diff --git a/apps/web/src/lib/server/db.ts b/apps/web/src/lib/server/db.ts
index 2b03d0b..83f6016 100644
--- a/apps/web/src/lib/server/db.ts
+++ b/apps/web/src/lib/server/db.ts
@@ -28,13 +28,21 @@ function applyDefaultPragmas(instance: any): void {
  * - En Node (Vite dev SSR): better-sqlite3
  */
 async function importSqliteDatabase(): Promise<any> {
+  // En tests, forzar bun:sqlite para evitar mezclar engines con la conexión de tests
+  const nodeEnv = String(process.env.NODE_ENV || '').toLowerCase();
+  if (nodeEnv === 'test') {
+    const mod: any = await import('bun:sqlite');
+    return (mod as any).Database || (mod as any).default || mod;
+  }
+
   // En desarrollo (Vite SSR), cargar better-sqlite3 vía require de Node para mantener el contexto CJS
-  if (import.meta.env.DEV) {
+  if (typeof import.meta !== 'undefined' && (import.meta as any).env?.DEV) {
     const modModule: any = await import('node:module');
     const require = modModule.createRequire(import.meta.url);
     const mod = require('better-sqlite3');
     return (mod as any).default || (mod as any).Database || mod;
   }
+
   // En producción (Bun en runtime), usar bun:sqlite nativo
   const mod: any = await import('bun:sqlite');
   return (mod as any).Database || (mod as any).default || mod;
@@ -163,3 +171,16 @@ export async function getDb(filename: string = 'tasks.db'): Promise<any> {
   _db = await openDb(filename);
   return _db;
 }
+
+/**
+ * Cierra y resetea la instancia compartida (útil en tests para evitar manejar
+ * un descriptor abierto al borrar el archivo de la BD en disco).
+ */
+export function closeDb(): void {
+  try {
+    if (_db && typeof _db.close === 'function') {
+      _db.close();
+    }
+  } catch {}
+  _db = null;
+}
diff --git a/tests/web/api.tasks.complete.reaction.test.ts b/tests/web/api.tasks.complete.reaction.test.ts
index 1601b6c..bd1120b 100644
--- a/tests/web/api.tasks.complete.reaction.test.ts
+++ b/tests/web/api.tasks.complete.reaction.test.ts
@@ -1,5 +1,6 @@
 import { beforeEach, afterEach, describe, expect, it } from 'bun:test';
 import { createTempDb } from './helpers/db';
+import { closeDb } from '../../apps/web/src/lib/server/db.ts';
 import { POST as completeHandler } from '../../apps/web/src/routes/api/tasks/[id]/complete/+server.ts';
 
 function toIsoSql(d: Date): string {
@@ -35,6 +36,8 @@ describe('Web API - completar tarea encola reacción ✅', () => {
   });
 
   afterEach(() => {
+    // Cerrar la conexión singleton de la web antes de borrar el archivo
+    try { closeDb(); } catch {}
     if (cleanup) cleanup();
     // Limpiar env relevantes
     delete process.env.DB_PATH;