A check that catches invisible characters before they ship

A no-break space or a zero-width space pasted into a regular expression is invisible in the editor, invisible in the diff and invisible in review — and if a later copy-paste flattens it to a plain space, the code still compiles and quietly stops matching the zero-width space, which \s does not cover. That bug was written twice here inside two days, and one of the two shipped. npm test now scans every .ts, .mjs, .js and .py file in the repo outside archive/ for literal invisible characters and fails with the file, the position and the escape to write instead; the structure skill carries the rule alongside the whitespace-trimming guidance it belongs with. Archived snapshots, published CSVs and the copied upstream issues are deliberately exempt: what a source actually said is evidence, not a defect.