Exclude queried artists from recommendations - only suggest new artists

backend/app/services/recommender.py

@@ -181,6 +181,8 @@ Discovery mode: {mode_instruction}
 
 {adventurousness_instruction}
 
+IMPORTANT: If the user mentions specific artists or songs in their request, do NOT recommend anything BY those artists. The user already knows them — recommend music by OTHER artists that match the vibe. For example, if they say "I like Sublime", recommend artists similar to Sublime, but NEVER Sublime themselves.
+
 Already in their library (do NOT recommend these):
 {', '.join(list(existing_tracks)[:50]) if existing_tracks else 'None provided'}
 {disliked_instruction}