Gdtyjr

Apologies for the rather general title, while trying to sort out a very specific problem:

I'm trying to enhance the framework that Alan Munn provided here
to represent naturally occurring discourse (with some extras, omitted here), with code from this answer by frougon.
The point of it all is to have a mechanism for Alan's code (which uses the expex package) to not print repeated labels of speakers. I thought I would be able to integrate the two solutions, yet, with increased complexity, somehow along the way I managed to screw it up and for the life of me I can't figure out what's wrong.

This is as minimal a WE as it gets:

% !TEX TS-program = xelatexmk
RequirePackagefilecontents

beginfilecontentsdiscourse.sty
NeedsTeXFormatLaTeX2e
ProvidesPackagediscourse

RequirePackage[user,savepos]zref
RequirePackageexpex
newcounterlinenum
newlengthlargestspkr
newlengthlargestnum
newcommanddeflargestlabel[2][99]
settowidthlargestnum#1
settowidthlargestspkr~#2
deflargestlabel[999]speaker~99

RequirePackageperpage

newcounterspkrcounter
 MakePerPagespkrcounter

newenvironmentdiscourseenv%
 setcounterlinenum0%
 setcounterspkrcounter0%
 ignorespaces
%
 parignorespacesafterend


DeclareOptionskiprepetitions%
 AtBeginDocumentletdiscourse@printdiscourse@print@skip%

DeclareOptionkeeprepetitions%
 AtBeginDocumentletdiscourse@printdiscourse@print@keep%

ExecuteOptionsskiprepetitions
ProcessOptionsrelax

RequirePackagexifthen

defdiscourse@storedval % create a macro to later store a value in

newcommandspkr[1]%
 % create line numbers:
 refstepcounterlinenummakebox[largestnum][r]thelinenumhspace1em
 ifthenelseisempty#1%
 makebox[largestspkr][l]% if empty > empty box
 % If this is the first stepcounterspkrcounter executed since the current
 % page was started, this sets 'spkrcounter' to 1.
 stepcounterspkrcounter% 
 discourse@print#1%
 defdiscourse@storedval#1%
 %


defdiscourse@print@skip#1%
 ifthenelsecnttestvaluespkrcounter>1AND
 equal#1discourse@storedval%
 makebox[largestspkr][l]% if repeated > empty box
 makebox[largestspkr][l]#1:%

defdiscourse@print@keep#1makebox[largestspkr][l]#1:

endfilecontents

documentclassarticle
usepackagediscourse

begindocument

Here it works:

spkrA OK

spkrA OK

spkrB OK

spkrA OK

vbox
Here too in the environment:

begindiscourseenv

spkrA OK

spkrA OK

spkrB OK

enddiscourseenv

vbox
But in combination with expex it screws up:

begindiscourseenv

ex[exno=spkrA, exnoformat=X] OK (prints A) xe

ex[exno=spkrA, exnoformat=X] OK (empty) xe

ex[exno=spkrB, exnoformat=X] OK (prints B) xe

ex[exno=spkrA, exnoformat=X] OK (empty) xe

ex[exno=spkrB, exnoformat=X] OK (prints B) xe

enddiscourseenv

begindiscourseenv

ex[exno=spkrB, exnoformat=X] OK (prints B) xe

newpage

ex[exno=spkrB, exnoformat=X] OK (prints B) xe

ex[exno=spkrB, exnoformat=X] This one should be empty xe

ex[exno=spkrB, exnoformat=X] This one should be empty xe

ex[exno=spkrA, exnoformat=X] This one should print A xe

ex[exno=spkrA, exnoformat=X] OK (empty) xe

enddiscourseenv

enddocument 

It works as expected on the first couple of instances of the spkr macro, but on the next page it behaves weirdly. Anyone able to spot what's wrong?