chatgpt-image-latest shuts down Dec 1: pin a Sume model id

OpenAI's deprecations page lists chatgpt-image-latest as shutting down on December 1, 2026, with gpt-image-2.5-sunburst or gpt-image-2.5-flare as replacements. Sume's docs list no floating "latest" image id: pin a catalog id such as openai/gpt-image-2.5, or send sume/auto and let Image Router choose.

Vendor facts are from OpenAI's deprecations page; Sume facts from the Image API docs, read 2026-09-30.

Why is a floating alias risky?

An alias points at whatever the vendor decides, and then at nothing once it is retired. A pinned id changes only when you change it, and a retirement shows up as an error you can search for instead of a silent model swap.

Which Sume choice fits which need?

How do I find the ids I can use?

The docs' model discovery section points at GET /v1/images/models. Each row's id is the slug to put in the model field, and supported_parameters shows what that model accepts.

What does an old alias return on Sume?

An id outside the catalog gets a 404 model_not_found with the message "Unknown image model id." and a catalog_url pointing at /v1/images/models. If your client stored an OpenAI alias, map it to a catalog id once, in one place. See also migrating between 2 and 2.5.