here's what i found: every AI coding environment i tested has the same structural bug when you type in Japanese.
not "some of them." all of them, across different codebases and different teams.
the bug isn't flashy. it doesn't crash anything. but if you type Japanese in an AI coding tool and wonder why it feels off, this is probably why.
what IME composition actually is
Japanese input works differently from English. you type roman characters to form a Japanese word, and the OS enters a "composition state" -- the text is provisional, unconfirmed. you press Enter (or a function key) to confirm the word and commit it to the field. the browser fires compositionstart, then compositionupdate as you type, then compositionend when you confirm.
