notmuch: Add function to sync tags

.emacs.d/lisp/init-notmuch-sync.el

@@ -0,0 +1,33 @@
+;; TODO: Report notmuch dump/tag sync technique upstream.
+(require 'seq)
+
+(unless (boundp 'notmuch-command)
+  ;; So that this file can be use in external scripts without require
+  ;; notmuch.el.
+  (setq notmuch-command "notmuch"))
+
+(defun notmuch-all-tags ()
+  (split-string
+   (with-output-to-string
+     (with-current-buffer standard-output
+       (call-process notmuch-command nil t
+                     nil "search" "--output=tags" "--exclude=false" "*")))))
+
+(defvar notmuch-unimportant-tags '("attachment" "deleted" "draft" "encrypted"
+                                   "flagged" "inbox" "passed" "replied" "sent"
+                                   "signed" "unread"))
+(defvar notmuch-dump-file (expand-file-name "~/personal/mail/notmuch.dump"))
+
+(defun notmuch-dump-important-tags (&optional file)
+  "Dump notmuch tag database to `notmuch-dump-file'.
+Messages with only `notmuch-unimportant-tags' are ignored."
+  (interactive)
+  (setq file (or file notmuch-dump-file))
+  (let* ((important-tags (seq-difference (notmuch-all-tags) notmuch-unimportant-tags))
+         (tags-arg (cons (concat "tag:" (car important-tags))
+                         (cl-loop for tag in (cdr important-tags)
+                                  append (list "or" (concat "tag:" tag))))))
+    (apply 'call-process notmuch-command nil `(:file ,file) nil
+           "dump" tags-arg)))
+
+(provide 'init-notmuch-sync)

.emacs.d/lisp/init-notmuch.el

@@ -2,6 +2,7 @@
 
 (require 'init-message)
 (require 'patch-notmuch)
+(require 'init-notmuch-sync)
 
 ;; To find files matching email:
 ;;   notmuch search --output=files FOO
@@ -41,6 +42,7 @@
                      notmuch-show-mode-map
                      notmuch-tree-mode-map))
     (define-key map "s" 'helm-notmuch)))
+
 (when (require 'org-notmuch nil 'noerror)
   (dolist (map (list notmuch-show-mode-map notmuch-tree-mode-map))
     (define-key map (kbd "C-c C-t") 'org-capture))