fix: podcast add to library

Core/Services/API/YTMusicClient.swift

@@ -1027,26 +1027,44 @@ final class YTMusicClient: YTMusicClientProtocol {
         APICache.shared.invalidate(matching: "browse:")
     }
 
+    // MARK: - Podcast ID Conversion
+
+    /// Converts a podcast show ID (MPSPP prefix) to a playlist ID (PL prefix) for the like/unlike API.
+    /// - Podcast show IDs use "MPSPP" + "L" + {idSuffix}, e.g. "MPSPPLXz2p9...".
+    /// - The corresponding playlist ID is "PL" + {idSuffix}, e.g. "PLXz2p9...".
+    /// - We strip "MPSPP" (5 chars) leaving "LXz2p9...", then prepend "P" to get "PLXz2p9...".
+    /// - Parameter showId: The podcast show ID to convert
+    /// - Returns: The playlist ID for the like API
+    /// - Throws: YTMusicError.invalidInput if the ID format is invalid
+    private func convertPodcastShowIdToPlaylistId(_ showId: String) throws -> String {
+        guard showId.hasPrefix("MPSPP") else {
+            self.logger.warning("ShowId does not have MPSPP prefix, using as-is: \(showId)")
+            return showId
+        }
+
+        let suffix = String(showId.dropFirst(5)) // "LXz2p9..."
+
+        guard !suffix.isEmpty else {
+            self.logger.error("Invalid podcast show ID (missing suffix after MPSPP): \(showId)")
+            throw YTMusicError.invalidInput("Invalid podcast show ID: \(showId)")
+        }
+
+        guard suffix.hasPrefix("L") else {
+            self.logger.error("Invalid podcast show ID (suffix must start with 'L'): \(showId)")
+            throw YTMusicError.invalidInput("Invalid podcast show ID format: \(showId)")
+        }
+
+        return "P" + suffix // "P" + "LXz2p9..." = "PLXz2p9..."
+    }
+
     /// Subscribes to a podcast show (adds to library).
-    /// This uses the playlist-style "like" subscription API (`like/like` endpoint) by treating podcast shows as playlist-like entities.
+    /// This uses the like/like endpoint with the playlist ID (PL prefix).
+    /// Podcast shows have an MPSPP prefix that maps to PL for the like API.
     /// - Parameter showId: The podcast show ID (MPSPP prefix)
     func subscribeToPodcast(showId: String) async throws {
         self.logger.info("Subscribing to podcast: \(showId)")
 
-        // Extract the playlist ID portion from MPSPP prefix.
-        // Podcast show IDs use the form "MPSPP" + {idSuffix}, where the corresponding
-        // playlist ID is "PL" + {idSuffix}. We validate the suffix is non-empty.
-        let playlistId: String
-        if showId.hasPrefix("MPSPP") {
-            let suffix = String(showId.dropFirst(5))
-            if suffix.isEmpty {
-                self.logger.error("Invalid podcast show ID (missing suffix after MPSPP): \(showId)")
-                throw YTMusicError.invalidInput("Invalid podcast show ID: \(showId)")
-            }
-            playlistId = "PL" + suffix
-        } else {
-            playlistId = showId
-        }
+        let playlistId = try self.convertPodcastShowIdToPlaylistId(showId)
 
         let body: [String: Any] = [
             "target": ["playlistId": playlistId],
@@ -1060,23 +1078,13 @@ final class YTMusicClient: YTMusicClientProtocol {
     }
 
     /// Unsubscribes from a podcast show (removes from library).
-    /// This uses the playlist-style "like" subscription API (`like/removelike` endpoint).
+    /// This uses the like/removelike endpoint with the playlist ID (PL prefix).
+    /// Podcast shows have an MPSPP prefix that maps to PL for the like API.
     /// - Parameter showId: The podcast show ID (MPSPP prefix)
     func unsubscribeFromPodcast(showId: String) async throws {
         self.logger.info("Unsubscribing from podcast: \(showId)")
 
-        // Extract the playlist ID portion from MPSPP prefix.
-        let playlistId: String
-        if showId.hasPrefix("MPSPP") {
-            let suffix = String(showId.dropFirst(5))
-            if suffix.isEmpty {
-                self.logger.error("Invalid podcast show ID (missing suffix after MPSPP): \(showId)")
-                throw YTMusicError.invalidInput("Invalid podcast show ID: \(showId)")
-            }
-            playlistId = "PL" + suffix
-        } else {
-            playlistId = showId
-        }
+        let playlistId = try self.convertPodcastShowIdToPlaylistId(showId)
 
         let body: [String: Any] = [
             "target": ["playlistId": playlistId],

Core/Utilities/IntelligenceModifier.swift

@@ -15,32 +15,36 @@ struct RequiresIntelligenceModifier: ViewModifier {
     /// Whether to show a sparkle overlay when AI is available and active.
     let showSparkleOverlay: Bool
 
-    /// Access to the Foundation Models service.
-    @State private var isAvailable = FoundationModelsService.shared.isAvailable
+    /// Reads availability directly from the @Observable singleton.
+    /// SwiftUI's Observation system automatically tracks this access
+    /// and triggers re-renders when the underlying value changes.
+    private var isAvailable: Bool {
+        FoundationModelsService.shared.isAvailable
+    }
 
     func body(content: Content) -> some View {
+        // Cache availability for consistent reads within this render pass
+        let isAvailable = self.isAvailable
+
         Group {
-            if self.hideWhenUnavailable, !self.isAvailable {
+            if self.hideWhenUnavailable, !isAvailable {
                 EmptyView()
             } else {
                 content
-                    .disabled(!self.isAvailable)
-                    .opacity(self.isAvailable ? 1.0 : 0.4)
+                    .disabled(!isAvailable)
+                    .opacity(isAvailable ? 1.0 : 0.4)
                     .overlay(alignment: .topTrailing) {
-                        if self.showSparkleOverlay, self.isAvailable {
+                        if self.showSparkleOverlay, isAvailable {
                             Image(systemName: "sparkle")
                                 .font(.system(size: 8, weight: .bold))
                                 .foregroundStyle(.purple)
                                 .offset(x: 2, y: -2)
                         }
                     }
-                    .help(self.isAvailable ? "" : self.unavailableMessage)
-                    .animation(.easeInOut(duration: 0.2), value: self.isAvailable)
+                    .help(isAvailable ? "" : self.unavailableMessage)
+                    .animation(.easeInOut(duration: 0.2), value: isAvailable)
             }
         }
-        .onReceive(NotificationCenter.default.publisher(for: .intelligenceAvailabilityChanged)) { _ in
-            self.isAvailable = FoundationModelsService.shared.isAvailable
-        }
     }
 }
 

Core/ViewModels/LibraryViewModel.swift

@@ -60,6 +60,16 @@ final class LibraryViewModel {
         self.libraryPlaylistIds.insert(playlistId)
     }
 
+    /// Adds a podcast to the library (called after successful subscription).
+    /// Updates both the ID set and the shows array for immediate UI update.
+    func addToLibrary(podcast: PodcastShow) {
+        self.libraryPodcastIds.insert(podcast.id)
+        // Add to shows array if not already present
+        if !self.podcastShows.contains(where: { $0.id == podcast.id }) {
+            self.podcastShows.insert(podcast, at: 0)
+        }
+    }
+
     /// Adds a podcast ID to the library set (called after successful subscription).
     func addToLibrarySet(podcastId: String) {
         self.libraryPodcastIds.insert(podcastId)
@@ -76,6 +86,13 @@ final class LibraryViewModel {
         }
     }
 
+    /// Removes a podcast from the library (called after successful unsubscribe).
+    /// Updates both the ID set and the shows array for immediate UI update.
+    func removeFromLibrary(podcastId: String) {
+        self.libraryPodcastIds.remove(podcastId)
+        self.podcastShows.removeAll { $0.id == podcastId }
+    }
+
     /// Removes a podcast ID from the library set (called after successful unsubscribe).
     func removeFromLibrarySet(podcastId: String) {
         self.libraryPodcastIds.remove(podcastId)

Tests/KasetTests/Helpers/MockYTMusicClient.swift

@@ -533,12 +533,32 @@ final class MockYTMusicClient: YTMusicClientProtocol {
         if let error = shouldThrowError { throw error }
     }
 
-    func subscribeToPodcast(showId _: String) async throws {
+    func subscribeToPodcast(showId: String) async throws {
         if let error = shouldThrowError { throw error }
+        // Validate podcast show ID format (mirrors real YTMusicClient behavior)
+        if showId.hasPrefix("MPSPP") {
+            let suffix = String(showId.dropFirst(5))
+            if suffix.isEmpty {
+                throw YTMusicError.invalidInput("Invalid podcast show ID: \(showId)")
+            }
+            if !suffix.hasPrefix("L") {
+                throw YTMusicError.invalidInput("Invalid podcast show ID format: \(showId)")
+            }
+        }
     }
 
-    func unsubscribeFromPodcast(showId _: String) async throws {
+    func unsubscribeFromPodcast(showId: String) async throws {
         if let error = shouldThrowError { throw error }
+        // Validate podcast show ID format (mirrors real YTMusicClient behavior)
+        if showId.hasPrefix("MPSPP") {
+            let suffix = String(showId.dropFirst(5))
+            if suffix.isEmpty {
+                throw YTMusicError.invalidInput("Invalid podcast show ID: \(showId)")
+            }
+            if !suffix.hasPrefix("L") {
+                throw YTMusicError.invalidInput("Invalid podcast show ID format: \(showId)")
+            }
+        }
     }
 
     func subscribeToArtist(channelId: String) async throws {

Tests/KasetTests/Helpers/TestFixtures.swift

@@ -161,4 +161,21 @@ enum TestFixtures {
             }
         )
     }
+
+    // MARK: - Podcasts
+
+    static func makePodcastShow(
+        id: String = "MPSPPLXz2p9test123",
+        title: String = "Test Podcast",
+        author: String? = "Test Host"
+    ) -> PodcastShow {
+        PodcastShow(
+            id: id,
+            title: title,
+            author: author,
+            description: "A test podcast show",
+            thumbnailURL: URL(string: "https://example.com/podcast.jpg"),
+            episodeCount: 50
+        )
+    }
 }

Tests/KasetTests/LibraryViewModelTests.swift

@@ -93,4 +93,76 @@ struct LibraryViewModelTests {
 
         #expect(self.viewModel.playlists.count == 2)
     }
+
+    // MARK: - Podcast Library Tests
+
+    @Test("addToLibrary inserts podcast at beginning and updates ID set")
+    func addToLibraryInsertsPodcast() {
+        let podcast = TestFixtures.makePodcastShow(id: "MPSPPLXz2p9test123", title: "Test Podcast")
+
+        self.viewModel.addToLibrary(podcast: podcast)
+
+        #expect(self.viewModel.libraryPodcastIds.contains("MPSPPLXz2p9test123"))
+        #expect(self.viewModel.podcastShows.first?.id == "MPSPPLXz2p9test123")
+        #expect(self.viewModel.podcastShows.first?.title == "Test Podcast")
+    }
+
+    @Test("addToLibrary does not duplicate existing podcast")
+    func addToLibraryNoDuplicate() {
+        let podcast = TestFixtures.makePodcastShow(id: "MPSPPLXz2p9test123")
+
+        self.viewModel.addToLibrary(podcast: podcast)
+        self.viewModel.addToLibrary(podcast: podcast)
+
+        #expect(self.viewModel.podcastShows.count(where: { $0.id == "MPSPPLXz2p9test123" }) == 1)
+        #expect(self.viewModel.libraryPodcastIds.count == 1)
+    }
+
+    @Test("addToLibrary inserts new podcast at position 0")
+    func addToLibraryInsertsAtBeginning() {
+        let podcast1 = TestFixtures.makePodcastShow(id: "MPSPPLA", title: "Podcast A")
+        let podcast2 = TestFixtures.makePodcastShow(id: "MPSPPLB", title: "Podcast B")
+
+        self.viewModel.addToLibrary(podcast: podcast1)
+        self.viewModel.addToLibrary(podcast: podcast2)
+
+        // Podcast B should be first (inserted at position 0)
+        #expect(self.viewModel.podcastShows.first?.id == "MPSPPLB")
+        #expect(self.viewModel.podcastShows[1].id == "MPSPPLA")
+    }
+
+    @Test("removeFromLibrary removes podcast from both set and array")
+    func removeFromLibraryRemovesPodcast() {
+        let podcast = TestFixtures.makePodcastShow(id: "MPSPPLXz2p9test123")
+        self.viewModel.addToLibrary(podcast: podcast)
+        #expect(self.viewModel.podcastShows.count == 1)
+        #expect(self.viewModel.libraryPodcastIds.count == 1)
+
+        self.viewModel.removeFromLibrary(podcastId: "MPSPPLXz2p9test123")
+
+        #expect(self.viewModel.podcastShows.isEmpty)
+        #expect(self.viewModel.libraryPodcastIds.isEmpty)
+    }
+
+    @Test("removeFromLibrary handles non-existent podcast gracefully")
+    func removeFromLibraryNonExistent() {
+        // Should not crash when removing non-existent podcast
+        self.viewModel.removeFromLibrary(podcastId: "nonexistent")
+
+        #expect(self.viewModel.podcastShows.isEmpty)
+        #expect(self.viewModel.libraryPodcastIds.isEmpty)
+    }
+
+    @Test("isInLibrary returns true for added podcast")
+    func isInLibraryForAddedPodcast() {
+        let podcast = TestFixtures.makePodcastShow(id: "MPSPPLXz2p9test123")
+        self.viewModel.addToLibrary(podcast: podcast)
+
+        #expect(self.viewModel.isInLibrary(podcastId: "MPSPPLXz2p9test123") == true)
+    }
+
+    @Test("isInLibrary returns false for non-added podcast")
+    func isInLibraryForNonAddedPodcast() {
+        #expect(self.viewModel.isInLibrary(podcastId: "MPSPPLXz2p9test123") == false)
+    }
 }