fix: return DateFieldBuilder from defaultNow() and onUpdateNow() for proper method chaining

packages/mizzle-orm/src/schema/__tests__/fields.test.ts

@@ -132,6 +132,22 @@ describe('Field Builders', () => {
       expect(field._config.onUpdateNow).toBe(true);
     });
 
+    it('should support defaultNow().onUpdateNow() chaining for timestamp fields', () => {
+      // Regression test: defaultNow() must return DateFieldBuilder so onUpdateNow() is available
+      // This pattern is common for updatedAt fields that need both default and auto-update behavior
+      const field = date().defaultNow().onUpdateNow();
+      expect(field._config.defaultNow).toBe(true);
+      expect(field._config.onUpdateNow).toBe(true);
+      expect(field._config.type).toBe(FieldType.DATE);
+    });
+
+    it('should support onUpdateNow().defaultNow() chaining in reverse order', () => {
+      // Ensure chaining works in either order
+      const field = date().onUpdateNow().defaultNow();
+      expect(field._config.defaultNow).toBe(true);
+      expect(field._config.onUpdateNow).toBe(true);
+    });
+
     it('should support soft delete flag', () => {
       const field = date().softDeleteFlag();
       expect(field._config.isSoftDeleteFlag).toBe(true);

packages/mizzle-orm/src/schema/field-builders-primitive.ts

@@ -123,20 +123,20 @@ export class DateFieldBuilder<TConfig extends FieldConfigState = EmptyConfig>
   extends FieldBuilder<Date, TConfig, DateFieldBuilder<TConfig>>
   implements IDateFieldBuilder<TConfig>
 {
-  constructor() {
-    super(FieldType.DATE);
+  constructor(config: Partial<import('../types/field').FieldConfig<Date>> = {}) {
+    super(FieldType.DATE, config);
   }
 
   defaultNow(): DateFieldBuilder<TConfig & { hasDefaultNow: true; hasDefault: true }> {
-    return new FieldBuilder(this._config.type, {
+    return new DateFieldBuilder({
       ...this._config,
       defaultNow: true,
       defaultValue: () => new Date(),
     }) as any;
   }
 
   onUpdateNow(): DateFieldBuilder<TConfig & { hasOnUpdateNow: true }> {
-    return new FieldBuilder(this._config.type, {
+    return new DateFieldBuilder({
       ...this._config,
       onUpdateNow: true,
     }) as any;