OpenCode would be nicer if they used normal terminal scrolling and not their own thing :(
Terminal scrolling opens a big can of worms for them, I doubt they'll ever implement it. The best you can do is enable scrollbars in opencode so you can quickly jump places.
It's a client/server architecture with an Open API spec at the boundary. You can tear off either side, put a proxy in the middle, whatever. Few hundred lines of diff weaponizes it.