fix(orm): don't build an empty IN() when zero rows match an update/updateMany on MySQL

packages/orm/src/client/executor/zenstack-query-executor.ts

@@ -460,6 +460,13 @@ export class ZenStackQueryExecutor extends DefaultQueryExecutor {
                 ? this.getInsertIds(mutationInfo.model, queryNode, queryResult)
                 : preUpdateIds;
 
+            if (mutatedIds && mutatedIds.length === 0) {
+                // zero rows matched (e.g. a policy-denied or genuinely empty
+                // updateMany/deleteMany) — nothing to reload, and NOT the "can't
+                // determine ids at all" case below, so don't warn.
+                return [];
+            }
+
             if (mutatedIds) {
                 const idFields = requireIdFields(this.client.$schema, mutationInfo.model);
                 const eb = expressionBuilder<any, any>();

tests/regression/test/issue-2884.test.ts

@@ -0,0 +1,29 @@
+import { createTestClient } from '@zenstackhq/testtools';
+import { describe, expect, it } from 'vitest';
+
+describe('Regression for issue 2884', () => {
+    it('zero-match updateMany on MySQL does not throw when an afterEntityMutation hook is registered', async () => {
+        const db = await createTestClient(
+            `
+model User {
+    id Int @id @default(autoincrement())
+    email String @unique
+}
+            `,
+            { provider: 'mysql', usePrismaPush: true },
+        );
+
+        const hooked = db.$use({
+            id: 'noop',
+            onEntityMutation: {
+                afterEntityMutation: async () => {},
+            },
+        });
+
+        // no row with id 999 exists -> preUpdateIds resolves to [] -> should be a
+        // normal zero-match update, not a thrown SQL syntax error
+        await expect(
+            hooked.user.updateMany({ where: { id: 999 }, data: { email: 'x@example.com' } }),
+        ).resolves.toEqual({ count: 0 });
+    });
+});