fix(m3u): guard the guide's initial group scope and track language changes

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

libs/playlist/m3u/feature-player/src/lib/epg-guide/m3u-epg-guide-source.service.spec.ts

@@ -2,6 +2,7 @@ import { signal } from '@angular/core';
 import { TestBed } from '@angular/core/testing';
 import { Store } from '@ngrx/store';
 import { TranslateService } from '@ngx-translate/core';
+import { Subject } from 'rxjs';
 import { EpgRuntimeBridgeService } from '@iptvnator/epg/data-access';
 import { ChannelActions } from '@iptvnator/m3u-state';
 import { SettingsStore } from '@iptvnator/services';
@@ -49,12 +50,16 @@ describe('M3uEpgGuideSourceService', () => {
     const getProgramCoverage = jest.fn();
     const searchPrograms = jest.fn();
     let service: M3uEpgGuideSourceService;
+    let translateStub: { instant: (key: string) => string };
+    let onLangChange: Subject<{ lang: string }>;
 
     beforeEach(() => {
         dispatch.mockReset();
         getProgramsForChannels.mockReset();
         getProgramCoverage.mockReset();
         searchPrograms.mockReset();
+        onLangChange = new Subject<{ lang: string }>();
+        translateStub = { instant: (key: string) => key };
         channels.set([
             makeChannel('a', { tvgId: 'a.tv', group: 'News' }),
             makeChannel('b', { name: 'Beta', group: 'Sports' }),
@@ -80,7 +85,12 @@ describe('M3uEpgGuideSourceService', () => {
                 },
                 {
                     provide: TranslateService,
-                    useValue: { instant: (key: string) => key },
+                    useValue: {
+                        get instant() {
+                            return translateStub.instant;
+                        },
+                        onLangChange,
+                    },
                 },
             ],
         });
@@ -165,6 +175,33 @@ describe('M3uEpgGuideSourceService', () => {
         expect(service.scopeId()).toBe('all');
     });
 
+    it("falls back to the all scope when the active channel's group has no eligible channels", () => {
+        const sportsOnlyChannels = signal<Channel[]>([
+            makeChannel('b', { name: 'Beta', group: 'Sports' }),
+        ]);
+        const newsActiveChannel = signal<Channel | null>(
+            makeChannel('a', { tvgId: 'a.tv', group: 'News' })
+        );
+        service.bind({
+            channels: sportsOnlyChannels,
+            favoriteIds,
+            activeChannel: newsActiveChannel,
+        });
+
+        service.applyInitialScope('groups');
+
+        expect(service.scopeId()).toBe('all');
+    });
+
+    it('re-labels scopes when the active language changes', () => {
+        expect(service.scopes()[0].label).toBe('CHANNELS.ALL_CHANNELS');
+
+        translateStub.instant = (key: string) => `${key}!`;
+        onLangChange.next({ lang: 'de' });
+
+        expect(service.scopes()[0].label).toBe('CHANNELS.ALL_CHANNELS!');
+    });
+
     it('forwards programme search to the bridge', async () => {
         searchPrograms.mockResolvedValue([program('a.tv'), program('x')]);
         const hits = await service.searchPrograms('news');

libs/playlist/m3u/feature-player/src/lib/epg-guide/m3u-epg-guide-source.service.ts

@@ -1,6 +1,8 @@
 import { computed, inject, Injectable, Signal, signal } from '@angular/core';
+import { toSignal } from '@angular/core/rxjs-interop';
 import { Store } from '@ngrx/store';
 import { TranslateService } from '@ngx-translate/core';
+import { startWith } from 'rxjs';
 import { EpgRuntimeBridgeService } from '@iptvnator/epg/data-access';
 import { resolveChannelEpgLookupKey } from '@iptvnator/m3u-state';
 import { SettingsStore } from '@iptvnator/services';
@@ -43,6 +45,10 @@ export class M3uEpgGuideSourceService implements EpgGuideSource {
 
     private readonly inputs = signal<M3uEpgGuideInputs | null>(null);
     private readonly scope = signal(SCOPE_ALL);
+    private readonly languageTick = toSignal(
+        this.translate.onLangChange.pipe(startWith(null)),
+        { initialValue: null }
+    );
 
     readonly scopeId = this.scope.asReadonly();
 
@@ -51,6 +57,7 @@ export class M3uEpgGuideSourceService implements EpgGuideSource {
     );
 
     readonly scopes = computed<EpgGuideScope[]>(() => {
+        this.languageTick();
         const groups: string[] = [];
         const seen = new Set<string>();
         for (const channel of this.allChannels()) {
@@ -123,8 +130,15 @@ export class M3uEpgGuideSourceService implements EpgGuideSource {
         const activeGroup = this.inputs()
             ?.activeChannel()
             ?.group?.title?.trim();
-        if (view === 'groups' && activeGroup) {
-            this.scope.set(`${GROUP_PREFIX}${activeGroup}`);
+        const groupScopeId = activeGroup
+            ? `${GROUP_PREFIX}${activeGroup}`
+            : null;
+        if (
+            view === 'groups' &&
+            groupScopeId &&
+            this.scopes().some((scope) => scope.id === groupScopeId)
+        ) {
+            this.scope.set(groupScopeId);
             return;
         }
         this.scope.set(SCOPE_ALL);
@@ -178,6 +192,10 @@ export class M3uEpgGuideSourceService implements EpgGuideSource {
         return covered;
     }
 
+    /**
+     * Looks up the channel in the current scope because the guide only ever
+     * passes back ids it rendered from `channels()`.
+     */
     activate(channelId: string): void {
         const channel = this.scopedChannels().find(
             (candidate) => candidate.id === channelId