Constant MAX_LINE_BYTES 

pub const MAX_LINE_BYTES: usize = _; // 10_485_760usize

Per-line byte cap. A single line above this size is truncated — prevents one unterminated multi-gigabyte line from OOMing before max_lines helps. 10 MiB comfortably covers the largest real-world log lines (long stack traces, flattened JSON payloads) without letting a hostile stream run away.