feat: TMDB collections in Details (rebased)

app/src/main/kotlin/com/arflix/tv/data/api/TmdbApi.kt

@@ -253,7 +253,16 @@ data class TmdbMovieDetails(
     val budget: Long = 0,
     val genres: List<TmdbGenre> = emptyList(),
     val status: String? = null,
-    val adult: Boolean = false
+    val adult: Boolean = false,
+    @SerializedName("belongs_to_collection") val belongsToCollection: TmdbCollectionRef? = null
+)
+
+/** Reference to a TMDB collection (franchise) returned inside movie/TV details. */
+data class TmdbCollectionRef(
+    val id: Int = 0,
+    val name: String? = null,
+    @SerializedName("poster_path") val posterPath: String? = null,
+    @SerializedName("backdrop_path") val backdropPath: String? = null
 )
 
 data class TmdbTvDetails(

app/src/main/kotlin/com/arflix/tv/data/repository/MediaRepository.kt

@@ -2395,7 +2395,33 @@ class MediaRepository @Inject constructor(
         detailsCache[cacheKey] = CacheEntry(item, System.currentTimeMillis())
         return item
     }
-
+
+    /**
+     * Get the TMDB collection (franchise) reference for a movie.
+     * Calls /movie/{id} directly to access the `belongs_to_collection` field,
+     * which is discarded by getMovieDetails() → toMediaItem().
+     * The response is cached by OkHttp, making the redundant call negligible.
+     */
+    suspend fun getMovieCollectionRef(movieId: Int): com.arflix.tv.data.api.TmdbCollectionRef? {
+        return runCatching {
+            tmdbApi.getMovieDetails(movieId, apiKey, language = contentLanguage).belongsToCollection
+        }.getOrNull()
+    }
+
+    /**
+     * Fetch all movies in a TMDB collection (franchise).
+     * Calls TMDB /collection/{id} and maps the parts array to Movie MediaItems.
+     * Used by the Details page to show franchise rows (e.g. "Cars Collection").
+     */
+    suspend fun getTmdbCollectionItems(collectionId: Int): List<MediaItem> {
+        val response = runCatching {
+            tmdbApi.getTmdbCollection(collectionId, apiKey, language = contentLanguage)
+        }.getOrNull() ?: return emptyList()
+        return response.parts
+            .sortedBy { it.releaseDate.orEmpty() }
+            .map { it.toMediaItem(MediaType.MOVIE) }
+    }
+
     /**
      * Get season episodes with Trakt watched status
      */

app/src/main/kotlin/com/arflix/tv/navigation/AppNavigation.kt

@@ -385,6 +385,9 @@ fun AppNavigation(
                 onNavigateToDetails = { type, id ->
                     navController.navigate(Screen.Details.createRoute(type, id))
                 },
+                onNavigateToCollection = { catalogId ->
+                    navController.navigate(Screen.CollectionDetails.createRoute(catalogId))
+                },
                 onNavigateToHome = {
                     navigateHome()
                 },

app/src/main/kotlin/com/arflix/tv/ui/screens/collections/CollectionDetailsScreen.kt

@@ -57,7 +57,12 @@ import androidx.tv.foundation.lazy.grid.itemsIndexed
 import androidx.tv.foundation.lazy.grid.rememberTvLazyGridState
 import coil.compose.AsyncImage
 import com.arflix.tv.data.model.CatalogConfig
+import com.arflix.tv.data.model.CatalogKind
+import com.arflix.tv.data.model.CatalogSourceType
 import com.arflix.tv.data.model.CollectionGroupKind
+import com.arflix.tv.data.model.CollectionSourceConfig
+import com.arflix.tv.data.model.CollectionSourceKind
+import com.arflix.tv.data.model.CollectionTileShape
 import com.arflix.tv.data.model.MediaItem
 import com.arflix.tv.data.model.MediaType
 import com.arflix.tv.data.repository.CatalogRepository
@@ -118,6 +123,7 @@ class CollectionDetailsViewModel @Inject constructor(
         const val FIRST_PAGE = 8
         const val PAGE_STEP = 12
         const val BACKGROUND_PREFETCH_DELAY_MS = 350L
+        const val TMDB_COLLECTION_PREFIX = "tmdb_collection:"
     }
 
     fun load(catalogId: String) {
@@ -130,6 +136,7 @@ class CollectionDetailsViewModel @Inject constructor(
 
             _uiState.value = CollectionDetailsUiState(isLoadingMovies = true, isLoadingSeries = true)
             val catalog = catalogRepository.getCatalogs().firstOrNull { it.id == catalogId }
+                ?: syntheticTmdbCollectionCatalog(catalogId)
             if (catalog == null) {
                 _uiState.value = CollectionDetailsUiState(
                     isLoadingMovies = false,
@@ -167,6 +174,34 @@ class CollectionDetailsViewModel @Inject constructor(
         }
     }
 
+    private fun syntheticTmdbCollectionCatalog(catalogId: String): CatalogConfig? {
+        if (!catalogId.startsWith(TMDB_COLLECTION_PREFIX)) return null
+
+        val payload = catalogId.removePrefix(TMDB_COLLECTION_PREFIX)
+        val collectionId = payload.substringBefore(":").toIntOrNull() ?: return null
+        val collectionName = payload.substringAfter(":", missingDelimiterValue = "")
+            .trim()
+            .takeIf { it.isNotBlank() }
+            ?: "Collection"
+
+        return CatalogConfig(
+            id = catalogId,
+            title = collectionName,
+            sourceType = CatalogSourceType.PREINSTALLED,
+            isPreinstalled = true,
+            kind = CatalogKind.COLLECTION,
+            collectionGroup = CollectionGroupKind.FRANCHISE,
+            collectionTileShape = CollectionTileShape.POSTER,
+            collectionSources = listOf(
+                CollectionSourceConfig(
+                    kind = CollectionSourceKind.TMDB_COLLECTION,
+                    mediaType = "movie",
+                    tmdbCollectionId = collectionId
+                )
+            )
+        )
+    }
+
     private suspend fun loadInitialTab(catalog: CatalogConfig, tab: CollectionTab) {
         val page = runCatching {
             mediaRepository.loadCollectionCatalogPage(