Currently the spoiled versions of a recipe's ingredients are added as shortcuts to the inserter into an assembler, while the spoiled versions of the recipe's results are shortcuts for the inserter out of the assembler. But actually both of those should be shortcuts on the inserter out of the assembler, not the inserter into the assembler.
For example: Let's say you are using Roc's Rusting Iron which makes iron plates spoil into rusted iron plates. And you have an assembler doing plates -> gears. Currently your mod gives the inserter into the assembler shortcuts for iron plates and rusted iron plates. The inserter out of the assembler gets shortcuts for gears and rusted gears. But there is never any situation where I want to insert rusty iron plates into the assembler. On the other hand, there is a reason to remove rusty iron plates from the assembler (to send them onto another belt for de-rusting).
Another example, this time with no mods, only Space Age: if you have a biochamber doing the recipe jelly -> iron bacteria then an inserter into the biochamber will have a shortcut for spoilage, which doesn't make sense. Trying to whitelist that filter will make the inserter not do anything.
