"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 moves: no spec key, Zod schema, export, config field or stored metadata shape is added, removed, renamed or re-spelled. The strict defineStack parse already refused every input this refuses, so an authored stack that passed its schema builds exactly as before; what narrows is the runtime behaviour of the strict: false door on inputs that bypassed that parse, and objectstack migrate meta has no document to rewrite for it.

"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"