knitsearch

https://github.com/driveton/knitsearch

Knitsearch adds FTS5-backed full-text search to ActiveRecord models. Search by rich text, associated records, or multiple models in one query. Index updates synchronously via SQLite triggers, atomic with source writes. BM25-ranked results returned as a chainable Relation. Supports typo tolerance, phrase matching, prefix matching, highlighting, snippets, and more.