Constant MAX_CAPTURE 

pub const MAX_CAPTURE: usize = _; // 1_048_576usize

The ceiling on any single captured buffer.

An agent can stream for hours; text, raw stdout and stderr would otherwise grow without bound and a long run would end in an OOM rather than an answer. A megabyte is far more prose than any consumer displays, and the fields this bounds are for reading and diagnosis, never for reconstructing the stream.