Constant WS_TRAILING 

pub const WS_TRAILING: u16 = _; // 128u16

B2.2 (2026-06-04): trailing-whitespace marker. Set in addition to WS_MARKER when the marker glyph stands in for whitespace after the last non-blank char on the line (or on an all-blank line). Lets a consumer resolve the trailing-whitespace foreground (theme.whitespace_trailing_style) from the run/cell alone — the DisplayLine model carries no byte positions, so without this bit a DisplayLine → CellMatrix projection could not reproduce the cell path’s trailing-red.