On an Amazon Bedrock OpenAI-compatible connection, GPT-5.6 and GPT-6 models have ids like `us.openai.gpt-6-sol` or `openai.gpt-6-luna`. These were not recognised as new OpenAI models, so `max_tokens` went upstream unchanged and Bedrock rejected it with a 400. Title and emoji generation failed on every chat, and any request with a token limit failed too. Setting `max_completion_tokens` by hand did not help, because non-OpenAI URLs convert it back to `max_tokens`.
`is_openai_new_model()` now drops a leading `openai.` or `<region>.openai.` (`us.`, `eu.`, `global.`, `us-gov.`) before matching, so these ids get the same handling as bare `gpt-5` ids. Ids that are not new models, such as `openai.gpt-oss-120b-1:0` and `gpt-4o`, are unchanged, and so is the LiteLLM `openai/` prefix.
Fixes#30510