feat: recommend server-generated mixes from Musify and YouTube Music

Mixes are their own concept, not playlists: they live in their own Mixes/MixItems tables, cannot be edited and never show up among the user's playlists. Each item is either a Musify track or a YouTube Music reference, so YouTube songs stream directly instead of being downloaded. A daily Hangfire job seeds the mixes from the listening history: one discovery mix, one daily mix and one per top artist. The per-user YouTube filler query was already in the working tree and rides along here because it shares files with this change.
2026-07-21 18:13:07 +02:00
parent 637e1ae583
commit 496a5f4a0b
36 changed files with 2667 additions and 13 deletions
@@ -9,6 +9,8 @@
    <PackageVersion Include="DispatchR.Mediator" Version="2.2.0" />
    <PackageVersion Include="ErrorOr" Version="2.1.1" />
    <PackageVersion Include="FluentValidation.DependencyInjectionExtensions" Version="12.1.1" />
+    <PackageVersion Include="Hangfire.NetCore" Version="1.8.24" />
+    <PackageVersion Include="Hangfire.PostgreSql" Version="1.21.1" />
    <PackageVersion Include="MassTransit" Version="8.5.9" />
    <PackageVersion Include="MassTransit.EntityFrameworkCore" Version="8.5.9" />
    <PackageVersion Include="MassTransit.RabbitMQ" Version="8.5.9" />
@@ -57,6 +57,12 @@
        "ThumbnailSize": 240,
        "ArtworkSize": 544
    },
+    "Mix": {
+        "ArtistMixCount": 3,
+        "ItemsPerMix": 12,
+        "SeedArtistCount": 3,
+        "YouTubeResultsPerSeed": 12
+    },
    "PlayList": {
        "Routes": {
            "UploadsFolder": "uploads",
@@ -0,0 +1,51 @@
+using Mediator;
+using Musify.Api.Authentication;
+using Musify.Api.Extensions;
+using Musify.Application.Mixes;
+using Musify.Application.Mixes.Responses;
+
+namespace Musify.Api.Endpoints;
+
+public static class MixEndpoints
+{
+    public static IEndpointRouteBuilder MapMixEndpoints(this IEndpointRouteBuilder app)
+    {
+        var group = app.MapGroup("/mixes")
+            .WithTags("Mixes")
+            .RequireAuthorization();
+
+        group.MapGet("/", GetMixes)
+            .WithName("GetMixes")
+            .WithSummary("Get The Server-Generated Mixes Of The Current User.")
+            .Produces<IReadOnlyList<MixApplicationResponse>>()
+            .Produces(StatusCodes.Status401Unauthorized);
+
+        group.MapGet("/{id}", GetMixById)
+            .WithName("GetMixById")
+            .WithSummary("Get A Mix With All Of Its Songs.")
+            .Produces<MixApplicationResponse>()
+            .Produces(StatusCodes.Status401Unauthorized)
+            .Produces(StatusCodes.Status404NotFound);
+
+        return app;
+    }
+
+    private static async Task<IResult> GetMixes(
+        IMediator mediator,
+        CurrentUser currentUser,
+        CancellationToken cancellationToken)
+    {
+        var result = await mediator.Send(new GetMixesByUserIdQuery(currentUser.RequiredId), cancellationToken);
+        return result.ToHttpResult();
+    }
+
+    private static async Task<IResult> GetMixById(
+        IMediator mediator,
+        CurrentUser currentUser,
+        Guid id,
+        CancellationToken cancellationToken)
+    {
+        var result = await mediator.Send(new GetMixByIdQuery(currentUser.RequiredId, id), cancellationToken);
+        return result.ToHttpResult();
+    }
+}
@@ -39,6 +39,7 @@ app.UseAuthorization();

 app
    .MapAlbumEndpoints()
+    .MapMixEndpoints()
    .MapPlayListEndpoints()
    .MapTrackEndpoints()
    .MapUserEndpoints()
@@ -18,6 +18,7 @@ public static class ApplicationDependencyInjection
        services.AddValidatedOptions<ApplicationStorageConfiguration>(configuration, ApplicationStorageConfiguration.SectionName);
        services.AddValidatedOptions<PlayListConfiguration>(configuration, PlayListConfiguration.SectionName);
        services.AddValidatedOptions<TrackConfiguration>(configuration, TrackConfiguration.SectionName);
+        services.AddValidatedOptions<MixConfiguration>(configuration, MixConfiguration.SectionName);
        services.AddValidatedOptions<StreamGatewayConfiguration>(configuration, StreamGatewayConfiguration.SectionName);
        services.AddValidatedOptions<UploadIntentConfiguration>(configuration, UploadIntentConfiguration.SectionName);

@@ -0,0 +1,21 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace Musify.Application.Configuration
+{
+    public class MixConfiguration
+    {
+        public const string SectionName = "Mix";
+
+        [Range(1, 20)]
+        public int ArtistMixCount { get; set; } = 3;
+
+        [Range(4, 100)]
+        public int ItemsPerMix { get; set; } = 12;
+
+        [Range(1, 10)]
+        public int SeedArtistCount { get; set; } = 3;
+
+        [Range(1, 100)]
+        public int YouTubeResultsPerSeed { get; set; } = 12;
+    }
+}
@@ -29,6 +29,10 @@ namespace Musify.Application.Contracts

        DbSet<PlayListHasTrack> PlayListHasTracks { get; }

+        DbSet<Mix> Mixes { get; }
+
+        DbSet<MixItem> MixItems { get; }
+
        DbSet<Upload> Uploads { get; }

        DbSet<UploadIntent> UploadIntents { get; }
@@ -0,0 +1,343 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Configuration;
+using Musify.Application.Contracts;
+using Musify.Application.Tracks.Responses;
+using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Mixes
+{
+    public record GenerateMixesForUserCommand(long UserId)
+        : ICommand<ErrorOr<Success>>;
+
+    public class GenerateMixesForUserCommandHandler(
+        IDatabase database,
+        IYouTubeMusicService youTubeMusicService,
+        MixConfiguration mixConfiguration,
+        ILogger<GenerateMixesForUserCommandHandler> logger)
+        : ICommandHandler<GenerateMixesForUserCommand, ErrorOr<Success>>
+    {
+        private sealed record SeedArtist(Guid Id, string Name);
+
+        private sealed record LocalCandidate(Guid TrackId, string Title, string? Artist, int DurationSeconds);
+
+        private sealed record MixDraft(string Title, string? Subtitle, IReadOnlyList<MixItem> Items);
+
+        private const int TitleLength = 300;
+        private const int ArtistLength = 300;
+        private const int ThumbnailUrlLength = 512;
+        private const int MixTitleLength = 100;
+
+        public async ValueTask<ErrorOr<Success>> Handle(GenerateMixesForUserCommand request, CancellationToken cancellationToken)
+        {
+            var userId = request.UserId;
+
+            var historyTrackIds = await database.ListeningHistories
+                .AsNoTracking()
+                .Where(history => history.UserId == userId)
+                .Select(history => history.TrackId)
+                .Distinct()
+                .ToListAsync(cancellationToken);
+
+            if (historyTrackIds.Count == 0)
+            {
+                logger.LogInformation("User {UserId} has no listening history yet, skipping mix generation", userId);
+                return new Success();
+            }
+
+            var seedArtists = await GetSeedArtistsAsync(historyTrackIds, cancellationToken);
+
+            if (seedArtists.Count == 0)
+            {
+                logger.LogInformation("User {UserId} has no artists to seed mixes from, skipping mix generation", userId);
+                return new Success();
+            }
+
+            var knownVideoIds = await database.ExternalTracks
+                .AsNoTracking()
+                .Where(track => track.Source == TrackSource.YouTube && historyTrackIds.Contains(track.Id))
+                .Select(track => track.ExternalId)
+                .ToListAsync(cancellationToken);
+
+            var excludedVideoIds = new HashSet<string>(knownVideoIds, StringComparer.OrdinalIgnoreCase);
+
+            var youTubeByArtist = await SearchYouTubeAsync(seedArtists, excludedVideoIds, cancellationToken);
+            var localByArtist = await GetLocalCandidatesAsync(seedArtists, historyTrackIds, cancellationToken);
+
+            var drafts = BuildDrafts(seedArtists, localByArtist, youTubeByArtist);
+
+            if (drafts.Count == 0)
+            {
+                logger.LogInformation("No candidate songs found for user {UserId}, skipping mix generation", userId);
+                return new Success();
+            }
+
+            await ReplaceMixesAsync(userId, drafts, cancellationToken);
+
+            try
+            {
+                await database.SaveChangesAsync(cancellationToken);
+            }
+            catch (Exception exception)
+            {
+                logger.LogError(exception, "Failed to generate mixes for user {UserId}", userId);
+                return Error.Failure(description: $"Failed to generate mixes for user {userId}");
+            }
+
+            logger.LogInformation("Generated {Count} mixes for user {UserId}", drafts.Count, userId);
+            return new Success();
+        }
+
+        private async Task<List<SeedArtist>> GetSeedArtistsAsync(
+            IReadOnlyList<Guid> historyTrackIds,
+            CancellationToken cancellationToken)
+        {
+            var ranked = await database.TrackArtists
+                .AsNoTracking()
+                .Where(trackArtist => historyTrackIds.Contains(trackArtist.TrackId))
+                .GroupBy(trackArtist => trackArtist.ArtistId)
+                .Select(group => new { ArtistId = group.Key, Listens = group.Count() })
+                .OrderByDescending(entry => entry.Listens)
+                .Take(mixConfiguration.SeedArtistCount)
+                .ToListAsync(cancellationToken);
+
+            var artistIds = ranked.Select(entry => entry.ArtistId).ToList();
+
+            var names = await database.Artists
+                .AsNoTracking()
+                .Where(artist => artistIds.Contains(artist.Id))
+                .ToDictionaryAsync(artist => artist.Id, artist => artist.Name, cancellationToken);
+
+            return [.. ranked
+                .Where(entry => names.ContainsKey(entry.ArtistId))
+                .Select(entry => new SeedArtist(entry.ArtistId, names[entry.ArtistId]))];
+        }
+
+        private async Task<Dictionary<Guid, List<MixItem>>> SearchYouTubeAsync(
+            IReadOnlyList<SeedArtist> seedArtists,
+            HashSet<string> excludedVideoIds,
+            CancellationToken cancellationToken)
+        {
+            var byArtist = new Dictionary<Guid, List<MixItem>>();
+
+            foreach (var seed in seedArtists)
+            {
+                var searchResult = await youTubeMusicService.SearchSongsAsync(seed.Name, string.Empty, cancellationToken);
+                if (searchResult.IsError)
+                {
+                    logger.LogWarning("YouTube Music search failed for seed artist {Artist}: {Error}",
+                        seed.Name, searchResult.FirstError.Description);
+                    byArtist[seed.Id] = [];
+                    continue;
+                }
+
+                var songs = new List<MixItem>();
+                foreach (var song in searchResult.Value.Items.Take(mixConfiguration.YouTubeResultsPerSeed))
+                {
+                    if (!excludedVideoIds.Add(song.VideoId))
+                        continue;
+
+                    songs.Add(new MixItem
+                    {
+                        MixId = Guid.Empty,
+                        Source = MixItemSource.YouTube,
+                        VideoId = song.VideoId,
+                        Title = Truncate(song.Title, TitleLength),
+                        Artist = Truncate(song.Artist, ArtistLength),
+                        ThumbnailUrl = Truncate(youTubeMusicService.ResolveArtworkUrl(song.ThumbnailUrl), ThumbnailUrlLength),
+                        DurationSeconds = song.DurationSeconds,
+                        IsExplicit = song.IsExplicit
+                    });
+                }
+
+                byArtist[seed.Id] = songs;
+            }
+
+            return byArtist;
+        }
+
+        private async Task<Dictionary<Guid, List<MixItem>>> GetLocalCandidatesAsync(
+            IReadOnlyList<SeedArtist> seedArtists,
+            IReadOnlyList<Guid> historyTrackIds,
+            CancellationToken cancellationToken)
+        {
+            var artistIds = seedArtists.Select(seed => seed.Id).ToList();
+
+            var links = await database.TrackArtists
+                .AsNoTracking()
+                .Where(trackArtist => artistIds.Contains(trackArtist.ArtistId) && !historyTrackIds.Contains(trackArtist.TrackId))
+                .Select(trackArtist => new { trackArtist.ArtistId, trackArtist.TrackId })
+                .ToListAsync(cancellationToken);
+
+            var trackIds = links.Select(link => link.TrackId).Distinct().ToList();
+
+            var candidates = await LoadCandidatesAsync(trackIds, cancellationToken);
+
+            var byArtist = new Dictionary<Guid, List<MixItem>>();
+            foreach (var seed in seedArtists)
+            {
+                byArtist[seed.Id] = [.. links
+                    .Where(link => link.ArtistId == seed.Id)
+                    .Select(link => candidates.GetValueOrDefault(link.TrackId))
+                    .Where(candidate => candidate is not null)
+                    .Select(candidate => ToMixItem(candidate!))];
+            }
+
+            return byArtist;
+        }
+
+        private async Task<Dictionary<Guid, LocalCandidate>> LoadCandidatesAsync(
+            IReadOnlyList<Guid> trackIds,
+            CancellationToken cancellationToken)
+        {
+            if (trackIds.Count == 0)
+                return [];
+
+            var tracks = await database.Tracks
+                .AsNoTracking()
+                .Where(track => trackIds.Contains(track.Id) && track.LifeCycleStatus == LifeCycleStatus.Active)
+                .Include(track => ((ExternalTrack)track).TrackArtists)
+                    .ThenInclude(trackArtist => trackArtist.Artist)
+                .Include(track => ((LocalTrack)track).Owner)
+                .ToListAsync(cancellationToken);
+
+            return tracks
+                .Select(track => TrackApplicationResponse.FromEntity(track, 0))
+                .ToDictionary(
+                    response => response.Id,
+                    response => new LocalCandidate(response.Id, response.Title, response.Artist, response.Duration));
+        }
+
+        private static MixItem ToMixItem(LocalCandidate candidate) => new()
+        {
+            MixId = Guid.Empty,
+            Source = MixItemSource.Musify,
+            TrackId = candidate.TrackId,
+            Title = candidate.Title,
+            Artist = candidate.Artist,
+            DurationSeconds = candidate.DurationSeconds
+        };
+
+        private List<MixDraft> BuildDrafts(
+            IReadOnlyList<SeedArtist> seedArtists,
+            IReadOnlyDictionary<Guid, List<MixItem>> localByArtist,
+            IReadOnlyDictionary<Guid, List<MixItem>> youTubeByArtist)
+        {
+            var drafts = new List<MixDraft>();
+
+            var everyYouTube = seedArtists.SelectMany(seed => youTubeByArtist[seed.Id]).ToList();
+            var everyLocal = seedArtists.SelectMany(seed => localByArtist[seed.Id]).ToList();
+
+            var discovery = Take(Shuffle(everyYouTube));
+            if (discovery.Count > 0)
+            {
+                drafts.Add(new MixDraft(
+                    "Descubrimiento",
+                    "Canciones nuevas de YouTube Music que todavía no has escuchado.",
+                    discovery));
+            }
+
+            var daily = Take(Interleave(Shuffle(everyLocal), Shuffle(everyYouTube)));
+            if (daily.Count > 0)
+            {
+                drafts.Add(new MixDraft(
+                    "Tu mezcla diaria",
+                    "Lo que más escuchas, con alguna sorpresa nueva.",
+                    daily));
+            }
+
+            foreach (var seed in seedArtists.Take(mixConfiguration.ArtistMixCount))
+            {
+                var items = Take(Interleave(Shuffle(localByArtist[seed.Id]), Shuffle(youTubeByArtist[seed.Id])));
+                if (items.Count == 0)
+                    continue;
+
+                drafts.Add(new MixDraft(
+                    Truncate($"Mezcla: {seed.Name}", MixTitleLength),
+                    $"Canciones de {seed.Name} en Musify y en YouTube Music.",
+                    items));
+            }
+
+            return drafts;
+        }
+
+        private List<MixItem> Take(IEnumerable<MixItem> items) =>
+            [.. items.Take(mixConfiguration.ItemsPerMix)];
+
+        private static string Truncate(string value, int maxLength) =>
+            value.Length <= maxLength ? value : value[..maxLength];
+
+        private static List<MixItem> Shuffle(IEnumerable<MixItem> items) =>
+            [.. items.OrderBy(_ => Guid.NewGuid())];
+
+        private static List<MixItem> Interleave(IReadOnlyList<MixItem> first, IReadOnlyList<MixItem> second)
+        {
+            var merged = new List<MixItem>(first.Count + second.Count);
+            for (var index = 0; index < Math.Max(first.Count, second.Count); index++)
+            {
+                if (index < first.Count)
+                    merged.Add(first[index]);
+                if (index < second.Count)
+                    merged.Add(second[index]);
+            }
+
+            return merged;
+        }
+
+        private async Task ReplaceMixesAsync(long userId, IReadOnlyList<MixDraft> drafts, CancellationToken cancellationToken)
+        {
+            var previousMixes = await database.Mixes
+                .Where(mix => mix.UserId == userId)
+                .ToListAsync(cancellationToken);
+
+            if (previousMixes.Count > 0)
+            {
+                var previousIds = previousMixes.Select(mix => mix.Id).ToList();
+                var previousItems = await database.MixItems
+                    .Where(item => previousIds.Contains(item.MixId))
+                    .ToListAsync(cancellationToken);
+
+                database.MixItems.RemoveRange(previousItems);
+                database.Mixes.RemoveRange(previousMixes);
+            }
+
+            var today = DateOnly.FromDateTime(DateTime.UtcNow);
+
+            for (var position = 0; position < drafts.Count; position++)
+            {
+                var draft = drafts[position];
+                var mix = new Mix
+                {
+                    UserId = userId,
+                    Title = draft.Title,
+                    Subtitle = draft.Subtitle,
+                    GeneratedOn = today,
+                    Position = position
+                };
+
+                await database.Mixes.AddAsync(mix, cancellationToken);
+
+                for (var itemPosition = 0; itemPosition < draft.Items.Count; itemPosition++)
+                {
+                    var item = draft.Items[itemPosition];
+                    await database.MixItems.AddAsync(new MixItem
+                    {
+                        MixId = mix.Id,
+                        Position = itemPosition,
+                        Source = item.Source,
+                        TrackId = item.TrackId,
+                        VideoId = item.VideoId,
+                        Title = item.Title,
+                        Artist = item.Artist,
+                        ThumbnailUrl = item.ThumbnailUrl,
+                        DurationSeconds = item.DurationSeconds,
+                        IsExplicit = item.IsExplicit
+                    }, cancellationToken);
+                }
+            }
+        }
+    }
+}
@@ -0,0 +1,30 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+using Musify.Application.Mixes.Responses;
+
+namespace Musify.Application.Mixes
+{
+    public record GetMixByIdQuery(long UserId, Guid MixId)
+        : IQuery<ErrorOr<MixApplicationResponse>>;
+
+    public class GetMixByIdQueryHandler(IDatabase database)
+        : IQueryHandler<GetMixByIdQuery, ErrorOr<MixApplicationResponse>>
+    {
+        public async ValueTask<ErrorOr<MixApplicationResponse>> Handle(GetMixByIdQuery request, CancellationToken cancellationToken)
+        {
+            var mix = await database.Mixes
+                .AsNoTracking()
+                .Include(mix => mix.Items)
+                .SingleOrDefaultAsync(mix => mix.Id == request.MixId && mix.UserId == request.UserId, cancellationToken);
+
+            if (mix is null)
+                return Error.NotFound(description: $"Mix {request.MixId} was not found");
+
+            var items = mix.Items.OrderBy(item => item.Position).ToList();
+
+            return MixApplicationResponse.FromEntity(mix, items.Count, items);
+        }
+    }
+}
@@ -0,0 +1,37 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+using Musify.Application.Mixes.Responses;
+
+namespace Musify.Application.Mixes
+{
+    public record GetMixesByUserIdQuery(long UserId)
+        : IQuery<ErrorOr<IReadOnlyList<MixApplicationResponse>>>;
+
+    public class GetMixesByUserIdQueryHandler(IDatabase database)
+        : IQueryHandler<GetMixesByUserIdQuery, ErrorOr<IReadOnlyList<MixApplicationResponse>>>
+    {
+        public async ValueTask<ErrorOr<IReadOnlyList<MixApplicationResponse>>> Handle(GetMixesByUserIdQuery request, CancellationToken cancellationToken)
+        {
+            var entries = await database.Mixes
+                .AsNoTracking()
+                .Where(mix => mix.UserId == request.UserId)
+                .OrderBy(mix => mix.Position)
+                .Select(mix => new
+                {
+                    Mix = mix,
+                    ItemCount = mix.Items.Count,
+                    CoverItems = mix.Items
+                        .OrderBy(item => item.Position)
+                        .Take(MixApplicationResponse.CoverItemCount)
+                        .ToList()
+                })
+                .ToListAsync(cancellationToken);
+
+            return entries
+                .Select(entry => MixApplicationResponse.FromEntity(entry.Mix, entry.ItemCount, entry.CoverItems))
+                .ToList();
+        }
+    }
+}
@@ -0,0 +1,27 @@
+using Musify.Domain.Entities;
+
+namespace Musify.Application.Mixes.Responses
+{
+    public record MixApplicationResponse(
+        Guid Id,
+        string Title,
+        string? Subtitle,
+        DateOnly GeneratedOn,
+        int ItemCount,
+        IReadOnlyList<MixItemApplicationResponse> Items)
+    {
+        public const int CoverItemCount = 4;
+
+        public static MixApplicationResponse FromEntity(
+            Mix mix,
+            int itemCount,
+            IReadOnlyList<MixItem> items) =>
+            new(
+                mix.Id,
+                mix.Title,
+                mix.Subtitle,
+                mix.GeneratedOn,
+                itemCount,
+                [.. items.Select(MixItemApplicationResponse.FromEntity)]);
+    }
+}
@@ -0,0 +1,27 @@
+using Musify.Domain.Entities;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Mixes.Responses
+{
+    public record MixItemApplicationResponse(
+        MixItemSource Source,
+        Guid? TrackId,
+        string? VideoId,
+        string Title,
+        string? Artist,
+        string? ThumbnailUrl,
+        int DurationSeconds,
+        bool IsExplicit)
+    {
+        public static MixItemApplicationResponse FromEntity(MixItem item) =>
+            new(
+                item.Source,
+                item.TrackId,
+                item.VideoId,
+                item.Title ?? string.Empty,
+                item.Artist,
+                item.ThumbnailUrl,
+                item.DurationSeconds,
+                item.IsExplicit);
+    }
+}
@@ -0,0 +1,42 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+using Musify.Domain.Abstractions;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    [Table("Mixes")]
+    public class Mix : IAuditable
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required long UserId { get; set; }
+
+        [Required]
+        [MaxLength(100)]
+        public required string Title { get; set; }
+
+        [MaxLength(256)]
+        public string? Subtitle { get; set; }
+
+        [Required]
+        public required DateOnly GeneratedOn { get; set; }
+
+        [Required]
+        public int Position { get; set; } = 0;
+
+        [Required]
+        public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+
+        [Required]
+        public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+
+        [ForeignKey(nameof(UserId))]
+        public User User { get; set; }
+
+        public ICollection<MixItem> Items { get; set; } = new List<MixItem>();
+    }
+}
@@ -0,0 +1,50 @@
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Domain.Entities
+{
+#pragma warning disable CS8618
+    [Table("MixItems")]
+    public class MixItem
+    {
+        [Key]
+        public Guid Id { get; set; } = Guid.NewGuid();
+
+        [Required]
+        public required Guid MixId { get; set; }
+
+        [Required]
+        public int Position { get; set; } = 0;
+
+        [Required]
+        public required MixItemSource Source { get; set; }
+
+        public Guid? TrackId { get; set; }
+
+        [MaxLength(64)]
+        public string? VideoId { get; set; }
+
+        [MaxLength(300)]
+        public string? Title { get; set; }
+
+        [MaxLength(300)]
+        public string? Artist { get; set; }
+
+        [MaxLength(512)]
+        public string? ThumbnailUrl { get; set; }
+
+        [Required]
+        public int DurationSeconds { get; set; } = 0;
+
+        [Required]
+        public bool IsExplicit { get; set; } = false;
+
+        [ForeignKey(nameof(MixId))]
+        public Mix Mix { get; set; }
+
+        [ForeignKey(nameof(TrackId))]
+        public Track? Track { get; set; }
+    }
+}
@@ -0,0 +1,8 @@
+namespace Musify.Domain.ValueObjects
+{
+    public enum MixItemSource
+    {
+        Musify = 0,
+        YouTube = 1
+    }
+}
@@ -0,0 +1,37 @@
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Application.Mixes;
+
+namespace Musify.Infrastructure.Jobs
+{
+    public class DailyMixGenerationJob(
+        IDatabase database,
+        IMediator mediator,
+        ILogger<DailyMixGenerationJob> logger)
+    {
+        public async Task RunAsync(CancellationToken cancellationToken)
+        {
+            var userIds = await database.ListeningHistories
+                .AsNoTracking()
+                .Select(history => history.UserId)
+                .Distinct()
+                .ToListAsync(cancellationToken);
+
+            logger.LogInformation("Starting daily mix generation for {Count} users", userIds.Count);
+
+            foreach (var userId in userIds)
+            {
+                var result = await mediator.Send(new GenerateMixesForUserCommand(userId), cancellationToken);
+                if (result.IsError)
+                {
+                    logger.LogWarning("Failed to generate mixes for user {UserId}: {Error}",
+                        userId, result.FirstError.Description);
+                }
+            }
+
+            logger.LogInformation("Finished daily mix generation");
+        }
+    }
+}
@@ -6,6 +6,8 @@

  <ItemGroup>
    <PackageReference Include="AWSSDK.S3" />
+    <PackageReference Include="Hangfire.NetCore" />
+    <PackageReference Include="Hangfire.PostgreSql" />
    <PackageReference Include="MassTransit" />
    <PackageReference Include="MassTransit.EntityFrameworkCore" />
    <PackageReference Include="MassTransit.RabbitMQ" />
@@ -137,6 +137,25 @@ namespace Musify.Infrastructure.Persistence
                .HasIndex(albumTrack => new { albumTrack.AlbumId, albumTrack.TrackId })
                .IsUnique();

+            modelBuilder.Entity<Mix>()
+                .HasIndex(mix => new { mix.UserId, mix.Position });
+
+            modelBuilder.Entity<MixItem>()
+                .HasOne(item => item.Mix)
+                .WithMany(mix => mix.Items)
+                .HasForeignKey(item => item.MixId)
+                .OnDelete(DeleteBehavior.Cascade);
+
+            modelBuilder.Entity<MixItem>()
+                .HasOne(item => item.Track)
+                .WithMany()
+                .HasForeignKey(item => item.TrackId)
+                .IsRequired(false)
+                .OnDelete(DeleteBehavior.Cascade);
+
+            modelBuilder.Entity<MixItem>()
+                .HasIndex(item => new { item.MixId, item.Position });
+
            var playListProcessing = modelBuilder.Entity<PlayListProcessingState>();
            playListProcessing.HasKey(state => state.CorrelationId);
            playListProcessing.Property(state => state.CorrelationId).ValueGeneratedNever();
@@ -167,6 +186,10 @@ namespace Musify.Infrastructure.Persistence

        public DbSet<PlayListHasTrack> PlayListHasTracks => Set<PlayListHasTrack>();

+        public DbSet<Mix> Mixes => Set<Mix>();
+
+        public DbSet<MixItem> MixItems => Set<MixItem>();
+
        public DbSet<Upload> Uploads => Set<Upload>();

        public DbSet<UploadIntent> UploadIntents => Set<UploadIntent>();
@@ -0,0 +1,97 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Musify.Infrastructure.Persistence.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddMixes : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "Mixes",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "uuid", nullable: false),
+                    UserId = table.Column<long>(type: "bigint", nullable: false),
+                    Title = table.Column<string>(type: "character varying(100)", maxLength: 100, nullable: false),
+                    Subtitle = table.Column<string>(type: "character varying(256)", maxLength: 256, nullable: true),
+                    GeneratedOn = table.Column<DateOnly>(type: "date", nullable: false),
+                    Position = table.Column<int>(type: "integer", nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_Mixes", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_Mixes_User_UserId",
+                        column: x => x.UserId,
+                        principalTable: "User",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateTable(
+                name: "MixItems",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "uuid", nullable: false),
+                    MixId = table.Column<Guid>(type: "uuid", nullable: false),
+                    Position = table.Column<int>(type: "integer", nullable: false),
+                    Source = table.Column<int>(type: "integer", nullable: false),
+                    TrackId = table.Column<Guid>(type: "uuid", nullable: true),
+                    VideoId = table.Column<string>(type: "character varying(64)", maxLength: 64, nullable: true),
+                    Title = table.Column<string>(type: "character varying(300)", maxLength: 300, nullable: true),
+                    Artist = table.Column<string>(type: "character varying(300)", maxLength: 300, nullable: true),
+                    ThumbnailUrl = table.Column<string>(type: "character varying(512)", maxLength: 512, nullable: true),
+                    DurationSeconds = table.Column<int>(type: "integer", nullable: false),
+                    IsExplicit = table.Column<bool>(type: "boolean", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_MixItems", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_MixItems_Mixes_MixId",
+                        column: x => x.MixId,
+                        principalTable: "Mixes",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_MixItems_Tracks_TrackId",
+                        column: x => x.TrackId,
+                        principalTable: "Tracks",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_Mixes_UserId_Position",
+                table: "Mixes",
+                columns: new[] { "UserId", "Position" });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_MixItems_MixId_Position",
+                table: "MixItems",
+                columns: new[] { "MixId", "Position" });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_MixItems_TrackId",
+                table: "MixItems",
+                column: "TrackId");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "MixItems");
+
+            migrationBuilder.DropTable(
+                name: "Mixes");
+        }
+    }
+}
@@ -316,6 +316,92 @@ namespace Musify.Infrastructure.Persistence.Migrations
                    b.ToTable("ListeningHistory");
                });

+            modelBuilder.Entity("Musify.Domain.Entities.Mix", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uuid");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<DateOnly>("GeneratedOn")
+                        .HasColumnType("date");
+
+                    b.Property<int>("Position")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("Subtitle")
+                        .HasMaxLength(256)
+                        .HasColumnType("character varying(256)");
+
+                    b.Property<string>("Title")
+                        .IsRequired()
+                        .HasMaxLength(100)
+                        .HasColumnType("character varying(100)");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<long>("UserId")
+                        .HasColumnType("bigint");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("UserId", "Position");
+
+                    b.ToTable("Mixes");
+                });
+
+            modelBuilder.Entity("Musify.Domain.Entities.MixItem", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uuid");
+
+                    b.Property<string>("Artist")
+                        .HasMaxLength(300)
+                        .HasColumnType("character varying(300)");
+
+                    b.Property<int>("DurationSeconds")
+                        .HasColumnType("integer");
+
+                    b.Property<bool>("IsExplicit")
+                        .HasColumnType("boolean");
+
+                    b.Property<Guid>("MixId")
+                        .HasColumnType("uuid");
+
+                    b.Property<int>("Position")
+                        .HasColumnType("integer");
+
+                    b.Property<int>("Source")
+                        .HasColumnType("integer");
+
+                    b.Property<string>("ThumbnailUrl")
+                        .HasMaxLength(512)
+                        .HasColumnType("character varying(512)");
+
+                    b.Property<string>("Title")
+                        .HasMaxLength(300)
+                        .HasColumnType("character varying(300)");
+
+                    b.Property<Guid?>("TrackId")
+                        .HasColumnType("uuid");
+
+                    b.Property<string>("VideoId")
+                        .HasMaxLength(64)
+                        .HasColumnType("character varying(64)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TrackId");
+
+                    b.HasIndex("MixId", "Position");
+
+                    b.ToTable("MixItems");
+                });
+
            modelBuilder.Entity("Musify.Domain.Entities.PlayList", b =>
                {
                    b.Property<Guid>("Id")
@@ -773,6 +859,35 @@ namespace Musify.Infrastructure.Persistence.Migrations
                    b.Navigation("User");
                });

+            modelBuilder.Entity("Musify.Domain.Entities.Mix", b =>
+                {
+                    b.HasOne("Musify.Domain.Entities.User", "User")
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("User");
+                });
+
+            modelBuilder.Entity("Musify.Domain.Entities.MixItem", b =>
+                {
+                    b.HasOne("Musify.Domain.Entities.Mix", "Mix")
+                        .WithMany("Items")
+                        .HasForeignKey("MixId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("Musify.Domain.Entities.Track", "Track")
+                        .WithMany()
+                        .HasForeignKey("TrackId")
+                        .OnDelete(DeleteBehavior.Cascade);
+
+                    b.Navigation("Mix");
+
+                    b.Navigation("Track");
+                });
+
            modelBuilder.Entity("Musify.Domain.Entities.PlayList", b =>
                {
                    b.HasOne("Musify.Domain.Entities.User", "User")
@@ -1025,6 +1140,11 @@ namespace Musify.Infrastructure.Persistence.Migrations
                    b.Navigation("TrackArtists");
                });

+            modelBuilder.Entity("Musify.Domain.Entities.Mix", b =>
+                {
+                    b.Navigation("Items");
+                });
+
            modelBuilder.Entity("Musify.Domain.Entities.PlayList", b =>
                {
                    b.Navigation("PlayListTracks");
@@ -1,4 +1,6 @@
 using Amazon.S3;
+using Hangfire;
+using Hangfire.PostgreSql;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
@@ -60,6 +62,21 @@ namespace Musify.Infrastructure.Services
            return serviceDescriptors;
        }

+        public static IServiceCollection AddDailyMixGenerationJob(this IServiceCollection serviceDescriptors, IConfiguration configuration)
+        {
+            serviceDescriptors.AddHangfire((serviceProvider, hangfireConfiguration) =>
+            {
+                var databaseConfiguration = serviceProvider.GetRequiredService<DatabaseConfiguration>();
+                hangfireConfiguration.UsePostgreSqlStorage(options =>
+                    options.UseNpgsqlConnection(databaseConfiguration.ConnectionString));
+            });
+
+            serviceDescriptors.AddHangfireServer();
+            serviceDescriptors.AddScoped<DailyMixGenerationJob>();
+
+            return serviceDescriptors;
+        }
+
        public static IServiceCollection AddStreamTicketService(this IServiceCollection serviceDescriptors, IConfiguration configuration)
        {
            serviceDescriptors
@@ -26,6 +26,12 @@
    "ApplicationStorage": {
        "Bucket": ""
    },
+    "Mix": {
+        "ArtistMixCount": 3,
+        "ItemsPerMix": 12,
+        "SeedArtistCount": 3,
+        "YouTubeResultsPerSeed": 12
+    },
    "PlayList": {
        "Routes": {
            "ParentFolders": "PlayLists",
@@ -1,10 +1,26 @@
+using Hangfire;
+using Mediator;
+using Microsoft.Extensions.DependencyInjection;
 using Musify.Application.Configuration;
+using Musify.Application.Services;
+using Musify.Infrastructure.Jobs;
 using Musify.Infrastructure.MassTransit;
 using Musify.Infrastructure.Persistence;
 using Musify.Infrastructure.Services;

 var builder = Host.CreateApplicationBuilder();

+// Registering Mediator pulls in every handler in Musify.Application, including ones
+// (e.g. CreatePlayList, CreateTrack) that depend on IEventBus, which the Worker never
+// registers because it only consumes events, it never publishes them. Only the handlers
+// this process actually dispatches (GenerateMixesForUserCommand) are ever constructed,
+// so the default eager validate-on-build check is too strict for this host.
+builder.ConfigureContainer(new DefaultServiceProviderFactory(new ServiceProviderOptions
+{
+    ValidateOnBuild = false,
+    ValidateScopes = true
+}));
+
 var configuration = builder.Configuration;

 var services = builder.Services;
@@ -12,6 +28,7 @@ var services = builder.Services;
 services.AddValidatedOptions<ApplicationStorageConfiguration>(configuration, ApplicationStorageConfiguration.SectionName);
 services.AddValidatedOptions<PlayListConfiguration>(configuration, PlayListConfiguration.SectionName);
 services.AddValidatedOptions<TrackConfiguration>(configuration, TrackConfiguration.SectionName);
+services.AddValidatedOptions<MixConfiguration>(configuration, MixConfiguration.SectionName);
 services.AddStorageService(configuration);
 services.AddAudioTranscoder(configuration);
 services.AddYouTubeDownloader(configuration);
@@ -20,7 +37,21 @@ services.AddPictureService(configuration);
 services.AddDatabase(configuration);
 services.AddMassTransitConsumers(configuration);
 services.AddUploadIntentJobs(configuration);
+services.AddMediator();
+services.AddScoped<YouTubeTrackProvisioner>();
+services.AddYouTubeMusicService(configuration);
+services.AddDailyMixGenerationJob(configuration);

 var host = builder.Build();

-host.Run();
+using (var scope = host.Services.CreateScope())
+{
+    var recurringJobManager = scope.ServiceProvider.GetRequiredService<IRecurringJobManager>();
+    recurringJobManager.AddOrUpdate<DailyMixGenerationJob>(
+        "daily-mix-generation",
+        job => job.RunAsync(CancellationToken.None),
+        Cron.Daily(),
+        new RecurringJobOptions { TimeZone = TimeZoneInfo.Utc });
+}
+
+host.Run();