Emacs 28.2 gnus: nntp read marks lost after going offline and online again

Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

I upgraded to debian 12 on my laptop yesterday and got emacs 28.2 in the
bargain.

And twice, since then, all of my nntp servers have lost all groups and
read marks.  Today it happened when I toggled gnus offline into online,
not sure that was what happened yesterday.

Both times I have gotten around losing anything by exiting without
saving, and not reading auto save files on gnus restart.

Prior to the upgrade, I have been running emacs 27 with a gnus from emacs
27, with gnus-cloud.el from emacs 28 (somewhat tinkered with to run
under emacs 27).

Now I'm running plain emacs 28.2 gnus.

And I'm using gnus agent and gnus-cloud (but I haven't restored anything
with gnus-cloud after upgrading).

And I'm running on debian 12 "bookworm" on an amd64 laptop.

Has anyone else seen something similar?

Is this a known issue?

Is there a better way to get out of the problem than the one I've tried?

Is there a way to stop this from happening again? :-)

- Steinar

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

> And twice, since then, all of my nntp servers have lost all groups and
> read marks.  Today it happened when I toggled gnus offline into online,
> not sure that was what happened yesterday.

Three times now.

This time when emacs was just sitting there doing nothing, and the nntp
groups went AWOL.

Could it be something in my config?

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[dick]

> Three times now

My news.gmane.io stopped refreshing twice in the preceding 24 hours.

I had to manually `gnus-server-close-server` followed by the normal 
`gnus-group-get-new-news` to get its newsgroups back online.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

>> And twice, since then, all of my nntp servers have lost all groups
>> and read marks.  Today it happened when I toggled gnus offline into
>> online, not sure that was what happened yesterday.

> Three times now.

> This time when emacs was just sitting there doing nothing, and the nntp
> groups went AWOL.

Happened again.  Four times now.

All ideas for how to track this down are welcome.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[dick]

> Happened again

My news.gmane.io stopped refreshing twice in the preceding 24 hours.

I had to manually `gnus-server-close-server` followed by the normal 
`gnus-group-get-new-news` to get its newsgroups back online.  Haven't
had a problem since roughly Jun 19, 12:00 GMT.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

>>> And twice, since then, all of my nntp servers have lost all groups
>>> and read marks.  Today it happened when I toggled gnus offline into
>>> online, not sure that was what happened yesterday.

>> Three times now.

>> This time when emacs was just sitting there doing nothing, and the
>> nntp groups went AWOL.

> Happened again.  Four times now.

Five times.

This time I did a normal 'q' (after first copying the ~/.newsrc and
~/.newsrc.eld files) and started gnus again and then everything was good
(nothing lost, everything restored).

> All ideas for how to track this down are welcome.

I would like it to stop.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> dick <dick.r.chiang@gmail.com>:
>> Happened again

> My news.gmane.io stopped refreshing twice in the preceding 24 hours.

> I had to manually `gnus-server-close-server` followed by the normal 
> `gnus-group-get-new-news` to get its newsgroups back online.  Haven't
> had a problem since roughly Jun 19, 12:00 GMT.

Does gnus look like this after it stops refresing?
 https://www.bang.priv.no/screenshots/gnus_no_articles.png

No servers have closed for me. This is the server buffer after articles
and groups have been lost:
 https://www.bang.priv.no/screenshots/gnus_server_no_articles.png

This is what gnus looks like, after stopping gnus and restarting it:
 https://www.bang.priv.no/screenshots/gnus_after_stop_and_start.png

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[dick]

"Read marks" means nothing to me.  It wasn't until you showed me the
png files that I now understand you mean the state data tracking which
messages you've already encountered.

When you couch your initial complaint in extraneous details like debian,
gnu-cloud, bookworm, and emacs-28.2, it's impossible to know what you're
after.

And no, I never lost "read marks."  Welcome to Gnus where everything and
anything can and will go wrong, and it takes an afternoon just to figure
out where to set the breakpoint for further investigation, never mind
actually solving the problem which could take months.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

>>>>> Steinar Bang <sb@dod.no>:
>>> And twice, since then, all of my nntp servers have lost all groups
>>> and read marks.  Today it happened when I toggled gnus offline into
>>> online, not sure that was what happened yesterday.

>> Three times now.

>> This time when emacs was just sitting there doing nothing, and the nntp
>> groups went AWOL.

> Happened again.  Four times now.

> All ideas for how to track this down are welcome.

This is what it looks like when the groups and articles have gone away:
 https://www.bang.priv.no/screenshots/gnus_no_articles.png

No servers have closed for me. This is the server buffer after articles
and groups have been lost:
 https://www.bang.priv.no/screenshots/gnus_server_no_articles.png

This is what gnus looks like, after stopping gnus and restarting it:
 https://www.bang.priv.no/screenshots/gnus_after_stop_and_start.png

Ie. everything works normal until gnus starts looking like the first
screenshot.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

>>>> And twice, since then, all of my nntp servers have lost all groups
>>>> and read marks.  Today it happened when I toggled gnus offline into
>>>> online, not sure that was what happened yesterday.

>>> Three times now.

>>> This time when emacs was just sitting there doing nothing, and the nntp
>>> groups went AWOL.

>> Happened again.  Four times now.

>> All ideas for how to track this down are welcome.

> This is what it looks like when the groups and articles have gone away:
>  https://www.bang.priv.no/screenshots/gnus_no_articles.png

> No servers have closed for me. This is the server buffer after articles
> and groups have been lost:
>  https://www.bang.priv.no/screenshots/gnus_server_no_articles.png

> This is what gnus looks like, after stopping gnus and restarting it:
>  https://www.bang.priv.no/screenshots/gnus_after_stop_and_start.png

> Ie. everything works normal until gnus starts looking like the first
> screenshot.

I saw it happen before my eyes now.  It happens when gnus fetches new
news, I think.

This is what was in the *Messages* buffer:

Checking new news...
Reading active file from cloud via nnimap...
Opening nnimap server on cloud...done
Reading active file from cloud via nnimap...done
Reading active file via nndiary...done
nnimap read 0k from imap.bang.priv.no (initial sync of 1 group; please wait)
Reading active file via nndraft...done
Reading active file via nnml...
Reading incoming mail from file...
nnml: Reading incoming mail (no new mail)...done
Reading active file via nnml...done
Checking new news...done

Two things of note here:
 1. It now apparently checks the cloud file automatically?
    That's new (for me)
 2. There are no lines of output for fetching with nntp

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Eric Abrahamsen]

Steinar Bang <sb@dod.no> writes:

>>>>>> Steinar Bang <sb@dod.no>:
>
>>>>> And twice, since then, all of my nntp servers have lost all groups
>>>>> and read marks.  Today it happened when I toggled gnus offline into
>>>>> online, not sure that was what happened yesterday.
>
>>>> Three times now.
>
>>>> This time when emacs was just sitting there doing nothing, and the nntp
>>>> groups went AWOL.
>
>>> Happened again.  Four times now.
>
>>> All ideas for how to track this down are welcome.
>
>> This is what it looks like when the groups and articles have gone away:
>>  https://www.bang.priv.no/screenshots/gnus_no_articles.png
>
>> No servers have closed for me. This is the server buffer after articles
>> and groups have been lost:
>>  https://www.bang.priv.no/screenshots/gnus_server_no_articles.png
>
>> This is what gnus looks like, after stopping gnus and restarting it:
>>  https://www.bang.priv.no/screenshots/gnus_after_stop_and_start.png
>
>> Ie. everything works normal until gnus starts looking like the first
>> screenshot.
>
> I saw it happen before my eyes now.  It happens when gnus fetches new
> news, I think.
>
> This is what was in the *Messages* buffer:
>
> Checking new news...
> Reading active file from cloud via nnimap...
> Opening nnimap server on cloud...done
> Reading active file from cloud via nnimap...done
> Reading active file via nndiary...done
> nnimap read 0k from imap.bang.priv.no (initial sync of 1 group; please wait)
> Reading active file via nndraft...done
> Reading active file via nnml...
> Reading incoming mail from file...
> nnml: Reading incoming mail (no new mail)...done
> Reading active file via nnml...done
> Checking new news...done
>
> Two things of note here:
>  1. It now apparently checks the cloud file automatically?
>     That's new (for me)
>  2. There are no lines of output for fetching with nntp

Yes, in your previous image of the Server buffer note all the
(cloud-sync) tags after servers, and the one (CLOUD-HOST). I've only
tried the gnus-cloud thing once several years ago, but the manual makes
it sound like you'd have to enable it manually -- did you not do that?

Anyway, even if gnus-cloud isn't the culprit it's likely to make
debugging harder. Try using "i" to toggle the cloud-sync servers, and
"I" to toggle the CLOUD-HOST server -- hopefully that will shut it off
altogether...

Eric

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Eric Abrahamsen <eric@ericabrahamsen.net>:

> Yes, in your previous image of the Server buffer note all the
> (cloud-sync) tags after servers, and the one (CLOUD-HOST). I've only
> tried the gnus-cloud thing once several years ago, but the manual makes
> it sound like you'd have to enable it manually -- did you not do that?

Well, I have enabled it on a much older version of gnus, on September 23
2021, and it may be that my old enablement doesn't work too well with
the current version.

Hm... digging further into the git history, I have tried using
gnus-cloud since July 24 2016, but I didn't have any success until
around 2019, and I didn't retire its predecessor gnus-sync until 2021
(when it stopped working).

There are some posts and threads. on this list about my experiments.
Probably last time was around the previous debian major version upgrade
when emacs switched from 26 to 27.

Also I have been running a hacked version of gnus-cloud, since the one
bundled with earlier gnus versions didn't work right.

Now I'm running with the plain emacs 28 gnus.

These are my settings to enable gnus-cloud:
(setq gnus-cloud-interactive nil
      gnus-cloud-method "nnimap:cloud"
      gnus-cloud-storage-method nil
      gnus-cloud-synced-files '((:directory "~/News" :match ".*.SCORE\\'"))
      mail-source-movemail-program "movemail")

(the movemail setting is gnus cloud related from August 18 2019, when
switching from emacs 25 to emacs 26 after a debian upgrade)

> Anyway, even if gnus-cloud isn't the culprit it's likely to make
> debugging harder. Try using "i" to toggle the cloud-sync servers, and
> "I" to toggle the CLOUD-HOST server -- hopefully that will shut it off
> altogether...

Ok. I'll try that and if that doesn't work I'll remove the gnus-cloud
config.

Am I the only current user of gnus-cloud, I wonder?

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

>> Anyway, even if gnus-cloud isn't the culprit it's likely to make
>> debugging harder. Try using "i" to toggle the cloud-sync servers, and
>> "I" to toggle the CLOUD-HOST server -- hopefully that will shut it off
>> altogether...

> Ok. I'll try that and if that doesn't work I'll remove the gnus-cloud
> config.

I i'd the cloud-sync servers, which removed the cloud-sync from them.
I then I'd the CLOUD-HOST server, and it uploaded something.

But a while later the groups and read marks of the nntp groups was gone
again.

I'll try to disable the gnus-cloud config.

> Am I the only current user of gnus-cloud, I wonder?

I probably am.

But if there are others out there, feel free to reach out.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

> I'll try to disable the gnus-cloud config.

For now I have deleted all gnus-cloud settings from .emacs, and I have
removed the nnimap server used for CLOUD-HOST from ~/.gnus.el and have
started gnus in a fresh emacs.

So we'll se if that makes the read marks and nntp groups disappear
again.

If the read marks and groups disappear again, the next thing to go is
the gnus daemon setting.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

>> I'll try to disable the gnus-cloud config.

> For now I have deleted all gnus-cloud settings from .emacs, and I have
> removed the nnimap server used for CLOUD-HOST from ~/.gnus.el and have
> started gnus in a fresh emacs.

> So we'll se if that makes the read marks and nntp groups disappear
> again.

> If the read marks and groups disappear again, the next thing to go is
> the gnus daemon setting.

The read marks and groups of the nntp groups disappeared again, even
after I had removed all of the gnus cloud stuff.

I have now removed these gnus-demon settings (from May 26 2003):

;; Automatically fetch news and mail every 15 minutes when idle
(defun sb-gnus-demon-scan-imap ()
  (let ((win (current-window-configuration)))
    (unwind-protect
	(save-window-excursion
	  (save-excursion
	    (when (gnus-alive-p)
	      (save-excursion
		(set-buffer gnus-group-buffer)
		(gnus-group-get-new-news 2)))))
      (set-window-configuration win))))

(gnus-demon-add-handler 'sb-gnus-demon-scan-imap 15 t)
(gnus-demon-add-rescan)

Looks like I had my own demon scan function and that I have had it for
just over 20 years.

(I have emacs config that dates back to the 80-ies, but only version
control history for that config that goes back to 2001 or thereabouts)

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

> I have now removed these gnus-demon settings (from May 26 2003):

> ;; Automatically fetch news and mail every 15 minutes when idle
> (defun sb-gnus-demon-scan-imap ()
>   (let ((win (current-window-configuration)))
>     (unwind-protect
> 	(save-window-excursion
> 	  (save-excursion
> 	    (when (gnus-alive-p)
> 	      (save-excursion
> 		(set-buffer gnus-group-buffer)
> 		(gnus-group-get-new-news 2)))))
>       (set-window-configuration win))))

The culprit was my May 26 2003 function above.

I ran sb-gnus-demon-scan-imap by putting
 (sb-gnus-demon-scan-imap)
in the minibuffer and typing Ctrl-J.

And the nntp groups and read marks went away.

I can't entirely remember why I wrote my own function here (it's been a
while...), but I think at that time I had nnml groups on level 1 and
nnimap groups on level 2 and nntp groups on level 3, and that I was
trying to scan only level 1 and level2 in the demon.

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Eric Abrahamsen]

Steinar Bang <sb@dod.no> writes:

>>>>>> Steinar Bang <sb@dod.no>:
>
>> I have now removed these gnus-demon settings (from May 26 2003):
>
>> ;; Automatically fetch news and mail every 15 minutes when idle
>> (defun sb-gnus-demon-scan-imap ()
>>   (let ((win (current-window-configuration)))
>>     (unwind-protect
>> 	(save-window-excursion
>> 	  (save-excursion
>> 	    (when (gnus-alive-p)
>> 	      (save-excursion
>> 		(set-buffer gnus-group-buffer)
>> 		(gnus-group-get-new-news 2)))))
>>       (set-window-configuration win))))
>
> The culprit was my May 26 2003 function above.
>
> I ran sb-gnus-demon-scan-imap by putting
>  (sb-gnus-demon-scan-imap)
> in the minibuffer and typing Ctrl-J.
>
> And the nntp groups and read marks went away.
>
> I can't entirely remember why I wrote my own function here (it's been a
> while...), but I think at that time I had nnml groups on level 1 and
> nnimap groups on level 2 and nntp groups on level 3, and that I was
> trying to scan only level 1 and level2 in the demon.

I'm glad you worked it out, and sorry for maligning Gnus cloud!

I guess with a few decades of personal config, some of it is bound to go stale...

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Dan Christensen]

On Jun 21, 2023, Steinar Bang <sb@dod.no> wrote:

>> ;; Automatically fetch news and mail every 15 minutes when idle
>> (defun sb-gnus-demon-scan-imap ()
>>   (let ((win (current-window-configuration)))
>>     (unwind-protect
>> 	(save-window-excursion
>> 	  (save-excursion
>> 	    (when (gnus-alive-p)
>> 	      (save-excursion
>> 		(set-buffer gnus-group-buffer)
>> 		(gnus-group-get-new-news 2)))))
>>       (set-window-configuration win))))
>
> The culprit was my May 26 2003 function above.
>
> I ran sb-gnus-demon-scan-imap by putting
>  (sb-gnus-demon-scan-imap)
> in the minibuffer and typing Ctrl-J.
>
> And the nntp groups and read marks went away.

I can't see why that function would cause problems.  Isn't it
essentially the same as doing `2 g' in the *Group* buffer?  When I do
that, my groups at levels greater than 2 are not shown any more, but
`3 l' redisplays them, and none of the information is lost.

Moreover, I just checked, and it turns out that I have almost
exactly the same function in my config, being run by the demon,
and it doesn't cause me any trouble.  I'm using git emacs/Gnus.

Dan

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Eric Abrahamsen <eric@ericabrahamsen.net>:

> I'm glad you worked it out, and sorry for maligning Gnus cloud!

No worries! :-)

I just wish it had more users, so I didn't feel so alone...:-)

I wonder where Ted Zlatanov (the original author of gnus-cloud and its
predecessor gnus-sync), is these days?

> I guess with a few decades of personal config, some of it is bound to go stale...

Yep! I dread every emacs major release. :-)

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Dan Christensen <jdc@uwo.ca>:

> I can't see why that function would cause problems.  Isn't it
> essentially the same as doing `2 g' in the *Group* buffer?

I can't remember how I made the exact code (git tells me this was 2003
(which means the .gnus.el file was versioned controlled in CVS,
probably)), but coding the equivalent of '2 g' was indeed what I tried
to do.

I had local mail groups on level 1, imap groups on level 2 and nntp
groups on level 3.

Still do, in fact, except I no longer have any local mail groups, except
for an nnmail:misc that appears when I receive local mail for something.

> When I do that, my groups at levels greater than 2 are not shown any
> more, but `3 l' redisplays them, and none of the information is lost.

The same thing happens with me: '2 g' makes groups greater than level 2
go away and '3 l' makes them reappear.

> Moreover, I just checked, and it turns out that I have almost
> exactly the same function in my config, being run by the demon,
> and it doesn't cause me any trouble.  I'm using git emacs/Gnus.

So this was possibly a transient issue in emacs 28?

That means I may be able to resurrect the function on emacs 29? :-)

Thanks for the heads up!

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Dan Christensen]

On Jun 24, 2023, Steinar Bang <sb@dod.no> wrote:

>>>>>> Dan Christensen <jdc@uwo.ca>:
>
>> I can't see why that function would cause problems.  Isn't it
>> essentially the same as doing `2 g' in the *Group* buffer?
>> 
>> When I do that, my groups at levels greater than 2 are not shown any
>> more, but `3 l' redisplays them, and none of the information is lost.
>
> The same thing happens with me: '2 g' makes groups greater than level 2
> go away and '3 l' makes them reappear.

So are you saying that `2 g' works fine for you, but the code you
posted does not work?  That seems really strange.

I just tested your exact code with git emacs, and it doesn't cause
any problem.  I skipped over emacs 28, so it could possibly be an
issue there, but I can't see how that code would cause a problem if
`2 g' doesn't.

Maybe it's some interaction between your function and other unique
things in your set-up?

Dan

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Steinar Bang <sb@dod.no>:

>>>>> Eric Abrahamsen <eric@ericabrahamsen.net>:
>> I'm glad you worked it out, and sorry for maligning Gnus cloud!

> No worries! :-)

> I just wish it had more users, so I didn't feel so alone...:-)

> I wonder where Ted Zlatanov (the original author of gnus-cloud and its
> predecessor gnus-sync), is these days?

I had to cherry-pick one mod from 2021, to stop sync from stopping
because gnus-cloud refuses to overwrite the backup files it has just
created (no idea why it creates the backup files, and even less idea why
it creates them twice (and the second time fails)):
 https://github.com/steinarb/emacs-gnus-cloud-sb/commit/e48bb24270f93e40192b18dcead2f95190e1b1a4

(the commit is on top of a branch created from tag emacs-28.2)

Re: Emacs 28.2 gnus: nntp read marks lost after going offline and online again

[Steinar Bang]

>>>>> Dan Christensen <jdc@uwo.ca>:

> On Jun 24, 2023, Steinar Bang <sb@dod.no> wrote:
>>>>>>> Dan Christensen <jdc@uwo.ca>:
>> 
>>> I can't see why that function would cause problems.  Isn't it
>>> essentially the same as doing `2 g' in the *Group* buffer?
>>> 
>>> When I do that, my groups at levels greater than 2 are not shown any
>>> more, but `3 l' redisplays them, and none of the information is lost.
>> 
>> The same thing happens with me: '2 g' makes groups greater than level 2
>> go away and '3 l' makes them reappear.

> So are you saying that `2 g' works fine for you, but the code you
> posted does not work?  That seems really strange.

No. I was trying to say that I observed the exact same behaviour as you did.

Both the function I posted and '2 g' had the same result: groups on
levels greater than 2 disappeared.

But '3 g' made them reappear (at least the ones on level 3).

list level not respected by gnus-group-get-new-news [was: Emacs 28.2 gnus: nntp read marks lost after going offline and online again]

[Dan Christensen]

On Jun 25, 2023, Steinar Bang <sb@dod.no> wrote:

>> So are you saying that `2 g' works fine for you, but the code you
>> posted does not work?  That seems really strange.
>
> No. I was trying to say that I observed the exact same behaviour as you did.
>
> Both the function I posted and '2 g' had the same result: groups on
> levels greater than 2 disappeared.
>
> But '3 g' made them reappear (at least the ones on level 3).

In the first message you said that the groups lost their marks, so
I was still under the impression that that was the issue.  If the
groups are just not being *displayed*, then `3 l' will show the groups
on levels <= 3.  Indeed, digging around shows this commit from two
years ago:

  https://github.com/emacs-mirror/emacs/commit/7f9ca3b2f4f1a9800d7557f64e25bb3ee5059cba

where lines 4208-4209 are changed from

  (gnus-group-list-groups (and (numberp arg)
                               (max (car gnus-group-list-mode) arg)))

to

  (gnus-group-list-groups (and (numberp arg) arg))

So the current list level is not taken into account any more.  I also
find this a bit annoying, to tell you the truth.  Even more, the new
code goes on to make this permanent:

    (when gnus-group-use-permanent-levels
      (setq gnus-group-use-permanent-levels (gnus-group-default-level arg)))))

Do others think it makes sense to hide groups currently being displayed
just because I refreshed groups at a lower level?

(I've changed the subject to reflect what's really going on here.)

Dan

Re: list level not respected by gnus-group-get-new-news [was: Emacs 28.2 gnus: nntp read marks lost after going offline and online again]

[Steinar Bang]

>>>>> Dan Christensen <jdc@uwo.ca>:

> In the first message you said that the groups lost their marks, so I
> was still under the impression that that was the issue.

Yeah, in my first message, I thought that was the issue.

Note that I feel very relieved to learn that this wasn't actually the issue. :-)

> If the groups are just not being *displayed*, then `3 l' will show the
> groups on levels <= 3.

Yup, I understood that part once you showed that '2 g' would make stuff
disappear, and '3 g' would make them reappear.

> Indeed, digging around shows this commit from two years ago:

>   https://github.com/emacs-mirror/emacs/commit/7f9ca3b2f4f1a9800d7557f64e25bb3ee5059cba

> where lines 4208-4209 are changed from

>   (gnus-group-list-groups (and (numberp arg)
>                                (max (car gnus-group-list-mode) arg)))

> to

>   (gnus-group-list-groups (and (numberp arg) arg))

> So the current list level is not taken into account any more.  I also
> find this a bit annoying, to tell you the truth.

Good to hear! :-)

> Even more, the new code goes on to make this permanent:

>     (when gnus-group-use-permanent-levels
>       (setq gnus-group-use-permanent-levels (gnus-group-default-level arg)))))

Hm...:-/

> Do others think it makes sense to hide groups currently being displayed
> just because I refreshed groups at a lower level?

> (I've changed the subject to reflect what's really going on here.)

Noted!