Display multi-file org agenda as a sparse tree?

Question

org-sparse-tree function lists selected information with the headline structure above it. This is useful when the meaning of org headings depends on context:

SPC m T (org-show-todo-tree)

org-agenda function prints the headings out of context, which can make the headings incomprehensible:

SPC a o o s Phrase: TODO (org-agenda, list all entries with keyword "TODO")

As far as I know, org-sparse-tree only works on one org file at a time. While org-agenda is derived from multiple org files.

Is there a way to display an agenda as a sparse tree? (when the agenda is derived from multiple files)

Alternatively, I could combine all my org project files into one. Is that the "org-mode way"? If not, I will customize org-mode after gaining more org-mode experience.

I am using Emacs 25.2.1 with Spacemacs, evil, and ivy on Linux.

The remainder of this question describes what I have tried so far.

googled: org-mode agenda sparse tree

I tried the org-occur-in-agenda-files function:

SPC a o /

Org-files matching: tasks.org
Searched 5 buffers; no matches for "tasks.org"

What should be entered after the "Org-files matching" prompt?

From my ~/.spacemacs file:

(setq org-agenda-files (list
                    "~/Documents/developer/editors/emacs/tasks_demo/proj1/notes1.org"
                    "~/Documents/developer/editors/emacs/tasks_demo/proj1/tasks.org"

                    "~/Documents/developer/editors/emacs/tasks_demo/proj2_per/notes2.org"
                    "~/Documents/developer/editors/emacs/tasks_demo/proj2_per/tasks.org"

                    "~/Documents/developer/editors/emacs/tasks_demo/tasks.org"
                    ))

This google search found none: "org-occur-in-agenda-files" "Org-files matching"

UPDATE_1

This works:
Search all the org files with org-agenda, and if a heading needs context, ENT on the heading, which opens the heading in the same window.
SPC b b (ivy-switch-buffer) *Org Agenda* returns window to the agenda.
Is there a faster way to jump back to agenda?
C-c & (org-mark-ring-goto) does not jump back to agenda.

This works:
Search all the org files with org-agenda, and if a heading needs context, mouse-3 on the heading, which opens the heading in another window.
But if another window is already open, that window's buffer is displaced.
Is there a way to open the agenda heading in a new window?

Answer 1

Have you tried the C-c a for org-agenda and then / that is the Multi-occur option?

According to the Org-mode Tutorial on topic Advanced Searching:

Org-mode uses Emacs' multi-occur command to search for any lines in the agenda files containing a regular expression. Simply type C-c a / followed by a word or regular expression and you will be presented a buffer with all lines that match the query, with each line conveniently linked to its original location.

Still in the same topic:

The commands we have examined so far typically search multiple files and display the resulting heading in a separate agenda buffer. But sometimes, you might want to search for various types of data within a single file, so as to see all the matching headlines and entries in context.

The way to accomplish this is via a sparse tree view (C-c /), which collapses the outline in the current file, showing only the portions that match a query.

So, if you want to make your search on all files you should start with Multi-occur and then use sparse trees on specific files.

Also, if you use Spacemacs I recommend you to make use of some shortcuts that starts with , (comma). You will find that, for example, org-agenda is accessible with just , a (comma, a), instead of SPC a o o.

Other examples:

org-show-todo-tree: , T = SPC m T

org-sparse-tree: , / = SPC m /

org-clock-in: , I = SPC m I

etc...

The remainder of this question describes what I have tried so far.

googled: org-mode agenda sparse tree

• Best resources on this topic are the Worg's Advanced search Tutorial and the Org-Mode Online Manual