Merge cms-track-replace-gating into dev

Replace track audio in CMS edit form + gate last-track delete.

DeepDrftContent/TrackContentService.cs

@@ -103,6 +103,84 @@ public class TrackContentService
         string? originalFileName = null) =>
         AddTrackAsync(wavFilePath, trackName, artist, album, genre, releaseDate, originalFileName);
 
+    /// <summary>
+    /// Swaps the audio bytes for an existing track in place: processes a new audio file and
+    /// re-registers it under the SAME <paramref name="entryKey"/> in the tracks vault. The track's
+    /// vault key — and therefore its SQL link, release membership, position, and metadata — is
+    /// untouched; only the binary changes. The new audio is written first; only on confirmed success
+    /// is a stale old backing file cleaned up. A cross-format replacement (e.g. .wav → .flac) leaves
+    /// the old file on disk under its former filename once the index is updated; the post-success
+    /// cleanup removes it. For a same-extension overwrite the register alone suffices — the file is
+    /// written in place. If the register fails the original audio is left intact and null is returned,
+    /// so the track remains playable. Returns the freshly stored <see cref="AudioBinary"/> on success
+    /// (so the caller can regenerate waveform data from the same bytes) — matching the FileDatabase
+    /// swallow-and-return-null contract.
+    /// </summary>
+    public async Task<AudioBinary?> ReplaceTrackAudioAsync(string entryKey, string audioFilePath)
+    {
+        try
+        {
+            // Capture the old extension before touching the vault. After register the index
+            // will point to the new extension, so we need the old value now to detect a
+            // cross-format swap and clean up the stale file post-success.
+            var existing = await _fileDatabase.LoadResourceAsync<AudioBinary>(VaultConstants.Tracks, entryKey);
+            var oldExtension = existing?.Extension;
+
+            var audioBinary = await _audioProcessorRouter.ProcessAudioFileAsync(audioFilePath);
+            if (audioBinary == null)
+            {
+                Console.WriteLine($"TrackContentService.ReplaceTrackAudioAsync: processing returned null for {entryKey}");
+                return null;
+            }
+
+            if (!_fileDatabase.HasVault(VaultConstants.Tracks))
+            {
+                await _fileDatabase.CreateVaultAsync(VaultConstants.Tracks, MediaVaultType.Audio);
+            }
+
+            // Register the new audio. This upserts the index entry (new extension recorded) and
+            // writes the new file to disk. If this fails the original entry and file are untouched.
+            var success = await _fileDatabase.RegisterResourceAsync(VaultConstants.Tracks, entryKey, audioBinary);
+            if (!success)
+            {
+                Console.WriteLine($"TrackContentService.ReplaceTrackAudioAsync: vault write failed for {entryKey}; original audio preserved");
+                return null;
+            }
+
+            // Post-success stale-file cleanup for cross-format swaps. The register wrote the new
+            // file (e.g. .flac) and updated the index to the new extension, but the old backing
+            // file (e.g. .wav) is now unreferenced on disk. Delete it directly by constructing the
+            // old path — RemoveResourceAsync would now resolve to the new extension and delete the
+            // wrong file. Non-fatal: an orphaned old file is a disk-hygiene concern, not a
+            // playback issue (the index no longer references it).
+            if (oldExtension != null && oldExtension != audioBinary.Extension)
+            {
+                var vault = _fileDatabase.GetVault(VaultConstants.Tracks);
+                if (vault != null)
+                {
+                    var sanitizedKey = System.Text.RegularExpressions.Regex.Replace(entryKey, @"[^a-zA-Z0-9]", "-");
+                    var staleFilePath = Path.Combine(vault.RootPath, $"{sanitizedKey}{oldExtension}");
+                    try
+                    {
+                        if (File.Exists(staleFilePath))
+                            File.Delete(staleFilePath);
+                    }
+                    catch (Exception ex)
+                    {
+                        Console.WriteLine($"TrackContentService.ReplaceTrackAudioAsync: stale backing-file removal failed for {entryKey} ({staleFilePath}): {ex.Message} — new audio is live; orphaned file may remain on disk");
+                    }
+                }
+            }
+
+            return audioBinary;
+        }
+        catch (Exception ex) when (ex is not OperationCanceledException)
+        {
+            Console.WriteLine($"TrackContentService.ReplaceTrackAudioAsync failed: {ex.Message}");
+            return null;
+        }
+    }
+
     /// <summary>
     /// Retrieves audio binary from FileDatabase
     /// </summary>