fix(tmdb): address PR review — best-effort fallback fetch, /embed/ scope, names-only trigger

- A failing original-language fallback fetch no longer costs the
  already-fetched primary details payload (Codex P2) — it is wrapped
  best-effort and the primary payload is returned on error.
- The YouTube Referer shim now scopes to /embed/ paths, so regular
  www.youtube.com requests keep their real (missing) Referer (greptile).
- seasonNeedsTextFallback also triggers when episode overviews exist but
  ALL episode names are empty (partially translated seasons; greptile).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/electron-backend/src/app/services/request-header-overrides.service.spec.ts

@@ -281,6 +281,21 @@ describe('request header overrides', () => {
         expect(headers['Referer']).toBeUndefined();
     });
 
+    it('does not inject the Referer for non-embed YouTube paths', async () => {
+        const { registerStaticHeaderShims } = await import(
+            './request-header-overrides.service'
+        );
+
+        registerStaticHeaderShims();
+        const listener = mockOnBeforeSendHeaders.mock.calls[0][1];
+        const headers = runHeaderListener(
+            listener,
+            'https://www.youtube.com/watch?v=abc123'
+        );
+
+        expect(headers['Referer']).toBeUndefined();
+    });
+
     it('does not inject the embed Referer for non-YouTube hosts', async () => {
         const { registerStaticHeaderShims } = await import(
             './request-header-overrides.service'

apps/electron-backend/src/app/services/request-header-overrides.service.ts

@@ -77,13 +77,18 @@ function applyYoutubeEmbedRefererShim(
     url: string,
     requestHeaders: Record<string, string>
 ): void {
-    let host: string;
+    let parsed: URL;
     try {
-        host = new URL(url).hostname;
+        parsed = new URL(url);
     } catch {
         return;
     }
-    if (!YOUTUBE_EMBED_HOSTS.has(host)) {
+    // Scope strictly to embed player requests — www.youtube.com also
+    // serves regular pages that must keep their real (missing) Referer
+    if (
+        !YOUTUBE_EMBED_HOSTS.has(parsed.hostname) ||
+        !parsed.pathname.startsWith('/embed/')
+    ) {
         return;
     }
 

libs/services/src/lib/tmdb/tmdb-enrichment.service.ts

@@ -222,12 +222,19 @@ export class TmdbEnrichmentService {
         if (!fallbackLanguage) {
             return details;
         }
-        const fallback = await this.fetchDetails(
-            mediaType,
-            tmdbId,
-            fallbackLanguage
-        );
-        return fillDetailsFromFallback(details, fallback);
+        // Best-effort: a failing fallback fetch must never cost the
+        // already-fetched primary payload (cast, artwork, trailer, ...)
+        try {
+            const fallback = await this.fetchDetails(
+                mediaType,
+                tmdbId,
+                fallbackLanguage
+            );
+            return fillDetailsFromFallback(details, fallback);
+        } catch (error) {
+            console.warn('TMDB fallback-language fetch failed:', error);
+            return details;
+        }
     }
 
     private async fetchDetails(

libs/services/src/lib/tmdb/tmdb-language-fallback.spec.ts

@@ -83,11 +83,25 @@ describe('season fallback', () => {
         expect(
             seasonNeedsTextFallback({
                 overview: '',
-                episodes: [{ episode_number: 1, overview: 'Text' }],
+                episodes: [
+                    { episode_number: 1, name: 'Ep 1', overview: 'Text' },
+                ],
             })
         ).toBe(false);
     });
 
+    it('triggers when episode overviews exist but ALL names are empty', () => {
+        expect(
+            seasonNeedsTextFallback({
+                overview: 'Season text',
+                episodes: [
+                    { episode_number: 1, name: '', overview: 'Text 1' },
+                    { episode_number: 2, name: ' ', overview: 'Text 2' },
+                ],
+            })
+        ).toBe(true);
+    });
+
     it('fills missing season overview and episode texts by number', () => {
         const merged = fillSeasonFromFallback(emptySeason, russianSeason);
         expect(merged.overview).toBe('Описание сезона');

libs/services/src/lib/tmdb/tmdb-language-fallback.ts

@@ -42,14 +42,23 @@ export function fillDetailsFromFallback(
         : primary;
 }
 
-/** True when the season payload carries no usable text at all */
+/**
+ * True when the season payload carries no usable text: no overviews at
+ * all, or episodes whose names are ALL empty (partially translated
+ * seasons keep localized overviews but lose the episode names).
+ */
 export function seasonNeedsTextFallback(season: TmdbSeasonDetails): boolean {
+    const episodes = season.episodes ?? [];
+    if (
+        episodes.length > 0 &&
+        !episodes.some((episode) => hasText(episode.name))
+    ) {
+        return true;
+    }
     if (hasText(season.overview)) {
         return false;
     }
-    return !(season.episodes ?? []).some((episode) =>
-        hasText(episode.overview)
-    );
+    return !episodes.some((episode) => hasText(episode.overview));
 }
 
 /**