Constant BYTES 

pub const BYTES: usize = _; // 4_194_304usize

The most rendered recording a run may accumulate, in bytes.

Four mebibytes of JSON is roughly what a browser will postMessage and JSON.parse without a visible pause. It is a second bound and not a replacement for the first, because the two fail on different programs: this one catches a few enormous moments, and MOMENTS catches many small ones.