> +    (synopsis "Replace @code{guix send-email} with @code{git send-email}")
> +    (description "This Guix extension provides a shell redirect from @code{guix
> +send-email} to @code{git send-email}.")

When I noticed 'gnu: Add guix-send-email', I expected a wrapper around 
'git send-email' that provided some additional functionality, more 
specifically, I expected you could do something like

$ guix send-email commit1..commit2 --base=commit1

and it would automatically take care of first sending the cover letter, 
then waiting for a response, then send the later e-mails to 
NNNNN@debbugs.gnu.org.

Without such additional functionality (*), I don't think it's really 
useful.  However, if it's added to Guix proper (maybe Guix proper could 
be tweaked to say 'hint: did you mean git send-email [...]?'), I think 
it could be valuable (I would think it's somewhat unlikely for people 
that need some help with figuring out that the correct command is "git 
send-email" and not "guix send-email", to determine that they need to 
install "guix-send-email", so I don't think it solves (b) well).

> [...] Or guix-vacuum-database, to wrap
> vacuuming /var/guix/db/db.sqlite in a guix extension.

If there is interest in such a command (and not 'merely' as an example 
on how to write Guix extensions), I think it would be valuable and 
low-cost to have this in Guix proper.  (Vacuuming is for reducing disk 
usage, if the disk is (close to) full and needs some vacuuming, it might 
be too late to install "guix-vacuum-database" ...)

Greetings,
Maxime

(*) integrating etc/teams stuff would be nice too.