Skills are notably more complex than that. They require metadata (which the model is given and uses to determine whether or not to load the main file), are intended to be loaded via a tool call, contain extra resources (also loaded by tool calls), etc. In contrast, with this system the harness doesn't need a tool to load the stored prompts, the prompts don't need to include metadata to allow for runtime discovery, etc.
Runtime discovery is the entire point of skills. Without it, this is just a templating prompt system that the user has to remember to use… except because this one changes your system prompt, it also busts your cache and costs you extra money when you use a prompt.
Skills are already dead-simple and this prompt system doesn’t at all tackle the same problem.
this concerns me. Skills are already just about the simplest possible thing; they're just prompts, in a directory!