"Waiting for touch" notification

When it's waiting for a touch it just waits with no user notification
outside of the yubikey blinking. Since I have a Yubikey 4 Nano the
blinking is not always in view, which makes me type "ssh"/"git push"
and just stare at the screen.

Has anyone explored how to surface this "please touch the smartcard"
or something message to the user with opensc?

I can imagine an ugly solution where if there's an outstanding "sign"
operation for more than epsilon time, then maybe connect to this unix socket
and say something, or shell out to this command. I can then use that
to do something better than, but similar to, running:
  xmessage 'touch the yubikey'

[1] https://blog.habets.se/2016/01/Yubikey-4-for-SSH-with-physical-presence-proof

-- 
typedef struct me_s {
 char name[]      = { "Thomas Habets" };
 char email[]     = { "[email protected]" };
 char kernel[]    = { "Linux" };
 char *pgpKey[]   = { "http://www.habets.pp.se/pubkey.txt" };
 char pgp[] = { "9907 8698 8A24 F52F 1C2E  87F6 39A4 9EEA 460A 0169" };
 char coolcmd[]   = { "echo '. ./_&. ./_'>_;. ./_" };
} me_t;

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