feat: Admin Area System: Database Backup/Restore and Danger Zone

frontend/src/app/features/challenges/challenges.store.ts

@@ -1,4 +1,4 @@
-import { DestroyRef, Injectable, computed, inject, signal } from '@angular/core';
+import { DestroyRef, Injectable, computed, effect, inject, signal } from '@angular/core';
 import { Observable } from 'rxjs';
 import {
   BoardCard,
@@ -17,11 +17,13 @@ import {
 } from './challenges.pure';
 import { ChallengesApiService } from './challenges.service';
 import { EventSourceLike } from '../../core/services/event-status.pure';
+import { SystemDataChangeService } from '../../core/services/system-data-change.service';
 
 @Injectable({ providedIn: 'root' })
 export class ChallengesStore {
   private readonly api: ChallengesApiService;
   private readonly destroyRef: DestroyRef;
+  private readonly dataChanges: SystemDataChangeService | null;
 
   private readonly _board = signal<BoardResponse | null>(null);
   private readonly _eventState = signal<EventStatePayloadLike['state']>('unconfigured');
@@ -35,10 +37,35 @@ export class ChallengesStore {
 
   private readonly solveListeners = new Map<string, Set<(p: SolveEventLivePayload) => void>>();
 
-  constructor(api?: ChallengesApiService, destroyRef?: DestroyRef) {
+  constructor(api?: ChallengesApiService, destroyRef?: DestroyRef, dataChanges?: SystemDataChangeService) {
     this.api = api ?? inject(ChallengesApiService);
     this.destroyRef = destroyRef ?? inject(DestroyRef);
+    this.dataChanges = dataChanges ?? null;
     this.destroyRef.onDestroy(() => this.stop());
+    this.installDataChangeListeners();
+  }
+
+  private installDataChangeListeners(): void {
+    if (!this.dataChanges) return;
+    const lastSeen = { ts: 0 };
+    effect(() => {
+      const evts = this.dataChanges!.events();
+      const latest = evts[evts.length - 1];
+      if (!latest || latest.ts === lastSeen.ts) return;
+      lastSeen.ts = latest.ts;
+      if (latest.kind === 'challenges-wiped' || latest.kind === 'restore-completed' || latest.kind === 'scores-reset') {
+        this.reset();
+      }
+    });
+  }
+
+  /**
+   * Exposed for callers that want to clear the cached board/selected detail
+   * after a destructive operation (e.g. challenge wipe). The signal
+   * subscription above re-evaluates when `events()` mutates.
+   */
+  invalidateForSystemChange(_kind: 'scores-reset' | 'challenges-wiped' | 'restore-completed'): void {
+    this.reset();
   }
 
   readonly board = this._board.asReadonly();