(defun my-fixup-gpg-agent (frame)
  "Tweak DISPLAY and GPG_TTY environment variables as appropriate to `FRAME'."
  (when (fboundp 'keychain-refresh-environment)
    (keychain-refresh-environment))
  (if (display-graphic-p frame)
      (setenv "DISPLAY" (terminal-name frame))
    (setenv "GPG_TTY" (terminal-name frame))
    (setenv "DISPLAY" nil)))

(add-hook 'after-make-frame-functions 'my-fixup-gpg-agent)

;; Simple caching
(defvar my-cached-passwords
  nil
  "Cache of passwords. Stored in plain text so you only want to cache
  them if of low value.")

(defun my-pass-password (pass-name &optional cache)
  "Return the password for the `PASS-NAME'."
  (let ((cached-pass (assoc-default pass-name my-cached-passwords)))
    (if cached-pass
        cached-pass
      (when (selected-frame)
        (my-fixup-gpg-agent (selected-frame))
        (let ((new-pass (chomp
                         (shell-command-to-string
                          (format "pass %s" pass-name)))))
          (when (and new-pass cache)
            (add-to-list 'my-cached-passwords (cons pass-name new-pass)))
          new-pass)))))