Model asserts a provider model "does not exist" after one incomplete API listing instead of cross-checking

While switching an image-generation pipeline to a newly released provider model (released 3 days prior), Claude Code (claude-fable-5) fetched the provider's public /models listing once — the first attempt returned non-JSON and was retried — did not find the model id, and then told the user the model "does not exist on this provider" inside a blocking multiple-choice question, offering three older models as the only options. The user had to disprove it with a screenshot of the provider's own model page; a follow-up authenticated request to the provider's per-model endpoint resolved the id immediately.

Expected: treat "absent from one listing response" as "not found via this endpoint" and cross-check (authenticated/per-model endpoint, web search, or ask the user what they saw) before asserting non-existence — especially for very recent releases, and especially when the same endpoint had just returned a malformed response in the same session.

Environment: Claude Code CLI, model claude-fable-5.