fix(server): config defaults (#11879)

packages/backend/server/src/base/config/__tests__/config.spec.ts

@@ -185,3 +185,28 @@ test('should clone from original config without modifications', t => {
 
   t.not(newConfig.auth.allowSignup, config.auth.allowSignup);
 });
+
+test('should override with undefined fields', async t => {
+  await using module = await createModule({
+    imports: [ConfigModule],
+  });
+
+  const config = module.get(Config);
+  const configFactory = module.get(ConfigFactory);
+
+  configFactory.override({
+    copilot: {
+      providers: {
+        // @ts-expect-error undefined field
+        unknown: {
+          apiKey: '123',
+        },
+      },
+    },
+  });
+
+  // @ts-expect-error undefined field
+  t.deepEqual(config.copilot.providers.unknown, {
+    apiKey: '123',
+  });
+});

packages/backend/server/src/base/config/factory.ts

@@ -7,7 +7,7 @@ export const OVERRIDE_CONFIG_TOKEN = Symbol('OVERRIDE_CONFIG_TOKEN');
 
 @Injectable()
 export class ConfigFactory {
-  #original: AppConfig;
+  readonly #original: AppConfig;
   readonly #config: AppConfig;
   get config() {
     return this.#config;
@@ -18,8 +18,8 @@ export class ConfigFactory {
     @Optional()
     private readonly overrides: DeepPartial<AppConfig> = {}
   ) {
-    this.#config = this.loadDefault();
-    this.#original = structuredClone(this.#config);
+    this.#original = this.loadDefault();
+    this.#config = structuredClone(this.#original);
   }
 
   clone() {
@@ -28,8 +28,8 @@ export class ConfigFactory {
   }
 
   override(updates: DeepPartial<AppConfig>) {
+    override(this.#original, updates);
     override(this.#config, updates);
-    this.#original = structuredClone(this.#config);
   }
 
   validate(updates: Array<{ module: string; key: string; value: any }>) {

packages/backend/server/src/base/config/register.ts

@@ -57,6 +57,10 @@ function typeFromShape(shape: z.ZodType<any>): ConfigType {
       return 'array';
     case z.ZodObject:
       return 'object';
+    case z.ZodOptional:
+    case z.ZodNullable:
+      // @ts-expect-error checked
+      return typeFromShape(shape.unwrap());
     default:
       return 'any';
   }
@@ -251,6 +255,14 @@ export function override(config: AppConfig, update: DeepPartial<AppConfig>) {
         return right;
       }
 
+      // EDGE CASE:
+      //   the right value is primitive and we're still not finding the key in descriptors,
+      //   which means the overrides has keys not defined
+      //   that's where we should return
+      if (typeof right !== 'object') {
+        return left;
+      }
+
       // go deeper
       return mergeWith(left, right, (left, right, key) => {
         return merge(left, right, path === '' ? key : `${path}.${key}`);