Reordering tracks inside a playlist had no client verb: addTracks takes only
[playlist_id, track_ids, no_duplicate] and appends, and updatePlaylistsPosition
reorders the user's PLAYLISTS, not the tracks within one.
The endpoint exists and is documented from a desktop web-player capture --
{playlist_id, playlist_track_ids, insert_before} -- not from the decompiled
Android route tables, which are not a valid source for this. Its exact argument
encoding is the one part no capture in the repo pins down, so every caller must
treat a failure as recoverable rather than fatal.
Written for the replacement flow, which needs the repaired track to land where
the dead one was instead of at the end of the playlist.
cc
vicrodh
8e52157299