Reading wider or differently-signed integers kept the low bits: i64 2^40+5 read as i32 was 5, u64::MAX read as i64 was -1, and -1 read as u64 was 4294967295. u32 data read as i32 also took the bulk-copy fast path meant for i32. Saturate at the target range like libhdf5's hard conversions (a negative value read as unsigned is 0), and keep the i32 fast path to signed data. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>