D2's Dagre layout uses Dagro, a native Go port of the Dagre 3.1.1 layout
surface used by D2:
https://github.com/d2lang/dagro

The complete Dagro, Dagre, and Graphlib attribution and MIT license text is in
../../THIRD_PARTY_NOTICES.txt. D2 includes that file in its native, MSI, and
npm/WASM release artifacts.
