Thanks for the chance to clarify. In the language of system requirements:

Designating and assembling one or more chests to receive incoming loot prior to filing, aka the Big Box(s) of Unfiled Stuff shall be done by the player.

Putting items into the bbus shall be done by the player.

Grouping items in the bbus into stacks shall be done by the game.

Rejecting an item when there is no more room shall be done by the game.

Taking stacks out of the bbus to file in permanent filing shall be done by the player.

Note that the game already does what it is required to do. The benefit to the player is that filing things in (automatically assembled) stacks is more efficient than filing them as they come in. The time you save can be startling if you to stick to the system and resist the temptation to file things as they come in.