pub fn entity_fts_document(entity: &Entity) -> TextDocumentExpand description
Build the TextDocument for an entity. This is the single source of truth for
entity FTS document shape; all write paths (create, update, merge, reindex, backfill)
must go through this function so search parity is guaranteed.
Body rule: when the entity has a non-empty description, prepend the name
("<name> <description>"). Otherwise the body is just the name. This
matches the FTS index contract: title and body are the ranked columns;
tags, metadata, and namespace are UNINDEXED.
updated_at is taken from the entity’s own timestamp so that backfill and
reindex runs record the entity’s actual mutation time rather than the
reindex execution time.