"The ubuntu-latest label will migrate to Ubuntu 26 beginning October 19, 2026. For more information, see https://github.com/actions/runner-images/issues/14748"

"The ubuntu-latest label will migrate to Ubuntu 26 beginning October 19, 2026. For more information, see https://github.com/actions/runner-images/issues/14748"

ADR-0087 exemption (no-migration-prescription): Nothing authorable is renamed, retired or re-typed: every object key, every `composeStacks` option and the `ConflictStrategySchema` enum 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, one step past the #14848 narrowing that answered the same question the same way: two stacks whose same-name objects both declare a fixed-shape config object (`enable`, `access`, `protection`, ...) with different values are now refused under `'merge'` where they used to compose with the earlier declaration silently replaced. The refusal text names the object, the key and both stacks and carries its own fix, no stored metadata row or authored file changes shape, and the repository measures zero non-test call sites passing `objectConflict` at all, so there is no document for a migration to act on.