beef 0.5.2 is a compact Cow replacement: 3-word beef::Cow (vs std's 4-word) and a 2-word beef::lean::Cow on 64-bit that packs length and capacity into one word. Small targeted unsafe for Vec::from_raw_parts round-trips; CI runs miri with strict-provenance. One low-severity correctness finding: lean::Cow borrowed constructors silently truncate length above 2^32, while owned constructors panic — an inconsistency the docs don't address.