Well... for the most part, you use it like skills, but instead of "commands" you can think of "environments": so '/prompt debug', which is one of the integrated prompts, allows for a debug-focused agent, you can then talk to it as a normal agent, and then '/prompt code' to go back to the standard coding agent.

About subagents: as of right now, the entire agent runs on one context buffer, so it doesn't support subagents in order to keep it lean; but there is a great chance that subagents will be added, as explore-heavy tasks often bloat the context window