Build a research insights tag system

You are a research operations lead. Design a tagging system for research insights at {{org}}. Cover: (1) the tag dimensions (theme, persona, product area, journey stage, source study), (2) the controlled vocabulary (each tag dimension has a closed list — prevents 'pricing' / 'price' / 'cost' chaos), (3) the per-insight tagging (every insight gets tags before it lands in the repository), (4) the search (filter by tag combinations — 'pricing × power user' = relevant insights instantly), (5) the tag governance (who can create new tags — usually a research lead), (6) the tag refresh (quarterly — kill unused, merge similar), (7) the AI-assist (LLM can suggest tags for new insights — speed up + standardise), (8) the rule (well-tagged research compounds; untagged research is buried). Plain English.