Composition
What a manifest declares, and what it means for something to be composed.
Placeholder. This essay walks modules.toml: the operator, commons, and repo slots, and what “composed” buys that “cloned into a folder” does not. It should show a real manifest and read it line by line, and it should be explicit that the manifest is declarative — the router knows a thing exists because the file names it, never because the router went looking.