As there were several posts requesting something that allows pre-setting filters on inserters, I decided to combine the ideas in a single post.

I have ideas in mind that could handle this request, and would like to get comments from users before implementing.

There will a toggle, whether a toolbar button, a held hotkey, or if robust enough, a mod setting, which will enable "smart pre-filtering", which will work as follows:

• An inserter pointing towards a belt/chest, will set a filter according to the outputs of the source and the items on the belt/chest. For example, an inserter pointing towards an ash belt will be set to ash. Research would be needed to see if we can filter by the drop lane.
• An inserter pointing towards a belt/chest, where a different inserter from that entity is already filtered, will be filtered by "what's left". For example, if another inserter filters ash, and this inserter is pointing towards a non-ash belt, it will be filtered by "not ash" or by the specific items.
• An inserter from an entity with multiple different items, pointing to anything other than a crafting machine, will be filtered to "whitelist". This is for entities such as platform hubs, landing pads, big mixed warehouses.
• An inserter pointing towards space will be filtered to "whitelist".

While it could be nice to change filters after the the inserter was placed, according to changing conditions e.g. a belt/assembler is removed, this can cause more chaos and would probably not be good.