diff --git a/server/src/schemas/tool-inputs/create-sales-order.ts b/server/src/schemas/tool-inputs/create-sales-order.ts
index 27c0238..7509986 100644
--- a/server/src/schemas/tool-inputs/create-sales-order.ts
+++ b/server/src/schemas/tool-inputs/create-sales-order.ts
@@ -1,9 +1,14 @@
 import { z } from 'zod';
 import { Order, OrderSchema } from '../entities/order.js';
+import { Customer, CustomerSchema } from '../entities/customer.js';
 import { makeZodFieldMap } from '../utils/schema-util.js';
 
 const immutableOrderFields = ['id', 'createdAt', 'updatedAt', 'tenantId'] as const satisfies (keyof Order)[];
+const serverOnlyCustomerFields = ['createdAt', 'updatedAt', 'tenantId'] as const satisfies (keyof Customer)[];
+
 export const CreateSalesOrderInputSchema = z.object({
-  order: OrderSchema.omit(makeZodFieldMap(immutableOrderFields)),
+  order: OrderSchema.omit(makeZodFieldMap(immutableOrderFields)).extend({
+    customer: CustomerSchema.omit(makeZodFieldMap(serverOnlyCustomerFields)).optional(),
+  }),
 });
 export type CreateSalesOrderInput = z.infer<typeof CreateSalesOrderInputSchema>;
diff --git a/server/tests/integration/adapter.test.ts b/server/tests/integration/adapter.test.ts
index 655c0e5..580b730 100644
--- a/server/tests/integration/adapter.test.ts
+++ b/server/tests/integration/adapter.test.ts
@@ -11,17 +11,11 @@ const baseAddress = (overrides: Partial<Record<string, string>> = {}) => ({
   ...overrides,
 });
 
-const buildCustomer = (extId: string) => {
-  const timestamp = new Date().toISOString();
-  return {
-    id: `CUST-${extId}-${Date.now()}`,
-    tenantId: 'mock-tenant',
-    createdAt: timestamp,
-    updatedAt: timestamp,
-    email: `${extId.toLowerCase()}@example.com`,
-    firstName: 'Adapter',
-  };
-};
+const buildCustomer = (extId: string) => ({
+  id: `CUST-${extId}-${Date.now()}`,
+  email: `${extId.toLowerCase()}@example.com`,
+  firstName: 'Adapter',
+});
 
 const buildOrder = (extId: string) => ({
   externalId: extId,
diff --git a/server/tests/integration/e2e-workflows.test.ts b/server/tests/integration/e2e-workflows.test.ts
index 642c79d..a0bd5ea 100644
--- a/server/tests/integration/e2e-workflows.test.ts
+++ b/server/tests/integration/e2e-workflows.test.ts
@@ -11,17 +11,11 @@ const address = (overrides: Partial<Record<string, string>> = {}) => ({
   ...overrides,
 });
 
-const buildCustomer = (prefix: string) => {
-  const timestamp = new Date().toISOString();
-  return {
-    id: `WF-CUST-${prefix}-${Date.now()}`,
-    tenantId: 'mock-tenant',
-    createdAt: timestamp,
-    updatedAt: timestamp,
-    email: `${prefix.toLowerCase()}@example.com`,
-    firstName: prefix,
-  };
-};
+const buildCustomer = (prefix: string) => ({
+  id: `WF-CUST-${prefix}-${Date.now()}`,
+  email: `${prefix.toLowerCase()}@example.com`,
+  firstName: prefix,
+});
 
 const buildOrderPayload = (prefix: string) => ({
   externalId: `${prefix}-${Date.now()}`,
diff --git a/server/tests/integration/tools.test.ts b/server/tests/integration/tools.test.ts
index ae07909..82a83d7 100644
--- a/server/tests/integration/tools.test.ts
+++ b/server/tests/integration/tools.test.ts
@@ -11,17 +11,11 @@ const requiredAddress = (overrides: Partial<Record<string, string>> = {}) => ({
   ...overrides,
 });
 
-const buildCustomer = (prefix: string) => {
-  const timestamp = new Date().toISOString();
-  return {
-    id: `CUST-${prefix}-${Date.now()}`,
-    tenantId: 'mock-tenant',
-    createdAt: timestamp,
-    updatedAt: timestamp,
-    email: `${prefix.toLowerCase()}@example.com`,
-    firstName: prefix,
-  };
-};
+const buildCustomer = (prefix: string) => ({
+  id: `CUST-${prefix}-${Date.now()}`,
+  email: `${prefix.toLowerCase()}@example.com`,
+  firstName: prefix,
+});
 
 const makeLineItem = (idSuffix: string) => ({
   id: `LI-${idSuffix}`,