChatGPT seat, saw nothing change. OpenAI did not disclose a reason for the removal or a timeline for whether other models face the same split treatment.
For procurement, the gap between the two access methods now carries real weight. A contract or internal tool built around ChatGPT sign-in was, as of that one changelog entry, subject to removal without the buyer initiating anything. A contract built around the API was not. Anyone evaluating Codex going forward has to ask which authentication path a given deployment uses, because that answer now determines how exposed the deployment is to OpenAI's own retirement schedule rather than to the buyer's own renewal cycle.
Operators running Codex in production should check, specifically, whether their integration authenticates through ChatGPT or through API keys, since those two paths now behave as separate products with separate lifespans. Switching from a ChatGPT-based Codex setup to an API-based one is not free: it typically means re-provisioning credentials, adjusting billing from seat-based to usage-based, and retesting whatever scripts or CI pipelines called the old path. None of that is disclosed in the changelog entry, which states only the removal and the carve-out for the API, leaving the operational burden for teams to work out on their own.
The lock-in risk here is subtle because it is not about switching vendors, it is about switching access methods within the same vendor. A buyer who assumed ChatGPT sign-in and API access were interchangeable now has evidence that OpenAI treats them as distinct products with independent retirement clocks. That distinction was not advertised ahead of time, it was learned from a changelog entry after the fact.
Buyers who want predictability out of Codex now have a concrete reason to default to API billing over ChatGPT sign-in, since only one of those two paths has shown it can be cut on a single day's notice.