• prompts now state the date format (YYYY-MM-DD / .YYYYMMDD); date card shows the composed answer so it's solvable from Tab without failing first
• accept true equivalents: wc -c < f for size in bytes, simpler charclasses for lines-with-numbers
• grader folds grep -E/-F/-P + egrep/fgrep on a literal to plain grep, and useless-cat (cat f | filter) to the direct form