fix(settings): derive the recommendations seed heading from the visible cards

The rail kept only the seeds that contributed a card to the original
selection, so a seed whose recommendations filled in after a relock (or
an offline prune) was missing from the "Because you watched" heading.
Every seed of the load is kept in order and the heading lists those that
contribute a card now.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/workspace/dashboard/data-access/src/lib/dashboard-recommendations.service.spec.ts

@@ -1044,4 +1044,36 @@ describe('DashboardRecommendationsService', () => {
 
         expect(service.seedTitles()).toEqual(['The Matrix']);
     });
+
+    it('derives the seed heading from the cards visible now', async () => {
+        recentVod = [
+            { title: 'The Matrix', type: 'movie' },
+            { title: 'Blade Runner', type: 'movie' },
+        ];
+        recentAll = [...recentVod];
+        const second = ['Akira', 'Ghost in the Shell', 'Paprika'];
+        enrichMovie.mockImplementation(async (query: { title: string }) => ({
+            recommendations: {
+                results:
+                    query.title === 'The Matrix'
+                        ? recTitles.map((t, i) => rec(100 + i, t))
+                        : second.map((t, i) => rec(300 + i, t)),
+            },
+        }));
+        // The second seed's recommendations sit in category 8.
+        matchTitles.mockImplementation(async (titles: string[]) =>
+            titles.map((title) =>
+                match(title, second.includes(title) ? { categoryId: 8 } : {})
+            )
+        );
+        // Locked at load: the second seed has no visible card yet.
+        withheldCategories.set(new Set([8]));
+        const service = createService();
+        await service.load();
+        expect(service.seedTitles()).toEqual(['The Matrix']);
+
+        // Unlocked: its cards appear, and so does its heading.
+        withheldCategories.set(new Set());
+        expect(service.seedTitles()).toEqual(['The Matrix', 'Blade Runner']);
+    });
 });

libs/workspace/dashboard/data-access/src/lib/dashboard-recommendations.service.ts

@@ -70,7 +70,12 @@ export class DashboardRecommendationsService {
 
     /** The last load's candidates and ALL their catalog matches. */
     private readonly loaded = signal<LoadedRecommendations>(EMPTY_LOAD);
-    private readonly matchedSeedTitles = signal<readonly string[]>([]);
+    /**
+     * Every seed of the last load, most recent first. `seedTitles` keeps
+     * those that contribute a card NOW: a relock can hide some cards and let
+     * another seed's recommendations fill their places.
+     */
+    private readonly seedOrder = signal<readonly string[]>([]);
     /**
      * The cards, built on READ from the matches the parental lock does not
      * withhold: a relock hides a card matched while unlocked, and a title
@@ -89,9 +94,7 @@ export class DashboardRecommendationsService {
     /** Seeds that contributed at least one visible card, most recent first */
     readonly seedTitles = computed(() => {
         const contributed = new Set(this.items().map((item) => item.seedTitle));
-        return this.matchedSeedTitles().filter((title) =>
-            contributed.has(title)
-        );
+        return this.seedOrder().filter((title) => contributed.has(title));
     });
     readonly loading = signal(false);
 
@@ -117,7 +120,7 @@ export class DashboardRecommendationsService {
             // The service outlives the dashboard (root-provided), so a
             // cleared watch history must clear the rail too.
             this.loaded.set(EMPTY_LOAD);
-            this.matchedSeedTitles.set([]);
+            this.seedOrder.set([]);
             this.loadedKey = null;
             return;
         }
@@ -161,15 +164,8 @@ export class DashboardRecommendationsService {
                     MAX_ITEMS
                 );
                 if (matched.length >= MIN_RECOMMENDATION_MATCHES) {
-                    const contributed = new Set(
-                        matched.map((item) => item.seedTitle)
-                    );
                     this.loaded.set(load);
-                    this.matchedSeedTitles.set(
-                        perSeed
-                            .map((seed) => seed.seedTitle)
-                            .filter((title) => contributed.has(title))
-                    );
+                    this.seedOrder.set(perSeed.map((seed) => seed.seedTitle));
                     // Latch only once EVERY seed answered. A seed that did
                     // not resolve may have failed transiently, and latching
                     // on its behalf would drop its recommendations for the
@@ -193,7 +189,7 @@ export class DashboardRecommendationsService {
                     // exact inputs (say, un-favoriting again) would
                     // otherwise hit the equality guard and stay empty.
                     this.loaded.set(EMPTY_LOAD);
-                    this.matchedSeedTitles.set([]);
+                    this.seedOrder.set([]);
                     this.loadedKey = null;
                 }
             }
@@ -253,15 +249,11 @@ export class DashboardRecommendationsService {
         );
         if (cards.length < MIN_RECOMMENDATION_MATCHES) {
             this.loaded.set(EMPTY_LOAD);
-            this.matchedSeedTitles.set([]);
+            this.seedOrder.set([]);
             return;
         }
 
-        const contributed = new Set(cards.map((item) => item.seedTitle));
         this.loaded.set(kept);
-        this.matchedSeedTitles.set(
-            this.matchedSeedTitles().filter((title) => contributed.has(title))
-        );
     }
 
     /**