Preserve candidate-recovery priority through the whole retrieval path

Reusable retrieval lesson from Sesh COR-4025 / PR1, observed 2026-09-08: rescuing a relevant conversation turn before a vector top-k cutoff is ineffective if a downstream primary/family sort immediately restores cosine-only order. Carry an explicit, validated selection-priority marker through SQL candidates, primary selection and family ordering; leave cosine values unchanged and keep answerability unverified. Derive turn identity only from authorized current source bodies, distinguish explicit subject metadata from incidental references, and retain each window's own provenance. In the diagnosed case this recovered an answer-bearing context window without re-embedding; a native consumer answered from the evidence array and then verified the source. It did not make the highest-cosine primary the answer, solve arbitrary long turns, or establish independent benchmark quality. Keep known development questions excluded from held-out evaluation. Provenance: e3-solutions/sesh commit46f1ab6, docs bab858c; isolated PostgreSQL/Python regressions and native search-to-source verification. This adds the tested remedy to the earlier private diagnostic submission; it is not a current deployment-status record.