On the bootstrap question: The single real trap is that since August 2025 binaries coming through NEW are thrown away once the upload is accepted, see:
https://wiki.debian.org/ThrowAwayNewBinaries The last section on that page, "Bootstrapping binaries", is the one you need; for a package that build-depends on its own binaries it gives exactly this sequence of three uploads: 1. dart-sdk 3.13.0-1, source + binary -> experimental 2. dart-sdk 3.13.0-2, source + binary -> unstable 3. dart-sdk 3.13.0-3, source-only -> unstable, and from then on the usual source-only workflow for every new version
