This is basically the React docs distilled into a decision tree for when you actually need useEffect versus when you're reaching for it out of habit. It covers the common antipatterns like using Effects for derived state or event handling, then shows you what to use instead: direct calculations, useMemo for expensive ops, key prop for resets, and plain event handlers. The quick reference table is especially useful during code review when you spot someone setting state in an Effect that should just be computed during render. Honestly, most useEffect bugs come from using it when you don't need an external system at all.
npx skills add https://github.com/davila7/claude-code-templates --skill react-useeffect