> Why “ghbdtn” means “привет”: how wrong-layout text happens

If you write in both English and Russian, you have seen it: you start typing a message, look up, and the screen says “ghbdtn” instead of “привет”, or “руддщ” instead of “hello”. Nothing is broken. Your fingers pressed the right keys — macOS was simply using the other input source.

> One key, two letters

A physical keyboard sends key positions, not letters. The active input source decides which character each position produces. On the US layout the key to the right of Tab is “q”; on the Russian ЙЦУКЕН layout the same key is “й”. Every letter key has such a pair:

q w e r t y u i o p [ ]
й ц у к е н г ш щ з х ъ

a s d f g h j k l ; '
ф ы в а п р о л д ж э

z x c v b n m , .
я ч с м и т ь б ю

So “привет” typed with the English layout active becomes g-h-b-d-t-n, because п sits on G, р on H, и on B, в on D, е on T and т on N.

> Why it is always reversible

The mapping is one-to-one: each key position yields exactly one character per layout. That means wrong-layout text loses no information — converting it back is a lookup, not a guess. The hard part is deciding when a word was typed in the wrong layout, because “ruby” is a valid English word and also the keys for “кгин”.

> How TextSwitcher decides

TextSwitcher looks at a finished word (after a space or punctuation) and asks whether it is plausible in the current layout or much more plausible after conversion. Real words and common letter combinations score high; key sequences like “ghbdtn” score near zero in English but form a common Russian word. Only clear cases are corrected, and everything happens on your Mac.

You can try the same conversion manually with the online keyboard layout translator on this site.