> Great progress from Anthropic! They really shouldn't change models from under the hood, however. A name should refer to a specific set of model weights, more or less.

In the API (https://docs.anthropic.com/en/docs/about-claude/models) they have proper naming you can rely on. I think the shorthand of "Sonnet 3.5" is just the "consumer friendly" name user-facing things will use. The new model in API parlance would be "claude-3-5-sonnet-20241022" whereas the previous one's full name is "claude-3-5-sonnet-20240620"