fix(takes): keyword search matches words in long claims via word_similarity (#3267)

Both engines' searchTakes used whole-string trigram similarity
(claim % query), which structurally cannot pass the 0.3 threshold for a
short keyword against a 100-200 char claim — keyword search returned
zero results on real brains. Switch the predicate to word similarity
(query <% claim) and rank by word_similarity(query, claim), in both
postgres-engine and pglite-engine per the engine-parity invariant.
Holder allow-list and source-scope filters unchanged.

Regression test: single-word query must match a long claim containing
it (fails under the old predicate).

Fixes #3267

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/core/pglite-engine.ts

@@ -4835,11 +4835,11 @@ export class PGLiteEngine implements BrainEngine {
     const { rows } = await this.db.query(
       `SELECT t.id AS take_id, t.page_id, p.slug AS page_slug, t.row_num,
               t.claim, t.kind, t.holder, t.weight,
-              similarity(t.claim, $1)::real AS score
+              word_similarity($1, t.claim)::real AS score
        FROM takes t
        JOIN pages p ON p.id = t.page_id
        WHERE t.active
-         AND t.claim % $1
+         AND $1 <% t.claim
          AND ($2::text[] IS NULL OR t.holder = ANY($2::text[]))
          AND ($4::text[] IS NULL OR p.source_id = ANY($4::text[]))
          AND ($5::text IS NULL OR p.source_id = $5::text)

src/core/postgres-engine.ts

@@ -4962,11 +4962,11 @@ export class PostgresEngine implements BrainEngine {
     const rows = await sql`
       SELECT t.id AS take_id, t.page_id, p.slug AS page_slug, t.row_num,
              t.claim, t.kind, t.holder, t.weight,
-             similarity(t.claim, ${query})::real AS score
+             word_similarity(${query}, t.claim)::real AS score
       FROM takes t
       JOIN pages p ON p.id = t.page_id
       WHERE t.active
-        AND t.claim % ${query}
+        AND ${query} <% t.claim
         AND (
           ${opts.takesHoldersAllowList ?? null}::text[] IS NULL
           OR t.holder = ANY(${opts.takesHoldersAllowList ?? null}::text[])

test/takes-engine.test.ts

@@ -100,6 +100,22 @@ describe('searchTakes', () => {
     const worldHits = await engine.searchTakes('founder', { takesHoldersAllowList: ['world'] });
     expect(worldHits.every(h => h.holder === 'world')).toBe(true);
   });
+
+  // #3267: whole-string trigram % structurally can't match a short keyword
+  // against a long claim (similarity between the full strings stays under the
+  // 0.3 threshold). word_similarity (<%) matches the keyword against the
+  // best-matching word span instead.
+  test('single-word keyword matches a long claim containing it (#3267)', async () => {
+    await engine.addTakesBatch([
+      {
+        page_id: acmePageId, row_num: 50,
+        claim: 'Acme will consolidate the mid-market vertical SaaS landscape through disciplined acquisitions and a shared billing platform over the next five years',
+        kind: 'bet', holder: 'garry', weight: 0.6,
+      },
+    ]);
+    const hits = await engine.searchTakes('consolidate');
+    expect(hits.some(h => h.claim.includes('consolidate the mid-market'))).toBe(true);
+  });
 });
 
 describe('updateTake', () => {