This is a decision framework for choosing between Box, Rc, Arc, and other smart pointers in Rust. It walks you through ownership patterns (single vs shared), threading context (Rc vs Arc), and cycle prevention (when to use Weak). The error table is smart, it reframes "use Weak" as "is the cycle necessary in design?" instead of just throwing syntax at you. The trace up/down sections connect pointer choices to broader architecture questions, which is useful when you're stuck deciding between Rc and Arc but the real issue is whether you actually need shared ownership at all. Comes with a flowchart and anti-pattern warnings about overusing Arc or RefCell everywhere.
npx skills add https://github.com/actionbook/rust-skills --skill m02-resource