diff --git a/src/ClaudeDo.Data/ClaudeDo.Data.csproj b/src/ClaudeDo.Data/ClaudeDo.Data.csproj
index 624930a..6bb4de7 100644
--- a/src/ClaudeDo.Data/ClaudeDo.Data.csproj
+++ b/src/ClaudeDo.Data/ClaudeDo.Data.csproj
@@ -7,7 +7,11 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Data.Sqlite" Version="10.0.5" />
+    <PackageReference Include="Microsoft.Data.Sqlite" Version="8.0.11" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Include="..\..\schema\schema.sql" Link="schema.sql" LogicalName="ClaudeDo.Data.schema.sql" />
   </ItemGroup>
 
 </Project>
diff --git a/src/ClaudeDo.Data/Models/ListEntity.cs b/src/ClaudeDo.Data/Models/ListEntity.cs
new file mode 100644
index 0000000..5c5809e
--- /dev/null
+++ b/src/ClaudeDo.Data/Models/ListEntity.cs
@@ -0,0 +1,10 @@
+namespace ClaudeDo.Data.Models;
+
+public sealed class ListEntity
+{
+    public required string Id { get; init; }
+    public required string Name { get; set; }
+    public required DateTime CreatedAt { get; init; }
+    public string? WorkingDir { get; set; }
+    public string DefaultCommitType { get; set; } = "chore";
+}
diff --git a/src/ClaudeDo.Data/Models/TagEntity.cs b/src/ClaudeDo.Data/Models/TagEntity.cs
new file mode 100644
index 0000000..01c8684
--- /dev/null
+++ b/src/ClaudeDo.Data/Models/TagEntity.cs
@@ -0,0 +1,7 @@
+namespace ClaudeDo.Data.Models;
+
+public sealed class TagEntity
+{
+    public long Id { get; init; }
+    public required string Name { get; set; }
+}
diff --git a/src/ClaudeDo.Data/Models/TaskEntity.cs b/src/ClaudeDo.Data/Models/TaskEntity.cs
new file mode 100644
index 0000000..eef77b4
--- /dev/null
+++ b/src/ClaudeDo.Data/Models/TaskEntity.cs
@@ -0,0 +1,26 @@
+namespace ClaudeDo.Data.Models;
+
+public enum TaskStatus
+{
+    Manual,
+    Queued,
+    Running,
+    Done,
+    Failed,
+}
+
+public sealed class TaskEntity
+{
+    public required string Id { get; init; }
+    public required string ListId { get; init; }
+    public required string Title { get; set; }
+    public string? Description { get; set; }
+    public TaskStatus Status { get; set; } = TaskStatus.Manual;
+    public DateTime? ScheduledFor { get; set; }
+    public string? Result { get; set; }
+    public string? LogPath { get; set; }
+    public required DateTime CreatedAt { get; init; }
+    public DateTime? StartedAt { get; set; }
+    public DateTime? FinishedAt { get; set; }
+    public string CommitType { get; set; } = "chore";
+}
diff --git a/src/ClaudeDo.Data/Models/WorktreeEntity.cs b/src/ClaudeDo.Data/Models/WorktreeEntity.cs
new file mode 100644
index 0000000..6378b78
--- /dev/null
+++ b/src/ClaudeDo.Data/Models/WorktreeEntity.cs
@@ -0,0 +1,21 @@
+namespace ClaudeDo.Data.Models;
+
+public enum WorktreeState
+{
+    Active,
+    Merged,
+    Discarded,
+    Kept,
+}
+
+public sealed class WorktreeEntity
+{
+    public required string TaskId { get; init; }
+    public required string Path { get; set; }
+    public required string BranchName { get; set; }
+    public required string BaseCommit { get; set; }
+    public string? HeadCommit { get; set; }
+    public string? DiffStat { get; set; }
+    public WorktreeState State { get; set; } = WorktreeState.Active;
+    public required DateTime CreatedAt { get; init; }
+}
diff --git a/src/ClaudeDo.Data/Paths.cs b/src/ClaudeDo.Data/Paths.cs
new file mode 100644
index 0000000..c55037f
--- /dev/null
+++ b/src/ClaudeDo.Data/Paths.cs
@@ -0,0 +1,31 @@
+namespace ClaudeDo.Data;
+
+public static class Paths
+{
+    /// <summary>
+    /// Expands a leading "~" or "%USERPROFILE%" and returns an absolute path.
+    /// Relative paths are resolved against <paramref name="baseDir"/> (default: current directory).
+    /// </summary>
+    public static string Expand(string path, string? baseDir = null)
+    {
+        if (string.IsNullOrWhiteSpace(path))
+            throw new ArgumentException("Path must not be empty.", nameof(path));
+
+        var expanded = Environment.ExpandEnvironmentVariables(path);
+
+        if (expanded.StartsWith("~", StringComparison.Ordinal))
+        {
+            var home = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile);
+            expanded = home + expanded[1..];
+        }
+
+        if (!Path.IsPathRooted(expanded))
+            expanded = Path.GetFullPath(expanded, baseDir ?? Environment.CurrentDirectory);
+
+        return Path.GetFullPath(expanded);
+    }
+
+    /// <summary>~/.todo-app — parent directory for db, logs, config, sandbox, worktrees.</summary>
+    public static string AppDataRoot() =>
+        Expand("~/.todo-app");
+}
diff --git a/src/ClaudeDo.Data/SchemaInitializer.cs b/src/ClaudeDo.Data/SchemaInitializer.cs
new file mode 100644
index 0000000..17eff67
--- /dev/null
+++ b/src/ClaudeDo.Data/SchemaInitializer.cs
@@ -0,0 +1,41 @@
+using System.Reflection;
+using Microsoft.Data.Sqlite;
+
+namespace ClaudeDo.Data;
+
+/// <summary>
+/// Applies the embedded schema.sql script. Safe to call on every start — the script uses
+/// IF NOT EXISTS / INSERT OR IGNORE.
+/// </summary>
+public static class SchemaInitializer
+{
+    private const string ResourceName = "ClaudeDo.Data.schema.sql";
+
+    public static void Apply(SqliteConnectionFactory factory)
+    {
+        using var conn = factory.Open();
+        ApplyTo(conn);
+    }
+
+    public static void ApplyTo(SqliteConnection conn)
+    {
+        var sql = LoadScript();
+        using var tx = conn.BeginTransaction();
+        using var cmd = conn.CreateCommand();
+        cmd.Transaction = tx;
+        cmd.CommandText = sql;
+        cmd.ExecuteNonQuery();
+        tx.Commit();
+    }
+
+    private static string LoadScript()
+    {
+        var asm = typeof(SchemaInitializer).Assembly;
+        using var stream = asm.GetManifestResourceStream(ResourceName)
+            ?? throw new InvalidOperationException(
+                $"Embedded resource '{ResourceName}' not found in {asm.GetName().Name}. " +
+                $"Available: {string.Join(", ", asm.GetManifestResourceNames())}");
+        using var reader = new StreamReader(stream);
+        return reader.ReadToEnd();
+    }
+}
diff --git a/src/ClaudeDo.Data/SqliteConnectionFactory.cs b/src/ClaudeDo.Data/SqliteConnectionFactory.cs
new file mode 100644
index 0000000..43da6fa
--- /dev/null
+++ b/src/ClaudeDo.Data/SqliteConnectionFactory.cs
@@ -0,0 +1,48 @@
+using Microsoft.Data.Sqlite;
+
+namespace ClaudeDo.Data;
+
+/// <summary>
+/// Opens <see cref="SqliteConnection"/> instances pointed at <see cref="DbPath"/>.
+/// First call ensures the parent directory exists, enables WAL and foreign keys.
+/// </summary>
+public sealed class SqliteConnectionFactory
+{
+    public string DbPath { get; }
+    private readonly string _connectionString;
+    private int _walApplied;
+
+    public SqliteConnectionFactory(string dbPath)
+    {
+        DbPath = Paths.Expand(dbPath);
+        Directory.CreateDirectory(Path.GetDirectoryName(DbPath)!);
+
+        _connectionString = new SqliteConnectionStringBuilder
+        {
+            DataSource = DbPath,
+            Mode = SqliteOpenMode.ReadWriteCreate,
+            Cache = SqliteCacheMode.Shared,
+        }.ToString();
+    }
+
+    public SqliteConnection Open()
+    {
+        var conn = new SqliteConnection(_connectionString);
+        conn.Open();
+
+        // WAL is a persistent DB-level setting; applying it once per process is enough,
+        // but idempotent so we do it defensively on the first connection we hand out.
+        if (Interlocked.Exchange(ref _walApplied, 1) == 0)
+        {
+            using var pragma = conn.CreateCommand();
+            pragma.CommandText = "PRAGMA journal_mode=WAL;";
+            pragma.ExecuteNonQuery();
+        }
+
+        using var fk = conn.CreateCommand();
+        fk.CommandText = "PRAGMA foreign_keys=ON;";
+        fk.ExecuteNonQuery();
+
+        return conn;
+    }
+}
diff --git a/src/ClaudeDo.Worker/ClaudeDo.Worker.csproj b/src/ClaudeDo.Worker/ClaudeDo.Worker.csproj
index 4cf11ce..ad75153 100644
--- a/src/ClaudeDo.Worker/ClaudeDo.Worker.csproj
+++ b/src/ClaudeDo.Worker/ClaudeDo.Worker.csproj
@@ -5,7 +5,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.Extensions.Hosting" Version="10.0.5" />
+    <PackageReference Include="Microsoft.Extensions.Hosting" Version="8.0.1" />
   </ItemGroup>
 
   <PropertyGroup>
diff --git a/src/ClaudeDo.Worker/Config/WorkerConfig.cs b/src/ClaudeDo.Worker/Config/WorkerConfig.cs
new file mode 100644
index 0000000..6ef4b0d
--- /dev/null
+++ b/src/ClaudeDo.Worker/Config/WorkerConfig.cs
@@ -0,0 +1,70 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using ClaudeDo.Data;
+
+namespace ClaudeDo.Worker.Config;
+
+public sealed class WorkerConfig
+{
+    [JsonPropertyName("db_path")]
+    public string DbPath { get; set; } = "~/.todo-app/todo.db";
+
+    [JsonPropertyName("sandbox_root")]
+    public string SandboxRoot { get; set; } = "~/.todo-app/sandbox";
+
+    [JsonPropertyName("log_root")]
+    public string LogRoot { get; set; } = "~/.todo-app/logs";
+
+    /// <summary>"sibling" → place worktrees next to the target repo; "central" → under <see cref="CentralWorktreeRoot"/>.</summary>
+    [JsonPropertyName("worktree_root_strategy")]
+    public string WorktreeRootStrategy { get; set; } = "sibling";
+
+    [JsonPropertyName("central_worktree_root")]
+    public string CentralWorktreeRoot { get; set; } = "~/.todo-app/worktrees";
+
+    [JsonPropertyName("queue_backstop_interval_ms")]
+    public int QueueBackstopIntervalMs { get; set; } = 30_000;
+
+    [JsonPropertyName("signalr_port")]
+    public int SignalRPort { get; set; } = 47_821;
+
+    [JsonPropertyName("claude_bin")]
+    public string ClaudeBin { get; set; } = "claude";
+
+    public static string DefaultConfigPath =>
+        Path.Combine(Paths.AppDataRoot(), "worker.config.json");
+
+    /// <summary>
+    /// Loads the config from <paramref name="path"/> (defaults to <see cref="DefaultConfigPath"/>).
+    /// Missing file → returns defaults. Resolves all path-typed fields to absolute paths.
+    /// </summary>
+    public static WorkerConfig Load(string? path = null)
+    {
+        path ??= DefaultConfigPath;
+
+        WorkerConfig cfg;
+        if (File.Exists(path))
+        {
+            var json = File.ReadAllText(path);
+            cfg = JsonSerializer.Deserialize<WorkerConfig>(json, JsonOpts)
+                ?? throw new InvalidOperationException($"Failed to parse {path}");
+        }
+        else
+        {
+            cfg = new WorkerConfig();
+        }
+
+        cfg.DbPath = Paths.Expand(cfg.DbPath);
+        cfg.SandboxRoot = Paths.Expand(cfg.SandboxRoot);
+        cfg.LogRoot = Paths.Expand(cfg.LogRoot);
+        cfg.CentralWorktreeRoot = Paths.Expand(cfg.CentralWorktreeRoot);
+
+        return cfg;
+    }
+
+    private static readonly JsonSerializerOptions JsonOpts = new()
+    {
+        ReadCommentHandling = JsonCommentHandling.Skip,
+        AllowTrailingCommas = true,
+    };
+}
diff --git a/src/ClaudeDo.Worker/Hub/WorkerHub.cs b/src/ClaudeDo.Worker/Hub/WorkerHub.cs
new file mode 100644
index 0000000..24d32ab
--- /dev/null
+++ b/src/ClaudeDo.Worker/Hub/WorkerHub.cs
@@ -0,0 +1,16 @@
+using System.Reflection;
+using Microsoft.AspNetCore.SignalR;
+
+namespace ClaudeDo.Worker.Hub;
+
+/// <summary>
+/// SignalR hub the UI connects to. Only <see cref="Ping"/> is implemented at this stage;
+/// RunNow/CancelTask/WakeQueue/GetActive land here once QueueService exists.
+/// </summary>
+public sealed class WorkerHub : Microsoft.AspNetCore.SignalR.Hub
+{
+    private static readonly string Version =
+        Assembly.GetExecutingAssembly().GetName().Version?.ToString(3) ?? "0.0.0";
+
+    public string Ping() => $"pong v{Version}";
+}
diff --git a/src/ClaudeDo.Worker/Program.cs b/src/ClaudeDo.Worker/Program.cs
index 1760df1..55386fb 100644
--- a/src/ClaudeDo.Worker/Program.cs
+++ b/src/ClaudeDo.Worker/Program.cs
@@ -1,6 +1,27 @@
+using ClaudeDo.Data;
+using ClaudeDo.Worker.Config;
+using ClaudeDo.Worker.Hub;
+
+var cfg = WorkerConfig.Load();
+
 var builder = WebApplication.CreateBuilder(args);
+
+// Initialize DB schema before the host starts accepting connections.
+var dbFactory = new SqliteConnectionFactory(cfg.DbPath);
+SchemaInitializer.Apply(dbFactory);
+
+builder.Services.AddSingleton(cfg);
+builder.Services.AddSingleton(dbFactory);
+builder.Services.AddSignalR();
+
+// Loopback-only bind. Firewall is irrelevant for 127.0.0.1.
+builder.WebHost.UseUrls($"http://127.0.0.1:{cfg.SignalRPort}");
+
 var app = builder.Build();
 
-app.MapGet("/", () => "Hello World!");
+app.MapHub<WorkerHub>("/hub");
+
+app.Logger.LogInformation("ClaudeDo.Worker listening on http://127.0.0.1:{Port} (db: {Db})",
+    cfg.SignalRPort, cfg.DbPath);
 
 app.Run();