feat(worker): configurable max parallel task executions

Add a "Max parallel executions" setting to the General settings tab so
the queue can run more than one task concurrently. QueueService now
tracks multiple active slots and reads the limit from app settings each
cycle, so changes take effect without restarting the worker.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/ClaudeDo.Data/Configuration/AppSettingsEntityConfiguration.cs

@@ -22,6 +22,9 @@ public class AppSettingsEntityConfiguration : IEntityTypeConfiguration<AppSettin
         builder.Property(s => s.DefaultPermissionMode)
             .HasColumnName("default_permission_mode").IsRequired().HasDefaultValue("bypassPermissions");
 
+        builder.Property(s => s.MaxParallelExecutions)
+            .HasColumnName("max_parallel_executions").IsRequired().HasDefaultValue(1);
+
         builder.Property(s => s.WorktreeStrategy)
             .HasColumnName("worktree_strategy").IsRequired().HasDefaultValue("sibling");
         builder.Property(s => s.CentralWorktreeRoot)

src/ClaudeDo.Data/Migrations/20260601133737_AddMaxParallelExecutions.Designer.cs

@@ -0,0 +1,607 @@
+// <auto-generated />
+using System;
+using ClaudeDo.Data;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Infrastructure;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+
+#nullable disable
+
+namespace ClaudeDo.Data.Migrations
+{
+    [DbContext(typeof(ClaudeDoDbContext))]
+    [Migration("20260601133737_AddMaxParallelExecutions")]
+    partial class AddMaxParallelExecutions
+    {
+        /// <inheritdoc />
+        protected override void BuildTargetModel(ModelBuilder modelBuilder)
+        {
+#pragma warning disable 612, 618
+            modelBuilder.HasAnnotation("ProductVersion", "8.0.11");
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.AppSettingsEntity", b =>
+                {
+                    b.Property<int>("Id")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("id");
+
+                    b.Property<string>("CentralWorktreeRoot")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("central_worktree_root");
+
+                    b.Property<string>("DefaultClaudeInstructions")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasDefaultValue("")
+                        .HasColumnName("default_claude_instructions");
+
+                    b.Property<int>("DefaultMaxTurns")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(30)
+                        .HasColumnName("default_max_turns");
+
+                    b.Property<string>("DefaultModel")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasDefaultValue("sonnet")
+                        .HasColumnName("default_model");
+
+                    b.Property<string>("DefaultPermissionMode")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasDefaultValue("bypassPermissions")
+                        .HasColumnName("default_permission_mode");
+
+                    b.Property<int>("MaxParallelExecutions")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(1)
+                        .HasColumnName("max_parallel_executions");
+
+                    b.Property<string>("RepoImportFolders")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("repo_import_folders");
+
+                    b.Property<int>("WorktreeAutoCleanupDays")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(7)
+                        .HasColumnName("worktree_auto_cleanup_days");
+
+                    b.Property<bool>("WorktreeAutoCleanupEnabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(false)
+                        .HasColumnName("worktree_auto_cleanup_enabled");
+
+                    b.Property<string>("WorktreeStrategy")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasDefaultValue("sibling")
+                        .HasColumnName("worktree_strategy");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("app_settings", (string)null);
+
+                    b.HasData(
+                        new
+                        {
+                            Id = 1,
+                            DefaultClaudeInstructions = "",
+                            DefaultMaxTurns = 100,
+                            DefaultModel = "sonnet",
+                            DefaultPermissionMode = "auto",
+                            MaxParallelExecutions = 1,
+                            WorktreeAutoCleanupDays = 7,
+                            WorktreeAutoCleanupEnabled = false,
+                            WorktreeStrategy = "sibling"
+                        });
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.ListConfigEntity", b =>
+                {
+                    b.Property<string>("ListId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("list_id");
+
+                    b.Property<string>("AgentPath")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("agent_path");
+
+                    b.Property<string>("Model")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("model");
+
+                    b.Property<string>("SystemPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("system_prompt");
+
+                    b.HasKey("ListId");
+
+                    b.ToTable("list_config", (string)null);
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.ListEntity", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("DefaultCommitType")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasDefaultValue("chore")
+                        .HasColumnName("default_commit_type");
+
+                    b.Property<string>("Name")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("name");
+
+                    b.Property<int>("SortOrder")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(0)
+                        .HasColumnName("sort_order");
+
+                    b.Property<string>("WorkingDir")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("working_dir");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("SortOrder")
+                        .HasDatabaseName("idx_lists_sort");
+
+                    b.ToTable("lists", (string)null);
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.PrimeScheduleEntity", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTimeOffset>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<bool>("Enabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(true)
+                        .HasColumnName("enabled");
+
+                    b.Property<DateOnly>("EndDate")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("end_date");
+
+                    b.Property<DateTimeOffset?>("LastRunAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_run_at");
+
+                    b.Property<string>("PromptOverride")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("prompt_override");
+
+                    b.Property<DateOnly>("StartDate")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("start_date");
+
+                    b.Property<TimeSpan>("TimeOfDay")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("time_of_day");
+
+                    b.Property<bool>("WorkdaysOnly")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(true)
+                        .HasColumnName("workdays_only");
+
+                    b.HasKey("Id");
+
+                    b.ToTable("prime_schedules", (string)null);
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.SubtaskEntity", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<bool>("Completed")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(false)
+                        .HasColumnName("completed");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<int>("OrderNum")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("order_num");
+
+                    b.Property<string>("TaskId")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("task_id");
+
+                    b.Property<string>("Title")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("title");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TaskId")
+                        .HasDatabaseName("idx_subtasks_task_id");
+
+                    b.ToTable("subtasks", (string)null);
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.TaskEntity", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("AgentPath")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("agent_path");
+
+                    b.Property<string>("BlockedByTaskId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("blocked_by_task_id");
+
+                    b.Property<string>("CommitType")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasDefaultValue("chore")
+                        .HasColumnName("commit_type");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("CreatedBy")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_by");
+
+                    b.Property<string>("Description")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("description");
+
+                    b.Property<DateTime?>("FinishedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("finished_at");
+
+                    b.Property<bool>("IsMyDay")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(false)
+                        .HasColumnName("is_my_day");
+
+                    b.Property<bool>("IsStarred")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(false)
+                        .HasColumnName("is_starred");
+
+                    b.Property<string>("ListId")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("list_id");
+
+                    b.Property<string>("LogPath")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("log_path");
+
+                    b.Property<string>("Model")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("model");
+
+                    b.Property<string>("Notes")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("notes");
+
+                    b.Property<string>("ParentTaskId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("parent_task_id");
+
+                    b.Property<DateTime?>("PlanningFinalizedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("planning_finalized_at");
+
+                    b.Property<string>("PlanningPhase")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasDefaultValue("none")
+                        .HasColumnName("planning_phase");
+
+                    b.Property<string>("PlanningSessionId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("planning_session_id");
+
+                    b.Property<string>("PlanningSessionToken")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("planning_session_token");
+
+                    b.Property<string>("Result")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("result");
+
+                    b.Property<DateTime?>("ScheduledFor")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("scheduled_for");
+
+                    b.Property<int>("SortOrder")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(0)
+                        .HasColumnName("sort_order");
+
+                    b.Property<DateTime?>("StartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("started_at");
+
+                    b.Property<string>("Status")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("status");
+
+                    b.Property<string>("SystemPrompt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("system_prompt");
+
+                    b.Property<string>("Title")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("title");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("BlockedByTaskId")
+                        .HasDatabaseName("idx_tasks_blocked_by");
+
+                    b.HasIndex("ListId")
+                        .HasDatabaseName("idx_tasks_list_id");
+
+                    b.HasIndex("ParentTaskId")
+                        .HasDatabaseName("idx_tasks_parent_task_id");
+
+                    b.HasIndex("Status")
+                        .HasDatabaseName("idx_tasks_status");
+
+                    b.HasIndex("ListId", "SortOrder")
+                        .HasDatabaseName("idx_tasks_list_sort");
+
+                    b.ToTable("tasks", (string)null);
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.TaskRunEntity", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<string>("ErrorMarkdown")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("error_markdown");
+
+                    b.Property<int?>("ExitCode")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("exit_code");
+
+                    b.Property<DateTime?>("FinishedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("finished_at");
+
+                    b.Property<bool>("IsRetry")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(false)
+                        .HasColumnName("is_retry");
+
+                    b.Property<string>("LogPath")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("log_path");
+
+                    b.Property<string>("Prompt")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("prompt");
+
+                    b.Property<string>("ResultMarkdown")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("result_markdown");
+
+                    b.Property<int>("RunNumber")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("run_number");
+
+                    b.Property<string>("SessionId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("session_id");
+
+                    b.Property<DateTime?>("StartedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("started_at");
+
+                    b.Property<string>("StructuredOutputJson")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("structured_output");
+
+                    b.Property<string>("TaskId")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("task_id");
+
+                    b.Property<int?>("TokensIn")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("tokens_in");
+
+                    b.Property<int?>("TokensOut")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("tokens_out");
+
+                    b.Property<int?>("TurnCount")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("turn_count");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("TaskId")
+                        .HasDatabaseName("idx_task_runs_task_id");
+
+                    b.ToTable("task_runs", (string)null);
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.WorktreeEntity", b =>
+                {
+                    b.Property<string>("TaskId")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("task_id");
+
+                    b.Property<string>("BaseCommit")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("base_commit");
+
+                    b.Property<string>("BranchName")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("branch_name");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<string>("DiffStat")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("diff_stat");
+
+                    b.Property<string>("HeadCommit")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("head_commit");
+
+                    b.Property<string>("Path")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("path");
+
+                    b.Property<string>("State")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("TEXT")
+                        .HasDefaultValue("active")
+                        .HasColumnName("state");
+
+                    b.HasKey("TaskId");
+
+                    b.ToTable("worktrees", (string)null);
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.ListConfigEntity", b =>
+                {
+                    b.HasOne("ClaudeDo.Data.Models.ListEntity", "List")
+                        .WithOne("Config")
+                        .HasForeignKey("ClaudeDo.Data.Models.ListConfigEntity", "ListId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("List");
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.SubtaskEntity", b =>
+                {
+                    b.HasOne("ClaudeDo.Data.Models.TaskEntity", "Task")
+                        .WithMany("Subtasks")
+                        .HasForeignKey("TaskId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Task");
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.TaskEntity", b =>
+                {
+                    b.HasOne("ClaudeDo.Data.Models.TaskEntity", null)
+                        .WithMany()
+                        .HasForeignKey("BlockedByTaskId")
+                        .OnDelete(DeleteBehavior.SetNull);
+
+                    b.HasOne("ClaudeDo.Data.Models.ListEntity", "List")
+                        .WithMany("Tasks")
+                        .HasForeignKey("ListId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("ClaudeDo.Data.Models.TaskEntity", "Parent")
+                        .WithMany("Children")
+                        .HasForeignKey("ParentTaskId")
+                        .OnDelete(DeleteBehavior.Restrict);
+
+                    b.Navigation("List");
+
+                    b.Navigation("Parent");
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.TaskRunEntity", b =>
+                {
+                    b.HasOne("ClaudeDo.Data.Models.TaskEntity", "Task")
+                        .WithMany("Runs")
+                        .HasForeignKey("TaskId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Task");
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.WorktreeEntity", b =>
+                {
+                    b.HasOne("ClaudeDo.Data.Models.TaskEntity", "Task")
+                        .WithOne("Worktree")
+                        .HasForeignKey("ClaudeDo.Data.Models.WorktreeEntity", "TaskId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Task");
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.ListEntity", b =>
+                {
+                    b.Navigation("Config");
+
+                    b.Navigation("Tasks");
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.TaskEntity", b =>
+                {
+                    b.Navigation("Children");
+
+                    b.Navigation("Runs");
+
+                    b.Navigation("Subtasks");
+
+                    b.Navigation("Worktree");
+                });
+#pragma warning restore 612, 618
+        }
+    }
+}

src/ClaudeDo.Data/Migrations/20260601133737_AddMaxParallelExecutions.cs

@@ -0,0 +1,36 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ClaudeDo.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddMaxParallelExecutions : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.AddColumn<int>(
+                name: "max_parallel_executions",
+                table: "app_settings",
+                type: "INTEGER",
+                nullable: false,
+                defaultValue: 1);
+
+            migrationBuilder.UpdateData(
+                table: "app_settings",
+                keyColumn: "id",
+                keyValue: 1,
+                column: "max_parallel_executions",
+                value: 1);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropColumn(
+                name: "max_parallel_executions",
+                table: "app_settings");
+        }
+    }
+}

src/ClaudeDo.Data/Migrations/ClaudeDoDbContextModelSnapshot.cs

@@ -54,6 +54,12 @@ namespace ClaudeDo.Data.Migrations
                         .HasDefaultValue("bypassPermissions")
                         .HasColumnName("default_permission_mode");
 
+                    b.Property<int>("MaxParallelExecutions")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(1)
+                        .HasColumnName("max_parallel_executions");
+
                     b.Property<string>("RepoImportFolders")
                         .HasColumnType("TEXT")
                         .HasColumnName("repo_import_folders");
@@ -89,6 +95,7 @@ namespace ClaudeDo.Data.Migrations
                             DefaultMaxTurns = 100,
                             DefaultModel = "sonnet",
                             DefaultPermissionMode = "auto",
+                            MaxParallelExecutions = 1,
                             WorktreeAutoCleanupDays = 7,
                             WorktreeAutoCleanupEnabled = false,
                             WorktreeStrategy = "sibling"

src/ClaudeDo.Data/Models/AppSettingsEntity.cs

@@ -11,6 +11,8 @@ public sealed class AppSettingsEntity
     public int DefaultMaxTurns { get; set; } = 100;
     public string DefaultPermissionMode { get; set; } = "auto";
 
+    public int MaxParallelExecutions { get; set; } = 1;
+
     public string WorktreeStrategy { get; set; } = "sibling";
     public string? CentralWorktreeRoot { get; set; }
     public bool WorktreeAutoCleanupEnabled { get; set; }

src/ClaudeDo.Data/Repositories/AppSettingsRepository.cs

@@ -44,6 +44,7 @@ public sealed class AppSettingsRepository
         row.DefaultMaxTurns = updated.DefaultMaxTurns;
         row.DefaultPermissionMode = string.IsNullOrWhiteSpace(updated.DefaultPermissionMode)
             ? "auto" : updated.DefaultPermissionMode;
+        row.MaxParallelExecutions = updated.MaxParallelExecutions < 1 ? 1 : updated.MaxParallelExecutions;
         row.WorktreeStrategy = string.IsNullOrWhiteSpace(updated.WorktreeStrategy) ? "sibling" : updated.WorktreeStrategy;
         row.CentralWorktreeRoot = string.IsNullOrWhiteSpace(updated.CentralWorktreeRoot)
             ? null : updated.CentralWorktreeRoot;

src/ClaudeDo.Ui/Services/WorkerClient.cs

@@ -450,6 +450,7 @@ public sealed record AppSettingsDto(
     string DefaultModel,
     int DefaultMaxTurns,
     string DefaultPermissionMode,
+    int MaxParallelExecutions,
     string WorktreeStrategy,
     string? CentralWorktreeRoot,
     bool WorktreeAutoCleanupEnabled,

src/ClaudeDo.Ui/ViewModels/Modals/Settings/GeneralSettingsTabViewModel.cs

@@ -9,6 +9,7 @@ public sealed partial class GeneralSettingsTabViewModel : ViewModelBase
     [ObservableProperty] private string _defaultModel = ModelRegistry.DefaultAlias;
     [ObservableProperty] private int _defaultMaxTurns = 100;
     [ObservableProperty] private string _defaultPermissionMode = PermissionModeRegistry.DefaultMode;
+    [ObservableProperty] private int _maxParallelExecutions = 1;
 
     public IReadOnlyList<string> Models { get; } = ModelRegistry.Aliases;
     public IReadOnlyList<string> PermissionModes { get; } = PermissionModeRegistry.Modes;
@@ -17,6 +18,8 @@ public sealed partial class GeneralSettingsTabViewModel : ViewModelBase
     {
         if (DefaultMaxTurns < 1 || DefaultMaxTurns > 200)
             return "Max turns must be between 1 and 200.";
+        if (MaxParallelExecutions < 1 || MaxParallelExecutions > 20)
+            return "Max parallel executions must be between 1 and 20.";
         return null;
     }
 }

src/ClaudeDo.Ui/ViewModels/Modals/SettingsModalViewModel.cs

@@ -42,6 +42,7 @@ public sealed partial class SettingsModalViewModel : ViewModelBase
                 General.DefaultModel = dto.DefaultModel ?? "sonnet";
                 General.DefaultMaxTurns = dto.DefaultMaxTurns;
                 General.DefaultPermissionMode = dto.DefaultPermissionMode ?? "auto";
+                General.MaxParallelExecutions = dto.MaxParallelExecutions;
                 Worktrees.WorktreeStrategy = dto.WorktreeStrategy ?? "sibling";
                 Worktrees.CentralWorktreeRoot = dto.CentralWorktreeRoot;
                 Worktrees.WorktreeAutoCleanupEnabled = dto.WorktreeAutoCleanupEnabled;
@@ -69,6 +70,7 @@ public sealed partial class SettingsModalViewModel : ViewModelBase
                 General.DefaultModel ?? "sonnet",
                 General.DefaultMaxTurns,
                 General.DefaultPermissionMode ?? "auto",
+                General.MaxParallelExecutions,
                 Worktrees.WorktreeStrategy ?? "sibling",
                 string.IsNullOrWhiteSpace(Worktrees.CentralWorktreeRoot) ? null : Worktrees.CentralWorktreeRoot,
                 Worktrees.WorktreeAutoCleanupEnabled,

src/ClaudeDo.Ui/Views/Modals/SettingsModalView.axaml

@@ -75,6 +75,14 @@
                             HorizontalAlignment="Stretch"/>
                 </StackPanel>
               </Grid>
+              <StackPanel Spacing="4">
+                <TextBlock Classes="field-label" Text="Max parallel executions"/>
+                <NumericUpDown Value="{Binding General.MaxParallelExecutions, Mode=TwoWay}"
+                               Minimum="1" Maximum="20" Increment="1" FormatString="0"
+                               HorizontalAlignment="Left" Width="140"/>
+                <TextBlock Text="How many queued tasks the worker runs at once."
+                           Opacity="0.6" FontSize="12"/>
+              </StackPanel>
             </StackPanel>
           </ScrollViewer>
         </TabItem>

src/ClaudeDo.Worker/Hub/WorkerHub.cs

@@ -22,6 +22,7 @@ public record AppSettingsDto(
     string DefaultModel,
     int DefaultMaxTurns,
     string DefaultPermissionMode,
+    int MaxParallelExecutions,
     string WorktreeStrategy,
     string? CentralWorktreeRoot,
     bool WorktreeAutoCleanupEnabled,
@@ -202,6 +203,7 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
             row.DefaultModel,
             row.DefaultMaxTurns,
             row.DefaultPermissionMode,
+            row.MaxParallelExecutions,
             row.WorktreeStrategy,
             row.CentralWorktreeRoot,
             row.WorktreeAutoCleanupEnabled,
@@ -219,6 +221,7 @@ public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
             DefaultModel = dto.DefaultModel ?? ModelRegistry.DefaultAlias,
             DefaultMaxTurns = dto.DefaultMaxTurns,
             DefaultPermissionMode = dto.DefaultPermissionMode ?? PermissionModeRegistry.DefaultMode,
+            MaxParallelExecutions = dto.MaxParallelExecutions,
             WorktreeStrategy = dto.WorktreeStrategy ?? "sibling",
             CentralWorktreeRoot = dto.CentralWorktreeRoot,
             WorktreeAutoCleanupEnabled = dto.WorktreeAutoCleanupEnabled,

src/ClaudeDo.Worker/Queue/QueueService.cs

@@ -18,7 +18,7 @@ public sealed class QueueService : BackgroundService
     private readonly OverrideSlotService _override;
 
     private readonly object _lock = new();
-    private volatile QueueSlotState? _queueSlot;
+    private readonly Dictionary<string, QueueSlotState> _queueSlots = new();
 
     public QueueService(
         IDbContextFactory<ClaudeDoDbContext> dbFactory,
@@ -41,8 +41,11 @@ public sealed class QueueService : BackgroundService
     public IReadOnlyList<(string slot, string taskId, DateTime startedAt)> GetActive()
     {
         var list = new List<(string, string, DateTime)>();
-        var q = _queueSlot;
+        lock (_lock)
-        if (q is not null) list.Add(("queue", q.TaskId, q.StartedAt));
+        {
+            foreach (var slot in _queueSlots.Values)
+                list.Add(("queue", slot.TaskId, slot.StartedAt));
+        }
         var o = _override.CurrentSlot;
         if (o is not null) list.Add(("override", o.TaskId, o.StartedAt));
         return list;
@@ -64,7 +67,7 @@ public sealed class QueueService : BackgroundService
     {
         lock (_lock)
         {
-            if (_queueSlot?.TaskId == taskId)
+            if (_queueSlots.ContainsKey(taskId))
                 throw new InvalidOperationException("task is already running in queue slot");
         }
     }
@@ -75,9 +78,9 @@ public sealed class QueueService : BackgroundService
 
         lock (_lock)
         {
-            if (_queueSlot is not null && _queueSlot.TaskId == taskId)
+            if (_queueSlots.TryGetValue(taskId, out var slot))
             {
-                _queueSlot.Cts.Cancel();
+                slot.Cts.Cancel();
                 return true;
             }
         }
@@ -100,28 +103,35 @@ public sealed class QueueService : BackgroundService
 
                 await Task.WhenAny(wakeTask, timerTask);
 
-                if (_queueSlot is not null) continue;
+                var maxParallel = await GetMaxParallelAsync(stoppingToken);
+
+                // Fill as many free slots as the limit allows.
+                while (!stoppingToken.IsCancellationRequested)
+                {
+                    lock (_lock)
+                    {
+                        if (_queueSlots.Count >= maxParallel) break;
+                    }
 
                     var task = await _picker.ClaimNextAsync(DateTime.UtcNow, stoppingToken);
-                if (task is null) continue;
+                    if (task is null) break;
 
                     lock (_lock)
                     {
-                    if (_queueSlot is not null) continue;
-
                         var cts = CancellationTokenSource.CreateLinkedTokenSource(stoppingToken);
-                    _queueSlot = new QueueSlotState { TaskId = task.Id, StartedAt = DateTime.UtcNow, Cts = cts };
+                        _queueSlots[task.Id] = new QueueSlotState { TaskId = task.Id, StartedAt = DateTime.UtcNow, Cts = cts };
 
                         _ = RunInSlotAsync(task.Id, cts.Token).ContinueWith(t =>
                         {
                             if (t.IsFaulted)
                                 _logger.LogError(t.Exception, "RunInSlotAsync failed for task {TaskId} in queue slot", task.Id);
-                        lock (_lock) { _queueSlot = null; }
+                            lock (_lock) { _queueSlots.Remove(task.Id); }
                             cts.Dispose();
                             _waker.Wake(); // Check for next task immediately.
                         }, TaskScheduler.Default);
                     }
                 }
+            }
             catch (OperationCanceledException) when (stoppingToken.IsCancellationRequested)
             {
                 break;
@@ -135,6 +145,21 @@ public sealed class QueueService : BackgroundService
         _logger.LogInformation("QueueService stopping");
     }
 
+    private async Task<int> GetMaxParallelAsync(CancellationToken ct)
+    {
+        try
+        {
+            using var context = _dbFactory.CreateDbContext();
+            var settings = await new AppSettingsRepository(context).GetAsync(ct);
+            return Math.Max(1, settings.MaxParallelExecutions);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "Failed to read max parallel executions; defaulting to 1");
+            return 1;
+        }
+    }
+
     private async Task RunInSlotAsync(string taskId, CancellationToken ct)
     {
         try