Hi. I was unable to find out how can I add a custom temperature line to temperature graph. Could you help me a little ?
That's a tough one. In theory, this is the file responsible for pulling the data together.
My guess is that this is something best done inside the core functionality of OctoPrint itself. And yet, one could in theory hook into the handler which updates the temperature graph and overclass it to add your own series of data.
Gina has talked about overhauling it in 1.4.x, it's a common request.