The character class used a single-quoted raw string with embedded ASCII single
quotes (r'[...""''...]'), which Python parsed as two implicitly-concatenated
literals — silently dropping the quotes from the class and emitting a
SyntaxWarning for \s. Switch to a double-quoted raw string so the class is a
single, correctly-closed character class. Adds a unit test asserting the class
is well-formed and contains all intended CJK punctuation + whitespace.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>