add function to determine local files to cache

bibtex-actions.el

@@ -235,6 +235,21 @@ offering the selection candidates"
              collect (cdr (or (assoc choice candidates)
                               (rassoc choice candidates))))))
 
+(defun bibtex-actions--normalize-paths (file-paths)
+  "Return a list of FILE-PATHS sorted and normalized with truename."
+  (cl-sort
+   (delete-dups
+    (mapcar (lambda (p) (file-truename p)) file-paths)) 'string-lessp))
+
+(defun bibtex-actions--local-files-to-cache ()
+  "The local bibliographic files not included in the global bibliography."
+  ;; We cache these locally to the buffer.
+  (let* ((local-bib-files
+          (bibtex-actions--normalize-paths (bibtex-completion-find-local-bibliography)))
+         (global-bib-files
+          (bibtex-actions--normalize-paths bibtex-completion-bibliography)))
+    (seq-difference local-bib-files global-bib-files)))
+
 (defun bibtex-actions--format-candidates ()
   "Transform candidates from 'bibtex-completion-candidates'.
 This both propertizes the candidates for display, and grabs the