diff --git a/src/ClaudeDo.Data/ClaudeDoDbContext.cs b/src/ClaudeDo.Data/ClaudeDoDbContext.cs
index ba196da..1990afa 100644
--- a/src/ClaudeDo.Data/ClaudeDoDbContext.cs
+++ b/src/ClaudeDo.Data/ClaudeDoDbContext.cs
@@ -1,6 +1,8 @@
+using System.Data.Common;
 using ClaudeDo.Data.Models;
 using ClaudeDo.Data.Seeding;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Infrastructure;
 using Microsoft.EntityFrameworkCore.Storage;
 using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
@@ -9,8 +11,35 @@ namespace ClaudeDo.Data;
 
 public class ClaudeDoDbContext : DbContext
 {
+    // Runs PRAGMA foreign_keys=ON on every EF-managed connection open so FK
+    // enforcement is active for all IDbContextFactory-created contexts, not
+    // just the single context used in MigrateAndConfigure.
+    private sealed class SqliteForeignKeyInterceptor : DbConnectionInterceptor
+    {
+        internal static readonly SqliteForeignKeyInterceptor Instance = new();
+
+        public override void ConnectionOpened(DbConnection connection, ConnectionEndEventData eventData)
+            => Apply(connection);
+
+        public override Task ConnectionOpenedAsync(DbConnection connection, ConnectionEndEventData eventData, CancellationToken cancellationToken = default)
+        {
+            Apply(connection);
+            return Task.CompletedTask;
+        }
+
+        private static void Apply(DbConnection connection)
+        {
+            using var cmd = connection.CreateCommand();
+            cmd.CommandText = "PRAGMA foreign_keys=ON;";
+            cmd.ExecuteNonQuery();
+        }
+    }
+
     public ClaudeDoDbContext(DbContextOptions<ClaudeDoDbContext> options) : base(options) { }
 
+    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+        => optionsBuilder.AddInterceptors(SqliteForeignKeyInterceptor.Instance);
+
     public DbSet<TaskEntity> Tasks => Set<TaskEntity>();
     public DbSet<ListEntity> Lists => Set<ListEntity>();
     public DbSet<ListConfigEntity> ListConfigs => Set<ListConfigEntity>();
diff --git a/src/ClaudeDo.Data/Configuration/ListEntityConfiguration.cs b/src/ClaudeDo.Data/Configuration/ListEntityConfiguration.cs
index cd48beb..61e727b 100644
--- a/src/ClaudeDo.Data/Configuration/ListEntityConfiguration.cs
+++ b/src/ClaudeDo.Data/Configuration/ListEntityConfiguration.cs
@@ -19,6 +19,7 @@ public class ListEntityConfiguration : IEntityTypeConfiguration<ListEntity>
         builder.Property(l => l.SortOrder).HasColumnName("sort_order").IsRequired().HasDefaultValue(0);
 
         builder.HasIndex(l => l.SortOrder).HasDatabaseName("idx_lists_sort");
+        builder.HasIndex(l => l.Name).IsUnique().HasDatabaseName("idx_lists_name");
 
         builder.HasOne(l => l.Config)
             .WithOne(c => c.List)
diff --git a/src/ClaudeDo.Data/Migrations/20260609000000_UniqueListName.Designer.cs b/src/ClaudeDo.Data/Migrations/20260609000000_UniqueListName.Designer.cs
new file mode 100644
index 0000000..da3dd8c
--- /dev/null
+++ b/src/ClaudeDo.Data/Migrations/20260609000000_UniqueListName.Designer.cs
@@ -0,0 +1,700 @@
+// <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("20260609000000_UniqueListName")]
+    partial class UniqueListName
+    {
+        /// <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<int>("DailyPrepMaxTasks")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(5)
+                        .HasColumnName("daily_prep_max_tasks");
+
+                    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<string>("ReportExcludedPaths")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("report_excluded_paths");
+
+                    b.Property<int>("StandupWeekday")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(3)
+                        .HasColumnName("standup_weekday");
+
+                    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,
+                            DailyPrepMaxTasks = 5,
+                            DefaultClaudeInstructions = "",
+                            DefaultMaxTurns = 100,
+                            DefaultModel = "sonnet",
+                            DefaultPermissionMode = "auto",
+                            MaxParallelExecutions = 1,
+                            StandupWeekday = 3,
+                            WorktreeAutoCleanupDays = 7,
+                            WorktreeAutoCleanupEnabled = false,
+                            WorktreeStrategy = "sibling"
+                        });
+                });
+
+            modelBuilder.Entity("ClaudeDo.Data.Models.DailyNoteEntity", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("created_at");
+
+                    b.Property<DateOnly>("Date")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("note_date");
+
+                    b.Property<int>("SortOrder")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("sort_order");
+
+                    b.Property<string>("Text")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("text");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("Date");
+
+                    b.ToTable("daily_notes", (string)null);
+                });
+
+            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<int?>("MaxTurns")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("max_turns");
+
+                    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("Name")
+                        .IsUnique()
+                        .HasDatabaseName("idx_lists_name");
+
+                    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<int>("Days")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(31)
+                        .HasColumnName("days_of_week");
+
+                    b.Property<bool>("Enabled")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(true)
+                        .HasColumnName("enabled");
+
+                    b.Property<DateTimeOffset?>("LastRunAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("last_run_at");
+
+                    b.Property<string>("PromptOverride")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("prompt_override");
+
+                    b.Property<TimeSpan>("TimeOfDay")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("time_of_day");
+
+                    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<int?>("MaxTurns")
+                        .HasColumnType("INTEGER")
+                        .HasColumnName("max_turns");
+
+                    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<string>("ReviewFeedback")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("review_feedback");
+
+                    b.Property<int>("RoadblockCount")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("INTEGER")
+                        .HasDefaultValue(0)
+                        .HasColumnName("roadblock_count");
+
+                    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.WeekReportEntity", b =>
+                {
+                    b.Property<string>("Id")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("id");
+
+                    b.Property<DateOnly>("EndDate")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("end_date");
+
+                    b.Property<DateTime>("GeneratedAt")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("generated_at");
+
+                    b.Property<string>("Markdown")
+                        .IsRequired()
+                        .HasColumnType("TEXT")
+                        .HasColumnName("markdown");
+
+                    b.Property<DateOnly>("StartDate")
+                        .HasColumnType("TEXT")
+                        .HasColumnName("start_date");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("StartDate", "EndDate")
+                        .IsUnique();
+
+                    b.ToTable("week_reports", (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
+        }
+    }
+}
diff --git a/src/ClaudeDo.Data/Migrations/20260609000000_UniqueListName.cs b/src/ClaudeDo.Data/Migrations/20260609000000_UniqueListName.cs
new file mode 100644
index 0000000..4043129
--- /dev/null
+++ b/src/ClaudeDo.Data/Migrations/20260609000000_UniqueListName.cs
@@ -0,0 +1,39 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace ClaudeDo.Data.Migrations
+{
+    /// <inheritdoc />
+    public partial class UniqueListName : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            // Remove duplicate list rows that have no tasks — keep the oldest rowid.
+            // This handles the startup-race case where both App and Worker seeded
+            // the same default list names concurrently.
+            migrationBuilder.Sql("""
+                DELETE FROM lists
+                WHERE (SELECT COUNT(*) FROM tasks WHERE list_id = lists.id) = 0
+                  AND rowid NOT IN (
+                      SELECT MIN(l2.rowid) FROM lists l2 WHERE l2.name = lists.name
+                  )
+                """);
+
+            migrationBuilder.CreateIndex(
+                name: "idx_lists_name",
+                table: "lists",
+                column: "name",
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "idx_lists_name",
+                table: "lists");
+        }
+    }
+}
diff --git a/src/ClaudeDo.Data/Migrations/ClaudeDoDbContextModelSnapshot.cs b/src/ClaudeDo.Data/Migrations/ClaudeDoDbContextModelSnapshot.cs
index c0f5a11..c05211b 100644
--- a/src/ClaudeDo.Data/Migrations/ClaudeDoDbContextModelSnapshot.cs
+++ b/src/ClaudeDo.Data/Migrations/ClaudeDoDbContextModelSnapshot.cs
@@ -211,6 +211,10 @@ namespace ClaudeDo.Data.Migrations
 
                     b.HasKey("Id");
 
+                    b.HasIndex("Name")
+                        .IsUnique()
+                        .HasDatabaseName("idx_lists_name");
+
                     b.HasIndex("SortOrder")
                         .HasDatabaseName("idx_lists_sort");
 
diff --git a/src/ClaudeDo.Data/Repositories/AppSettingsRepository.cs b/src/ClaudeDo.Data/Repositories/AppSettingsRepository.cs
index 7e68210..0a4f9a6 100644
--- a/src/ClaudeDo.Data/Repositories/AppSettingsRepository.cs
+++ b/src/ClaudeDo.Data/Repositories/AppSettingsRepository.cs
@@ -18,8 +18,18 @@ public sealed class AppSettingsRepository
 
         row = new AppSettingsEntity { Id = AppSettingsEntity.SingletonId };
         _context.AppSettings.Add(row);
-        await _context.SaveChangesAsync(ct);
-        _context.Entry(row).State = EntityState.Detached;
+        try
+        {
+            await _context.SaveChangesAsync(ct);
+            _context.Entry(row).State = EntityState.Detached;
+        }
+        catch (DbUpdateException)
+        {
+            // Concurrent process already inserted the singleton — discard our attempt and re-read.
+            _context.Entry(row).State = EntityState.Detached;
+            row = await _context.AppSettings.AsNoTracking()
+                .FirstAsync(s => s.Id == AppSettingsEntity.SingletonId, ct);
+        }
         return row;
     }
 
diff --git a/src/ClaudeDo.Data/Seeding/DefaultListsSeeder.cs b/src/ClaudeDo.Data/Seeding/DefaultListsSeeder.cs
index ac579b6..a30c539 100644
--- a/src/ClaudeDo.Data/Seeding/DefaultListsSeeder.cs
+++ b/src/ClaudeDo.Data/Seeding/DefaultListsSeeder.cs
@@ -1,4 +1,3 @@
-using ClaudeDo.Data.Models;
 using Microsoft.EntityFrameworkCore;
 
 namespace ClaudeDo.Data.Seeding;
@@ -9,17 +8,18 @@ public static class DefaultListsSeeder
 
     public static async Task SeedAsync(ClaudeDoDbContext ctx, CancellationToken ct = default)
     {
-        var existing = await ctx.Lists.Select(l => l.Name).ToListAsync(ct);
         var now = DateTime.UtcNow;
-        foreach (var name in Defaults.Where(n => !existing.Contains(n)))
+        foreach (var name in Defaults)
         {
-            ctx.Lists.Add(new ListEntity
-            {
-                Id = Guid.NewGuid().ToString(),
-                Name = name,
-                CreatedAt = now,
-            });
+            var id = Guid.NewGuid().ToString();
+            // Atomic conditional insert: the SELECT ... WHERE NOT EXISTS is a single
+            // SQLite statement and cannot race — only one writer holds the lock.
+            await ctx.Database.ExecuteSqlAsync(
+                $"""
+                INSERT INTO lists (id, name, created_at, default_commit_type, sort_order)
+                SELECT {id}, {name}, {now}, 'chore', 0
+                WHERE NOT EXISTS (SELECT 1 FROM lists WHERE name = {name})
+                """, ct);
         }
-        await ctx.SaveChangesAsync(ct);
     }
 }
diff --git a/tests/ClaudeDo.Data.Tests/ForeignKeyTests.cs b/tests/ClaudeDo.Data.Tests/ForeignKeyTests.cs
new file mode 100644
index 0000000..0dd3eb7
--- /dev/null
+++ b/tests/ClaudeDo.Data.Tests/ForeignKeyTests.cs
@@ -0,0 +1,115 @@
+using ClaudeDo.Data;
+using ClaudeDo.Data.Models;
+using ClaudeDo.Data.Repositories;
+using Microsoft.EntityFrameworkCore;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+
+namespace ClaudeDo.Data.Tests;
+
+/// <summary>
+/// Proves that FK enforcement (PRAGMA foreign_keys=ON) is active on every
+/// IDbContextFactory-created context, not just the MigrateAndConfigure context.
+/// </summary>
+public sealed class ForeignKeyTests : IDisposable
+{
+    private readonly string _dbPath;
+    private readonly DbContextOptions<ClaudeDoDbContext> _options;
+
+    public ForeignKeyTests()
+    {
+        _dbPath = Path.Combine(Path.GetTempPath(), $"claudedo_fktest_{Guid.NewGuid():N}.db");
+        _options = new DbContextOptionsBuilder<ClaudeDoDbContext>()
+            .UseSqlite($"Data Source={_dbPath}")
+            .Options;
+
+        // EnsureCreated creates the schema including FK constraints in DDL.
+        using var ctx = new ClaudeDoDbContext(_options);
+        ctx.Database.EnsureCreated();
+    }
+
+    public void Dispose()
+    {
+        foreach (var suffix in new[] { "", "-wal", "-shm" })
+            try { File.Delete(_dbPath + suffix); } catch { }
+    }
+
+    private ClaudeDoDbContext Open() => new(_options);
+
+    // ---- FK interceptor: ON DELETE SET NULL ----
+
+    [Fact]
+    public async Task BlockedByTaskId_is_nulled_when_predecessor_deleted_on_fresh_context()
+    {
+        var listId = Guid.NewGuid().ToString();
+        var parentId = Guid.NewGuid().ToString();
+        var childId = Guid.NewGuid().ToString();
+
+        await using (var ctx = Open())
+        {
+            ctx.Lists.Add(new ListEntity { Id = listId, Name = "L", CreatedAt = DateTime.UtcNow });
+            ctx.Tasks.Add(new TaskEntity { Id = parentId, ListId = listId, Title = "Predecessor", Status = TaskStatus.Idle, CreatedAt = DateTime.UtcNow });
+            ctx.Tasks.Add(new TaskEntity { Id = childId, ListId = listId, Title = "Blocked", Status = TaskStatus.Idle, BlockedByTaskId = parentId, CreatedAt = DateTime.UtcNow });
+            await ctx.SaveChangesAsync();
+        }
+
+        // Delete predecessor in a brand-new context (simulates factory-created context).
+        // Without the FK interceptor, PRAGMA foreign_keys is OFF and SQLite silently
+        // leaves blocked_by_task_id pointing at the deleted row.
+        await using (var ctx = Open())
+        {
+            var predecessor = await ctx.Tasks.FindAsync(parentId);
+            ctx.Tasks.Remove(predecessor!);
+            await ctx.SaveChangesAsync();
+        }
+
+        await using (var ctx = Open())
+        {
+            var child = await ctx.Tasks.AsNoTracking().FirstAsync(t => t.Id == childId);
+            Assert.Null(child.BlockedByTaskId);
+        }
+    }
+
+    // ---- AppSettingsRepository: get-or-create resilience ----
+
+    [Fact]
+    public async Task GetAsync_returns_existing_row_when_present()
+    {
+        await using var ctx = Open();
+        var repo = new AppSettingsRepository(ctx);
+
+        var first = await repo.GetAsync();
+        var second = await repo.GetAsync();
+
+        Assert.Equal(AppSettingsEntity.SingletonId, first.Id);
+        Assert.Equal(AppSettingsEntity.SingletonId, second.Id);
+    }
+
+    [Fact]
+    public async Task GetAsync_creates_row_when_absent()
+    {
+        // Use a fresh DB with no HasData seed (EnsureCreated skips HasData seeding).
+        var path = Path.Combine(Path.GetTempPath(), $"claudedo_fktest_empty_{Guid.NewGuid():N}.db");
+        try
+        {
+            var opts = new DbContextOptionsBuilder<ClaudeDoDbContext>()
+                .UseSqlite($"Data Source={path}")
+                .Options;
+            await using var ctx = new ClaudeDoDbContext(opts);
+            ctx.Database.EnsureCreated();
+
+            var repo = new AppSettingsRepository(ctx);
+            var settings = await repo.GetAsync();
+
+            Assert.Equal(AppSettingsEntity.SingletonId, settings.Id);
+
+            // A second call should find the row and not re-insert.
+            var settings2 = await repo.GetAsync();
+            Assert.Equal(AppSettingsEntity.SingletonId, settings2.Id);
+        }
+        finally
+        {
+            foreach (var suffix in new[] { "", "-wal", "-shm" })
+                try { File.Delete(path + suffix); } catch { }
+        }
+    }
+}