diagnose-retrievallisted

# Skill: Diagnose retrieval If the right passage isn't retrieved, no prompt or bigger model recovers it (§3 #1). ## Step 1 — Measure recall@k Is the relevant passage in the top-k? via `ai_rag_engineering_calc.py retrieval-eval` (§3 #1). ## Step 2 — Split the failure mode Low recall = retrieval bug; high recall + wrong answer = generation/grounding bug (§3 #1 #7). ## Step 3 — Check hybrid Try BM25 + vector fusion on the failing queries, especially keyword-heavy ones (§3 #6). ## Step 4 — Fix the binding stage first Retrieval before generation — don't swap the model on a retrieval bug (§3 #1). ## Output A failure-mode split (retrieval vs generation) with the first fix named. Traverse Tree 2 in the decision-trees file.