feat(interactive): fresh-worktree-on-demand + ad-hoc launch specs

BuildForTaskAsync now creates a worktree on demand (via WorktreeManager.CreateAsync,
the same path TaskRunner uses) when a task has a configured working dir but no
Active/Kept worktree, returning a fresh-start spec -- so never-run tasks can be
opened interactively. Adds BuildForDirectoryAsync + GetAdHocLaunchSpec hub/client
for ad-hoc sessions in an arbitrary directory (no task, no worktree, no skill seeding).

tests/ClaudeDo.Worker.Tests/Runner/InteractiveLaunchSpecServiceTests.cs

@@ -1,9 +1,11 @@
+using ClaudeDo.Data.Git;
 using ClaudeDo.Data.Models;
 using ClaudeDo.Data.Repositories;
 using ClaudeDo.Worker.Config;
 using ClaudeDo.Worker.Runner;
 using ClaudeDo.Worker.Skills;
 using ClaudeDo.Worker.Tests.Infrastructure;
+using Microsoft.Extensions.Logging.Abstractions;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
 
 namespace ClaudeDo.Worker.Tests.Runner;
@@ -21,6 +23,9 @@ public sealed class InteractiveLaunchSpecServiceTests : IDisposable
     private readonly string _claudeStubPath;
     private readonly FakeSessionSkillSeeder _seeder = new();
     private readonly FakeSessionSkillRegistry _registry = new();
+    private readonly List<GitRepoFixture> _gitFixtures = new();
+
+    private static bool GitAvailable => GitRepoFixture.IsGitAvailable();
 
     public InteractiveLaunchSpecServiceTests()
     {
@@ -34,9 +39,17 @@ public sealed class InteractiveLaunchSpecServiceTests : IDisposable
         File.WriteAllText(_claudeStubPath, "stub");
     }
 
+    private GitRepoFixture CreateRepo()
+    {
+        var f = new GitRepoFixture();
+        _gitFixtures.Add(f);
+        return f;
+    }
+
     public void Dispose()
     {
         _db.Dispose();
+        foreach (var f in _gitFixtures) f.Dispose();
         try { Directory.Delete(_tempDir, true); } catch { /* best effort */ }
     }
 
@@ -52,15 +65,17 @@ public sealed class InteractiveLaunchSpecServiceTests : IDisposable
     }
 
     private InteractiveLaunchSpecService BuildService() =>
-        new(_db.CreateFactory(), _seeder, _registry, new WorkerConfig { ClaudeBin = _claudeStubPath });
+        new(_db.CreateFactory(), _seeder, _registry,
+            new WorktreeManager(new GitService(), _db.CreateFactory(), new WorkerConfig(), NullLogger<WorktreeManager>.Instance),
+            new WorkerConfig { ClaudeBin = _claudeStubPath });
 
-    private async Task<string> SeedListAsync()
+    private async Task<string> SeedListAsync(string? workingDir = null)
     {
         var listId = Guid.NewGuid().ToString();
         using var ctx = _db.CreateContext();
         await new ListRepository(ctx).AddAsync(new ListEntity
         {
-            Id = listId, Name = "L", WorkingDir = _tempDir, CreatedAt = DateTime.UtcNow,
+            Id = listId, Name = "L", WorkingDir = workingDir ?? _tempDir, CreatedAt = DateTime.UtcNow,
         });
         return listId;
     }
@@ -122,7 +137,7 @@ public sealed class InteractiveLaunchSpecServiceTests : IDisposable
     }
 
     [Fact]
-    public async Task BuildForTaskAsync_NoWorktreeRow_ThrowsInvalidOperation()
+    public async Task BuildForTaskAsync_NoWorktreeRow_NotAGitRepo_ThrowsInvalidOperation()
     {
         var listId = await SeedListAsync();
         var taskId = Guid.NewGuid().ToString();
@@ -133,6 +148,43 @@ public sealed class InteractiveLaunchSpecServiceTests : IDisposable
             () => svc.BuildForTaskAsync(taskId, CancellationToken.None));
     }
 
+    [Fact]
+    public async Task BuildForTaskAsync_NoWorktreeRow_NoWorkingDirConfigured_ThrowsInvalidOperation()
+    {
+        var listId = await SeedListAsync(workingDir: null);
+        var taskId = Guid.NewGuid().ToString();
+        await SeedTaskAsync(taskId, listId, TaskStatus.Idle);
+
+        var svc = BuildService();
+        await Assert.ThrowsAsync<InvalidOperationException>(
+            () => svc.BuildForTaskAsync(taskId, CancellationToken.None));
+    }
+
+    [Fact]
+    public async Task BuildForTaskAsync_FreshTask_NoWorktreeButGitRepoConfigured_CreatesWorktreeOnDemand()
+    {
+        if (!GitAvailable) { Assert.True(true, "git not available -- skipping"); return; }
+
+        var repo = CreateRepo();
+        var listId = await SeedListAsync(workingDir: repo.RepoDir);
+        var taskId = Guid.NewGuid().ToString();
+        await SeedTaskAsync(taskId, listId, TaskStatus.Idle);
+        // No worktree row seeded -- task has never run.
+
+        var svc = BuildService();
+        var spec = await svc.BuildForTaskAsync(taskId, CancellationToken.None);
+
+        using var readCtx = _db.CreateContext();
+        var wtRow = await new WorktreeRepository(readCtx).GetByTaskIdAsync(taskId);
+        Assert.NotNull(wtRow);
+        Assert.Equal(WorktreeState.Active, wtRow!.State);
+        Assert.True(Directory.Exists(wtRow.Path));
+
+        Assert.Equal(wtRow.Path, spec.Cwd);
+        Assert.Empty(spec.Args);
+        Assert.Equal(_claudeStubPath, spec.Exe);
+    }
+
     [Theory]
     [InlineData(WorktreeState.Merged)]
     [InlineData(WorktreeState.Discarded)]
@@ -249,4 +301,25 @@ public sealed class InteractiveLaunchSpecServiceTests : IDisposable
         Assert.True(call.IsWorktree);
         Assert.Equal(new[] { "installed-skill" }, call.SkillNames);
     }
+
+    [Fact]
+    public async Task BuildForDirectoryAsync_ExistingDirectory_ReturnsFreshStartSpec()
+    {
+        var svc = BuildService();
+        var spec = await svc.BuildForDirectoryAsync(_tempDir, CancellationToken.None);
+
+        Assert.Equal(_tempDir, spec.Cwd);
+        Assert.Equal(_claudeStubPath, spec.Exe);
+        Assert.Empty(spec.Args);
+        Assert.Equal("200000", spec.Env["MCP_TOOL_TIMEOUT"]);
+        Assert.Empty(_seeder.Calls);
+    }
+
+    [Fact]
+    public async Task BuildForDirectoryAsync_NonExistentDirectory_ThrowsInvalidOperation()
+    {
+        var svc = BuildService();
+        await Assert.ThrowsAsync<InvalidOperationException>(
+            () => svc.BuildForDirectoryAsync(Path.Combine(_tempDir, "does-not-exist"), CancellationToken.None));
+    }
 }