fix: address code review - improve type safety and warning message in I18nServicePlugin

Co-authored-by: hotlong <50353452+hotlong@users.noreply.github.com>

Author: Copilot

CHANGELOG.md

@@ -7,19 +7,28 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+- **i18n route self-registration** — Moved i18n REST endpoint registration from `RestServer` to
+  `I18nServicePlugin` (and kernel fallback). The i18n plugin now self-registers `/api/v1/i18n/*`
+  routes via the `kernel:ready` hook, following the same autonomous plugin pattern used by
+  `AuthPlugin`, `WorkflowPlugin`, and other service plugins. `RestServer` no longer registers or
+  manages any i18n endpoints, keeping it strictly a protocol-driven gateway.
+- Removed `enableI18n` flag from `RestApiConfig` schema (`rest-server.zod.ts`) — i18n endpoints
+  are now controlled by the i18n service plugin's own `registerRoutes` option (default: `true`).
+- Removed `registerI18nEndpoints()` method from `RestServer` class.
+- `I18nServicePlugin` now accepts `registerRoutes` and `basePath` options for HTTP route control.
+- i18n endpoints now work independently of `RestServer`, enabling MSW/mock test environments
+  to serve i18n routes without any REST API gateway dependency.
+
 ### Added
 - **i18n as core built-in service** — The i18n service is now a `core` criticality service with
   automatic in-memory fallback. When no plugin (e.g. `I18nServicePlugin`) registers an i18n service,
   the kernel auto-injects `createMemoryI18n` (in-memory Map-backed II18nService implementation)
   during `validateSystemRequirements()`. This ensures `/api/v1/i18n/*` routes and discovery always
   report i18n as available, even without `plugin-i18n` installed.
-- **REST i18n route auto-registration** — `RestServer.registerRoutes()` now automatically registers
-  `/api/v1/i18n/locales` and `/api/v1/i18n/translations/:locale` endpoints, controlled by the new
-  `enableI18n` config flag (default: `true`).
 - `createMemoryI18n` fallback factory in `@objectstack/core` (packages/core/src/fallbacks/memory-i18n.ts)
   implementing `II18nService` contract with translation loading, dot-notation key resolution, parameter
   interpolation, and locale management.
-- `enableI18n` flag in `RestApiConfig` schema (`rest-server.zod.ts`) for toggling i18n API endpoints.
 
 ### Changed
 - `ServiceRequirementDef.i18n` upgraded from `'optional'` to `'core'` — kernel now warns (instead

ROADMAP.md

@@ -842,7 +842,7 @@ Final polish and advanced features.
 | 19 | Automation Service | `IAutomationService` | ✅ | `@objectstack/service-automation` | DAG engine + HTTP API CRUD + Client SDK + typed returns (67 tests) |
 | 20 | Workflow Service | `IWorkflowService` | ❌ | `@objectstack/service-workflow` (planned) | Spec only |
 | 21 | GraphQL Service | `IGraphQLService` | ❌ | `@objectstack/service-graphql` (planned) | Spec only |
-| 22 | i18n Service | `II18nService` | ✅ | `@objectstack/service-i18n` | File-based locale loading |
+| 22 | i18n Service | `II18nService` | ✅ | `@objectstack/service-i18n` | File-based locale loading, self-registered REST routes |
 | 23 | UI Service | `IUIService` | ⚠️ | — | **Deprecated** — merged into `IMetadataService` |
 | 24 | Schema Driver | `ISchemaDriver` | ❌ | — | Spec only |
 | 25 | Startup Orchestrator | `IStartupOrchestrator` | ❌ | — | Kernel handles basics |

packages/services/service-i18n/src/i18n-service-plugin.ts

@@ -81,7 +81,7 @@ export class I18nServicePlugin implements Plugin {
     this.i18n = new FileI18nAdapter(adapterOptions);
     ctx.registerService('i18n', this.i18n);
     ctx.logger.info(
-      `I18nServicePlugin: registered file-based i18n adapter (default: ${this.i18n.getDefaultLocale!()})`,
+      `I18nServicePlugin: registered file-based i18n adapter (default: ${this.i18n.getDefaultLocale?.() ?? 'en'})`,
     );
   }
 
@@ -105,7 +105,7 @@ export class I18nServicePlugin implements Plugin {
         } else {
           ctx.logger.warn(
             'No HTTP server available — i18n routes not registered. ' +
-            'i18n service is still available for MSW/mock environments via HttpDispatcher.'
+            'i18n service is still available programmatically via kernel.getService("i18n").'
           );
         }
       });
@@ -169,8 +169,12 @@ export class I18nServicePlugin implements Plugin {
           res.status(400).json({ error: 'Missing object or locale parameter' });
           return;
         }
-        if (typeof (i18n as any).getFieldLabels === 'function') {
-          const labels = (i18n as any).getFieldLabels(objectName, locale);
+        // Some implementations may provide a dedicated getFieldLabels method
+        const hasGetFieldLabels = 'getFieldLabels' in i18n
+          && typeof (i18n as Record<string, unknown>)['getFieldLabels'] === 'function';
+        if (hasGetFieldLabels) {
+          const labels = (i18n as II18nService & { getFieldLabels(obj: string, loc: string): Record<string, string> })
+            .getFieldLabels(objectName, locale);
           res.json({ data: { object: objectName, locale, labels } });
         } else {
           // Fallback: derive field labels from full translation bundle