Dependencies without cycles

Claim: code dependencies between folders never form a cycle, so every folder sits on a level above everything it uses.

• Grade: convention, argued from design practice.
• Evidence: file structure, against (dependencies).
• Check: tree-shape (exact for static Python imports): a cycle between folders fails.
• Reader styles: none override it.

What it asks

• No two folders that import each other, directly or through others.
• Shared code goes into a folder of its own, declared as a lower level, that the others import.
• A link between documents is a reference, not a dependency, and may cycle: a note and the note it cites may point at each other.

Why

Without cycles a system can be levelized: each component gets a level above all it uses, and can be understood, tested and replaced from the bottom up (Lakos 1996; the acyclic dependencies principle, Martin 2017). A cycle is the one shape that makes placing shared code at a common ancestor impossible.

Limits

The support is argument, not a controlled study. A rule on path shapes (never import a sibling folder) contradicts levelization, which puts shared code exactly in a sibling; check levels and cycles, not paths.