I'd like to bring your attention to this old issue:
I have a fairly long list of old printed gcode files on my octoprint instances, but often they have generic filenames and it's hard to remember what they were after a while. I wish the file browser could give me more information about existing files!
I would like to suggest a different variant of the proposed thumbnail feature that should be easier to implement than STL/gcode previews, where OctoPrint just snaps a still from the webcam at the end of a print and associate a small icon of it with each file. It would allow more types of file lists, with icon views, gallery views etc. It would also allow previews for the timelapse download list.
Something along the lines of with the ability to click to zoom in.
Another addition that I would really love to see in the file browser is the ability to sort the file list by "copies printed" .. I don't know how OctoPrint tracks the success status of each uploaded file today, but perhaps this metadata can be extended with more fields like copies printed, previous print duration, previous failure type and so on?