ADR-0087 exemption (no-migration-prescription): No key of any schema is added, removed, renamed or re-shaped, and no export or type of the package's public surface changes. `composeStacks` now applies, over every input, the cross-reference rule strict `defineStack` already applies to one stack (ADR-0015 amendment D7): a datasource's `external.connector` must name a declared connector instance with a provider and an auth credential. The refused artifacts are authoring defects that a `strict: false` input carried past the per-stack pass, fixed by declaring the instance or correcting the name in the package source. There is nothing for `objectstack migrate meta` to rewrite.