Per-project org-agenda

For my personal projects I tend to keep a HACKING.org file where I write down project specific stuff. Adding each of those files to org-agenda-files would be tiresome plus I would see the information relating to every project each time I open the agenda. This would be a surefire way to get overwhelmed by the amount of information. Instead I use the following snippet to showing the project specific agenda when I'm inside a project that has a HACKING.org file.

(defun my/org-agenda-list ()
  (interactive)
  (cl-flet ((find-hacking-file ()
                            (let* ((tld (or (locate-dominating-file default-directory ".git/")
                                            (locate-dominating-file default-directory "HACKING.org")))
                                   (hacking-file (concat  default-directory "HACKING.org")))
                              (and (file-exists-p hacking-file)
                                   hacking-file))))
    (let ((local-agenda-file (find-hacking-file)))
      (if local-agenda-file
          (let* ((lexical-binding nil)
                 (org-agenda-files (list local-agenda-file)))
            (org-agenda-list))
        (org-agenda-list)))))