Because there is no .desktop file, and my test desktop is built without a terminal emulator, I tried running cappuccino as root:
bash$ ssh root@bootstrap2020 'DISPLAY=:0 XAUTHORITY=$(echo /var/lib/xdm/authdir/authfiles/*)' cappuccino
Warning: Permanently added '[localhost]:2022' (ED25519) to the list of known hosts.
__main__.py:148: PyGIDeprecationWarning: GObject.timeout_add is deprecated; use GLib.timeout_add instead
/bin/sh: 1: polygen: not found
__main__.py:72: DeprecationWarning: Gtk.Alignment.set is deprecated
/bin/sh: 1: polygen: not found
__main__.py:84: PyGIDeprecationWarning: GObject.timeout_add is deprecated; use GLib.timeout_add instead
__main__.py:85: PyGIDeprecationWarning: GObject.timeout_add is deprecated; use GLib.timeout_add instead
/bin/sh: 1: polygen: not found
Traceback (most recent call last):
File "__main__.py", line 107, in update_log
IndexError: pop from empty list
/bin/sh: 1: polygen: not found
This is happening because /usr/games/polygen is not in the default $PATH unless you 1) log in as a non-root user; and 2) pass through PAM session.
In the above case, neither (1) nor (2) happens.
For (2) it does not happen because "ssh host command" bypasses the login shell.
These situations are unlikely to occur, but given the failure
behaviour is pretty weird, I think simply hard-coding the default path
to "/usr/games/polygen" instead of "polygen" would suffice.
The manpage didn't suggest any CLI option to easily work around this.
PS: note that cappuccino itself is NOT installed in /usr/games/.
Moving it there would, I guess, be an equally easy fix.