Resolve one connected lineage and retain its root-to-parent capabilities. Backends validate ancestor identity/membership and refresh all policy metadata inside the same boundary as target validators and typed dispatch; hidden/replaced ancestors reject as NotFound without invocation or effects. Preserve pinned leaf and configured-root capabilities. Covers MR ANCESTOR_VISIBILITY_TOCTOU with HTTP memory and Linux replacement/budget/guard regressions; all T-19 workspace acceptance commands pass (Clippy via Nix shell).
Add 21 independent memory-backend external-style tests, both principal HTTP flows, atomic validator/target/effect checks, budgets and sanitized failures; document migration and implementer responsibilities. All T-19 acceptance commands pass; Clippy runs in the repository Nix development shell.