Did I miss something? If I am right, I offer to write the necessary patch, copied and adapted from the tag plugin, to generate the pages `archive_base/year/month.mdwn` on the fly.
--- Spalax
+-- [[Louis|spalax]]
> Good spotting, `ikiwiki-calendar` predates the `add_autofile` API used to
> autocreate tag pages and was bolted in as an easy way to create calendar
> That last is, arguably, the real point of running ikiwiki-calendar in
> a cron job. Of course all it really does is run `ikiwiki -setup foo
> -refresh`. --[[Joey]]
+
+> > [[Patch|todo/calendar_autocreate]]. -- [[Louis|spalax]]
--- /dev/null
+Here is a patch that makes [[ikiwiki-calendar]] almost useless.
+
+It adds some options, the main one being `calendar_autocreate`, which is
+similar to the `tag_autocreate` option of the [[tag|plugins/tag]]: it create
+archive pages when needed.
+
+The documentation is updated as well (but as a non-native English speaker, I
+won't be offended if you correct stuff you consider awkward):
+
+- [[plugin|https://github.com/paternal/ikiwiki/blob/calendar-autocreate/doc/plugins/calendar.mdwn]]
+- [[directive|https://github.com/paternal/ikiwiki/blob/calendar-autocreate/doc/ikiwiki/directive/calendar.mdwn]]
+
+[[!tag patch]]
+[[!template id=gitbranch branch=spalax/calendar-autocreate browse="https://github.com/paternal/ikiwiki/tree/calendar-autocreate" author="[[Louis|spalax]]"]]
+
+--[[Louis|spalax]]