Well I feel dumb for not knowing the problem here, but I have

node_terminus = exec
    external_nodes = /opt/puppetlabs/server/apps/puppetserver/bin/enc.sh

Said script just does

#!/usr/bin/env

cat <<EOF
classes:
  - foo
EOF

exit

environment.conf

has

manifest

set to an empty directory. But running the agent just does... nothing. I see the

replace_facts

command in

puppetserver.log

, but nothing else happens. Am I missing something obvious?