Design patterns·The shape of the whole application
an import from the domain package to the database package failed the build, and the arrow only ever points inward.
Dependency rule
Also calledthe dependency rule, inward-pointing dependencies
Clean architecture's single load-bearing constraint: source dependencies point only toward higher-level policy, never outward toward detail. Everything else in the diagram — the circles, the names of the layers — follows from it, and enforcing it with an automated check is worth more than any amount of documentation. Where control has to flow outward, dependency inversion is what turns the arrow around.