On a phone, we don't have any room for the side rail -- but we don't want to stick all the side rail stuff at the top of the screen for everyone. Flow can be a perfect discussion tool for users on phones, but it's not a good experience for users to scroll down past all the metadata boxes.
For phones and small browsers, shrink the side rail down to a collapsible tab, as seen in the mockup. The text says:
10 notes on this discussion
with "10" being the number of templates in the side rail.
When the user taps/clicks on the tab, it opens to display the full side rail. When it's open, you can tap on the "10 notes on this discussion" label to close it again.
Default will be collapsed, with a sticky preference for logged-in users.