Function sanitize 

pub fn sanitize(s: &str) -> String

Replace every character that could forge the shape of a digest with a space, so a value read out of the graph cannot fake a line break, a section header, or a terminal escape sequence — and cannot reorder or hide what it sits next to when rendered.

Three classes, and each is the class rather than the examples: neutralising only U+202E would leave U+202D, and only U+2028 would leave U+0085.

• ASCII controls 0x00-0x1f and 0x7f, tabs and newlines included.
• Line and paragraph separators outside ASCII: U+0085, U+2028, U+2029.
• Bidi controls and zero-width characters: U+200B-U+200F, U+202A-U+202E, U+2066-U+2069, U+FEFF. These reorder or conceal rendered text without changing the bytes a reader would diff.

One char in, one char out, so a caller’s character budget is unaffected and the byte length can only shrink — never grow.