perf: batch gateway submits and isolate callbacks

api/src/prisma/prisma.service.spec.ts

@@ -7,7 +7,25 @@ describe('PrismaService', () => {
     expect(Object.getOwnPropertyDescriptor(prisma, 'operationLog')).toEqual(
       expect.objectContaining({ configurable: true }),
     );
+    expect(prisma.getPoolState()).toEqual({ max: 32, total: 0, idle: 0, waiting: 0 });
 
     await prisma.$disconnect();
   });
+
+  it('reserves a bounded database pool for the isolated Gateway callback process', async () => {
+    const previousRole = process.env.CMPP_PROCESS_ROLE;
+    const previousMax = process.env.API_CALLBACK_DB_POOL_MAX;
+    process.env.CMPP_PROCESS_ROLE = 'callback';
+    process.env.API_CALLBACK_DB_POOL_MAX = '12';
+    try {
+      const prisma = new PrismaService();
+      expect(prisma.getPoolState()).toEqual({ max: 12, total: 0, idle: 0, waiting: 0 });
+      await prisma.$disconnect();
+    } finally {
+      if (previousRole === undefined) delete process.env.CMPP_PROCESS_ROLE;
+      else process.env.CMPP_PROCESS_ROLE = previousRole;
+      if (previousMax === undefined) delete process.env.API_CALLBACK_DB_POOL_MAX;
+      else process.env.API_CALLBACK_DB_POOL_MAX = previousMax;
+    }
+  });
 });