feat(worker): add get_effective_run_config MCP tool

Adds a read-only get_effective_run_config(taskId) tool that reports the
model/max-turns/effort/permission-mode/agent-path/system-prompt/skills a
task will actually run with, each tagged with its source (task/list/
preset/global), plus max-turns' raw requested value and clamp status.

Extracted the model/max-turns/agent-path resolution out of
TaskRunner.ResolveConfigAsync into EffectiveRunConfigResolver so the run
path and the new reporting tool share one codepath instead of risking
drift, per docs/explore-notes/worker-task-pipeline.md's max-turns trap.

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

@@ -0,0 +1,81 @@
+using ClaudeDo.Data;
+using ClaudeDo.Data.Git;
+using ClaudeDo.Data.Models;
+using ClaudeDo.Data.Repositories;
+using ClaudeDo.Worker.Config;
+using ClaudeDo.Worker.External;
+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;
+
+/// <summary>
+/// get_effective_run_config (ConfigMcpTools) must report exactly what TaskRunner actually
+/// dispatches with — both go through EffectiveRunConfigResolver.Resolve, but this test proves
+/// it end to end via TaskRunner's real CLI args instead of trusting the shared code path alone.
+/// </summary>
+public sealed class EffectiveRunConfigParityTests : IDisposable
+{
+    private readonly DbFixture _db = new();
+    private readonly string _tempDir;
+    private readonly WorkerConfig _cfg;
+
+    public EffectiveRunConfigParityTests()
+    {
+        _tempDir = Path.Combine(Path.GetTempPath(), $"cd_effparity_{Guid.NewGuid():N}");
+        Directory.CreateDirectory(_tempDir);
+        _cfg = new WorkerConfig { SandboxRoot = _tempDir, LogRoot = _tempDir };
+    }
+
+    public void Dispose() { _db.Dispose(); try { Directory.Delete(_tempDir, true); } catch { } }
+
+    [Fact]
+    public async Task Reported_model_and_max_turns_match_what_TaskRunner_dispatches_with()
+    {
+        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", Model = "opus", MaxTurns = 999 });
+            ctx.Tasks.Add(new TaskEntity
+            {
+                Id = "t1", ListId = "l1", Title = "Task", Status = TaskStatus.Idle, CreatedAt = DateTime.UtcNow,
+            });
+            await ctx.SaveChangesAsync();
+        }
+
+        var state = TaskStateServiceBuilder.Build(dbFactory).State;
+        var wt = new WorktreeManager(new GitService(), dbFactory, _cfg, NullLogger<WorktreeManager>.Instance);
+        IReadOnlyList<string>? capturedArgs = null;
+        var fake = new FakeClaudeProcess((_, _, args, _, _) =>
+        {
+            capturedArgs = args;
+            return Task.FromResult(new RunResult { ExitCode = 0, ResultMarkdown = "ok" });
+        });
+        var runner = new TaskRunner(fake, dbFactory, new HubBroadcaster(new CapturingHubContext()), wt,
+            new ClaudeArgsBuilder(), _cfg, NullLogger<TaskRunner>.Instance, state, new TaskRunTokenRegistry(),
+            new AttachmentStore(), new FakeSessionSkillSeeder(), new FakeTranscriptUsageReader());
+
+        using (var ctx = _db.CreateContext())
+            await runner.RunAsync((await new TaskRepository(ctx).GetByIdAsync("t1"))!, "slot-1", CancellationToken.None);
+
+        var args = capturedArgs!.ToList();
+        var actualModel = args[args.IndexOf("--model") + 1];
+        var actualMaxTurns = args[args.IndexOf("--max-turns") + 1];
+
+        using var reportCtx = _db.CreateContext();
+        var tools = new ConfigMcpTools(
+            new ListRepository(reportCtx), new TaskRepository(reportCtx),
+            new HubBroadcaster(new CapturingHubContext()), dbFactory);
+        var effective = await tools.GetEffectiveRunConfig("t1", CancellationToken.None);
+
+        Assert.Equal(actualModel, effective.Model.Value);
+        Assert.Equal(actualMaxTurns, effective.MaxTurns.Effective.ToString());
+        Assert.Equal(999, effective.MaxTurns.Requested);
+        Assert.True(effective.MaxTurns.Clamped);
+    }
+}