You're nerd sniping me, #MDN, don't you!?
Native messaging #API
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Native_messaging
"Native messaging enables an extension to exchange messages with a native application, installed on the user's computer. The native messaging serves the extensions without additional accesses over the web."
"On the native app side, messages are received using standard input (stdin) and sent using standard output (stdout)."
So many possibilities! 
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