Minimal I/O: write/1 writeln/1 print/1 nl/0 -- canonical functor(args) text via Episteme.Term.to_text/1 (no operator-aware pretty-printing yet) -- plus format/1,2, a directive-based formatter over the same to_text/1 rendering. Each succeeds exactly once, side effect aside.

format/2's own directive set is deliberately a practical subset, not ISO/SWI's full one -- no column/radix directives (~t, ~|, ~Nr, ...), no numeric-prefixed ~Nd (SWI's "insert a decimal point N digits from the right"). ~w/~p/~q are all the same thing here (to_text/1), since there's no operator-aware or quoted writer to tell them apart with yet -- see write/1's own note above.