Rust Memory and State

Use this when the question is really "who owns this, who may mutate it, and how long must it stay valid?"

Working stance

• Prefer one clear owner and cheap borrowed reads.
• Reach for cloning last, not first.
• If cloning appears mainly to placate the borrow checker, fix the data flow before keeping the clone.
• Treat Rc, Arc, RefCell, Mutex, and RwLock as ownership decisions, not syntax bandages.
• If a lifetime gets hard to express, ask whether the type should own the data.
• Use RAII to make cleanup happen by scope, not by hope.

Decision surface