pub type MatchSlices = (String, String, String);Expand description
(before, matched, after) slices around a match. Used by the VM to push a
BufferEventKind::Matched describing how the cursor advanced.
All three strings carry the full bytes around the match, untruncated.
The viewer reconstructs each shell’s append-only buffer from the grew
stream and validates that before + matched + after equals the
currently-unmatched buffer tail at the moment of the match.