Move, clone, and Copy

Not every assignment moves heap data.

Trait / type	Behavior	Example
Copy	Bitwise duplicate on stack	i32, bool, [u8; 4]
Move	Transfer ownership	String, Vec<u8>
Clone	Explicit deep copy	payload.clone()

Use OwnershipVisualizer — toggle Move vs Borrow to see when the original stays valid.

When to clone in services

Clone when two parts of the pipeline need independent copies (e.g. log message + Kafka payload). Prefer borrow when reading without taking ownership.

Cost awareness

Cloning large JSON payloads on every webhook adds CPU — structure types so you move once into Kafka.

Teach-back prompt

Why is let n = counter; counter += 1 valid for i32 but not for String?