Attached with TINYCHECK.

Unfortunately I don't have the time to write a test right now because
I'll be traveling from tomorrow on. (You'd to wait for at least 6
weeks..)

Here's a sketch for a test case:
 * Show an agenda with that has org-agenda-multi
 * In the agenda buffer, assert that org-todo-keywords-for-agenda and
   (org-done-keywords-for-agenda) are not nil.

Best,
Tim


On Fri, 2023-03-10 at 11:48 +0000, Ihor Radchenko wrote:
> Tim Ruffing <crypto@timruffing.de> writes:
> 
> > * org-agenda.el (org-prepare-agenda): Don't reset
> > `org-todo-keywords-for-agenda' when org-agenda-multi.
> > 
> > Fixes a bug with TODO keywords that came to light in org-modern,
> > see https://github.com/minad/org-modern/issues/26.
> > 
> > This is very similar to cd2d138883a55cad48394a3f473da8b973a99a5e,
> > which fixed the same for `org-done-keywords-for-agenda` (to fix
> > a similar styling issue).
> 
> Thanks for the patch!
> Unfortunately, it does not apply.
> Could you re-send the patch as attachment?
> 
> In addition, may you add TINYCHANGE cookie to the commit message if
> you
> don't have FSF assignment done (see
> https://orgmode.org/worg/org-contribute.html#first-patch)? And, if
> you
> can, write a test.
>