AI Implementation feature(863): Challenges Page and Challenge Solve Modal (#45)

docs/architecture/backend-modules.md

@@ -3,7 +3,7 @@ type: architecture
 title: Backend Module Map
 description: NestJS modules, controllers, services, and how they are wired together.
 tags: [architecture, backend, nestjs, modules]
-timestamp: 2026-07-21T22:19:08Z
+timestamp: 2026-07-23T00:10:00Z
 ---
 
 # Module Map
@@ -30,6 +30,7 @@ also registers two global providers:
 | `AdminModule`    | `backend/src/modules/admin/admin.module.ts`   | Four controllers (`AdminController` for `/api/v1/admin/users*`, `AdminGeneralController` for `/api/v1/admin/general/*`, `AdminCategoriesController` for `/api/v1/admin/categories*`, `AdminChallengesController` for `/api/v1/admin/challenges*`) plus their services (`AdminService`, `AdminGeneralService`, `AdminCategoriesService`, `AdminChallengesService`, `ChallengeFilesService`). Gated by `AdminGuard` + `@Roles('admin')`. Imports `TypeOrmModule.forFeature([UserEntity, CategoryEntity, ChallengeEntity, ChallengeFileEntity, SolveEntity])`, `AuthModule`, `UsersModule`, `SettingsModule`, and `CommonModule` (for `SseHubService`, `ThemeLoaderService`). |
 | `UploadsModule`  | `backend/src/modules/uploads/uploads.module.ts` | `UploadsController` (`/api/v1/uploads/*`). Admin-only multipart.                            |
 | `BlogModule`     | `backend/src/modules/blog/blog.module.ts`     | `BlogController` (`GET /api/v1/blog/posts`) + `BlogService` (lists `status='published'` rows). |
+| `ChallengesModule` | `backend/src/modules/challenges/challenges.module.ts` | `ChallengesController` (`/api/v1/challenges/{board,status,:id,:id/solves}`) + `ChallengesEventsController` (authenticated SSE `/api/v1/events`) + `ChallengesService` (board, detail, submit, scoring util). |
 | `FrontendModule` | `backend/src/frontend/frontend.module.ts`     | Registers `SpaFallbackMiddleware` and the uploads static helper.                              |
 
 # Controllers
@@ -46,6 +47,8 @@ also registers two global providers:
 | `SystemController`     | `/api/v1`               | Mixed (bootstrap/event/scoreboard/settings are public; `events/status` SSE is JWT-protected) | `backend/src/modules/system/system.controller.ts` |
 | `UploadsController`    | `/api/v1/uploads`       | Admin only   | `backend/src/modules/uploads/uploads.controller.ts`          |
 | `BlogController`       | `/api/v1/blog`          | Public       | `backend/src/modules/blog/blog.controller.ts`               |
+| `ChallengesController` | `/api/v1/challenges`    | Authenticated | `backend/src/modules/challenges/challenges.controller.ts` |
+| `ChallengesEventsController` | `/api/v1/events` | Authenticated (SSE) | `backend/src/modules/challenges/events.controller.ts` |
 
 # Common services
 
@@ -63,6 +66,7 @@ also registers two global providers:
 | `ThemeLoaderService`             | `backend/src/common/utils/theme-loader.service.ts`            | Loads + validates the 10 canonical themes.             |
 | `ZodValidationPipe`              | `backend/src/common/pipes/zod-validation.pipe.ts`            | Replaces `ValidationPipe` for zod-validated DTOs.       |
 | `TransformInterceptor`           | `backend/src/common/interceptors/transform.interceptor.ts`   | Optional response transformer.                          |
+| `scoring.util`                   | `backend/src/modules/challenges/scoring.util.ts`             | `computeLivePoints`, `rankBonusForPosition`, `compareDifficulty`, and `safeEqualString` (constant-time flag compare). |
 
 # Decorators