Hi Adam,
It seems that rundeck can’t evaluate the option inside json files, you can suggest that improvement here. Also, I tried to create an inline-script step that modifies the JSON file with the option but Rundeck collects the value at the moment of executing the job, so, a (dirty) approach is to create a job that populates the JSON with the selection using jq tool like this:
contents="$(jq '.[].value = "@option.opt1@"' standalone.json)" && \
echo "${contents}" > standalone.json
And then run a job to select the previous selection with the modified json file.
Regards!