NOTE: Coding style guide for this file: This model runner is shared by all models: text and multimodal, generative and embedding, public and private. As a result, this file must only contain code that is common to every model. Model-specific behavior belongs in the appropriate model-specific files.
In other words: * Be paranoid about changing this file. It should remain stable. * Be even more paranoid about adding new lines. It should remain minimal.
Even for shared features (for example, different parallelism modes), keep the complexity out of this path. The less common the feature, the more it should be hidden. Prefer utility functions defined elsewhere and call them from here, instead of embedding feature-specific logic directly.