It is great, I love the attention you are putting on the UX!

I would suggest to make this function more visible adding two distinct buttons on the top left ("new post" is obvious, it could be removed to save space): minimize and discard; the slidedown gesture can a be a more discoverable adding a tooltip "do you know..." the first 2/3 times the user use the minimize button.

Finally I would make the bottom sticky bar purple, to highlight the ongoing edit.