Why drop items to the ground instead of having bots pick them up directly?

When using bots to remove items from a container (like a roboport), the bot targets a specific inventory slot position. If other items are removed between the bot receiving the order and arriving at the container, the inventory shifts — the bot may end up collecting the wrong item entirely. This is a race condition that gets worse the more items are being moved at once.

This mod drops items synchronously in a single game tick — everything happens instantly with no window for inventory positions to shift. Items land on the ground immediately, and from there normal logistics (bots, belts, or manual pickup) can move them wherever they need to go. This separation of concerns is both more reliable and simpler.

Why are there two separate items — the planner and the selection tool?

Ideally this mod would work like the vanilla deconstruction planner — a single item that both stores filter configuration and acts as a drag selection tool. However, that behaviour is hardcoded into the game engine for vanilla planner types and is not available to mods.

The workaround is two items:

Item Dropper Planner (item-with-tags) — lives in your inventory, stores filter configuration per instance via a unique item number
Item Dropper Selection (hidden selection-tool) — only exists in your cursor while dragging, discarded immediately after

When you click "Use", the planner is safely moved back to inventory and the hidden selection tool is placed in your cursor. After dragging, the selection tool is gone and your planner remains in inventory unchanged. From the player's perspective it behaves as one seamless tool.