I've been playing around with the "Superpowers" [0] plugin in Claude Code on a new small project and really like it. Simple enough to understand quickly by reading the GitHub repo and seems to improve the output quality of my projects.
There's basically a "brainstorm" /slash command that you go back and forth with, and it places what you came up with in docs/plans/YYYY-MM-DD-<topic>-design.md.
Then you can run a "write-plan" /slash command on the docs/plans/YYYY-MM-DD-<topic>-design.md file, and it'll give you a docs/plans/YYYY-MM-DD-<topic>-implementation.md file that you can then feed to the "execute-plan" /slash command, where it breaks everything down into batches, tasks, etc, and actually implements everything (so three /slash commands total.)
There's also "GET SHIT DONE" (GSD) [1] that I want to look at, but at first glance it seems to be a bit more involved than Superpowers with more commands. Maybe it'd be better for larger projects.