hermes - 💡(How to fix) Fix Named custom /model switches bypass custom endpoint routes [1 pull requests]

Bug

When the active provider is a named custom provider such as custom:bifrost, /model <bare-model-name> can be rewritten to a native provider before the custom endpoint sees it.

Example:

/model deepseek-v4-pro

on a Bifrost/OpenAI-compatible custom endpoint switches to native deepseek because provider autodetection treats custom:bifrost differently from bare custom.

Impact

Custom gateways and proxies can define route aliases or fallback chains for bare model names. If Hermes rewrites the model to a native provider first, those gateway routes never run, and validation happens against the wrong provider catalog.

Expected behavior

Named custom providers should behave like custom: keep the model switch on the current endpoint unless the user explicitly chooses another provider.

Reproduction shape

1. Configure a custom provider named bifrost with base URL https://.../v1.
2. Make it the active provider as custom:bifrost.
3. Run /model deepseek-v4-pro.
4. Hermes switches to native DeepSeek instead of keeping the request on custom:bifrost.