I wonder if the problem is prefetch ... yes, I think it is.

This seems to work:

my $rs= $c->schema->resultset("TSeminar")->search(
    { 'semcode' => $code },
    {   "join"      => [ 'marketcode', {'programcode'=>'progfee'} ],
        "prefetch"  => [ 'marketcode', {'programcode'=>'progfee'} ],
        "order_by"  => [qw/semcode/], 
        "rows"      => 1});
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In DBIx::Class::Manual there is a section called “multi-step prefetch” which I had failed to notice before. It says:

From 0.04999_05 onwards, prefetch can be nested more than one relationship deep using the same syntax as a multi-step join ...

And so it appears that this is indeed the syntax that you have to use.

I'm writing this because it appears to work (that is to say, “it does not croak anymore”), and I'll now verify that it does work. (Unless I write to say otherwise, “it did.”)