This is caused by this.replyBodyWidget.off( 'change' ); in ReplyWidgetPlain#teardown and ReplyWidgetVisual#teardown. @Esanders I am not sure what this was for. Is it supposed to only remove the onFirstTransaction handler?

Notes:

• You can stll submit with Ctrl+Enter
• Only the comment you cancelled on is affected, the reply buttons for other comments work fine

Change 595590 had a related patch set uploaded (by Bartosz Dziewoński; owner: Bartosz Dziewoński):
[mediawiki/extensions/VisualEditor@master] Fix #unwrapParsoidSections for pseudo-sections (generated by templates)

Change 595589 had a related patch set uploaded (by Bartosz Dziewoński; owner: Bartosz Dziewoński):
[mediawiki/extensions/DiscussionTools@master] Show real error message when an exception is thrown

In T234966#6120342, @Pelagic wrote:

On the other hand, if the timestamp uses a distinct <time> element, then selectors like ".mw-signature>span" and ".mw-signature>time" should work?

In T234966#5634049, @Jc86035 wrote:

Would this be generated by an extension tag or parser function, or would that HTML be directly saved into the page by the editor? The former approach would presumably be cleaner in terms of the wikitext source code.

Updating the task description with the basic outline @Whatamidoing-WMF and I discussed during today's meeting as well as with a link to the plan we've started drafted on Office wiki: https://office.wikimedia.org/wiki/Community_Relations_Specialists/Audiences/DiscussionTools#Reply_tool:_draft_deployment_plan

Is a CSS class on the whole block sufficient, or should we have additional separate classes for the configurable-text and timestamp sub-components? The intent of T27141 is to allow users to remove custom styling, either would do. Are there use cases where people would want to style the components separately?

Is the sig. really a typeof Comment? (As illustrated in the example at T234966#5575981 above.) Wouldn't the associated text (usually but not necessarily preceding the signature) be the Comment?

Change 595239 merged by jenkins-bot:
[mediawiki/extensions/DiscussionTools@master] Manually clear out session storage on teardown

Change 595239 had a related patch set uploaded (by Esanders; owner: Esanders):
[mediawiki/extensions/DiscussionTools@master] Manually clear out session storage on teardown

In T252176#6120185, @matmarex wrote:

Ed's work on switching editors refactored a bunch of things in teardown, maybe it broke this.

This is actually caused by an exception, the error message is wrong:

TypeError: section.firstChild.setAttribute is not a function
    at <anonymous>:393:25306
    at NodeList.forEach (<anonymous>)
    at Object.mw.libs.ve.unwrapParsoidSections (<anonymous>:393:25105)
...

Apparently section.firstChild is this case is a comment node

It looks like we don't clear the auto-save anymore when posting or discarding the reply. This used to work, but it was actually a bit fragile now that I think of it, I noted that:

Yes, I have only seen this response on this specific user page.

@AdHuikeshoven: I can only reproduce this on nlwiki user talk pages, is that correct for you?

German Wikipedia does not want that threads in a talk archive might be continued.

• Talk archive pages are in the related talk (or other) space.

Are these pages marked in anyway that would let us know they are archived?

There are various templates, but all of them use both __NOEDITSECTION__ and __NONEWSECTIONLINK__ to prevent thread editing by accident.

Are these pages marked in anyway that would let us know they are archived?

In T249293#6101999, @PerfektesChaos wrote:

German Wikipedia does not want that threads in a talk archive might be continued.

• Talk archive pages are in the related talk (or other) space.

Are these pages marked in anyway that would let us know they are archived?

@ovasileva Swedish Wikipedia would be very happy to see the link turned on for unregistered users and see what happens.

That will be part of our new discussion tool which we have started work on: https://www.mediawiki.org/wiki/Talk_pages_project/New_discussion

@PerfektesChaos: good example. The Hungarian Wikipedia uses the same practice.

In T245890#6101967, @Samat wrote:

The only thing came into my mind: how can a user start a discussion on pages where the tool is not visible because of lack of signatures (but available in the background)?

Is the idea here that after some time we will remove all the customised feedback links and direct everyone to mediawiki.org?

German Wikipedia does not want that threads in a talk archive might be continued.

• Talk archive pages are in the related talk (or other) space.
• Talk archive pages are marked as terminated by any archive template and those request explicitly __NOEDITSECTION__ and __NONEWSECTIONLINK__ to prevent thread editing by accident.

DiscussionTool must not invite to reply in a terminated thread.

And just to be sure, by saying, "I haven't seen any problem with it until now." are you saying you have not observed any issues so far?

In T245890#6095338, @Samat wrote:

I like that the tool does not appear on pages with NEWSECTIONLINK where there is no discussion.

Excellent. Thank you for letting us know, @Samat.

In T245890#6094529, @JTannerWMF wrote:

This task needs to be resolved and a new parent task should take its place @ppelberg. Once Ppelberg cleans this up and make QA clear it can be moved.

Potential approach
In discussing this with @Esanders, he shared one approach we could take to adding the support this task is asking for...