What are you asking to be done here?

trevj wrote:

Thanks for asking. Sorry for my delayed reply.

When viewing a static historical page of specific revision, the desire is to transclude any templates/subpages from their static representations at that time too. Currently the *present* versions of templates/subpages are transcluded. This would help in summarising subpages in main articles (using <noinclude> and/or <includeonly>) by preserving their rendered state at that time. If it can be implemented (maybe further discussion at Village Pump (Technical) would be needed for consensus) then there would be the issue of deleted pages. In such cases, perhaps a standard template warning could be rendered instead. Thanks.

To perhaps clarify slightly, what I believe is being asked for here is for the historical revisions of pages with transcluded content to display the transcluded content as it appeared at the time of the historical revision.

For example, when viewing the revision of en:Greenwich from 11:11 30 September 2011, which transcludes template {{infobox UK place}}, the current behaviour is to display the present version of the template. The desired behaviour is to display {{infobox UK place}} as it appeared at 11:11 30 September 2011, which in this case is the version as of 10:43, 19 May 2011‎.

If there are multiple versions of a template that existed while the viewed page was live, then the one that should be displayed is the one that was live at the time the selected revision was saved. This then gives an appearance at a defined moment in time. An option to see other versions would be the most desirable, but it is maybe not worth the extra effort required.

Obviously there are issues with transcluded pages that have since been deleted. In some cases there is no harm in displaying the deleted content (e.g. if it was deleted as redundant to a later template, or the page was moved without a redirect), and in other cases there is potential harm (e.g. when a page was deleted as libellous).
The possible options for this scenario would seem to be:

1. display the deleted content regardless.
2. display only a notice that the content was deleted
3. display the deleted content to those users who could see the deleted content directly, and a notice to other users.
4. set a flag that controls which of the above options is chosen on a per revision or per page basis. The default state of this flag should be configurable on a per wiki basis.

In some cases templates have revisions in their history that were vandalised which were simply reverted e.g. http://en.wikipedia.org/w/index.php?title=Template:Shortcut&diff=next&oldid=12423059
In these situations the vandalised content would be visible on old revisions at the same time. If this is a problem then maybe the revisions could be deleted. Another possibility would be to note which revisions were reverted and instead (optionally) show the version reverted to.

This leads on to the problem of handling deleted revisions. If option 1 is chosen above, then this same should be applied here.
If other options are chosen, then perhaps an option to select an alternative revision that was also live during the time the article revision being viewed was current (if any) instead would be good, although again I don't know if the effort required to implement this would be worth it.

Finally, specific versions of templates could be created and set to be displayed in the place of any or all deleted revisions of a page (maybe similar to how editnotices work?). This may be better filed as a separate request dependent on this one?

trevj wrote:

Thank you, Chris, for explaining things more thoroughly and accurately. Perhaps I should take this up again with an RfC on en-wp.

In T36244#393271, @Thryduulf wrote:

To perhaps clarify slightly, what I believe is being asked for here is for the historical revisions of pages with transcluded content to display the transcluded content as it appeared at the time of the historical revision.

How does this differ from T2851: when viewing an old version of a page, use old version of templates?

In T36244#6453416, @Nemo_bis wrote:

In T36244#393271, @Thryduulf wrote:

To perhaps clarify slightly, what I believe is being asked for here is for the historical revisions of pages with transcluded content to display the transcluded content as it appeared at the time of the historical revision.

How does this differ from T2851: when viewing an old version of a page, use old version of templates?

As best I can tell, despite the title T2851 is asking for an exact snapshot of a page as it appeared at a given moment in time (and for that appearance to be citable?) - templates, images, skin (etc?). This request is only for templates and so (if I've interpreted the other task correctly) is a subtask of that, assuming that the code that would add this feature for templates would not also do it for images, skins or other page elements. (I'm no coder, but I think that is a safe assumption)