feat(worker): resolve and seed session skills before each run

src/ClaudeDo.Worker/Program.cs

@@ -18,6 +18,7 @@ using ClaudeDo.Worker.Prime;
 using ClaudeDo.Worker.Refine;
 using ClaudeDo.Worker.Report;
 using ClaudeDo.Worker.Report.Interfaces;
+using ClaudeDo.Worker.Skills;
 using ClaudeDo.Worker.Worktrees;
 using Microsoft.EntityFrameworkCore;
 using Serilog;
@@ -73,6 +74,9 @@ builder.Services.AddSingleton<WorktreeManager>();
 builder.Services.AddSingleton<ClaudeArgsBuilder>();
 builder.Services.AddSingleton<TaskRunTokenRegistry>();
 builder.Services.AddSingleton<PendingQuestionRegistry>();
+builder.Services.AddSingleton<IRepoCloner, GitRepoCloner>();
+builder.Services.AddSingleton<ISessionSkillRegistry, SessionSkillRegistry>();
+builder.Services.AddSingleton<ISessionSkillSeeder, SessionSkillSeeder>();
 builder.Services.AddSingleton<TaskRunner>();
 builder.Services.AddSingleton<WorktreeMaintenanceService>();
 builder.Services.AddSingleton<TaskResetService>();

src/ClaudeDo.Worker/Runner/ClaudeArgsBuilder.cs

@@ -10,8 +10,12 @@ public sealed record ClaudeRunConfig(
     int? MaxTurns = null,
     string? PermissionMode = null,
     string? McpConfigPath = null,
-    string? AllowedTools = null
+    string? AllowedTools = null,
-);
+    IReadOnlyList<string>? SkillNames = null
+)
+{
+    public IReadOnlyList<string> SkillNames { get; init; } = SkillNames ?? Array.Empty<string>();
+}
 
 public sealed class ClaudeArgsBuilder
 {

src/ClaudeDo.Worker/Runner/TaskRunner.cs

@@ -4,6 +4,7 @@ using ClaudeDo.Data.Models;
 using ClaudeDo.Data.Repositories;
 using ClaudeDo.Worker.Config;
 using ClaudeDo.Worker.Hub;
+using ClaudeDo.Worker.Skills;
 using ClaudeDo.Worker.State;
 using Microsoft.EntityFrameworkCore;
 using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
@@ -22,6 +23,7 @@ public sealed class TaskRunner
     private readonly ITaskStateService _state;
     private readonly TaskRunTokenRegistry _tokens;
     private readonly AttachmentStore _attachments;
+    private readonly ISessionSkillSeeder _skillSeeder;
 
     public TaskRunner(
         IClaudeProcess claude,
@@ -33,7 +35,8 @@ public sealed class TaskRunner
         ILogger<TaskRunner> logger,
         ITaskStateService state,
         TaskRunTokenRegistry tokens,
-        AttachmentStore attachments)
+        AttachmentStore attachments,
+        ISessionSkillSeeder skillSeeder)
     {
         _claude = claude;
         _dbFactory = dbFactory;
@@ -45,6 +48,7 @@ public sealed class TaskRunner
         _state = state;
         _tokens = tokens;
         _attachments = attachments;
+        _skillSeeder = skillSeeder;
     }
 
     public async Task RunAsync(TaskEntity task, string slot, CancellationToken ct, bool alreadyClaimed = false)
@@ -122,6 +126,8 @@ public sealed class TaskRunner
             }
             await _broadcaster.TaskStarted(slot, task.Id, now);
 
+            await _skillSeeder.SeedAsync(runDir, resolvedConfig.SkillNames, wtCtx is not null, ct);
+
             // Build prompt: title + description + only the OPEN sub-tasks (resolved ones are dropped).
             var prompt = TaskPromptComposer.Compose(
                 task.Title, task.Description,
@@ -242,6 +248,8 @@ public sealed class TaskRunner
         }
         await _broadcaster.TaskStarted(slot, taskId, now);
 
+        await _skillSeeder.SeedAsync(runDir, resolvedConfig.SkillNames, wtCtx is not null, ct);
+
         try
         {
             var nextRunNumber = lastRun.RunNumber + 1;
@@ -505,13 +513,70 @@ public sealed class TaskRunner
         var instructions = MergeInstructions(
             systemFile, improvementPrompt, global.DefaultClaudeInstructions, listConfig?.SystemPrompt, task.SystemPrompt);
 
+        var requestedSkills = UnionSkillNames(task.SessionSkills, listConfig?.SessionSkills, global.SessionSkills);
+        var skillNames = await FilterToInstalledSkillsAsync(task.Id, requestedSkills, ct);
+
         return new ClaudeRunConfig(
             Model: task.Model ?? listConfig?.Model ?? global.DefaultModel,
             SystemPrompt: string.IsNullOrWhiteSpace(instructions) ? null : instructions,
             AgentPath: task.AgentPath ?? listConfig?.AgentPath,
             ResumeSessionId: resumeSessionId,
             MaxTurns: ResolveMaxTurns(task.MaxTurns, listConfig?.MaxTurns, global.DefaultMaxTurns),
-            PermissionMode: global.DefaultPermissionMode);
+            PermissionMode: global.DefaultPermissionMode,
+            SkillNames: skillNames);
+    }
+
+    private async Task<IReadOnlyList<string>> FilterToInstalledSkillsAsync(
+        string taskId, IReadOnlyList<string> requestedSkills, CancellationToken ct)
+    {
+        if (requestedSkills.Count == 0) return requestedSkills;
+
+        List<SessionSkillEntity> installed;
+        using (var ctx = _dbFactory.CreateDbContext())
+        {
+            var skillRepo = new SessionSkillRepository(ctx);
+            installed = (await skillRepo.ListAsync(ct)).ToList();
+        }
+
+        var installedNames = installed.Select(s => s.Name).ToHashSet(StringComparer.Ordinal);
+        var resolved = requestedSkills.Where(installedNames.Contains).ToList();
+        var dropped = requestedSkills.Where(n => !installedNames.Contains(n)).ToList();
+        if (dropped.Count > 0)
+        {
+            _logger.LogWarning(
+                "Task {TaskId}: dropped unknown session skill(s) not found in registry: {SkillNames}",
+                taskId, string.Join(", ", dropped));
+        }
+
+        return resolved;
+    }
+
+    internal static IReadOnlyList<string> UnionSkillNames(params string?[] jsonArrays)
+    {
+        var names = new List<string>();
+        var seen = new HashSet<string>(StringComparer.Ordinal);
+        foreach (var json in jsonArrays)
+        {
+            if (string.IsNullOrWhiteSpace(json)) continue;
+
+            string[]? parsed;
+            try
+            {
+                parsed = JsonSerializer.Deserialize<string[]>(json);
+            }
+            catch (JsonException)
+            {
+                continue;
+            }
+            if (parsed is null) continue;
+
+            foreach (var name in parsed)
+            {
+                if (!string.IsNullOrWhiteSpace(name) && seen.Add(name))
+                    names.Add(name);
+            }
+        }
+        return names;
     }
 
     internal static int? ResolveMaxTurns(int? taskTurns, int? listTurns, int globalDefault)

src/ClaudeDo.Worker/Skills/Interfaces/ISessionSkillSeeder.cs

@@ -0,0 +1,6 @@
+namespace ClaudeDo.Worker.Skills;
+
+public interface ISessionSkillSeeder
+{
+    Task SeedAsync(string workingDir, IReadOnlyList<string> skillNames, bool isWorktree, CancellationToken ct);
+}

src/ClaudeDo.Worker/Skills/SessionSkillSeeder.cs

@@ -0,0 +1,116 @@
+using System.Diagnostics;
+using System.Text;
+using ClaudeDo.Data;
+using Microsoft.Extensions.Logging;
+
+namespace ClaudeDo.Worker.Skills;
+
+public sealed class SessionSkillSeeder : ISessionSkillSeeder
+{
+    private readonly string _skillsRoot;
+    private readonly ILogger<SessionSkillSeeder> _logger;
+
+    public SessionSkillSeeder(ILogger<SessionSkillSeeder> logger, string? skillsRoot = null)
+    {
+        _logger = logger;
+        _skillsRoot = skillsRoot ?? Path.Combine(Paths.AppDataRoot(), "session-skills");
+    }
+
+    public async Task SeedAsync(string workingDir, IReadOnlyList<string> skillNames, bool isWorktree, CancellationToken ct)
+    {
+        if (skillNames.Count == 0) return;
+
+        var skillsDestRoot = Path.Combine(workingDir, ".claude", "skills");
+
+        foreach (var name in skillNames)
+        {
+            var sourceDir = Path.Combine(_skillsRoot, name);
+            if (!Directory.Exists(sourceDir))
+            {
+                _logger.LogWarning("Session skill '{SkillName}' not found on disk at {SourceDir}; skipping", name, sourceDir);
+                continue;
+            }
+
+            var destDir = Path.Combine(skillsDestRoot, name);
+            CopyDirectory(sourceDir, destDir);
+
+            if (isWorktree)
+                await AppendExcludeLineAsync(workingDir, $"/.claude/skills/{name}/", ct);
+        }
+    }
+
+    private static void CopyDirectory(string sourceDir, string destDir)
+    {
+        Directory.CreateDirectory(destDir);
+        foreach (var file in Directory.EnumerateFiles(sourceDir, "*", SearchOption.AllDirectories))
+        {
+            var relative = Path.GetRelativePath(sourceDir, file);
+            var destPath = Path.Combine(destDir, relative);
+            var destParent = Path.GetDirectoryName(destPath);
+            if (!string.IsNullOrEmpty(destParent))
+                Directory.CreateDirectory(destParent);
+            File.Copy(file, destPath, overwrite: true);
+        }
+    }
+
+    private static async Task AppendExcludeLineAsync(string workingDir, string excludeLine, CancellationToken ct)
+    {
+        var relativeExcludePath = await RunGitCaptureAsync(workingDir, ["rev-parse", "--git-path", "info/exclude"], ct);
+        var excludeFile = Path.IsPathRooted(relativeExcludePath)
+            ? relativeExcludePath
+            : Path.GetFullPath(Path.Combine(workingDir, relativeExcludePath));
+
+        var excludeDir = Path.GetDirectoryName(excludeFile);
+        if (!string.IsNullOrEmpty(excludeDir))
+            Directory.CreateDirectory(excludeDir);
+
+        if (File.Exists(excludeFile))
+        {
+            var existingLines = await File.ReadAllLinesAsync(excludeFile, ct);
+            if (existingLines.Any(l => l.Trim() == excludeLine))
+                return;
+        }
+
+        await File.AppendAllTextAsync(excludeFile, excludeLine + Environment.NewLine, ct);
+    }
+
+    private static async Task<string> RunGitCaptureAsync(string workingDir, IEnumerable<string> args, CancellationToken ct)
+    {
+        var psi = new ProcessStartInfo
+        {
+            FileName = "git",
+            RedirectStandardOutput = true,
+            RedirectStandardError = true,
+            UseShellExecute = false,
+            CreateNoWindow = true,
+            StandardOutputEncoding = Encoding.UTF8,
+            StandardErrorEncoding = Encoding.UTF8,
+        };
+        psi.ArgumentList.Add("-C");
+        psi.ArgumentList.Add(workingDir);
+        foreach (var a in args) psi.ArgumentList.Add(a);
+
+        using var proc = new Process { StartInfo = psi };
+        proc.Start();
+
+        await using var ctr = ct.Register(() =>
+        {
+            try { proc.Kill(entireProcessTree: true); }
+            catch { /* already exited */ }
+        });
+
+        var stdoutTask = proc.StandardOutput.ReadToEndAsync();
+        var stderrTask = proc.StandardError.ReadToEndAsync();
+
+        await proc.WaitForExitAsync(CancellationToken.None);
+        var stdout = await stdoutTask;
+        var stderr = await stderrTask;
+
+        ct.ThrowIfCancellationRequested();
+
+        if (proc.ExitCode != 0)
+            throw new InvalidOperationException($"git rev-parse --git-path failed (exit {proc.ExitCode}): {stderr.TrimEnd()}");
+
+        return stdout.TrimEnd('\r', '\n');
+    }
+}

tests/ClaudeDo.Worker.Tests/External/AddSubtaskToolTests.cs

@@ -69,7 +69,7 @@ public sealed class AddSubtaskToolTests : IDisposable
         var argsBuilder = new ClaudeArgsBuilder();
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var runner = new TaskRunner(fake, dbFactory, broadcaster, wtManager, argsBuilder, cfg,
-            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
         var waker = new ClaudeDo.Worker.Queue.QueueWaker();
         var picker = new ClaudeDo.Worker.Queue.QueuePicker(dbFactory);
         var overrideSlot = new OverrideSlotService(dbFactory, runner, NullLogger<OverrideSlotService>.Instance);

tests/ClaudeDo.Worker.Tests/External/BatchMcpToolsTests.cs

@@ -87,7 +87,7 @@ public sealed class BatchMcpToolsTests : IDisposable
         var wtManager = new WorktreeManager(new GitService(), dbFactory, cfg, NullLogger<WorktreeManager>.Instance);
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var runner = new TaskRunner(new FakeClaudeProcess(), dbFactory, broadcaster, wtManager, new ClaudeArgsBuilder(), cfg,
-            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
         var overrideSlot = new OverrideSlotService(dbFactory, runner, NullLogger<OverrideSlotService>.Instance);
         return new QueueService(dbFactory, runner, cfg, NullLogger<QueueService>.Instance,
             new QueueWaker(), new QueuePicker(dbFactory), overrideSlot, state);

tests/ClaudeDo.Worker.Tests/External/ExternalMcpServiceTests.cs

@@ -149,7 +149,7 @@ public sealed class ExternalMcpServiceTests : IDisposable
         var argsBuilder = new ClaudeArgsBuilder();
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var runner = new TaskRunner(fake, dbFactory, broadcaster, wtManager, argsBuilder, cfg,
-            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
         var waker = new ClaudeDo.Worker.Queue.QueueWaker();
         var picker = new ClaudeDo.Worker.Queue.QueuePicker(dbFactory);
         var overrideSlot = new OverrideSlotService(dbFactory, runner, NullLogger<OverrideSlotService>.Instance);

tests/ClaudeDo.Worker.Tests/Infrastructure/FakeSessionSkillSeeder.cs

@@ -0,0 +1,18 @@
+using System.Collections.Concurrent;
+using ClaudeDo.Worker.Skills;
+
+namespace ClaudeDo.Worker.Tests.Infrastructure;
+
+public sealed class FakeSessionSkillSeeder : ISessionSkillSeeder
+{
+    public int CallCount;
+    public readonly record struct Call(string WorkingDir, IReadOnlyList<string> SkillNames, bool IsWorktree);
+    public readonly ConcurrentQueue<Call> Calls = new();
+
+    public Task SeedAsync(string workingDir, IReadOnlyList<string> skillNames, bool isWorktree, CancellationToken ct)
+    {
+        Interlocked.Increment(ref CallCount);
+        Calls.Enqueue(new Call(workingDir, skillNames, isWorktree));
+        return Task.CompletedTask;
+    }
+}

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

@@ -36,7 +36,7 @@ public sealed class ContinueAsyncExceptionTests : IDisposable
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var wt = new WorktreeManager(new ClaudeDo.Data.Git.GitService(), dbFactory, _cfg, NullLogger<WorktreeManager>.Instance);
         return new TaskRunner(claude, dbFactory, broadcaster, wt, new ClaudeArgsBuilder(), _cfg,
-            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
     }
 
     [Fact]

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

@@ -0,0 +1,44 @@
+using ClaudeDo.Worker.Runner;
+using Xunit;
+
+namespace ClaudeDo.Worker.Tests.Runner;
+
+public class SkillResolutionTests
+{
+    [Fact]
+    public void Null_and_empty_sources_contribute_nothing()
+        => Assert.Empty(TaskRunner.UnionSkillNames(null, "", "   ", "[]"));
+
+    [Fact]
+    public void Single_source_is_returned_in_order()
+        => Assert.Equal(["a", "b"], TaskRunner.UnionSkillNames("""["a","b"]"""));
+
+    [Fact]
+    public void Unions_across_task_list_global_levels()
+    {
+        var result = TaskRunner.UnionSkillNames("""["a"]""", """["b"]""", """["c"]""");
+        Assert.Equal(["a", "b", "c"], result);
+    }
+
+    [Fact]
+    public void Dedups_ordinal_preserving_first_occurrence_order()
+    {
+        var result = TaskRunner.UnionSkillNames("""["a","b"]""", """["b","c"]""", """["a","d"]""");
+        Assert.Equal(["a", "b", "c", "d"], result);
+    }
+
+    [Fact]
+    public void Dedup_is_case_sensitive_ordinal()
+    {
+        var result = TaskRunner.UnionSkillNames("""["Foo"]""", """["foo"]""");
+        Assert.Equal(["Foo", "foo"], result);
+    }
+
+    [Fact]
+    public void Malformed_json_is_ignored_not_thrown()
+        => Assert.Equal(["a"], TaskRunner.UnionSkillNames("not json", """["a"]"""));
+
+    [Fact]
+    public void Blank_entries_within_array_are_skipped()
+        => Assert.Equal(["a"], TaskRunner.UnionSkillNames("""["a", "", "   ", null]"""));
+}

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

@@ -0,0 +1,141 @@
+using ClaudeDo.Data;
+using ClaudeDo.Data.Git;
+using ClaudeDo.Data.Models;
+using ClaudeDo.Data.Repositories;
+using ClaudeDo.Worker.Config;
+using ClaudeDo.Worker.Hub;
+using ClaudeDo.Worker.Runner;
+using ClaudeDo.Worker.Tests.Infrastructure;
+using Microsoft.Extensions.Logging.Abstractions;
+using TaskStatus = ClaudeDo.Data.Models.TaskStatus;
+using Xunit;
+
+namespace ClaudeDo.Worker.Tests.Runner;
+
+/// Verifies that ResolveConfigAsync's skill resolution (union of task/list/global,
+/// filtered to what's actually installed in the registry) reaches the seeder call
+/// before Claude is invoked.
+public sealed class SkillSeedingWireTests : IDisposable
+{
+    private readonly DbFixture _db = new();
+    private readonly string _tempDir;
+    private readonly WorkerConfig _cfg;
+
+    public SkillSeedingWireTests()
+    {
+        _tempDir = Path.Combine(Path.GetTempPath(), $"cd_skillwire_{Guid.NewGuid():N}");
+        Directory.CreateDirectory(_tempDir);
+        _cfg = new WorkerConfig { SandboxRoot = _tempDir, LogRoot = _tempDir };
+    }
+
+    public void Dispose() { _db.Dispose(); try { Directory.Delete(_tempDir, true); } catch { } }
+
+    private (TaskRunner Runner, FakeSessionSkillSeeder Seeder) BuildRunner()
+    {
+        var dbFactory = _db.CreateFactory();
+        var state = TaskStateServiceBuilder.Build(dbFactory).State;
+        var wt = new WorktreeManager(new GitService(), dbFactory, _cfg, NullLogger<WorktreeManager>.Instance);
+        var fake = new FakeClaudeProcess((_, _, _, _, _) =>
+            Task.FromResult(new RunResult { ExitCode = 0, ResultMarkdown = "ok" }));
+        var seeder = new FakeSessionSkillSeeder();
+        var runner = new TaskRunner(fake, dbFactory, new HubBroadcaster(new CapturingHubContext()), wt,
+            new ClaudeArgsBuilder(), _cfg, NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(),
+            new AttachmentStore(), seeder);
+        return (runner, seeder);
+    }
+
+    private async Task SeedInstalledSkillAsync(string name)
+    {
+        using var ctx = _db.CreateContext();
+        await new SessionSkillRepository(ctx).UpsertAsync(new SessionSkillEntity
+        {
+            Name = name,
+            SourceUrl = "https://example.test/repo.git",
+            PinnedRef = "deadbeef",
+            Subpath = $"skills/{name}",
+            Description = "test skill",
+            AddedAt = DateTimeOffset.UtcNow,
+        });
+    }
+
+    [Fact]
+    public async Task Union_of_task_list_global_skills_reaches_seeder_when_all_installed()
+    {
+        await SeedInstalledSkillAsync("alpha");
+        await SeedInstalledSkillAsync("beta");
+        await SeedInstalledSkillAsync("gamma");
+
+        var dbFactory = _db.CreateFactory();
+        using (var ctx = _db.CreateContext())
+        {
+            ctx.Lists.Add(new ListEntity { Id = "l1", Name = "L", WorkingDir = null, CreatedAt = DateTime.UtcNow });
+            ctx.ListConfigs.Add(new ListConfigEntity { ListId = "l1", SessionSkills = """["beta"]""" });
+            ctx.Tasks.Add(new TaskEntity
+            {
+                Id = "t1", ListId = "l1", Title = "Task", Status = TaskStatus.Idle,
+                CreatedAt = DateTime.UtcNow, SessionSkills = """["alpha"]""",
+            });
+            // AppSettingsRepository.UpdateAsync doesn't round-trip SessionSkills yet (out of
+            // scope here), so seed the singleton row directly.
+            await new AppSettingsRepository(ctx).GetAsync();
+            ctx.AppSettings.First(s => s.Id == AppSettingsEntity.SingletonId).SessionSkills = """["gamma"]""";
+            await ctx.SaveChangesAsync();
+        }
+
+        var (runner, seeder) = BuildRunner();
+        using (var ctx = _db.CreateContext())
+            await runner.RunAsync((await new TaskRepository(ctx).GetByIdAsync("t1"))!, "slot-1", CancellationToken.None);
+
+        Assert.Single(seeder.Calls);
+        var call = seeder.Calls.Single();
+        Assert.Equal(["alpha", "beta", "gamma"], call.SkillNames);
+        Assert.False(call.IsWorktree);
+    }
+
+    [Fact]
+    public async Task Unknown_skill_names_are_dropped_before_seeding()
+    {
+        await SeedInstalledSkillAsync("known");
+
+        var dbFactory = _db.CreateFactory();
+        using (var ctx = _db.CreateContext())
+        {
+            ctx.Lists.Add(new ListEntity { Id = "l1", Name = "L", WorkingDir = null, CreatedAt = DateTime.UtcNow });
+            ctx.Tasks.Add(new TaskEntity
+            {
+                Id = "t1", ListId = "l1", Title = "Task", Status = TaskStatus.Idle,
+                CreatedAt = DateTime.UtcNow, SessionSkills = """["known","not-installed"]""",
+            });
+            await ctx.SaveChangesAsync();
+        }
+
+        var (runner, seeder) = BuildRunner();
+        using (var ctx = _db.CreateContext())
+            await runner.RunAsync((await new TaskRepository(ctx).GetByIdAsync("t1"))!, "slot-1", CancellationToken.None);
+
+        Assert.Single(seeder.Calls);
+        Assert.Equal(["known"], seeder.Calls.Single().SkillNames);
+    }
+
+    [Fact]
+    public async Task No_skills_configured_seeds_empty_list()
+    {
+        var dbFactory = _db.CreateFactory();
+        using (var ctx = _db.CreateContext())
+        {
+            ctx.Lists.Add(new ListEntity { Id = "l1", Name = "L", WorkingDir = null, CreatedAt = DateTime.UtcNow });
+            ctx.Tasks.Add(new TaskEntity
+            {
+                Id = "t1", ListId = "l1", Title = "Task", Status = TaskStatus.Idle, CreatedAt = DateTime.UtcNow,
+            });
+            await ctx.SaveChangesAsync();
+        }
+
+        var (runner, seeder) = BuildRunner();
+        using (var ctx = _db.CreateContext())
+            await runner.RunAsync((await new TaskRepository(ctx).GetByIdAsync("t1"))!, "slot-1", CancellationToken.None);
+
+        Assert.Single(seeder.Calls);
+        Assert.Empty(seeder.Calls.Single().SkillNames);
+    }
+}

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

@@ -45,7 +45,7 @@ public sealed class StandaloneChildrenRoutingTests : IDisposable
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var wt = new WorktreeManager(new GitService(), dbFactory, _cfg, NullLogger<WorktreeManager>.Instance);
         var runner = new TaskRunner(fake, dbFactory, broadcaster, wt, new ClaudeArgsBuilder(), _cfg,
-            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
 
         using (var ctx = _db.CreateContext())
             await runner.RunAsync((await new TaskRepository(ctx).GetByIdAsync("p1"))!, "slot-1", default, alreadyClaimed: true);
@@ -72,7 +72,7 @@ public sealed class StandaloneChildrenRoutingTests : IDisposable
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var wt = new WorktreeManager(new GitService(), dbFactory, _cfg, NullLogger<WorktreeManager>.Instance);
         var runner = new TaskRunner(fake, dbFactory, new HubBroadcaster(new CapturingHubContext()), wt,
-            new ClaudeArgsBuilder(), _cfg, NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            new ClaudeArgsBuilder(), _cfg, NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
 
         using (var ctx = _db.CreateContext())
             await runner.RunAsync((await new TaskRepository(ctx).GetByIdAsync("solo"))!, "slot-1", default, alreadyClaimed: true);

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

@@ -33,7 +33,7 @@ public sealed class StartRunningGuardTests : IDisposable
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var wt = new WorktreeManager(new ClaudeDo.Data.Git.GitService(), dbFactory, _cfg, NullLogger<WorktreeManager>.Instance);
         return new TaskRunner(claude, dbFactory, new HubBroadcaster(new CapturingHubContext()), wt,
-            new ClaudeArgsBuilder(), _cfg, NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            new ClaudeArgsBuilder(), _cfg, NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
     }
 
     [Fact]

tests/ClaudeDo.Worker.Tests/Services/QueueServiceSlotGuardTests.cs

@@ -54,7 +54,7 @@ public sealed class QueueServiceSlotGuardTests : IDisposable
         var argsBuilder = new ClaudeArgsBuilder();
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var runner = new TaskRunner(fake, dbFactory, broadcaster, wtManager, argsBuilder, _cfg,
-            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
         _waker = new QueueWaker();
         var picker = new QueuePicker(dbFactory);
         var overrideSlot = new OverrideSlotService(dbFactory, runner, NullLogger<OverrideSlotService>.Instance);

tests/ClaudeDo.Worker.Tests/Services/QueueServiceTests.cs

@@ -55,7 +55,7 @@ public sealed class QueueServiceTests : IDisposable
         var argsBuilder = new ClaudeArgsBuilder();
         var state = TaskStateServiceBuilder.Build(dbFactory).State;
         var runner = new TaskRunner(fake, dbFactory, broadcaster, wtManager, argsBuilder, _cfg,
-            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore());
+            NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(), new AttachmentStore(), new FakeSessionSkillSeeder());
         _waker = new QueueWaker();
         var picker = new QueuePicker(dbFactory);
         var overrideSlot = new OverrideSlotService(dbFactory, runner, NullLogger<OverrideSlotService>.Instance);

tests/ClaudeDo.Worker.Tests/Skills/SessionSkillSeederTests.cs

@@ -0,0 +1,135 @@
+using ClaudeDo.Worker.Skills;
+using ClaudeDo.Worker.Tests.Infrastructure;
+using Microsoft.Extensions.Logging.Abstractions;
+using Xunit;
+
+namespace ClaudeDo.Worker.Tests.Skills;
+
+public sealed class SessionSkillSeederTests : IDisposable
+{
+    private readonly string _rootDir;
+    private readonly string _skillsRoot;
+    private readonly string _workingDir;
+
+    public SessionSkillSeederTests()
+    {
+        _rootDir = Path.Combine(Path.GetTempPath(), $"claudedo_seeder_test_{Guid.NewGuid():N}");
+        _skillsRoot = Path.Combine(_rootDir, "session-skills");
+        _workingDir = Path.Combine(_rootDir, "workdir");
+        Directory.CreateDirectory(_skillsRoot);
+        Directory.CreateDirectory(_workingDir);
+    }
+
+    public void Dispose()
+    {
+        try { Directory.Delete(_rootDir, recursive: true); } catch { /* best effort */ }
+    }
+
+    private SessionSkillSeeder CreateSeeder() => new(NullLogger<SessionSkillSeeder>.Instance, _skillsRoot);
+
+    private void WriteInstalledSkill(string name, string fileName = "SKILL.md", string content = "# body")
+    {
+        var dir = Path.Combine(_skillsRoot, name);
+        Directory.CreateDirectory(dir);
+        File.WriteAllText(Path.Combine(dir, fileName), content);
+    }
+
+    [Fact]
+    public async Task SeedAsync_copies_skill_files_into_dot_claude_skills()
+    {
+        const string skillName = "ponytail";
+        WriteInstalledSkill(skillName);
+        var seeder = CreateSeeder();
+
+        await seeder.SeedAsync(_workingDir, [skillName], isWorktree: false, CancellationToken.None);
+
+        var destFile = Path.Combine(_workingDir, ".claude", "skills", skillName, "SKILL.md");
+        Assert.True(File.Exists(destFile));
+        Assert.Equal("# body", File.ReadAllText(destFile));
+    }
+
+    [Fact]
+    public async Task SeedAsync_empty_list_creates_no_dot_claude_dir()
+    {
+        var seeder = CreateSeeder();
+
+        await seeder.SeedAsync(_workingDir, [], isWorktree: false, CancellationToken.None);
+
+        Assert.False(Directory.Exists(Path.Combine(_workingDir, ".claude")));
+    }
+
+    [Fact]
+    public async Task SeedAsync_missing_source_skill_logs_warning_and_does_not_throw()
+    {
+        var seeder = CreateSeeder();
+
+        await seeder.SeedAsync(_workingDir, ["does-not-exist"], isWorktree: false, CancellationToken.None);
+
+        Assert.False(Directory.Exists(Path.Combine(_workingDir, ".claude", "skills", "does-not-exist")));
+    }
+
+    [Fact]
+    public async Task SeedAsync_re_seeding_is_idempotent_and_overwrites()
+    {
+        const string skillName = "ponytail";
+        WriteInstalledSkill(skillName, content: "v1");
+        var seeder = CreateSeeder();
+        await seeder.SeedAsync(_workingDir, [skillName], isWorktree: false, CancellationToken.None);
+
+        WriteInstalledSkill(skillName, content: "v2");
+        await seeder.SeedAsync(_workingDir, [skillName], isWorktree: false, CancellationToken.None);
+
+        var destFile = Path.Combine(_workingDir, ".claude", "skills", skillName, "SKILL.md");
+        Assert.Equal("v2", File.ReadAllText(destFile));
+    }
+
+    [Fact]
+    public async Task SeedAsync_non_worktree_does_not_touch_git_exclude()
+    {
+        // _workingDir is a plain directory (no .git), so a git call would throw if attempted.
+        WriteInstalledSkill("ponytail");
+        var seeder = CreateSeeder();
+
+        await seeder.SeedAsync(_workingDir, ["ponytail"], isWorktree: false, CancellationToken.None);
+
+        // No exception means git rev-parse was correctly skipped for isWorktree=false.
+        Assert.True(Directory.Exists(Path.Combine(_workingDir, ".claude", "skills", "ponytail")));
+    }
+
+    [Fact]
+    public async Task SeedAsync_worktree_appends_exclude_line_once()
+    {
+        if (!GitRepoFixture.IsGitAvailable()) return;
+
+        using var repo = new GitRepoFixture();
+        WriteInstalledSkill("ponytail");
+        var seeder = CreateSeeder();
+
+        await seeder.SeedAsync(repo.RepoDir, ["ponytail"], isWorktree: true, CancellationToken.None);
+
+        var excludeFile = Path.Combine(repo.RepoDir, ".git", "info", "exclude");
+        Assert.True(File.Exists(excludeFile));
+        var lines = await File.ReadAllLinesAsync(excludeFile);
+        Assert.Single(lines, l => l.Trim() == "/.claude/skills/ponytail/");
+
+        // Re-seed: exclude line must not be duplicated.
+        await seeder.SeedAsync(repo.RepoDir, ["ponytail"], isWorktree: true, CancellationToken.None);
+        var linesAfter = await File.ReadAllLinesAsync(excludeFile);
+        Assert.Single(linesAfter, l => l.Trim() == "/.claude/skills/ponytail/");
+    }
+
+    [Fact]
+    public async Task SeedAsync_worktree_seeded_skill_path_is_ignored_by_git_status()
+    {
+        if (!GitRepoFixture.IsGitAvailable()) return;
+
+        using var repo = new GitRepoFixture();
+        WriteInstalledSkill("ponytail");
+        var seeder = CreateSeeder();
+
+        await seeder.SeedAsync(repo.RepoDir, ["ponytail"], isWorktree: true, CancellationToken.None);
+
+        var status = GitRepoFixture.RunGit(repo.RepoDir, "status", "--porcelain");
+        Assert.Equal(string.Empty, status.Trim());
+    }
+}