Jameson Graef Rollins <jrollins@phys.columbia.edu> writes:

Hi Jameson,

> (add-hook 'notmuch-search-mode
>   (define-key notmuch-search-mode-map "A" 'notmuch-show-mark-read-then-archive-thread)
> )

`notmuch-search-mode' is no hook, and even if it was, you couldn't add
what you like, because that's no function.  You would need to define a
function that doesn that or wrap it in a lambda function.

Anyway, this should do the trick:

(define-key notmuch-search-mode-map "A" 'notmuch-show-mark-read-then-archive-thread)

Bye,
Tassilo