ErsatzTV.Application/ConcurrencyExtensions.cs

@@ -15,9 +15,10 @@ public static class ConcurrencyExtensions
     ///     UPDATE of that row with <c>WHERE Version=@orig</c>, so a concurrent bump from a replace-all
     ///     editor would otherwise surface as an unhandled <see cref="DbUpdateConcurrencyException" /> →
     ///     500 (issue #253 / #269). Phase-1 semantics for a missing <c>If-Match</c> is <b>force-write</b>,
-    ///     so on a concurrency failure we adopt the stored token as both original (the retry's WHERE then
-    ///     matches) and current (so we don't revert the concurrent bump) and retry — a client-wins merge
-    ///     scoped to the token; our own modified scalars still win. Bounded to avoid a livelock; if the row
+    ///     so on a concurrency failure we rebase onto the stored token: original becomes the stored value
+    ///     (the retry's WHERE then matches) and current becomes stored + our pending delta (a bumper's ++
+    ///     still advances the ETag past the concurrent writer's value — #269 rotation; a non-bumper adopts
+    ///     it unchanged) and retry; our own modified scalars still win. Bounded to avoid a livelock; if the row
     ///     was deleted out from under us, that's a genuine conflict and rethrows.
     /// </summary>
     public static async Task<int> SaveChangesForcingVersion(
@@ -48,9 +49,16 @@ public static class ConcurrencyExtensions
                     }
 
                     PropertyEntry version = entry.Property(nameof(IVersionedAggregate.Version));
-                    object currentVersion = databaseValues[nameof(IVersionedAggregate.Version)]!;
-                    version.OriginalValue = currentVersion;
-                    version.CurrentValue = currentVersion;
+                    int dbVersion = (int)databaseValues[nameof(IVersionedAggregate.Version)]!;
+
+                    // Rebase our pending delta on top of the stored token instead of adopting it verbatim:
+                    // a Version-bumping sibling (pending current = original + 1) must still advance the
+                    // ETag PAST the concurrent writer's value, or an editor holding that writer's ETag is
+                    // never invalidated by our change (#269 rotation silently lost under race). Non-bumpers
+                    // (delta 0, e.g. ErasePlayoutHistory) still adopt the stored token unchanged.
+                    int pendingDelta = (int)version.CurrentValue! - (int)version.OriginalValue!;
+                    version.OriginalValue = dbVersion;
+                    version.CurrentValue = dbVersion + pendingDelta;
                     resolvedAny = true;
                 }
 

ErsatzTV.Application/MediaCollections/Commands/AddArtistToCollectionHandler.cs

@@ -42,17 +42,28 @@ public class AddArtistToCollectionHandler :
 
     private async Task<Unit> ApplyAddArtistRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.Artist);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.Artist.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Artist.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.Artist);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Artist.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddEpisodeToCollectionHandler.cs

@@ -44,17 +44,28 @@ public class AddEpisodeToCollectionHandler :
 
     private async Task<Unit> ApplyAddTelevisionEpisodeRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.Episode);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.Episode.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Episode.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.Episode);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Episode.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddImageToCollectionHandler.cs

@@ -41,17 +41,28 @@ public class AddImageToCollectionHandler : IRequestHandler<AddImageToCollection,
 
     private async Task<Unit> ApplyAddImageRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.Image);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.Image.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Image.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.Image);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Image.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddItemsToCollectionHandler.cs

@@ -73,24 +73,35 @@ public class AddItemsToCollectionHandler :
             .ToList();
 
         var toAddIds = allItems.Where(item => collection.MediaItems.All(mi => mi.Id != item)).ToList();
+
+        // No-op when every requested item is already a member: don't rotate the ETag or fan out
+        // rebuilds for an idempotent re-add — #269.
+        if (toAddIds.Count == 0)
+        {
+            return Unit.Default;
+        }
+
         List<MediaItem> toAdd = await dbContext.MediaItems
             .Filter(mi => toAddIds.Contains(mi.Id))
             .ToListAsync(cancellationToken);
 
         collection.MediaItems.AddRange(toAdd);
 
-        if (await dbContext.SaveChangesAsync(cancellationToken) > 0)
-        {
-            // post-commit side effect runs on CancellationToken.None so a late request cancellation
-            // can't abort it after the commit landed (#254)
-            await _searchChannel.WriteAsync(new ReindexMediaItems(toAddIds.ToArray()), CancellationToken.None);
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a).
+        collection.Version++;
+        await dbContext.SaveChangesForcingVersion(cancellationToken);
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(request.CollectionId))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
-            }
+        // post-commit side effect runs on CancellationToken.None so a late request cancellation
+        // can't abort it after the commit landed (#254)
+        await _searchChannel.WriteAsync(new ReindexMediaItems(toAddIds.ToArray()), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(request.CollectionId))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddMediaItemToCollectionHandler.cs

@@ -42,17 +42,28 @@ public class AddMediaItemToCollectionHandler :
 
     private async Task<Unit> ApplyAddMediaItemRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.MediaItem);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.MediaItem.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.MediaItem.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.MediaItem);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.MediaItem.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddMovieToCollectionHandler.cs

@@ -42,17 +42,28 @@ public class AddMovieToCollectionHandler :
 
     private async Task<Unit> ApplyAddMovieRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.Movie);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.Movie.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Movie.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.Movie);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Movie.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddMusicVideoToCollectionHandler.cs

@@ -44,17 +44,28 @@ public class AddMusicVideoToCollectionHandler :
 
     private async Task<Unit> ApplyAddMusicVideoRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.MusicVideo);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.MusicVideo.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.MusicVideo.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.MusicVideo);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.MusicVideo.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddOtherVideoToCollectionHandler.cs

@@ -44,17 +44,28 @@ public class AddOtherVideoToCollectionHandler :
 
     private async Task<Unit> ApplyAddOtherVideoRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.OtherVideo);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.OtherVideo.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.OtherVideo.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.OtherVideo);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.OtherVideo.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddSeasonToCollectionHandler.cs

@@ -42,17 +42,28 @@ public class AddSeasonToCollectionHandler :
 
     private async Task<Unit> ApplyAddSeasonRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.Season);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.Season.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Season.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.Season);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Season.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddShowToCollectionHandler.cs

@@ -42,17 +42,28 @@ public class AddShowToCollectionHandler :
 
     private async Task<Unit> ApplyAddShowRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.Show);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.Show.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Show.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.Show);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Show.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/AddSongToCollectionHandler.cs

@@ -42,17 +42,28 @@ public class AddSongToCollectionHandler :
 
     private async Task<Unit> ApplyAddSongRequest(TvContext dbContext, Parameters parameters)
     {
-        parameters.Collection.MediaItems.Add(parameters.Song);
-        if (await dbContext.SaveChangesAsync() > 0)
+        // No-op on an idempotent re-add: don't rotate the ETag or fan out rebuilds for an item that is
+        // already a member (also avoids a duplicate CollectionItem row) — #269.
+        if (parameters.Collection.MediaItems.Any(mi => mi.Id == parameters.Song.Id))
         {
-            await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Song.Id]));
+            return Unit.Default;
+        }
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository
-                         .PlayoutIdsUsingCollection(parameters.Collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh));
-            }
+        parameters.Collection.MediaItems.Add(parameters.Song);
+
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this add takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a). Post-commit enqueues run on CancellationToken.None.
+        parameters.Collection.Version++;
+        await dbContext.SaveChangesForcingVersion(CancellationToken.None);
+
+        await _searchChannel.WriteAsync(new ReindexMediaItems([parameters.Song.Id]), CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository
+                     .PlayoutIdsUsingCollection(parameters.Collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/RemoveItemsFromCollectionHandler.cs

@@ -59,21 +59,30 @@ public class RemoveItemsFromCollectionHandler : IRequestHandler<RemoveItemsFromC
             return new NotFoundError("Collection item does not exist.");
         }
 
+        // No-op when nothing is actually removed: don't rotate the ETag or fan out rebuilds — #269.
+        if (itemsToRemove.Count == 0)
+        {
+            return Unit.Default;
+        }
+
         itemsToRemove.ForEach(m => collection.MediaItems.Remove(m));
 
-        if (itemsToRemove.Count != 0 && await dbContext.SaveChangesAsync(cancellationToken) > 0)
-        {
-            // post-commit side effect runs on CancellationToken.None so a late request cancellation
-            // can't abort it after the commit landed (#254)
-            await _searchChannel.WriteAsync(
-                new ReindexMediaItems(itemsToRemove.Select(mi => mi.Id).ToArray()),
-                CancellationToken.None);
+        // Rotate the collection ETag so an open custom-order editor's If-Match invalidates (#269);
+        // force-write past a concurrent replace-all Version bump — this remove takes no If-Match, so a
+        // benign race must not 500 (#253/#269 §7a).
+        collection.Version++;
+        await dbContext.SaveChangesForcingVersion(cancellationToken);
 
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository.PlayoutIdsUsingCollection(collection.Id))
-            {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
-            }
+        // post-commit side effect runs on CancellationToken.None so a late request cancellation
+        // can't abort it after the commit landed (#254)
+        await _searchChannel.WriteAsync(
+            new ReindexMediaItems(itemsToRemove.Select(mi => mi.Id).ToArray()),
+            CancellationToken.None);
+
+        // refresh all playouts that use this collection
+        foreach (int playoutId in await _mediaCollectionRepository.PlayoutIdsUsingCollection(collection.Id))
+        {
+            await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
         }
 
         return Unit.Default;

ErsatzTV.Application/MediaCollections/Commands/UpdateCollectionHandler.cs

@@ -59,17 +59,25 @@ public class UpdateCollectionHandler : IRequestHandler<UpdateCollection, Either<
             c.UseCustomPlaybackOrder = useCustomPlaybackOrder;
         }
 
-        // Force-write past a concurrent Version bump from the custom-order editor (this name/flag writer
-        // doesn't participate in If-Match, so the active token must not 500 a benign race) — #253/#269.
-        if (await dbContext.SaveChangesForcingVersion(cancellationToken) > 0 && request.UseCustomPlaybackOrder.IsSome)
+        // Only rotate the ETag when the name/flag actually changed — a no-op re-submit must not bump the
+        // Version (spurious rebuilds / editor invalidation) — #269. When it did change, force-write past a
+        // concurrent bump from the custom-order editor (this writer takes no If-Match, so a benign race
+        // must not 500) — #253/#269 §7a.
+        if (dbContext.ChangeTracker.HasChanges())
         {
-            // post-commit side effect runs on CancellationToken.None so a late request cancellation
-            // can't abort it after the commit landed (#254)
-            // refresh all playouts that use this collection
-            foreach (int playoutId in await _mediaCollectionRepository.PlayoutIdsUsingCollection(
-                         request.CollectionId))
+            c.Version++;
+            await dbContext.SaveChangesForcingVersion(cancellationToken);
+
+            if (request.UseCustomPlaybackOrder.IsSome)
             {
-                await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
+                // post-commit side effect runs on CancellationToken.None so a late request cancellation
+                // can't abort it after the commit landed (#254)
+                // refresh all playouts that use this collection
+                foreach (int playoutId in await _mediaCollectionRepository.PlayoutIdsUsingCollection(
+                             request.CollectionId))
+                {
+                    await _channel.WriteAsync(new BuildPlayout(playoutId, PlayoutBuildMode.Refresh), CancellationToken.None);
+                }
             }
         }
 

ErsatzTV.Application/Playouts/Commands/UpdateExternalJsonPlayoutHandler.cs

@@ -40,10 +40,14 @@ public class
     {
         playout.ScheduleFile = request.ScheduleFile;
 
-        // Force-write past a concurrent Version bump from a replace-all editor (schedule-file writer
-        // doesn't participate in If-Match, so an active token must not 500 a benign race) — #253/#269.
-        if (await dbContext.SaveChangesForcingVersion(cancellationToken) > 0)
+        // Rotate the playout ETag only when the schedule-file actually changed — a no-op re-submit must
+        // not bump (#269). When it changed, force-write past a concurrent Version bump from a replace-all
+        // editor (this writer takes no If-Match, so a benign race must not 500) — #253/#269 §7a.
+        if (dbContext.ChangeTracker.HasChanges())
         {
+            playout.Version++;
+            await dbContext.SaveChangesForcingVersion(cancellationToken);
+
             // post-commit side effect runs on CancellationToken.None so a late request cancellation
             // can't abort it after the commit landed (#254)
             await _workerChannel.WriteAsync(new RefreshChannelData(playout.Channel.Number), CancellationToken.None);

ErsatzTV.Application/Playouts/Commands/UpdatePlayoutHandler.cs

@@ -35,9 +35,15 @@ public class UpdatePlayoutHandler : IRequestHandler<UpdatePlayout, Either<BaseEr
             playout.DailyRebuildTime = dailyRebuildTime;
         }
 
-        // Force-write past a concurrent Version bump from a replace-all editor (this settings writer
-        // doesn't participate in If-Match, so a missing token = force-write, not a 500) — #253/#269.
-        await dbContext.SaveChangesForcingVersion(cancellationToken);
+        // Rotate the playout ETag only when the daily-rebuild-time actually changed — a no-op re-submit
+        // must not bump (#269). When it changed, force-write past a concurrent Version bump from a
+        // replace-all editor (this settings writer takes no If-Match, so a benign race must not 500) —
+        // #253/#269 §7a.
+        if (dbContext.ChangeTracker.HasChanges())
+        {
+            playout.Version++;
+            await dbContext.SaveChangesForcingVersion(cancellationToken);
+        }
 
         return new PlayoutNameViewModel(
             playout.Id,

ErsatzTV.Application/Playouts/Commands/UpdateScriptedPlayoutHandler.cs

@@ -35,10 +35,14 @@ public class
     {
         playout.ScheduleFile = request.ScheduleFile;
 
-        // Force-write past a concurrent Version bump from a replace-all editor (schedule-file writer
-        // doesn't participate in If-Match, so an active token must not 500 a benign race) — #253/#269.
-        if (await dbContext.SaveChangesForcingVersion(cancellationToken) > 0)
+        // Rotate the playout ETag only when the schedule-file actually changed — a no-op re-submit must
+        // not bump (#269). When it changed, force-write past a concurrent Version bump from a replace-all
+        // editor (this writer takes no If-Match, so a benign race must not 500) — #253/#269 §7a.
+        if (dbContext.ChangeTracker.HasChanges())
         {
+            playout.Version++;
+            await dbContext.SaveChangesForcingVersion(cancellationToken);
+
             // post-commit side effect runs on CancellationToken.None so a late request cancellation
             // can't abort it after the commit landed (#254)
             await workerChannel.WriteAsync(new RefreshChannelData(playout.Channel.Number), CancellationToken.None);

ErsatzTV.Application/Playouts/Commands/UpdateSequentialPlayoutHandler.cs

@@ -40,10 +40,14 @@ public class
     {
         playout.ScheduleFile = request.ScheduleFile;
 
-        // Force-write past a concurrent Version bump from a replace-all editor (schedule-file writer
-        // doesn't participate in If-Match, so an active token must not 500 a benign race) — #253/#269.
-        if (await dbContext.SaveChangesForcingVersion(cancellationToken) > 0)
+        // Rotate the playout ETag only when the schedule-file actually changed — a no-op re-submit must
+        // not bump (#269). When it changed, force-write past a concurrent Version bump from a replace-all
+        // editor (this writer takes no If-Match, so a benign race must not 500) — #253/#269 §7a.
+        if (dbContext.ChangeTracker.HasChanges())
         {
+            playout.Version++;
+            await dbContext.SaveChangesForcingVersion(cancellationToken);
+
             // post-commit side effect runs on CancellationToken.None so a late request cancellation
             // can't abort it after the commit landed (#254)
             await _workerChannel.WriteAsync(new RefreshChannelData(playout.Channel.Number), CancellationToken.None);

ErsatzTV.Tests/Application/MediaCollections/CollectionEtagRotationTests.cs

@@ -0,0 +1,248 @@
+using System.Threading.Channels;
+using ErsatzTV.Application;
+using ErsatzTV.Application.MediaCollections;
+using ErsatzTV.Application.Search;
+using ErsatzTV.Core;
+using ErsatzTV.Core.Domain;
+using ErsatzTV.Core.Interfaces.Repositories;
+using ErsatzTV.Infrastructure.Data;
+using ErsatzTV.Tests.Support;
+using LanguageExt;
+using Microsoft.EntityFrameworkCore;
+using NSubstitute;
+using NUnit.Framework;
+using Shouldly;
+using Unit = LanguageExt.Unit;
+using static LanguageExt.Prelude;
+
+namespace ErsatzTV.Tests.Application.MediaCollections;
+
+/// <summary>
+///     #269: the non-If-Match config-sibling writers of a Collection (name/flag edit, membership
+///     add/remove) rotate the aggregate ETag by bumping <c>Collection.Version</c>, so an open
+///     custom-order editor's stale <c>If-Match</c> invalidates. Two invariants beyond the bump: an
+///     idempotent no-op (re-add an existing member / re-submit the same name) must NOT bump the Version
+///     or fan out playout rebuilds (the <c>SaveChanges() &gt; 0</c> side-effect gate would otherwise fire
+///     spuriously once the bump makes it always-true — Fable D1), and the bump must force-write past a
+///     concurrent replace-all bump rather than 500 (these writers take no <c>If-Match</c>).
+/// </summary>
+[TestFixture]
+public class CollectionEtagRotationTests
+{
+    private InMemoryTvContext _db = null!;
+
+    [SetUp]
+    public async Task SetUp() => _db = await InMemoryTvContext.CreateAsync();
+
+    [TearDown]
+    public async Task TearDown() => await _db.DisposeAsync();
+
+    private sealed class PreTrackedFactory(TvContext context) : IDbContextFactory<TvContext>
+    {
+        public TvContext CreateDbContext() => context;
+    }
+
+    private async Task SeedCollection(int id, int version, bool withMovie, string name = "Manual")
+    {
+        await using TvContext context = _db.CreateContext();
+
+        var library = new LocalLibrary
+        {
+            Id = 1,
+            Name = "Library",
+            MediaKind = LibraryMediaKind.Movies,
+            Paths = []
+        };
+        var path = new LibraryPath { Id = 1, Path = "/media", Library = library, LibraryFolders = [], MediaItems = [] };
+        library.Paths.Add(path);
+
+        context.Movies.Add(new Movie
+        {
+            Id = 10,
+            LibraryPath = path,
+            Collections = [],
+            CollectionItems = [],
+            TraktListItems = [],
+            MovieMetadata =
+            [
+                new MovieMetadata
+                {
+                    Title = "Movie", SortTitle = "Movie", Artwork = [], Genres = [], Tags = [], Studios = [],
+                    Actors = [], Guids = [], Subtitles = [], Directors = [], Writers = []
+                }
+            ],
+            MediaVersions = [new MediaVersion { Duration = TimeSpan.FromMinutes(30) }]
+        });
+
+        context.Collections.Add(new Collection
+        {
+            Id = id,
+            Name = name,
+            Version = version,
+            MediaItems = [],
+            CollectionItems = withMovie ? [new CollectionItem { MediaItemId = 10, CustomIndex = null }] : []
+        });
+
+        await context.SaveChangesAsync();
+    }
+
+    private async Task<int> ReadVersion(int id)
+    {
+        await using TvContext context = _db.CreateContext();
+        return await context.Collections.Where(c => c.Id == id).Select(c => c.Version).SingleAsync();
+    }
+
+    private static (IMediaCollectionRepository repo, Channel<IBackgroundServiceRequest> worker,
+        ChannelWriter<ISearchIndexBackgroundServiceRequest> search) Deps()
+    {
+        IMediaCollectionRepository repo = Substitute.For<IMediaCollectionRepository>();
+        // A single playout uses the collection, so a genuine mutation enqueues exactly one rebuild.
+        repo.PlayoutIdsUsingCollection(Arg.Any<int>()).Returns([1]);
+        Channel<IBackgroundServiceRequest> worker = System.Threading.Channels.Channel.CreateUnbounded<IBackgroundServiceRequest>();
+        ChannelWriter<ISearchIndexBackgroundServiceRequest> search =
+            System.Threading.Channels.Channel.CreateUnbounded<ISearchIndexBackgroundServiceRequest>().Writer;
+        return (repo, worker, search);
+    }
+
+    [Test]
+    public async Task AddItem_To_Collection_Should_Bump_Version_And_Enqueue_Rebuild()
+    {
+        await SeedCollection(1, version: 1, withMovie: false);
+        (IMediaCollectionRepository repo, Channel<IBackgroundServiceRequest> worker,
+            ChannelWriter<ISearchIndexBackgroundServiceRequest> search) = Deps();
+
+        var handler = new AddMovieToCollectionHandler(_db.Factory, repo, worker.Writer, search);
+        Either<BaseError, Unit> result = await handler.Handle(new AddMovieToCollection(1, 10), CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        (await ReadVersion(1)).ShouldBe(2);
+        worker.Reader.Count.ShouldBe(1); // rebuild fanned out to the one playout using the collection
+    }
+
+    [Test]
+    public async Task Idempotent_ReAdd_Should_Be_A_NoOp_Without_Bump_Or_Rebuild()
+    {
+        // The item is already a member — Fable D1: an unconditional bump here would make the
+        // SaveChanges()>0 gate always-true and fire a spurious rebuild on every duplicate add.
+        await SeedCollection(1, version: 1, withMovie: true);
+        (IMediaCollectionRepository repo, Channel<IBackgroundServiceRequest> worker,
+            ChannelWriter<ISearchIndexBackgroundServiceRequest> search) = Deps();
+
+        var handler = new AddMovieToCollectionHandler(_db.Factory, repo, worker.Writer, search);
+        Either<BaseError, Unit> result = await handler.Handle(new AddMovieToCollection(1, 10), CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        (await ReadVersion(1)).ShouldBe(1); // no bump
+        worker.Reader.Count.ShouldBe(0); // no spurious rebuild
+    }
+
+    [Test]
+    public async Task AddItem_Should_Force_Write_Past_A_Concurrent_Version_Bump()
+    {
+        await SeedCollection(1, version: 1, withMovie: false);
+
+        // The handler's context has loaded the collection at version 1 (tracked via identity map).
+        TvContext handlerContext = _db.CreateContext();
+        _ = await handlerContext.Collections.Include(c => c.MediaItems).SingleAsync(c => c.Id == 1);
+
+        // A concurrent replace-all editor bumps the same row to version 2 in the DB.
+        await using (TvContext other = _db.CreateContext())
+        {
+            Collection c = await other.Collections.SingleAsync(x => x.Id == 1);
+            c.Version++;
+            await other.SaveChangesAsync();
+        }
+
+        (IMediaCollectionRepository repo, Channel<IBackgroundServiceRequest> worker,
+            ChannelWriter<ISearchIndexBackgroundServiceRequest> search) = Deps();
+        var handler = new AddMovieToCollectionHandler(new PreTrackedFactory(handlerContext), repo, worker.Writer, search);
+
+        // Must not throw (plain SaveChangesAsync would 500 here); the add force-writes past the bump.
+        Either<BaseError, Unit> result = await handler.Handle(new AddMovieToCollection(1, 10), CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        await using TvContext verify = _db.CreateContext();
+        (await verify.CollectionItems.AnyAsync(ci => ci.CollectionId == 1 && ci.MediaItemId == 10)).ShouldBeTrue();
+
+        // The force-write must rebase our bump ON TOP of the concurrent bump (1 →(other) 2 →(ours) 3), not
+        // adopt the stored token verbatim — otherwise an editor holding the concurrent writer's ETag ("2")
+        // is never invalidated by this add and the #269 rotation is silently lost under race.
+        (await ReadVersion(1)).ShouldBe(3);
+    }
+
+    [Test]
+    public async Task RemoveItem_From_Collection_Should_Bump_Version()
+    {
+        await SeedCollection(1, version: 1, withMovie: true);
+        (IMediaCollectionRepository repo, Channel<IBackgroundServiceRequest> worker,
+            ChannelWriter<ISearchIndexBackgroundServiceRequest> search) = Deps();
+
+        var handler = new RemoveItemsFromCollectionHandler(_db.Factory, repo, worker.Writer, search);
+        Either<BaseError, Unit> result = await handler.Handle(
+            new RemoveItemsFromCollection(1) { MediaItemIds = [10] },
+            CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        (await ReadVersion(1)).ShouldBe(2);
+        worker.Reader.Count.ShouldBe(1);
+    }
+
+    [Test]
+    public async Task RemoveItem_With_Nothing_To_Remove_Should_Be_A_NoOp_Without_Bump()
+    {
+        await SeedCollection(1, version: 1, withMovie: true);
+        (IMediaCollectionRepository repo, Channel<IBackgroundServiceRequest> worker,
+            ChannelWriter<ISearchIndexBackgroundServiceRequest> search) = Deps();
+
+        var handler = new RemoveItemsFromCollectionHandler(_db.Factory, repo, worker.Writer, search);
+        Either<BaseError, Unit> result = await handler.Handle(
+            new RemoveItemsFromCollection(1) { MediaItemIds = [] },
+            CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        (await ReadVersion(1)).ShouldBe(1);
+        worker.Reader.Count.ShouldBe(0);
+    }
+
+    [Test]
+    public async Task UpdateCollection_Name_Change_Should_Bump_Version()
+    {
+        await SeedCollection(1, version: 1, withMovie: false, name: "Before");
+
+        IMediaCollectionRepository repo = Substitute.For<IMediaCollectionRepository>();
+        repo.PlayoutIdsUsingCollection(Arg.Any<int>()).Returns([]);
+        var handler = new UpdateCollectionHandler(
+            _db.Factory,
+            repo,
+            System.Threading.Channels.Channel.CreateUnbounded<IBackgroundServiceRequest>().Writer,
+            Substitute.For<ErsatzTV.Core.Interfaces.Search.ISearchTargets>());
+
+        Either<BaseError, Unit> result = await handler.Handle(
+            new UpdateCollection(1, "After"),
+            CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        (await ReadVersion(1)).ShouldBe(2);
+    }
+
+    [Test]
+    public async Task UpdateCollection_Same_Name_Should_Be_A_NoOp_Without_Bump()
+    {
+        await SeedCollection(1, version: 1, withMovie: false, name: "Same");
+
+        IMediaCollectionRepository repo = Substitute.For<IMediaCollectionRepository>();
+        repo.PlayoutIdsUsingCollection(Arg.Any<int>()).Returns([]);
+        var handler = new UpdateCollectionHandler(
+            _db.Factory,
+            repo,
+            System.Threading.Channels.Channel.CreateUnbounded<IBackgroundServiceRequest>().Writer,
+            Substitute.For<ErsatzTV.Core.Interfaces.Search.ISearchTargets>());
+
+        Either<BaseError, Unit> result = await handler.Handle(
+            new UpdateCollection(1, "Same"),
+            CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        (await ReadVersion(1)).ShouldBe(1);
+    }
+}

ErsatzTV.Tests/Application/Playouts/PlayoutScheduleFileEtagRotationTests.cs

@@ -0,0 +1,144 @@
+using System.Threading.Channels;
+using ErsatzTV.Application;
+using ErsatzTV.Application.Channels;
+using ErsatzTV.Application.Playouts;
+using ErsatzTV.Core;
+using ErsatzTV.Core.Domain;
+using ErsatzTV.Infrastructure.Data;
+using ErsatzTV.Tests.Support;
+using LanguageExt;
+using Microsoft.EntityFrameworkCore;
+using NUnit.Framework;
+using Shouldly;
+
+namespace ErsatzTV.Tests.Application.Playouts;
+
+/// <summary>
+///     #269: the Playout schedule-file writer rotates the aggregate ETag (bumps <c>Playout.Version</c>)
+///     when the schedule-file actually changes, so an open alt-schedule/template editor's stale
+///     <c>If-Match</c> invalidates — but a no-op re-submit (same schedule-file) must NOT bump the Version
+///     or enqueue a channel refresh (the <c>SaveChanges() &gt; 0</c> side-effect gate would otherwise fire
+///     spuriously once the bump makes it always-true). The bump force-writes past a concurrent replace-all
+///     bump rather than 500 (this writer takes no <c>If-Match</c>).
+/// </summary>
+[TestFixture]
+public class PlayoutScheduleFileEtagRotationTests
+{
+    private InMemoryTvContext _db = null!;
+
+    [SetUp]
+    public async Task SetUp() => _db = await InMemoryTvContext.CreateAsync();
+
+    [TearDown]
+    public async Task TearDown() => await _db.DisposeAsync();
+
+    private async Task SeedPlayout(int id, int version, string scheduleFile)
+    {
+        await using TvContext context = _db.CreateContext();
+        var channel = new ErsatzTV.Core.Domain.Channel(Guid.NewGuid())
+        {
+            Id = 1,
+            Number = "1",
+            Name = "Channel",
+            Group = "",
+            Categories = "",
+            Playouts = [],
+            Artwork = []
+        };
+        context.Channels.Add(channel);
+        context.Playouts.Add(new Playout
+        {
+            Id = id,
+            ChannelId = 1,
+            Channel = channel,
+            Version = version,
+            ScheduleKind = PlayoutScheduleKind.Sequential,
+            ScheduleFile = scheduleFile,
+            Seed = 0,
+            Items = []
+        });
+        await context.SaveChangesAsync();
+    }
+
+    private async Task<int> ReadVersion(int id)
+    {
+        await using TvContext context = _db.CreateContext();
+        return await context.Playouts.Where(p => p.Id == id).Select(p => p.Version).SingleAsync();
+    }
+
+    private static (UpdateSequentialPlayoutHandler handler, Channel<IBackgroundServiceRequest> worker) MakeHandler(
+        IDbContextFactory<TvContext> factory)
+    {
+        Channel<IBackgroundServiceRequest> worker = System.Threading.Channels.Channel.CreateUnbounded<IBackgroundServiceRequest>();
+        return (new UpdateSequentialPlayoutHandler(factory, worker.Writer), worker);
+    }
+
+    [Test]
+    public async Task Changing_The_Schedule_File_Should_Bump_Version_And_Refresh()
+    {
+        await SeedPlayout(1, version: 1, scheduleFile: "before.yml");
+        (UpdateSequentialPlayoutHandler handler, Channel<IBackgroundServiceRequest> worker) = MakeHandler(_db.Factory);
+
+        Either<BaseError, PlayoutNameViewModel> result = await handler.Handle(
+            new UpdateSequentialPlayout(1, "after.yml"),
+            CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        (await ReadVersion(1)).ShouldBe(2);
+        worker.Reader.Count.ShouldBe(1); // channel refresh enqueued
+    }
+
+    [Test]
+    public async Task Resubmitting_The_Same_Schedule_File_Should_Be_A_NoOp_Without_Bump_Or_Refresh()
+    {
+        await SeedPlayout(1, version: 1, scheduleFile: "same.yml");
+        (UpdateSequentialPlayoutHandler handler, Channel<IBackgroundServiceRequest> worker) = MakeHandler(_db.Factory);
+
+        Either<BaseError, PlayoutNameViewModel> result = await handler.Handle(
+            new UpdateSequentialPlayout(1, "same.yml"),
+            CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+        (await ReadVersion(1)).ShouldBe(1); // no bump
+        worker.Reader.Count.ShouldBe(0); // no spurious refresh
+    }
+
+    private sealed class PreTrackedFactory(TvContext context) : IDbContextFactory<TvContext>
+    {
+        public TvContext CreateDbContext() => context;
+    }
+
+    [Test]
+    public async Task Schedule_File_Change_Should_Force_Write_Past_A_Concurrent_Version_Bump_And_Still_Rotate()
+    {
+        await SeedPlayout(1, version: 1, scheduleFile: "before.yml");
+
+        // The handler's context has loaded the playout at version 1 (tracked via identity map).
+        TvContext handlerContext = _db.CreateContext();
+        _ = await handlerContext.Playouts.SingleAsync(p => p.Id == 1);
+
+        // A concurrent replace-all editor bumps the same row to version 2 in the DB.
+        await using (TvContext other = _db.CreateContext())
+        {
+            Playout p = await other.Playouts.SingleAsync(x => x.Id == 1);
+            p.Version++;
+            await other.SaveChangesAsync();
+        }
+
+        (UpdateSequentialPlayoutHandler handler, Channel<IBackgroundServiceRequest> worker) =
+            MakeHandler(new PreTrackedFactory(handlerContext));
+
+        // Must not throw (plain SaveChangesAsync would 500 here) …
+        Either<BaseError, PlayoutNameViewModel> result = await handler.Handle(
+            new UpdateSequentialPlayout(1, "after.yml"),
+            CancellationToken.None);
+
+        result.IsRight.ShouldBeTrue();
+
+        // … and the force-write must rebase our bump ON TOP of the concurrent bump (1 →(other) 2 →(ours) 3):
+        // adopting the stored token verbatim would leave the concurrent writer's ETag ("2") valid and the
+        // #269 rotation silently lost under race.
+        (await ReadVersion(1)).ShouldBe(3);
+        worker.Reader.Count.ShouldBe(1); // the genuine change still refreshes the channel
+    }
+}

docs/api-conventions.md

@@ -446,8 +446,10 @@ exception, so it needs no guard).
 makes EF append `WHERE Version=@orig` to *every* UPDATE **and DELETE** of the root — so a plain
 `SaveChangesAsync` writer that is *not* part of the If-Match contract throws an unhandled
 `DbUpdateConcurrencyException`→**500** when a replace-all editor bumps the row in its load→save window. Every
-such writer now saves through `SaveChangesForcingVersion(ct)` (Phase-1 force-write: adopt the stored token and
-retry; rethrow only if the row was genuinely deleted out from under it). **The exposure filter is "any
+such writer now saves through `SaveChangesForcingVersion(ct)` (Phase-1 force-write: rebase onto the stored
+token — original = stored, current = stored + the pending delta, so a `Version`-bumper's rotation still
+advances the ETag *past* the concurrent writer's value instead of silently adopting it — and retry; rethrow
+only if the row was genuinely deleted out from under it). **The exposure filter is "any
 handler that leaves a versioned root `Modified` or `Deleted` on plain `SaveChangesAsync`", NOT just
 `Version`-bumpers + deletes** — `ErasePlayoutHistoryHandler` modifies Playout scalars *without* bumping and
 is exposed too. Covered (18 writers): the **9 aggregate delete handlers** (a delete has no ETag to rotate, so
@@ -467,12 +469,26 @@ config is correct. (2) **Item-add force-write can leave a duplicate/gap `Index`*
 Phase-1 effect): the index is computed from the handler's stale child list, so a concurrent replace-all that
 grew the list makes the add land at a colliding index (no unique constraint). Non-corrupting, self-correcting
 on next edit, strictly better than the pre-#269 500; a reload-and-recompute-on-conflict refinement is a #197
-candidate. **Still deferred to #197
-(cross-editor ETag rotation only):** the non-bumping config siblings
-(`RemoveItemsFromCollectionHandler`, `UpdatePlayoutHandler`'s `DailyRebuildTime`, and the repository-mediated
-`Add*ToCollection` family, shared with the scanner hot path) don't bump `Version`, so editing through them
-doesn't rotate an open editor's ETag. That is an invalidation-completeness refinement — not a lost-update or a
-500; the primary endpoints' own bump+guard fully cover the two-tab lost-update this contract targets.
+candidate.
+
+**Cross-editor ETag rotation — completed (#269).** The remaining non-bumping config siblings now rotate the
+aggregate ETag so a concurrent editor of the *same root* invalidates on its next save: the Collection
+`Add*ToCollection` family (all 11 handlers) and `RemoveItemsFromCollectionHandler` bump `Collection.Version`,
+and `UpdateCollectionHandler` (name/flag), `UpdatePlayoutHandler` (`DailyRebuildTime`), and the three
+`ScheduleFile` writers — which already force-wrote — now also bump. All rotate via `SaveChangesForcingVersion`
+(they take no `If-Match`, so a concurrent bump force-writes, never 412/500). **Correction:** the
+`Add*ToCollection` family is *not* repository-mediated — each handler loads the `Collection` into its own
+`dbContext` and writes directly (`IMediaCollectionRepository` is read-only), so the rotation bump is purely an
+API-layer concern and the scanner's separate membership-write path is unaffected (a background scan does not
+rotate the editor ETag). **No-op idempotence (the trap):** these handlers gate their reindex/`BuildPlayout`
+fan-out on `SaveChanges() > 0`; an *unconditional* bump makes that gate always-true, so an idempotent re-add /
+same-value re-submit would fire spurious rebuilds. Each therefore short-circuits a genuine no-op **before** the
+bump — the Add handlers by an explicit membership check (also fixing the latent duplicate-`CollectionItem`
+insert on a *sequential* re-add; two *concurrent* adds of the same item can still both pass the check and the
+loser 500s on the composite-PK violation — a narrow, pre-existing race, tracked as #308), the scalar
+writers by `ChangeTracker.HasChanges()` — so a no-op neither bumps nor rebuilds. This is an
+invalidation-completeness refinement; the primary endpoints' own bump+guard already covered the two-tab
+lost-update the contract targets.
 
 ## 7b. Post-commit side effects run on `CancellationToken.None`
 

docs/decisions.md

@@ -75,6 +75,7 @@ keep append-only from accreting stale, contradictory, or unreadably-large histor
 - [2026-07-12 — Blocking CI gate for API-contract artifacts (#303 H4/H5)](#2026-07-12--blocking-ci-gate-for-api-contract-artifacts-303-h45)
 - [2026-07-12 — decisions.md is append-only, enforced; root-screenshot guard (#303 H9/H3)](#2026-07-12--decisionsmd-is-append-only-enforced-root-screenshot-guard-303-h9h3)
 - [2026-07-12 — Review-verdict merge-gate: latest commit must be reviewed (#303 H10)](#2026-07-12--review-verdict-merge-gate-latest-commit-must-be-reviewed-303-h10)
+- [2026-07-12 — Cross-editor ETag rotation completed for Collection/Playout config siblings (#269)](#2026-07-12--cross-editor-etag-rotation-completed-for-collectionplayout-config-siblings-269)
 
 ---
 
@@ -1409,3 +1410,58 @@ Scope: the Claude PreToolUse gate on the Gitea merge tool only. A direct `git pu
 PR comments to check, so the `.husky/pre-push` backstop is not extended for H10 (the merge tool is the
 real merge path; docs-only PRs remain exempt via H6's file-set exemption). Rationale, as with the whole
 Wave-1/2/3 hook set: make the process rule a derivation/hook, not prose to remember (#303).
+---
+
+## 2026-07-12 — Cross-editor ETag rotation completed for Collection/Playout config siblings (#269)
+
+The #253 optimistic-concurrency contract (§7a) had a documented tail: the non-If-Match config-sibling
+writers of a versioned root mutated editor-visible state **without** bumping `Version`, so editing through
+them did not rotate an open editor's ETag (a cross-editor invalidation gap — never a lost-update or a 500,
+which the primary endpoints' bump+guard already cover). #269's first slice (PR #302) removed the 500 exposure
+by routing those writers through `SaveChangesForcingVersion`; this slice completes the **rotation**.
+
+Handlers now bumping `Version` (all via `SaveChangesForcingVersion`, since they take no `If-Match` → a
+concurrent replace-all bump force-writes, never 412/500): the Collection `Add*ToCollection` family (11
+handlers) and `RemoveItemsFromCollectionHandler` bump `Collection.Version`; `UpdateCollectionHandler`
+(name/flag), `UpdatePlayoutHandler` (`DailyRebuildTime`), and the three `ScheduleFile` writers
+(`UpdateSequential`/`UpdateScripted`/`UpdateExternalJsonPlayout`) — which already force-wrote — now also bump.
+
+Decisions frozen (ratified with Fable before implementation, feeding the #197 contract freeze):
+
+- **Rotate on every editor-visible config change, no per-aggregate carve-outs.** §7a's config-only boundary
+  ("every mutating handler of a root's editor-visible config bumps `Version`") already held for Playlist
+  `Add*`/schedule item writers; the Collection/Playout siblings were an inconsistency, not a judgment call. A
+  membership add rotating an open custom-order editor's ETag (→ 412 → reload) is correct: its list is genuinely
+  stale. Blast radius of the aggressive-but-safe rotation is a reload, never data loss.
+- **No-op idempotence — the trap Fable caught.** These handlers gate their reindex/`BuildPlayout` fan-out on
+  `SaveChanges() > 0`. An *unconditional* bump makes that gate always-true, so an idempotent re-add / same-value
+  re-submit would fire spurious rebuilds across every playout using the aggregate. Fix: short-circuit a genuine
+  no-op **before** the bump — the Add handlers by an explicit membership check (which also fixes the latent
+  duplicate-`CollectionItem` insert on a *sequential* re-add; two *concurrent* same-item adds can still both
+  pass the check and the loser 500s on the composite-PK unique violation — `SaveChangesForcingVersion` catches
+  only `DbUpdateConcurrencyException`, not `DbUpdateException`. That race is narrow and pre-existing, deferred
+  to #308), the scalar writers (`UpdateCollection`, `UpdatePlayout`, the
+  three `ScheduleFile` writers) by `ChangeTracker.HasChanges()`. A no-op neither bumps nor rebuilds nor rotates
+  the ETag — which is itself correct (nothing changed).
+- **The `Add*ToCollection` family is not repository-mediated.** #269's original framing ("repository-mediated,
+  shared with the scanner hot path") was wrong: `IMediaCollectionRepository` is read-only; each handler loads
+  the `Collection` into its own `dbContext` and writes directly. So the rotation bump is a pure API-layer
+  concern and the scanner's separate membership-write path is untouched — a background scan does **not** rotate
+  the editor ETag (correct: background indexing is not an editor action).
+- **Force-write rebases the bump, never adopts the stored token verbatim (Codex review of this PR).**
+  `SaveChangesForcingVersion` originally resolved a conflict by setting current=original=stored — which
+  silently *discarded* a sibling's pending `Version++` when a versioned writer committed in its load→save
+  window (sibling loads 1, bumps to pending 2, concurrent PUT commits 2 → retry wrote 2, so the concurrent
+  writer's ETag "2" stayed valid and the rotation was lost under exactly the race it exists for). Fixed in
+  this PR (it affects all 25 bumpers routed through the helper, including the pre-existing playlist/schedule
+  ones): the retry now rebases — original = stored, current = stored + (pending current − pending original) —
+  so a bumper lands at stored+1 and a non-bumper (delta 0, e.g. `ErasePlayoutHistory`) adopts stored unchanged.
+  The race tests assert the post-race Version (3, not 2) and fail against the verbatim-adopt implementation.
+- **No new status codes.** These endpoints take no `If-Match` and force-write, so they never 412; no
+  `[ProducesResponseType(...412...)]` and no OpenAPI regen (response types unchanged). Only §7a prose changes.
+
+Tests: `CollectionEtagRotationTests` (rotation + no-op-without-bump-or-rebuild + force-write-past-concurrent-bump
+for Add/Remove/Update) and `PlayoutScheduleFileEtagRotationTests` (ScheduleFile rotation + no-op-without-refresh),
+the no-op guard proven non-vacuous by inverting the membership check. The `#265` RFC-7232 If-Match parser
+refinement (valid-but-non-matching/weak/list → 412 not 400) is a **separate** PR (disjoint surface: the shared
+parser + `CheckVersion`, not the handler saves). Refs #253 #269 #197 · `api-conventions.md` §7a.