i'd heard people report this and seen recorded evidence that it existed but had never even come close to reproducing it. the reports we got covered effectively every single possible combination of browser and OS. there was no commonality we could find in the reports other than "no one on staff has ever experienced it and can not figure out how to reproduce it."
TURNS OUT there was a missing piece of the puzzle: the only users impacted weren't cohost plus subscribers. i discovered this tidbit this morning and it immediately set everything into place.
we check for cohost plus status exactly twice in the post editor: to determine which emoji should show up in the picker, and to display the text reminding you that your upload limit is 10mb. that last one has the unintended effect of making the inherent content width wider than the max width (65ch), making the post composer max width by default. even though we thought we had our CSS right, if that paragraph wasn't there then the composer started reeeeeally narrow and got wider as you typed. we had never noticed this because everyone on staff has cohost plus.
the moral of the story: css sucks sometimes. bugs are weird. good luck writing software that works for everyone all the time.
(side note: this is my first change to cohost in like two months. sorry to my coworkers that i touched the codebase even though i was expressly told not to.)
wait holy shit i thought this was intentional and was just mildly annoyed at it
