Handle "split" programs.
Channel5 in the UK has a habit of splitting films into two parts. When viewing the first part in Kodi the program length is shown as the combined length of the two parts, but only contains the first half of the film. If you select both parts for recording from the epg and you include "%n" in the path specification you will end up with two files, with the second containing "-1" from the "%n" specifier. This is fine, you can watch the complete film by watching both files, so long as you remember to record both parts.
You can set up an autorec on the first part, which will record the second part, but this is better used for actual series recording. Both parts have identical uris in the epg, so it would be nice if tvheadend set a timer for both parts if either was selected from the epg. This is assuming that epg uris are unique (except when a program is split into multiple parts).
It would also be very helpful if there was a new path specifier, say %N, which was a "part count" which would add "pt<n>" to the filename if a multi part program is selected for recording. This would then trigger kodis "file stacking" logic which would treat the multiple parts as one program.
If you do this file renaming manually and tell TVH using dvr/entry/filemoved, it seems to work quite well, although it does upset the new advert break indicators in Kodi 19 although the actual advert breaks are actioned correctly, it is just the display which is wrong.