It’s invisible on screen. It prints correctly. But when text is extracted from the PDF — by an accessibility checker, a search engine, or a copy-paste — U+00AD surfaces as a garbage character between syllables. Here’s what it is, where it comes from, and how to find it.
Producing a PDF/X-4 press-ready file from LuaLaTeX without touching Ghostscript: the pdfx package, TrimBox/BleedBox geometry in points, FOGRA39 OutputIntent, CMYK-only color discipline, and XMP metadata — everything a print shop will verify.
