I did look at the scripts and started playing. I didn’t want to copy and paste a solution, because I feel like I need to understand it myself. So I got the custom metadata setup and working. My question now is, do I have to run this every time I update a document? Should I change ‘On Demand’ to ‘After Saving’ - is that the best option?
This is a really useful solution for doing certain searches on markdown documents that wouldn’t have been possible otherwise.
Based on the custom metadata field updated with MD contents through the smart rule, I was able to set up a smart group for Markdown items that contain a specific type of cross-link.