>> >> +  (add-function :around (local 'isearch-search-fun-function)
>> >> +                #'dired-isearch-search-filenames)
>> >
>> > And: Is it intended that this is unconditional (I would expect a
>> > `dired-isearch-filenames-mode' test)?
>>
>> Currently it is unconditional when it's using isearch-filter-predicate.
>> So maybe it should be kept this way since it's what was used for many years?
>> Or is there a reason to change the current behavior?
>
> Ok, then better let's keep it.

For more customizability I added a new user option
'wdired-search-replace-filenames' enabled by default.

> A different thing: I found that
>
> | + (setq-local replace-re-search-function #'dired-isearch-search-filenames)
>
> is not correct - of course, `dired-isearch-search-filenames' is a higher
> order function (used for the around advice), not something suitable for
> searching.  With the patch installed query-replace in wdired errors.
>
> What's the correct value - the current binding of
> `isearch-search-fun-function'?

You are right, the correct value is the current binding of
`isearch-search-fun-function'.  Everything is fixed now
in this patch, i.e. search/replace works ok in dired/wdired buffers
(except ^ at the beginning of filenames that is a separate feature):