fix: standardize timestamps to DateTimeOffset UTC (fixes #386)

PolyPilot.Console/Models/AgentSession.cs

@@ -3,13 +3,13 @@
 
 namespace PolyPilot.Models;
 
-public record ChatMessage(string Role, string Content, DateTime Timestamp);
+public record ChatMessage(string Role, string Content, DateTimeOffset Timestamp);
 
 public class AgentSession : IAsyncDisposable
 {
     public string Name { get; }
     public string Model { get; }
-    public DateTime CreatedAt { get; }
+    public DateTimeOffset CreatedAt { get; }
     public List<ChatMessage> History { get; } = new();
     public bool IsProcessing { get; private set; }
     public string? SessionId { get; }
@@ -26,7 +26,7 @@ public AgentSession(string name, string model, CopilotSession session, string? s
     {
         Name = name;
         Model = model;
-        CreatedAt = DateTime.Now;
+        CreatedAt = DateTimeOffset.UtcNow;
         SessionId = sessionId;
         IsResumed = isResumed;
         _session = session;
@@ -78,7 +78,7 @@ private void CompleteResponse()
         var response = _currentResponse.ToString();
         if (!string.IsNullOrEmpty(response))
         {
-            History.Add(new ChatMessage("assistant", response, DateTime.Now));
+            History.Add(new ChatMessage("assistant", response, DateTimeOffset.UtcNow));
         }
         _responseCompletion?.TrySetResult(response);
         _currentResponse.Clear();
@@ -98,7 +98,7 @@ public async Task<string> SendPromptAsync(string prompt, CancellationToken cance
         _currentResponse.Clear();
         _hasReceivedDeltasThisTurn = false;
 
-        History.Add(new ChatMessage("user", prompt, DateTime.Now));
+        History.Add(new ChatMessage("user", prompt, DateTimeOffset.UtcNow));
 
         try
         {

PolyPilot.IntegrationTests/QuotaDisplayTests.cs

@@ -0,0 +1,141 @@
+using PolyPilot.IntegrationTests.Fixtures;
+
+namespace PolyPilot.IntegrationTests;
+
+/// <summary>
+/// Integration tests for the quota display feature.
+/// Creates a session, sends a message to trigger AssistantUsageEvent with quota data,
+/// then verifies the quota indicator appears in the Dashboard header.
+/// </summary>
+[Collection("PolyPilot")]
+[Trait("Category", "QuotaDisplay")]
+public class QuotaDisplayTests : IntegrationTestBase
+{
+    public QuotaDisplayTests(AppFixture app, ITestOutputHelper output)
+        : base(app, output) { }
+
+    [Fact]
+    public async Task QuotaIndicator_AppearsAfterSendingMessage()
+    {
+        await WaitForCdpReadyAsync();
+        await ScreenshotAsync("quota-01-before");
+
+        // Step 1: Create a new session by clicking "+" → "Session"
+        await ClickAsync("[title='Create new session'], button.new-session-btn");
+        await Task.Delay(1000);
+
+        var menuItem = await CdpEvalAsync(
+            "const items = [...document.querySelectorAll('.sidebar-new-menu-item, .popover-item, button')]; " +
+            "const btn = items.find(b => b.textContent?.includes('Session') || b.textContent?.includes('Empty')); " +
+            "btn?.click(); btn ? 'clicked: ' + btn.textContent?.trim()?.substring(0,20) : 'no session btn'");
+        Output.WriteLine($"Create session: {menuItem}");
+        await Task.Delay(2000);
+
+        // Step 2: Find the input area and type a message
+        var fillResult = await CdpEvalAsync(
+            "const sel = '.card-input input, .card-input textarea, .input-row textarea, textarea'; " +
+            "const input = [...document.querySelectorAll(sel)].find(i => i.offsetParent !== null); " +
+            "if (input) { input.value = 'Say hello'; " +
+            "input.dispatchEvent(new Event('input', {bubbles:true})); " +
+            "input.dispatchEvent(new Event('change', {bubbles:true})); 'filled'; } else { 'no input'; }");
+        Output.WriteLine($"Fill input: {fillResult}");
+
+        // Step 3: Click send
+        var sendResult = await CdpEvalAsync(
+            "const sel = '.card-input input, .card-input textarea, .input-row textarea, textarea'; " +
+            "const input = [...document.querySelectorAll(sel)].find(i => i.offsetParent !== null); " +
+            "if (input) { const container = input.closest('.card-input') || input.closest('.input-row'); " +
+            "const sendBtn = container?.querySelector('.send-btn:not(.stop-btn)') || " +
+            "container?.querySelectorAll('button')?.[container?.querySelectorAll('button')?.length - 1]; " +
+            "if (sendBtn) { sendBtn.click(); 'sent: ' + sendBtn.className; } " +
+            "else { input.dispatchEvent(new KeyboardEvent('keydown', {key: 'Enter', bubbles: true})); 'enter'; } " +
+            "} else { 'no input'; }");
+        Output.WriteLine($"Send: {sendResult}");
+
+        // Step 4: Wait for response + quota event (up to 60 seconds)
+        Output.WriteLine("Waiting for Copilot response + quota data...");
+        var hasQuota = false;
+        for (var i = 0; i < 30; i++)
+        {
+            var quotaExists = await ExistsAsync("#quota-indicator, .quota-indicator, .quota-pill");
+            if (quotaExists)
+            {
+                hasQuota = true;
+                Output.WriteLine($"Quota indicator appeared after {i * 2}s");
+                break;
+            }
+            if (i % 5 == 0)
+            {
+                var pageState = await CdpEvalAsync(
+                    "JSON.stringify({quota: !!document.querySelector('#quota-indicator, .quota-indicator'), " +
+                    "messages: document.querySelectorAll('.message-content, .markdown-body').length, " +
+                    "processing: !!document.querySelector('.thinking, .processing, .spinner')})");
+                Output.WriteLine($"Poll {i * 2}s: {pageState}");
+            }
+            await Task.Delay(2000);
+        }
+
+        await ScreenshotAsync("quota-02-after-message");
+
+        if (hasQuota)
+        {
+            // Verify quota indicator content
+            var quotaText = await GetTextAsync("#quota-indicator, .quota-indicator, .quota-pill");
+            Output.WriteLine($"Quota indicator text: '{quotaText}'");
+            Assert.False(string.IsNullOrWhiteSpace(quotaText), "Quota indicator should show percentage");
+
+            await ScreenshotAsync("quota-03-indicator-visible");
+        }
+        else
+        {
+            Output.WriteLine("Quota indicator did not appear — may need more messages or token may not have quota data");
+            // Don't fail — the test documents the behavior. Quota depends on the account's plan.
+        }
+    }
+
+    [Fact]
+    public async Task Dashboard_LoadsWithoutErrors()
+    {
+        await WaitForCdpReadyAsync();
+
+        var dashboardLoaded = await ExistsAsync(".dashboard, #scheduled-tasks-page, .session-item");
+        Assert.True(dashboardLoaded, "Dashboard should render without errors");
+
+        await ScreenshotAsync("quota-dashboard");
+    }
+
+    [Fact]
+    public async Task UsageCommand_ShowsQuotaInfo()
+    {
+        await WaitForCdpReadyAsync();
+
+        // Navigate to a session if not already in one
+        var hasSession = await ExistsAsync(".session-item, .session-list-item");
+        if (hasSession)
+        {
+            await ClickAsync(".session-item, .session-list-item");
+            await Task.Delay(2000);
+        }
+
+        // Type /usage command
+        var fillResult = await CdpEvalAsync(
+            "const sel = '.card-input input, .card-input textarea, .input-row textarea, textarea'; " +
+            "const input = [...document.querySelectorAll(sel)].find(i => i.offsetParent !== null); " +
+            "if (input) { input.value = '/usage'; " +
+            "input.dispatchEvent(new Event('input', {bubbles:true})); " +
+            "input.dispatchEvent(new Event('change', {bubbles:true})); 'filled'; } else { 'no input'; }");
+        Output.WriteLine($"Fill /usage: {fillResult}");
+
+        if (fillResult == "filled")
+        {
+            // Send it
+            await CdpEvalAsync(
+                "const sel = '.card-input input, .card-input textarea, .input-row textarea, textarea'; " +
+                "const input = [...document.querySelectorAll(sel)].find(i => i.offsetParent !== null); " +
+                "if (input) { input.dispatchEvent(new KeyboardEvent('keydown', {key: 'Enter', bubbles: true})); }");
+            await Task.Delay(2000);
+
+            await ScreenshotAsync("quota-usage-command");
+        }
+    }
+}

PolyPilot.Tests/AgentSessionInfoTests.cs

@@ -78,7 +78,7 @@ public void MessageQueue_CanEnqueueAndDequeue()
     [Fact]
     public void Properties_CanBeSet()
     {
-        var now = DateTime.Now;
+        var now = DateTimeOffset.UtcNow;
         var session = new AgentSessionInfo
         {
             Name = "my-session",

PolyPilot.Tests/ChatMessageTests.cs

@@ -111,15 +111,15 @@ public void ReflectionMessage_SetsReflectionType()
     public void Constructor_UserRole_OverridesMessageType()
     {
         // When role is "user", MessageType should always be User regardless of what's passed
-        var msg = new ChatMessage("user", "test", DateTime.Now, ChatMessageType.Assistant);
+        var msg = new ChatMessage("user", "test", DateTimeOffset.UtcNow, ChatMessageType.Assistant);
         Assert.Equal(ChatMessageType.User, msg.MessageType);
     }
 
     [Fact]
     public void Constructor_AssistantRole_WithUserType_CorrectToAssistant()
     {
         // When role is not "user" but messageType is User, it should correct to Assistant
-        var msg = new ChatMessage("assistant", "test", DateTime.Now, ChatMessageType.User);
+        var msg = new ChatMessage("assistant", "test", DateTimeOffset.UtcNow, ChatMessageType.User);
         Assert.Equal(ChatMessageType.Assistant, msg.MessageType);
     }
 
@@ -151,14 +151,14 @@ public void Model_DefaultsToNull()
     [Fact]
     public void Model_CanBeSetViaInitializer()
     {
-        var msg = new ChatMessage("assistant", "test", DateTime.Now) { Model = "gpt-4.1" };
+        var msg = new ChatMessage("assistant", "test", DateTimeOffset.UtcNow) { Model = "gpt-4.1" };
         Assert.Equal("gpt-4.1", msg.Model);
     }
 
     [Fact]
     public void Model_PreservedOnAssistantMessages()
     {
-        var msg = new ChatMessage("assistant", "response", DateTime.Now) { Model = "claude-sonnet-4.5" };
+        var msg = new ChatMessage("assistant", "response", DateTimeOffset.UtcNow) { Model = "claude-sonnet-4.5" };
         Assert.True(msg.IsAssistant);
         Assert.Equal("claude-sonnet-4.5", msg.Model);
     }
@@ -190,7 +190,7 @@ public void OriginalContent_CanBeSet()
     [Fact]
     public void OriginalContent_PreservedOnDeserialization()
     {
-        var msg = new ChatMessage("user", "full orchestration prompt", DateTime.Now)
+        var msg = new ChatMessage("user", "full orchestration prompt", DateTimeOffset.UtcNow)
         {
             OriginalContent = "user typed this"
         };
@@ -282,8 +282,8 @@ public void ElapsedDisplay_LessThanOneSecond_ShowsLessThan1s()
     {
         var activity = new ToolActivity
         {
-            StartedAt = DateTime.Now,
-            CompletedAt = DateTime.Now.AddMilliseconds(500)
+            StartedAt = DateTimeOffset.UtcNow,
+            CompletedAt = DateTimeOffset.UtcNow.AddMilliseconds(500)
         };
         Assert.Equal("<1s", activity.ElapsedDisplay);
     }
@@ -293,8 +293,8 @@ public void ElapsedDisplay_MultipleSeconds_ShowsRoundedSeconds()
     {
         var activity = new ToolActivity
         {
-            StartedAt = DateTime.Now.AddSeconds(-5),
-            CompletedAt = DateTime.Now
+            StartedAt = DateTimeOffset.UtcNow.AddSeconds(-5),
+            CompletedAt = DateTimeOffset.UtcNow
         };
         Assert.Equal("5s", activity.ElapsedDisplay);
     }
@@ -304,11 +304,75 @@ public void ElapsedDisplay_NotCompleted_UsesCurrentTime()
     {
         var activity = new ToolActivity
         {
-            StartedAt = DateTime.Now.AddSeconds(-2),
+            StartedAt = DateTimeOffset.UtcNow.AddSeconds(-2),
             CompletedAt = null
         };
-        // Should be ~2s since it measures against DateTime.Now
+        // Should be ~2s since it measures against DateTimeOffset.UtcNow
         var display = activity.ElapsedDisplay;
         Assert.Matches(@"^\d+s$", display);
     }
+
+    [Fact]
+    public void FactoryMethods_UseUtcTimestamps()
+    {
+        // All factory methods should produce UTC timestamps (issue #386)
+        var before = DateTimeOffset.UtcNow;
+        var user = ChatMessage.UserMessage("test");
+        var assistant = ChatMessage.AssistantMessage("test");
+        var system = ChatMessage.SystemMessage("test");
+        var error = ChatMessage.ErrorMessage("test");
+        var after = DateTimeOffset.UtcNow;
+
+        Assert.Equal(TimeSpan.Zero, user.Timestamp.Offset);
+        Assert.Equal(TimeSpan.Zero, assistant.Timestamp.Offset);
+        Assert.Equal(TimeSpan.Zero, system.Timestamp.Offset);
+        Assert.Equal(TimeSpan.Zero, error.Timestamp.Offset);
+
+        Assert.InRange(user.Timestamp, before, after);
+        Assert.InRange(assistant.Timestamp, before, after);
+    }
+
+    [Fact]
+    public void Timestamp_IsDateTimeOffset()
+    {
+        // ChatMessage.Timestamp should be DateTimeOffset, not DateTime (issue #386)
+        var msg = ChatMessage.UserMessage("test");
+        Assert.IsType<DateTimeOffset>(msg.Timestamp);
+    }
+
+    [Fact]
+    public void Timestamp_CrossTimezoneComparison_Works()
+    {
+        // The core bug: comparing UTC dispatch time with local message timestamps.
+        // With DateTimeOffset, this comparison is timezone-aware.
+        var utcTime = new DateTimeOffset(2026, 4, 23, 15, 0, 0, TimeSpan.Zero);
+        var localTime = new DateTimeOffset(2026, 4, 23, 11, 0, 0, TimeSpan.FromHours(-4)); // Same instant, different offset
+
+        var msg = new ChatMessage("user", "test", localTime);
+        // These represent the same instant — comparison should be equal
+        Assert.True(msg.Timestamp >= utcTime);
+        Assert.True(msg.Timestamp <= utcTime);
+    }
+
+    [Fact]
+    public void ToolActivity_UsesDateTimeOffset()
+    {
+        var activity = new ToolActivity
+        {
+            Name = "test",
+            StartedAt = DateTimeOffset.UtcNow,
+            CompletedAt = DateTimeOffset.UtcNow.AddSeconds(5)
+        };
+        Assert.Equal(TimeSpan.Zero, activity.StartedAt.Offset);
+        Assert.Equal(TimeSpan.Zero, activity.CompletedAt!.Value.Offset);
+        Assert.Equal("5s", activity.ElapsedDisplay);
+    }
+
+    [Fact]
+    public void DefaultConstructor_ProducesUtcTimestamp()
+    {
+        // Parameterless constructor (used by JSON deserialization) should produce UTC
+        var msg = new ChatMessage();
+        Assert.Equal(TimeSpan.Zero, msg.Timestamp.Offset);
+    }
 }

PolyPilot.Tests/ConsecutiveStuckSessionTests.cs

@@ -245,7 +245,7 @@ public async Task HistorySize_DoesNotGrow_AfterRepeatedStucks()
         for (int i = 0; i < 200; i++)
         {
             session.History.Add(new ChatMessage(i % 2 == 0 ? "user" : "assistant",
-                $"Message {i}", DateTime.Now));
+                $"Message {i}", DateTimeOffset.UtcNow));
         }
         var initialCount = session.History.Count;
 
@@ -320,7 +320,7 @@ public void RepeatedStuckMessage_SuggestsNewSession()
         // The error message for repeated stucks should suggest creating a new session
         var info = new AgentSessionInfo { Name = "test", Model = "test-model" };
         for (int i = 0; i < 200; i++)
-            info.History.Add(new ChatMessage("user", $"msg {i}", DateTime.Now));
+            info.History.Add(new ChatMessage("user", $"msg {i}", DateTimeOffset.UtcNow));
         info.ConsecutiveStuckCount = 3;
 
         // Simulate the message format from the watchdog