In a climbing RAG system, 'recommend the next route' (progression) and 'recommend a similar route' (similarity) were conflated by a single hasSimilarRouteIntent() function, causing recommendation quality to collapse. The fix is a two-stage intent classification with a Regex Fast Path + LLM Fallback.
The RAG system's extractRouteReference() used a for...return pattern that grabbed only the first match — so when a user provided five completed routes, only one was used. The fix evolves through three layers: rule-based multi-entity extraction, user profile aggregation, and embedding centroid.
Query: 'I just sent Beauty in the Mirror 5.11b — recommend routes of similar difficulty.' The results came back full of routes with similar-sounding names, not similar grades. Root cause: dense embeddings compress multiple attributes into a single vector, and the rarity of the route name drowns out the grade signal. The fix: three layers of defense — metadata pre-filtering, query rewriting, and score fusion.