Koru Standard Library: the `explain` part of supervisor.kz — joined via `~part explain`; members land in koru_supervisor. `supervised` is the most elaborating surface in std: the arm you write retargets the call that produced its branch (retarget_producer), the outcome dispatch moves to a generated step tor, and every name inside a re-entry expression resolves in the STEP's scope — the attempt's inputs and the retry counter, not the caller's. The explainer lifts exactly that: per site it reports the producer, the child's declared vocabulary (a void branch stays void), the step tor and `#`/`@` fold the site becomes, the policy it read, and which names the re-entry expressions actually rebind. Then it shows the work: the program is cloned, the real transform pass runs over the clone, and the generated step decl + the retargeted home flow print through the canonical AST printer (src/ast_printer.zig). The elaborated view cannot drift from the transform — it IS the transform's output.