This is a Proof Of Concept of a feature I miss in VLC: "stop after this track"

stop-after-this-track.lua

--[[

This is a Proof Of Concept of a feature I miss in VLC: "stop after this track"

This is my first time hacking VLC, so I have some questions:
1) Is "descriptor().description" useful? (I can't find how it is used by VLC)
2) When is "meta_changed()" called and what is it supposed to return?
3) Is there a VLC Lua API's documentation? (I read https://www.videolan.org/developers/vlc/share/lua/README.txt but I had to pick up some stuff from existing extensions on GitHub to get this done)
4) Is there a "standard" way to handle localization?
5) Is it possible to add an entry to the tray icon's context menu? (How?)

]]

function descriptor()
	return {
		title = "Stop after this track",
		version = "1.0.0-alpha",
		author = "David Sferruzza",
		shortdesc = "Allows you to tell VLC that you want to stop when the current track is over",
		description = "Allows you to tell VLC that you want to stop when the current track is over", -- Is this really useful?
		capabilities = {"input-listener"},
		url = "https://github.com/dsferruzza",
	}
end

function dbg(m)
	vlc.msg.dbg("[" .. descriptor().title .. "] " .. m)
end

function activate()
	if vlc.input.is_playing() then
		dbg("Stopping after the current track")
		vlc.osd.message("Stopping after the current track", nil, nil, 4 * 1000000)
	else
		dbg("Player is already stopped")
		deactivate()
	end
end

function deactivate()
	vlc.deactivate()
end

-- I'm not really sure what is the point of that, but I get an error if it's not there
function meta_changed()
	return false
end

-- This will be triggered when the extension is activated and the current track changes
function input_changed()
	dbg("Stopping")
	vlc.playlist.stop()
	deactivate()
end

Seems it doesn't work.
I copy this script to vlc extensions, start vlc and play a track, meanwhile I call lua stop-after-this-track.lua, but nothing changed after the end (the next played, as before).
The script gave no output, the return code was 0 (which is normal return in bash).