ADR-0087 exemption (no-migration-prescription): Nothing authorable is renamed, retired or re-typed: every object key, every `composeStacks` option and the `ConflictStrategySchema` enum (`'error' | 'override' | 'merge'`) parse exactly as before, so `objectstack migrate meta` has nothing to rewrite. What narrows is the ACCEPT SET of one option value at composition time — two stacks whose same-name objects both declare an object-level collection with different values are now refused under `'merge'` where they used to compose with the earlier stack's entries silently dropped. The refusal text carries the whole prescription (declare the collection in one stack, make the declarations identical, or use `'override'`), and the repository measures zero non-test call sites passing `objectConflict` at all (see below), so there is no stored artifact and no authored file for a migration to act on.