Function create_model_provider_from_ref 

pub fn create_model_provider_from_ref(
    config: &Config,
    name: &str,
) -> Result<Box<dyn ModelProvider>, Error>

Build a bare (non-resilient) provider named by name - a bare family ("llamacpp"), a dotted alias ("llamacpp.text_model"), or a custom:<url> ref - resolving its alias-specific runtime options from config: the vision capability override, the endpoint URI, and per-alias credentials from [providers.models.<family>.<alias>].

Unlike the legacy create_model_provider(name, None) (which passes config = None and ModelProviderRuntimeOptions::default(), so it cannot see any per-alias config), this honors the alias’s vision override and typed config while returning an un-wrapped provider - the shape the dedicated vision route needs so its configured [multimodal] vision_model_provider respects a per-alias vision = true/false.