Add the migration tree(s) (offline bundles).
OptionalmigrationPlatform: DbPlatformNarrow to one platform's tree; omitted = both (a sparse fetch tolerates a path that doesn't exist at the ref).
Add the pre-built Claude pack source. Default true
matches the assembler's auto-include behavior; pass false to skip the fetch
entirely when IncludeClaudePack: false was set on the assemble options.
A sparse fetch tolerates a path that doesn't exist at the ref, so the older-tag
case (no pack present) is fine either way.
The repo-relative source paths a sparse fetch must check out so that DistributionAssembler.Plan has everything it needs: the mapped code directories, the base tsconfigs inlined during flattening, and the root
distribution.*template files.