drag and drop api

an instance of a tool with a specific doc might be a container for other kinds of docs, or patchwork-view elements, or views over docs, or items from a dock. if i drag a todo item from one todo list into another, that should work. a todo project can contain items, but todo items cannot contain projects. but a todo item's title/body might be able to contain a ... what are you dragging? are you copying, linking, moving? copying the item, or copying the item's contents? how does the dragged thing present what it contains? how do i select multiple items and drag all of them? where is the "currently selected items" state? what is in that state? is that the same as the drag api contract? at what level of granularity can you drag multiple things? if i select two files in the sidebar, should i be able to drag them together (yes) what about two rectangles in a tldraw? what about two rectangles from two tldraws? what about two todo items each from a different list? what about if the sidebar is showing multiple folders? what if those folders are rendered by different tools? what about things that are not containers, but are lists? what about lists that maintain a specific order of items? what about things that can be dragged above or below or on? what about opening a container by hesitating? what about when the droptarget is able to contain several of the things offered by your drag, how do you choose which one (say a tldraw can embed the `` OR the contents themselves)? what about when it can contain only one? what about dragging to the desktop? what about dragging from the desktop? is that the same as importing and exporting a file? if i drag a todo item out of a list onto the desktop, what is that? is it data? text? an automerge doc? html? an image? how do i choose?