setlocale(LC_ALL, "") maps to the ANSI code page on Windows -- 936 (GBK)
on a Chinese system -- so wcrtomb() produces GBK where the protocol wants
UTF-8, and mbrtowc() reads UTF-8 as GBK. Typed Chinese therefore reached
the model as mojibake, and once the buffer held correct UTF-8 the input
line rendered as mojibake instead. Windows' C runtime has no ".UTF-8"
locale to switch to, so the conversion has to be explicit.
os_compat.[ch]
* add os_utf8_encode() and os_utf8_decode(), locale-independent, with
range and overlong-form checks
src/tui.c
* input_put_wc(), the command-palette filter and the ask_user buffer use
os_utf8_encode() instead of wcrtomb()
src/textsel.c
* cst_utf8_decode() uses os_utf8_decode() instead of mbrtowc()
XYZ