Answer by Kamil Maciorowski for How do I specify tmux terminal-features in my config like I do with "-T"?

In a shell inside tmux invoke

tmux show-option -s terminal-features

In my case the above command prints:

terminal-features[0] xterm*:clipboard:ccolour:cstyle:focus:titleterminal-features[1] screen*:titleterminal-features[2] rxvt*:ignorefkeys

The first entry means that if my $TERM when starting a tmux client matches xterm* (e.g. it's xterm-256color) then inside tmux the command tmux display -p "#{client_termfeatures}" will print a comma-separated string containing (but not necessarily limited to) entries clipboard,ccolour,cstyle,focus and title.

If I want to add hyperlinks to this array, I need to invoke

tmux set -as terminal-features 'xterm*:hyperlinks'

Then I have to detach the client (prefixD, where prefix is by default Ctrl+B) and attach anew (tmux a). Then tmux display -p "#{client_termfeatures}" will include hyperlinks.

In ~/.tmux.conf the line will be:

set -as terminal-features 'xterm*:hyperlinks'

In practice this method does not give me the hyperlink support because my setup without tmux does not support hyperlinks anyway. I understand you've got it covered, so the method should work for you. But you need to adjust the line to $TERMyour tmux client will see. E.g. if your $TERM outside tmux is gnome-256color then use gnome* instead of xterm*.

You can even use * instead of xterm* to make tmux enable hyperlinks for any value of $TERM seen by the client. It will be like using -T hyperlinks unconditionally. I'm not sure what can go wrong if you enable the feature in tmux when the terminal of the tmux client does not support it. Settings things up in a way that only enables hyperlinks when hyperlinks are really supported seems neater.