Function snap_to_nearest_corner 

pub fn snap_to_nearest_corner(
    pos: BubblePosition,
    window_width: i32,
    window_height: i32,
    monitor: MonitorBounds,
    snap_radius_px: i32,
    inset_px: i32,
) -> Option<(BubblePosition, Corner)>

If the bubble’s top-left is within snap_radius_px of any monitor’s nearest corner (measured corner-to-corner of the window vs monitor), snap to that corner’s exact position and return the snapped (BubblePosition, Corner). Otherwise None.

“Nearest corner of the monitor for this window position” means:

• Top-left → window’s top-left near monitor’s top-left
• Top-right → window’s top-right near monitor’s top-right
• Bottom-* → analogous

So the comparison is between matching corners of the window and the monitor. Snapping rewrites the window’s top-left so the matched corners align exactly (with optional inset — see inset_px).