fix: register-new-then-remove-old in ReplaceTrackAudioAsync; replace wording in timeout messages; doc comment on ExistingTrackCount

On partial failure the old path deleted the original audio before
confirming the new write succeeded. Now: load old extension, register
new audio first (original untouched on failure), then clean up stale
backing file only on success and only when extension changed.

DeepDrftContent/TrackContentService.cs

@@ -104,16 +104,25 @@ public class TrackContentService
     /// 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 prior entry is removed first so a replacement whose
-    /// extension differs from the original (e.g. .wav → .flac) does not strand the old file on disk
-    /// under its former filename. Returns the freshly stored <see cref="AudioBinary"/> on success
-    /// (so the caller can regenerate waveform data from the same bytes), or null on processing or
-    /// vault failure — matching the FileDatabase swallow-and-return-null contract.
+    /// 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)
             {
@@ -126,19 +135,40 @@ public class TrackContentService
                 await _fileDatabase.CreateVaultAsync(VaultConstants.Tracks, MediaVaultType.Audio);
             }
 
-            // Drop the old entry first. The backing file is keyed by entryKey + its *stored*
-            // extension, so a register alone would leave a stale file when the new format differs.
-            // A null/false removal is non-fatal (the entry may already be absent); the register
-            // below is the authoritative write.
-            await _fileDatabase.RemoveResourceAsync(VaultConstants.Tracks, entryKey);
-
+            // 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($"TrackContentService.ReplaceTrackAudioAsync: vault write failed for {entryKey}");
+                Console.WriteLine($"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)

DeepDrftManager/Components/Pages/Tracks/BatchEdit.razor

@@ -59,6 +59,9 @@
            single-track medium, mirroring BatchUpload's same-named collapse. Cut keeps the full list. *@
         <MudGrid>
             <MudItem xs="12" md="5">
+                @* ExistingTrackCount counts edit-session persisted rows (Id.HasValue), not authoritative
+                   live release count — acceptable because this gate only hides a UI control; the
+                   TrySoftDeleteEmptyReleaseAsync backstop remains the authoritative guard. *@
                 <BatchTrackList Tracks="_tracks"
                                 @bind-SelectedIndex="_selectedIndex"
                                 Disabled="_saving"

DeepDrftManager/Services/CmsTrackService.cs

@@ -272,12 +272,12 @@ public class CmsTrackService : ICmsTrackService
                     _owner._logger.LogWarning("{Operation} stalled — no progress for {IdleSeconds}s; aborting.",
                         operationLabel, _owner._uploadIdleTimeout.TotalSeconds);
                     return LargeBodySendResult.Fail(
-                        $"Upload stalled — no data transferred for {_owner._uploadIdleTimeout.TotalSeconds:0}s. Please retry.");
+                        $"{operationLabel} stalled — no data transferred for {_owner._uploadIdleTimeout.TotalSeconds:0}s. Please retry.");
                 }
                 _owner._logger.LogWarning("{Operation} timed out waiting for server response after {ResponseSeconds}s.",
                     operationLabel, _owner._uploadResponseTimeout.TotalSeconds);
                 return LargeBodySendResult.Fail(
-                    $"Upload timed out waiting for the server to respond after {_owner._uploadResponseTimeout.TotalSeconds:0}s. Please retry.");
+                    $"{operationLabel} timed out waiting for the server to respond after {_owner._uploadResponseTimeout.TotalSeconds:0}s. Please retry.");
             }
             catch (Exception ex)
             {

DeepDrftTests/TrackReplaceAudioTests.cs

@@ -90,7 +90,8 @@ public class TrackReplaceAudioTests
         var content = CreateContentService(fileDatabase!);
 
         // A .wav original replaced by a .flac: the backing filename is keyed by extension, so a
-        // register-only swap would strand the old .wav. The replace removes the old entry first.
+        // register-only swap would strand the old .wav. The replace writes the new entry first, then
+        // cleans up the stale old backing file (detected by comparing old vs. new extension).
         var original = await WriteWavAsync(BuildMinimalPcmWav(2.0), ".wav");
         var seeded = await content.AddTrackAsync(original, "Original", "Artist");
         var entryKey = seeded!.EntryKey;