3 · Network
One component, two modes. In create mode it owns a VPC; in adopt mode it builds nothing and re-exports someone else's through the same outputs.
The VPC and its subnet tiers, and the two modes every network component supports — create one, or adopt one that already exists.
Create and adopt are a single contract rather than two code paths, which is what lets the same component serve a greenfield account and an existing enterprise network. The validations that reject an adopt-only input in create mode are the enforcement.
Drawn from its model, and rendered by the atlas project innanohype/.github.