fix: playout gap correctness in ui

CHANGELOG.md

@@ -17,6 +17,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Fix regression from `v26.2.0` that caused channel logo watermarks to be ignored when the logo is a url
   - This affected external logo urls and generated channel logos
 - Maintain collection progress when refreshing a classic playout containing playlists
+- Fix UI bug where on-demand channels would always show out of date gaps (unscheduled time)
+- Fix UI bug where gaps (unscheduled time) would be shown from previous playout build, not current build
 
 ## [26.7.0] - 2026-07-27
 ### Added

ErsatzTV.Application/Playouts/Commands/BuildPlayoutHandler.cs

@@ -26,6 +26,7 @@ public class BuildPlayoutHandler : IRequestHandler<BuildPlayout, Either<BaseErro
     private readonly IExternalJsonPlayoutBuilder _externalJsonPlayoutBuilder;
     private readonly IFFmpegSegmenterService _ffmpegSegmenterService;
     private readonly IPlayoutBuilder _playoutBuilder;
+    private readonly IPlayoutGapInserter _playoutGapInserter;
     private readonly IPlayoutTimeShifter _playoutTimeShifter;
     private readonly ChannelWriter<IBackgroundServiceRequest> _workerChannel;
     private readonly ILogger<BuildPlayoutHandler> _logger;
@@ -43,6 +44,7 @@ public class BuildPlayoutHandler : IRequestHandler<BuildPlayout, Either<BaseErro
         IFFmpegSegmenterService ffmpegSegmenterService,
         IEntityLocker entityLocker,
         IPlayoutTimeShifter playoutTimeShifter,
+        IPlayoutGapInserter playoutGapInserter,
         ChannelWriter<IBackgroundServiceRequest> workerChannel,
         ILogger<BuildPlayoutHandler> logger)
     {
@@ -56,6 +58,7 @@ public class BuildPlayoutHandler : IRequestHandler<BuildPlayout, Either<BaseErro
         _ffmpegSegmenterService = ffmpegSegmenterService;
         _entityLocker = entityLocker;
         _playoutTimeShifter = playoutTimeShifter;
+        _playoutGapInserter = playoutGapInserter;
         _workerChannel = workerChannel;
         _logger = logger;
     }
@@ -89,6 +92,10 @@ public class BuildPlayoutHandler : IRequestHandler<BuildPlayout, Either<BaseErro
                     await _playoutTimeShifter.TimeShift(request.PlayoutId, timeShiftTo, false, cancellationToken);
                 }
 
+                // must happen after any time shift, and before the playout is unlocked so that
+                // the ui sees items and gaps from the same build
+                await _playoutGapInserter.InsertGaps(request.PlayoutId, cancellationToken);
+
                 if (playoutBuildResult.Warnings.TailFillerTooLong > 0)
                 {
                     _logger.LogDebug(
@@ -305,8 +312,6 @@ public class BuildPlayoutHandler : IRequestHandler<BuildPlayout, Either<BaseErro
                         new CheckForOverlappingPlayoutItems(request.PlayoutId),
                         cancellationToken);
 
-                    await _workerChannel.WriteAsync(new InsertPlayoutGaps(request.PlayoutId), cancellationToken);
-
                     string fileName = Path.Combine(FileSystemLayout.ChannelGuideCacheFolder, $"{channelNumber}.xml");
                     if (hasChanges || !File.Exists(fileName) ||
                         playout.ScheduleKind is PlayoutScheduleKind.ExternalJson)

ErsatzTV.Application/Playouts/Commands/InsertPlayoutGaps.cs

@@ -1,3 +0,0 @@
-namespace ErsatzTV.Application.Playouts;
-
-public record InsertPlayoutGaps(int PlayoutId) : IRequest, IBackgroundServiceRequest;

ErsatzTV.Core/Interfaces/Scheduling/IPlayoutGapInserter.cs

@@ -0,0 +1,6 @@
+namespace ErsatzTV.Core.Interfaces.Scheduling;
+
+public interface IPlayoutGapInserter
+{
+    Task InsertGaps(int playoutId, CancellationToken cancellationToken);
+}

ErsatzTV.Infrastructure/Scheduling/PlayoutGapInserter.cs

@@ -1,21 +1,22 @@
 using EFCore.BulkExtensions;
 using ErsatzTV.Core.Domain;
+using ErsatzTV.Core.Interfaces.Scheduling;
 using ErsatzTV.Infrastructure.Data;
 using Microsoft.EntityFrameworkCore;
 
-namespace ErsatzTV.Application.Playouts;
+namespace ErsatzTV.Infrastructure.Scheduling;
 
-public class InsertPlayoutGapsHandler(IDbContextFactory<TvContext> dbContextFactory)
-    : IRequestHandler<InsertPlayoutGaps>
+public class PlayoutGapInserter(IDbContextFactory<TvContext> dbContextFactory) : IPlayoutGapInserter
 {
-    public async Task Handle(InsertPlayoutGaps request, CancellationToken cancellationToken)
+    public async Task InsertGaps(int playoutId, CancellationToken cancellationToken)
     {
         await using TvContext dbContext = await dbContextFactory.CreateDbContextAsync(cancellationToken);
 
         var toAdd = new List<PlayoutGap>();
 
         IOrderedQueryable<PlayoutItem> query = dbContext.PlayoutItems
-            .Filter(pi => pi.PlayoutId == request.PlayoutId)
+            .AsNoTracking()
+            .Filter(pi => pi.PlayoutId == playoutId)
             .OrderBy(i => i.Start);
 
         var queue = new Queue<PlayoutItem>(query);
@@ -27,14 +28,15 @@ public class InsertPlayoutGapsHandler(IDbContextFactory<TvContext> dbContextFact
             DateTime start = one.Finish;
             DateTime finish = two.Start;
 
-            if (start == finish)
+            // overlapping items would otherwise produce a negative-duration gap
+            if (start >= finish)
             {
                 continue;
             }
 
             var gap = new PlayoutGap
             {
-                PlayoutId = request.PlayoutId,
+                PlayoutId = playoutId,
                 Start = start,
                 Finish = finish
             };
@@ -44,7 +46,7 @@ public class InsertPlayoutGapsHandler(IDbContextFactory<TvContext> dbContextFact
 
         // delete all existing gaps
         await dbContext.PlayoutGaps
-            .Where(pg => pg.PlayoutId == request.PlayoutId)
+            .Where(pg => pg.PlayoutId == playoutId)
             .ExecuteDeleteAsync(cancellationToken);
 
         // insert new gaps

ErsatzTV.Infrastructure/Scheduling/PlayoutTimeShifter.cs

@@ -30,6 +30,7 @@ public class PlayoutTimeShifter(
             Option<Playout> maybePlayout = await dbContext.Playouts
                 .Include(p => p.Channel)
                 .Include(p => p.Items)
+                .Include(p => p.Gaps)
                 .Include(p => p.Anchor)
                 .Include(p => p.ProgramScheduleAnchors)
                 .Include(p => p.PlayoutHistory)
@@ -85,6 +86,8 @@ public class PlayoutTimeShifter(
                             playout.Channel.Number,
                             playout.Channel.Name);
                     }
+
+                    playout.Gaps.RemoveAll(g => g.Finish < checkpointUtc);
                 }
 
                 TimeSpan toOffset = now - playout.OnDemandCheckpoint.IfNone(now);
@@ -119,6 +122,13 @@ public class PlayoutTimeShifter(
                     }
                 }
 
+                // time shift gaps along with the items they were calculated from
+                foreach (PlayoutGap gap in playout.Gaps)
+                {
+                    gap.Start += toOffset;
+                    gap.Finish += toOffset;
+                }
+
                 // time shift anchors
                 foreach (PlayoutProgramScheduleAnchor anchor in playout.ProgramScheduleAnchors)
                 {

ErsatzTV/Services/WorkerService.cs

@@ -87,9 +87,6 @@ public class WorkerService : BackgroundService
                         case CheckForOverlappingPlayoutItems checkForOverlappingPlayoutItems:
                             await mediator.Send(checkForOverlappingPlayoutItems, stoppingToken);
                             break;
-                        case InsertPlayoutGaps insertPlayoutGaps:
-                            await mediator.Send(insertPlayoutGaps, stoppingToken);
-                            break;
                         case TimeShiftOnDemandPlayout timeShiftOnDemandPlayout:
                             await mediator.Send(timeShiftOnDemandPlayout, stoppingToken);
                             break;

ErsatzTV/Startup.cs

@@ -788,6 +788,7 @@ public class Startup
         services.AddScoped<ISchedulingEngine, SchedulingEngine>();
         services.AddScoped<IExternalJsonPlayoutBuilder, ExternalJsonPlayoutBuilder>();
         services.AddScoped<IPlayoutTimeShifter, PlayoutTimeShifter>();
+        services.AddScoped<IPlayoutGapInserter, PlayoutGapInserter>();
         services.AddScoped<IImageCache, ImageCache>();
         services.AddScoped<ILocalFileSystem, LocalFileSystem>();
         services.AddScoped<IPlexServerApiClient, PlexServerApiClient>();