First, thanks for this mod! Oh how I wish I would have discovered it a couple weeks ago, it would have saved me literal hours (full explanation below suggestion if you are interested).
Suggestion: Copy output to circuit condition similar to arithmetic/decider combinator.
Explanation: Your mod will currently allow you to copy from an Assembling Machine to an arithmetic or decider combinator, prefilling the item box with the output item. I'm suggesting that same functionality, but with enabled circuit conditions like a circuit connected inserter.
Example Use: For many designs, a circuit connected inserter is used to limit production (for example, in a mall). It would be neat if by copying from the assembler and clicking on that circuit connected inserter, the enabled condition was preloaded with the output item.
My use case: I designed a mall in SE that uses long columns of warehouses interconnected by filter inserters that can pass any item anywhere in the chain. To do that, I designed a circuit network that required each warehouse have a combinator to specify which items were needed. So I manually entered hundreds of items on combinators - and with your mod I could have done that with two clicks. But, like most malls, I also use an inserter to limit production of each item so the warehouse/chest doesn't fill to the brim with the item. In my particular use case, it's Item > 0 so that change would solve 100% of the problem. But even for a more traditional mall, it takes out the searching, and you'd only need to enter the number.
Thanks again!