Letter case is a mapping, not a one-byte switch. CaseShift iterates code points and reports both sides instead of assuming equal length.
One character can become two
For example, an uppercase mapping may turn ß into SS. The output is correct under the selected platform mapping but is longer in code points.
Normalization is not hidden
CaseShift does not compose or decompose combining marks. It changes case only, so visually similar inputs may retain different code-point sequences.
Check locale and destination behavior
The active interface locale is part of the case-mapping contract, while the tool never detects the language of pasted text. Repeat a representative sample containing accents, an acronym, a proper name, a digit, punctuation, and an emoji. Compare the visible output and both code-point totals. Then paste into the real editor and check whether that editor applies normalization, autocorrection, smart punctuation, identifier rules, or another rewrite after CaseShift has finished.