Anam #03: "One collection per principle breaks cross-domain retrieval. This is a hierarchical taxonomy assumption that fails from day one."
Problem: "Interest rate increases slow capital allocation to emerging markets" belongs in macro_economics, equity_analysis, market_structure, AND geopolitics simultaneously. Single-label fails.
Proposed: Replace collection (string) with collections (list of {id, weight}). Primary collection = highest weight. Update Stage 2 extraction prompt to assign 1–3 collections with weights. Two-level index becomes weighted routing, not hard assignment.
Migration: Existing single-label nodes: set collections = [{id: current_collection, weight: 1.0}]. Then run re-tagging pass on high-gravity nodes to assign secondary collections.
v3 2026-04-05 Q Mapped to whitepaper sections
v2 2026-04-05 Q Imported SPEC-040 from model_specifications_v2.html
v1 2026-04-05 Q Created spec: SPEC-040: Multi-Label Collections