fix(scanner): track podcast show audio paths during folder reconcile

Extract listPodcastShowAudioFiles and record each show's audio paths in
seenPaths during ScanPodcastFolder so reconciliation does not treat
still-present episodes as removed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/scanner/podcast.go

@@ -32,23 +32,10 @@ type parsedPodcastEpisode struct {
 // Returns an os.ErrNotExist-wrapped error if the folder contains zero
 // audio files.
 func parsePodcastShow(ctx context.Context, ffprobePath string, folderPath string) (*parsedPodcastShow, error) {
-	entries, err := os.ReadDir(folderPath)
+	audioFiles, err := listPodcastShowAudioFiles(folderPath)
 	if err != nil {
-		return nil, fmt.Errorf("read podcast folder %s: %w", folderPath, err)
+		return nil, err
 	}
-	var audioFiles []string
-	for _, entry := range entries {
-		if entry.IsDir() {
-			continue
-		}
-		if SupportsAudioFile(entry.Name()) {
-			audioFiles = append(audioFiles, filepath.Join(folderPath, entry.Name()))
-		}
-	}
-	if len(audioFiles) == 0 {
-		return nil, fmt.Errorf("podcast show %s: %w", folderPath, os.ErrNotExist)
-	}
-	sort.Strings(audioFiles)
 
 	show := &parsedPodcastShow{}
 	for idx, path := range audioFiles {
@@ -83,6 +70,27 @@ func parsePodcastShow(ctx context.Context, ffprobePath string, folderPath string
 	return show, nil
 }
 
+func listPodcastShowAudioFiles(folderPath string) ([]string, error) {
+	entries, err := os.ReadDir(folderPath)
+	if err != nil {
+		return nil, fmt.Errorf("read podcast folder %s: %w", folderPath, err)
+	}
+	var audioFiles []string
+	for _, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		if SupportsAudioFile(entry.Name()) {
+			audioFiles = append(audioFiles, filepath.Join(folderPath, entry.Name()))
+		}
+	}
+	if len(audioFiles) == 0 {
+		return nil, fmt.Errorf("podcast show %s: %w", folderPath, os.ErrNotExist)
+	}
+	sort.Strings(audioFiles)
+	return audioFiles, nil
+}
+
 // parseTrackNumber accepts ID3-style track values which may be "5" or
 // "5/12". Returns 0 if no leading integer is present.
 func parseTrackNumber(s string) int {

internal/scanner/podcast_scan.go

@@ -56,6 +56,11 @@ func (s *Scanner) ScanPodcastFolder(ctx context.Context, folder *models.MediaFol
 				return err
 			}
 			attempted++
+			if paths, err := listPodcastShowAudioFiles(subPath); err == nil {
+				for _, path := range paths {
+					seenPaths[path] = true
+				}
+			}
 			episodePaths, err := s.reconcilePodcastShow(ctx, folder, subPath)
 			if err != nil {
 				if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {

internal/scanner/podcast_test.go

@@ -98,6 +98,41 @@ func TestScanPodcastFolderReturnsCanceledContext(t *testing.T) {
 	}
 }
 
+func TestListPodcastShowAudioFilesReturnsSortedAudioPaths(t *testing.T) {
+	root := t.TempDir()
+	if err := os.WriteFile(filepath.Join(root, "02.mp3"), []byte("audio"), 0o644); err != nil {
+		t.Fatalf("write audio: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "notes.txt"), []byte("notes"), 0o644); err != nil {
+		t.Fatalf("write notes: %v", err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "01.flac"), []byte("audio"), 0o644); err != nil {
+		t.Fatalf("write audio: %v", err)
+	}
+	if err := os.Mkdir(filepath.Join(root, "nested"), 0o755); err != nil {
+		t.Fatalf("mkdir nested: %v", err)
+	}
+
+	got, err := listPodcastShowAudioFiles(root)
+	if err != nil {
+		t.Fatalf("listPodcastShowAudioFiles: %v", err)
+	}
+	want := []string{
+		filepath.Join(root, "01.flac"),
+		filepath.Join(root, "02.mp3"),
+	}
+	if strings.Join(got, "\n") != strings.Join(want, "\n") {
+		t.Fatalf("audio files = %#v, want %#v", got, want)
+	}
+}
+
+func TestListPodcastShowAudioFilesReturnsNotExistForEmptyShow(t *testing.T) {
+	_, err := listPodcastShowAudioFiles(t.TempDir())
+	if !errors.Is(err, os.ErrNotExist) {
+		t.Fatalf("empty podcast show error = %v, want os.ErrNotExist", err)
+	}
+}
+
 func TestResolvePodcastMediaItemReusesRootScopedContentID(t *testing.T) {
 	finder := &fakeRootContentFinder{contentID: "podcast-root-id"}
 	writer := &fakeFilesystemItemWriter{}