Function is_multi_file_layout 

pub fn is_multi_file_layout(rel_path: &Path, qualified_name: &str) -> bool

v0.132: does rel_path (src-stripped) place qualified_name under a directory of that name — the multi_file_match branch of unit_path_matches?

This is the layout where production emits out/<name>/*.ts per file and no aggregate out/<name>.ts, so the test path’s import * as ns from "./<name>.js" dangles and needs an aggregating barrel. A single-file commons (<name>.bynk) already owns out/<name>.ts and returns false, so a barrel keyed on this predicate can never collide with it.