Namespacing custom prompts

What feature would you like to see?

I'm working on supporting Codex CLI in https://github.com/bmad-code-org/BMAD-METHOD, which is a collection (fairly complex system, actually) of custom prompts. It would be really nice if I could have nested subdirectories under ~/.codex/prompts/ so that we could put our stuff into ~/.codex/prompts/bmad/ , so that we are not overwriting someone else's files. Would be even nicer if I could have nested subdirectories under that, to keep everything organized. Claude Code does that, it's pretty useful.

Example:
~/.codex/prompts/bmad/agents/dev.md exposed in Codex session as /bmad::agents::dev

Additional information

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