theStoreDoesNotAliasTheArrayItWasGiven

The store must copy what it is given, not keep a reference to the caller's array.

The caller owns the array it passed and is entitled to reuse it — a buffer pooled across writes is the ordinary reason to. A backend that keeps the reference has a stored value that changes underneath it with no write, which is unattributable from the caller's side because nothing appears to have happened.

The mutation is applied before the read rather than after, so a backend that copies lazily on read is caught too.