const PREVIEW_TAIL_BYTES: i64 = 4096;Expand description
Bounded tail window read directly off the live FileStore file in
last_line_preview_and_activity’s fast path — deliberately small
relative to a whole session (which can be many MB): only needs to
comfortably contain the single last non-blank line, not search for a
specific frame shape the way LAST_ERROR_TAIL_BYTES’s window does.