Constant MAX_LOG_TAIL_BYTES 

pub const MAX_LOG_TAIL_BYTES: usize = 4096;

Byte cap for status.logTail (and the stderr tail inside FailureBlock): the mover truncates to the LAST MAX_LOG_TAIL_BYTES bytes before patching status, so a noisy kopia run can’t bloat etcd. Full logs live in the mover Job’s pod. ADR §3.4/§4.10.