Meaning made useful
An expression may be an article, tutorial, reference, diagram, or application artifact. The broader idea is not limited to web pages. This site currently implements a publishing collection of articles and resources.
One file, one canonical record
Expressions live under content/expressions/{pillar}/{cluster}/{expression}.md.
The root node supplies semantic identity; Markdown supplies the reading experience.
Do not maintain a second copy of that node under content/graph/.
A generated artifact is not automatically new evidence. Review its facts and relationships before treating it as an accepted part of the model.