When creating an org-agenda-custom-commands command, how can I make the (agenda) portion only display certain tags?

Question

I add custom org-agenda commands to the org-agenda-custom-commands like so

  (setq w-view
           `("W" "Work"
             (
              (agenda ""
                      (
                       (org-agenda-span 'day)
                       (org-deadline-warning-days 365)
                       ))
              (tags-todo "work"
                         ((org-agenda-overriding-header "All Work")
                          (org-agenda-files '("~/Dropbox/org/inbox.org"))
                          (org-agenda-sorting-strategy '(deadline-up priority-down tag-up))
                          ))
              (tags-todo "work"
                         ((org-agenda-overriding-header "Work Projects")
                          (org-agenda-files '("~/Dropbox/org/projects.org"))
                          (org-agenda-sorting-strategy '(deadline-up priority-down tag-up))
                          ))
              nil
              )
             )
           )
  (add-to-list 'org-agenda-custom-commands `,w-view)

I understand that items can start with "agenda," "tags-todo," or "tags," and possibly other things, though I'm not clear on what exactly as the documentation doesn't say.

I do know that an agenda item shows my TODO items that have deadlines or are scheduled, in order and with their timestamps. I also know that I can create custom headers, i.e. like I do for "All Work" or "Work Projects." I know that I can determine what TODO items are displayed under those custom headers because I start those sections with tags-todo.

What I don't understand is how I can make a custom section that starts with agenda only show TODO items of a certain tag.

I've tried the following:

          (agenda ""
                  ((tags-todo "work")
                   (org-agenda-span 'day)
                   (org-deadline-warning-days 365)
                   ))

Which didn't throw any errors but also shows all TODO items regardless of tags, i.e., didn't change anything.

When making a custom org-agenda-custom-commands view, and using the "agenda" custom header identifier, how can I make that custom agenda view only display certain tags?

I'm not sure what to call the "agenda" or "tags-todo" or "tags" custom header identifier, help in the vocabulary sense so I can edit and clarify this question would be appreciated.

Answer 1

This can be done using built in tools using org-agenda-skip-function (I've used this answer on Stack Overflow in the past).

If you don't mind external packages, org-super-agenda makes this easy:

(add-to-list 'org-agenda-custom-commands
             '("w" "Work agenda" agenda ""
              ((org-super-agenda-groups
                '((:discard (:not (:tag ("work"))))
                 ))
               )
        ))

This will remove any item that doesn't match the selector (:tag ("work")), that is will show only :work: items. This is also significantly faster than using org-agenda-skip-function.

You can give multiple tags and combine them using :and and :or. For example,

(:or 
  (:not (:tag ("work"))) 
  (:and 
    (:tag ("home")) 
    (:tag ("urgent"))))

will match work items, but also :urgent: items at home. For even more advanced matching, check out org-ql, which is very powerful and fast