fix: align auth success status contract

src/auth/auth.controller.spec.ts

@@ -0,0 +1,21 @@
+import { HTTP_CODE_METADATA } from '@nestjs/common/constants';
+
+jest.mock('./auth.service', () => ({
+  AuthService: class AuthService {},
+}));
+
+import { AuthController } from './auth.controller';
+
+describe('AuthController response statuses', () => {
+  it.each(['register', 'login', 'refresh'] as const)(
+    '%s explicitly returns HTTP 200',
+    (handler) => {
+      // Nest stores @HttpCode metadata on the unbound handler function.
+      const handlerTarget = Object.getOwnPropertyDescriptor(
+        AuthController.prototype,
+        handler,
+      )?.value as object;
+      expect(Reflect.getMetadata(HTTP_CODE_METADATA, handlerTarget)).toBe(200);
+    },
+  );
+});

src/auth/auth.controller.ts

@@ -49,6 +49,7 @@ export class AuthController {
   constructor(private readonly auth: AuthService) {}
 
   @Post('register')
+  @HttpCode(200)
   @ApiOkResponse({ type: AuthenticationDto })
   async register(
     @Body() credentials: CredentialsDto,
@@ -61,6 +62,7 @@ export class AuthController {
   }
 
   @Post('login')
+  @HttpCode(200)
   @ApiOkResponse({ type: AuthenticationDto })
   async login(
     @Body() credentials: CredentialsDto,
@@ -73,6 +75,7 @@ export class AuthController {
   }
 
   @Post('refresh')
+  @HttpCode(200)
   @ApiOkResponse({ type: AuthenticationDto })
   async refresh(
     @Req() request: Request,