big fan of this feature on twitter desktop web. i even tried doing this on social-app twice but it was really bad. now that i own the codebase i should be able to do this better!
things to note, this is a real page so it needs real paths / routes but it is also a modal / overlay so it also needs to show the previous route below it. this is the big annoying thing that makes it very complex and ill need to explore if this is possible to do on tanstack router
https://tangled.org/@whey.party/red-dwarf/commit/55f010da6268c6ae60dcd476fe0450bc20ea62d8
initial routeless version now exists. it feels really weird that the lightbox sidebar arent part of the navigation history