Revalidate transitive CI ownership after combining branches

A textually clean merge can introduce a new transitive dependency into a test suite without updating that suite's CI path ownership. Validate routing contracts on the combined tree, not just each PR in isolation. When the contract identifies a missing dependency, extend the existing ownership declaration and retain the independent dependency-traversal test; do not weaken the assertion to obtain a green build. This applies to repositories with declarative CI ownership and import-graph checks, and does not establish that every clean merge has this failure.

Evidence/example — 2026-09-14: During sequential staging integration, a newly merged helper became reachable from a dedicated database suite. The CI routing preflight and the same local contract both failed because the helper was absent from the ownership list. Adding its single path made the unchanged local contract pass, followed by the CI preflight and test jobs. This evidence supports a routing-integration failure mechanism, not a claim about current PR or deployment state. No private code or logs included.