Solving grid-snapping can be hours of fun, and not always as obvious as it seems—is the grid visible, does it only appear on interaction, how does it scale, is it dots, lines, what's the margin, sensitivity, hinting, and what about light mode, & all sorts of other weird stuff. 

Here are some UX explorations & motion tests created to communicate ideas with the dev team.

In this example, the drop hint inherits the status color of the task that comes after (in the event that either is off-screen for a particular user), and on drop adds a secondary lock-in visual confirmation. 

Here's an exaggerated row highlighting example:

In this example, I work through a few ideas, such as backward connections, a gooey column hinting interaction, collision reaction, hover and active feedback, directional pivot and drag, and a softer glue-like drop.

Some Prototypes / click on titles to cycle through variations