diff --git a/src/ClaudeDo.App/App.axaml.cs b/src/ClaudeDo.App/App.axaml.cs
index 5d7c6733..0d9667aa 100644
--- a/src/ClaudeDo.App/App.axaml.cs
+++ b/src/ClaudeDo.App/App.axaml.cs
@@ -52,6 +52,7 @@ public partial class App : Application
             Dispatcher.UIThread.UnhandledException += (_, e) =>
             {
                 e.Handled = true;
+                Serilog.Log.Error(e.Exception, "Unhandled exception on the UI dispatcher");
                 shell.FlashFooterError(Loc.T("vm.shell.unexpectedError", e.Exception.Message));
             };
 
diff --git a/src/ClaudeDo.App/ClaudeDo.App.csproj b/src/ClaudeDo.App/ClaudeDo.App.csproj
index 1257d87c..e0b0481c 100644
--- a/src/ClaudeDo.App/ClaudeDo.App.csproj
+++ b/src/ClaudeDo.App/ClaudeDo.App.csproj
@@ -26,6 +26,8 @@
     </PackageReference>
     <PackageReference Include="CommunityToolkit.Mvvm" Version="8.4.1" />
     <PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="8.0.1" />
+    <PackageReference Include="Serilog" Version="4.0.0" />
+    <PackageReference Include="Serilog.Sinks.File" Version="6.0.0" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/ClaudeDo.App/Program.cs b/src/ClaudeDo.App/Program.cs
index 381207fc..88221107 100644
--- a/src/ClaudeDo.App/Program.cs
+++ b/src/ClaudeDo.App/Program.cs
@@ -13,6 +13,7 @@ using ClaudeDo.Ui.ViewModels.Modals;
 using ClaudeDo.Ui.ViewModels.Modals.Settings;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
+using Serilog;
 using System;
 using System.Globalization;
 using System.IO;
@@ -20,6 +21,7 @@ using System.Linq;
 using System.Net.Http;
 using System.Reflection;
 using System.Runtime.InteropServices;
+using System.Threading.Tasks;
 
 namespace ClaudeDo.App;
 
@@ -34,6 +36,35 @@ sealed class Program
         if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
             SetCurrentProcessExplicitAppUserModelID("ClaudeDo.App");
 
+        var logRoot = Path.Combine(Paths.AppDataRoot(), "logs");
+        Directory.CreateDirectory(logRoot);
+        Log.Logger = new LoggerConfiguration()
+            .MinimumLevel.Information()
+            .WriteTo.File(
+                Path.Combine(logRoot, "ui-.log"),
+                rollingInterval: RollingInterval.Day,
+                retainedFileCountLimit: 7,
+                shared: true)
+            .CreateLogger();
+
+        var version = Assembly.GetEntryAssembly()?
+            .GetCustomAttribute<AssemblyInformationalVersionAttribute>()?.InformationalVersion
+            ?? "0.0.0";
+        Log.Information("ClaudeDo.App starting (version: {Version})", version);
+
+        // Last-resort net: any exception that misses every other handler still gets one
+        // Fatal line in the log before the process dies.
+        AppDomain.CurrentDomain.UnhandledException += (_, e) =>
+        {
+            Log.Fatal(e.ExceptionObject as Exception, "Unhandled exception, terminating (IsTerminating: {IsTerminating})", e.IsTerminating);
+            Log.CloseAndFlush();
+        };
+        TaskScheduler.UnobservedTaskException += (_, e) =>
+        {
+            Log.Error(e.Exception, "Unobserved task exception");
+            e.SetObserved();
+        };
+
         var services = BuildServices();
 
         using (var scope = services.CreateScope())
@@ -62,6 +93,8 @@ sealed class Program
             {
                 /* best effort on shutdown */
             }
+
+            Log.CloseAndFlush();
         }
     }
 
diff --git a/src/ClaudeDo.Ui/ClaudeDo.Ui.csproj b/src/ClaudeDo.Ui/ClaudeDo.Ui.csproj
index 4b4dc211..9de87d15 100644
--- a/src/ClaudeDo.Ui/ClaudeDo.Ui.csproj
+++ b/src/ClaudeDo.Ui/ClaudeDo.Ui.csproj
@@ -17,6 +17,7 @@
     <PackageReference Include="Microsoft.Win32.Registry" Version="5.0.0" />
     <PackageReference Include="Duende.IdentityModel.OidcClient" Version="7.1.0" />
     <PackageReference Include="Iciclecreek.Avalonia.Terminal" Version="2.0.3" />
+    <PackageReference Include="Serilog" Version="4.0.0" />
   </ItemGroup>
 
   <ItemGroup>
diff --git a/src/ClaudeDo.Ui/Services/WorkerClient.cs b/src/ClaudeDo.Ui/Services/WorkerClient.cs
index 7943e390..51e36120 100644
--- a/src/ClaudeDo.Ui/Services/WorkerClient.cs
+++ b/src/ClaudeDo.Ui/Services/WorkerClient.cs
@@ -304,7 +304,11 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
             ok = true;
             return result;
         }
-        catch { return default; }
+        catch (Exception ex)
+        {
+            Serilog.Log.Warning(ex, "Hub call {Method} failed", method);
+            return default;
+        }
         finally { OperationTiming.Shared.Record("hub", method, sw.Elapsed, ok); }
     }
 
@@ -318,6 +322,11 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
             await invoke();
             ok = true;
         }
+        catch (Exception ex)
+        {
+            Serilog.Log.Warning(ex, "Hub call {Method} failed", method);
+            throw;
+        }
         finally { OperationTiming.Shared.Record("hub", method, sw.Elapsed, ok); }
     }
 
@@ -332,6 +341,11 @@ public partial class WorkerClient : ObservableObject, IAsyncDisposable, IWorkerC
             ok = true;
             return result;
         }
+        catch (Exception ex)
+        {
+            Serilog.Log.Warning(ex, "Hub call {Method} failed", method);
+            throw;
+        }
         finally { OperationTiming.Shared.Record("hub", method, sw.Elapsed, ok); }
     }
 
diff --git a/src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs b/src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs
index 8ee08b02..6a4c9ac4 100644
--- a/src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/IslandsShellViewModel.cs
@@ -208,6 +208,9 @@ public sealed partial class IslandsShellViewModel : ViewModelBase, IDisposable
 
     private void FlashFooter(string message, WorkerLogLevel level)
     {
+        if (level == WorkerLogLevel.Error)
+            Serilog.Log.Warning("Footer error: {Message}", message);
+
         WorkerLogText = $"{DateTime.Now:HH:mm} · {message}";
         WorkerLogLevel = level;
         IsWorkerLogVisible = true;
diff --git a/src/ClaudeDo.Worker/Hub/HubExceptionLoggingFilter.cs b/src/ClaudeDo.Worker/Hub/HubExceptionLoggingFilter.cs
new file mode 100644
index 00000000..0c70ddc8
--- /dev/null
+++ b/src/ClaudeDo.Worker/Hub/HubExceptionLoggingFilter.cs
@@ -0,0 +1,27 @@
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.Extensions.Logging;
+
+namespace ClaudeDo.Worker.Hub;
+
+/// <summary>
+/// Logs a Warning for any exception thrown out of a hub method body, so a failed UI action
+/// leaves a trace in <c>worker-.log</c> instead of only a generic error at the caller.
+/// Does NOT see an argument-binding failure (e.g. a stray CancellationToken parameter) — SignalR
+/// rejects those while parsing the invocation message, before a hub method is ever dispatched.
+/// </summary>
+public sealed class HubExceptionLoggingFilter(ILogger<HubExceptionLoggingFilter> logger) : IHubFilter
+{
+    public async ValueTask<object?> InvokeMethodAsync(
+        HubInvocationContext invocationContext, Func<HubInvocationContext, ValueTask<object?>> next)
+    {
+        try
+        {
+            return await next(invocationContext);
+        }
+        catch (Exception ex)
+        {
+            logger.LogWarning(ex, "Hub method {Method} failed", invocationContext.HubMethodName);
+            throw;
+        }
+    }
+}
diff --git a/src/ClaudeDo.Worker/Program.cs b/src/ClaudeDo.Worker/Program.cs
index 638dda93..cef3743f 100644
--- a/src/ClaudeDo.Worker/Program.cs
+++ b/src/ClaudeDo.Worker/Program.cs
@@ -28,6 +28,7 @@ using ClaudeDo.Worker.Usage.Interfaces;
 using ClaudeDo.Worker.Usage.TokenTracker;
 using ClaudeDo.Worker.Usage.TokenTracker.Interfaces;
 using ClaudeDo.Worker.Worktrees;
+using Microsoft.AspNetCore.SignalR;
 using Microsoft.EntityFrameworkCore;
 using Serilog;
 
@@ -58,6 +59,11 @@ builder.Host.UseSerilog((ctx, lc) => lc
     .MinimumLevel.Information()
     .MinimumLevel.Override("Microsoft.EntityFrameworkCore", Serilog.Events.LogEventLevel.Warning)
     .MinimumLevel.Override("Microsoft.AspNetCore", Serilog.Events.LogEventLevel.Warning)
+    // SignalR logs an argument-binding failure (e.g. a stray CancellationToken parameter, see
+    // fix 352aaa52) at Debug on this specific source context — HubExceptionLoggingFilter can't
+    // see it either, since SignalR rejects the invocation while parsing the message, before any
+    // hub method (and its filter pipeline) is dispatched.
+    .MinimumLevel.Override("Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher", Serilog.Events.LogEventLevel.Debug)
     .WriteTo.File(
         System.IO.Path.Combine(logRoot, "worker-.log"),
         rollingInterval: RollingInterval.Day,
@@ -90,7 +96,11 @@ builder.Services.AddHostedService<UntrackedWorktreeRecovery>();
 // Default MaximumParallelInvocationsPerClient=1 serializes every hub call on one connection —
 // a slow one (e.g. GetTicketProjects hitting an unreachable ticket system) blocks unrelated
 // calls like UpdateList/UpdateListConfig behind it for the same 10s.
-builder.Services.AddSignalR(options => options.MaximumParallelInvocationsPerClient = 10)
+builder.Services.AddSignalR(options =>
+    {
+        options.MaximumParallelInvocationsPerClient = 10;
+        options.AddFilter<HubExceptionLoggingFilter>();
+    })
     .AddJsonProtocol(options =>
     {
         options.PayloadSerializerOptions.Converters.Add(new System.Text.Json.Serialization.JsonStringEnumConverter());