Thanks
andi, both for this very quick and useful answer, and for moving my post to a more appropriate forum. I'll use Development for this sort of thing in future.
andi wroteYou could also write an action plugin that directly feeds you IM API.
True, but I probably won't attempt a plugin to do that, since I have [almost] all the code I need to make my bot do this already in a context outside DokuWiki, so all I need to do is iterate through the text file and extract variables. Also, in my scenario, there are some fairly strict access controls in place, which mean it's easier for me to monitor the text file on the DokuWiki host from another host, which then accesses the IM API (this is certainly not your problem!)
On the other hand, I can see that one advantage of my writing a plugin would be easy access to richer info like the "first heading" page name, rather than only the underlying page name.
I couldn't see any file recording user page views, other than access.log; is there something simple and similar to _dokuwiki.changes which would allow me to do something like:
[11:27] WikiBot: User Jane.Doe is reading page "Leap Year special procedures" under namespace "Procedures/Calendar"