When org-agenda-follow-mode is on, how do I make the buffer showing the items in the agenda narrow to the subtree of the relevant item?
Basically all you need to do this is to have
org-narrow-to-subtree run right after whatever function
org-follow-mode is calling, which happen to be
org-agenda-goto. You have to be a little careful writing the advice because
org-agenda-goto is sometimes called with an argument, which
org-narrow-to-subtree can't take. Here's what we need:
(advice-add 'org-agenda-goto :after (lambda (&rest args) (org-narrow-to-subtree)))
Late response, but it may be helpful to someone.
There's another possibility to view tree in indirect buffer only for item at point with
C-c C-x b
This indirect buffer can also be used in follow mode when you set
org-agenda-follow-indirect to non-nil value like this:
(setq org-agenda-follow-indirect t)