diff --git a/apps/server/test/integration/search-ru-en-migration.int-spec.ts b/apps/server/test/integration/search-ru-en-migration.int-spec.ts
new file mode 100644
index 00000000..4bf0030a
--- /dev/null
+++ b/apps/server/test/integration/search-ru-en-migration.int-spec.ts
@@ -0,0 +1,72 @@
+import { Kysely, sql } from 'kysely';
+import { getTestDb, destroyTestDb } from './db';
+import * as migration from '../../src/database/migrations/20260707T120000-search-ru-en-config';
+
+/**
+ * #529 A1 — the ru_en config migration must be REVERSIBLE in the correct order:
+ * down() moves pages.tsv + page_embeddings.fts back to `english` BEFORE dropping
+ * the ru_en config (a generated column still depending on ru_en would block the
+ * DROP). This roundtrips down()→up() on the already-migrated test DB and asserts
+ * the config, the pages trigger and the fts generated expression each flip and
+ * flip back — the deploy-critical property.
+ */
+describe('search ru_en config migration [integration]', () => {
+  let db: Kysely<any>;
+
+  const configExists = async () => {
+    const r = await sql<{ n: number }>`
+      SELECT count(*)::int AS n FROM pg_ts_config WHERE cfgname = 'ru_en'
+    `.execute(db);
+    return r.rows[0].n > 0;
+  };
+
+  const ftsDef = async () => {
+    const r = await sql<{ def: string }>`
+      SELECT pg_get_expr(adbin, adrelid) AS def
+      FROM pg_attrdef d
+      JOIN pg_attribute a ON a.attrelid = d.adrelid AND a.attnum = d.adnum
+      WHERE a.attname = 'fts' AND a.attrelid = 'page_embeddings'::regclass
+    `.execute(db);
+    return r.rows[0]?.def ?? '';
+  };
+
+  const triggerSrc = async () => {
+    const r = await sql<{ src: string }>`
+      SELECT prosrc AS src FROM pg_proc WHERE proname = 'pages_tsvector_trigger'
+    `.execute(db);
+    return r.rows[0]?.src ?? '';
+  };
+
+  beforeAll(() => {
+    db = getTestDb();
+  });
+
+  afterAll(async () => {
+    // Restore the migrated (ru_en) state for any later suite, then close.
+    if (!(await configExists())) {
+      await migration.up(db);
+    }
+    await destroyTestDb();
+  });
+
+  it('starts at ru_en (config present, trigger + fts on ru_en)', async () => {
+    expect(await configExists()).toBe(true);
+    expect(await ftsDef()).toContain('ru_en');
+    expect(await triggerSrc()).toContain('ru_en');
+  });
+
+  it('down() reverts tsv + fts to english THEN drops the config', async () => {
+    await migration.down(db);
+    expect(await configExists()).toBe(false);
+    expect(await ftsDef()).toContain('english');
+    expect(await ftsDef()).not.toContain('ru_en');
+    expect(await triggerSrc()).toContain('english');
+  });
+
+  it('up() re-applies ru_en cleanly (idempotent config create)', async () => {
+    await migration.up(db);
+    expect(await configExists()).toBe(true);
+    expect(await ftsDef()).toContain('ru_en');
+    expect(await triggerSrc()).toContain('ru_en');
+  });
+});