// Copyright (c) Microsoft. All rights reserved.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json;
using System.Threading.Tasks;
using Microsoft.Agents.AI.AGUI.Shared;
using Microsoft.Extensions.AI;

namespace Microsoft.Agents.AI.AGUI.UnitTests;

public sealed class ChatResponseUpdateAGUIExtensionsTests
{
    [Fact]
    public async Task AsChatResponseUpdatesAsync_ConvertsRunStartedEvent_ToResponseUpdateWithMetadataAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Single(updates);
        Assert.Equal(ChatRole.Assistant, updates[0].Role);
        Assert.Equal("run1", updates[0].ResponseId);
        Assert.NotNull(updates[0].CreatedAt);
        Assert.Equal("thread1", updates[0].ConversationId);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_ConvertsRunFinishedEvent_ToResponseUpdateWithMetadataAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1", Result = JsonSerializer.SerializeToElement("Success") }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Equal(2, updates.Count);
        // First update is RunStarted
        Assert.Equal(ChatRole.Assistant, updates[0].Role);
        Assert.Equal("run1", updates[0].ResponseId);
        // Second update is RunFinished
        Assert.Equal(ChatRole.Assistant, updates[1].Role);
        Assert.Equal("run1", updates[1].ResponseId);
        Assert.NotNull(updates[1].CreatedAt);
        TextContent content = Assert.IsType<TextContent>(updates[1].Contents[0]);
        Assert.Equal("\"Success\"", content.Text); // JSON string representation includes quotes
        // ConversationId is stored in the ChatResponseUpdate
        Assert.Equal("thread1", updates[1].ConversationId);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_ConvertsRunErrorEvent_ToErrorContentAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new RunErrorEvent { Message = "Error occurred", Code = "ERR001" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Single(updates);
        Assert.Equal(ChatRole.Assistant, updates[0].Role);
        ErrorContent content = Assert.IsType<ErrorContent>(updates[0].Contents[0]);
        Assert.Equal("Error occurred", content.Message);
        // Code is stored in ErrorCode property
        Assert.Equal("ERR001", content.ErrorCode);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_ConvertsTextMessageSequence_ToTextUpdatesWithCorrectRoleAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new TextMessageStartEvent { MessageId = "msg1", Role = AGUIRoles.Assistant },
            new TextMessageContentEvent { MessageId = "msg1", Delta = "Hello" },
            new TextMessageContentEvent { MessageId = "msg1", Delta = " World" },
            new TextMessageEndEvent { MessageId = "msg1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Equal(2, updates.Count);
        Assert.All(updates, u => Assert.Equal(ChatRole.Assistant, u.Role));
        Assert.Equal("Hello", ((TextContent)updates[0].Contents[0]).Text);
        Assert.Equal(" World", ((TextContent)updates[1].Contents[0]).Text);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithTextMessageStartWhileMessageInProgress_ThrowsInvalidOperationExceptionAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new TextMessageStartEvent { MessageId = "msg1", Role = AGUIRoles.Assistant },
            new TextMessageContentEvent { MessageId = "msg1", Delta = "Hello" },
            new TextMessageStartEvent { MessageId = "msg2", Role = AGUIRoles.User }
        ];

        // Act & Assert
        await Assert.ThrowsAsync<InvalidOperationException>(async () =>
        {
            await foreach (var _ in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
            {
                // Intentionally empty - consuming stream to trigger exception
            }
        });
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithTextMessageEndForWrongMessageId_ThrowsInvalidOperationExceptionAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new TextMessageStartEvent { MessageId = "msg1", Role = AGUIRoles.Assistant },
            new TextMessageContentEvent { MessageId = "msg1", Delta = "Hello" },
            new TextMessageEndEvent { MessageId = "msg2" }
        ];

        // Act & Assert
        await Assert.ThrowsAsync<InvalidOperationException>(async () =>
        {
            await foreach (var _ in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
            {
                // Intentionally empty - consuming stream to trigger exception
            }
        });
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_MaintainsMessageContext_AcrossMultipleContentEventsAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new TextMessageStartEvent { MessageId = "msg1", Role = AGUIRoles.Assistant },
            new TextMessageContentEvent { MessageId = "msg1", Delta = "Hello" },
            new TextMessageContentEvent { MessageId = "msg1", Delta = " " },
            new TextMessageContentEvent { MessageId = "msg1", Delta = "World" },
            new TextMessageEndEvent { MessageId = "msg1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Equal(3, updates.Count);
        Assert.All(updates, u => Assert.Equal(ChatRole.Assistant, u.Role));
        Assert.All(updates, u => Assert.Equal("msg1", u.MessageId));
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_ConvertsToolCallEvents_ToFunctionCallContentAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new ToolCallStartEvent { ToolCallId = "call_1", ToolCallName = "GetWeather", ParentMessageId = "msg1" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "{\"location\":" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "\"Seattle\"}" },
            new ToolCallEndEvent { ToolCallId = "call_1" },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        ChatResponseUpdate toolCallUpdate = updates.First(u => u.Contents.Any(c => c is FunctionCallContent));
        FunctionCallContent functionCall = Assert.IsType<FunctionCallContent>(toolCallUpdate.Contents[0]);
        Assert.Equal("call_1", functionCall.CallId);
        Assert.Equal("GetWeather", functionCall.Name);
        Assert.NotNull(functionCall.Arguments);
        Assert.Equal("Seattle", functionCall.Arguments!["location"]?.ToString());
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithMultipleToolCallArgsEvents_AccumulatesArgsCorrectlyAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ToolCallStartEvent { ToolCallId = "call_1", ToolCallName = "TestTool", ParentMessageId = "msg1" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "{\"par" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "t1\":\"val" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "ue1\",\"part2" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "\":\"value2\"}" },
            new ToolCallEndEvent { ToolCallId = "call_1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        FunctionCallContent functionCall = updates
            .SelectMany(u => u.Contents)
            .OfType<FunctionCallContent>()
            .Single();
        Assert.Equal("value1", functionCall.Arguments!["part1"]?.ToString());
        Assert.Equal("value2", functionCall.Arguments!["part2"]?.ToString());
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithEmptyToolCallArgs_HandlesGracefullyAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ToolCallStartEvent { ToolCallId = "call_1", ToolCallName = "NoArgsTool", ParentMessageId = "msg1" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "" },
            new ToolCallEndEvent { ToolCallId = "call_1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        FunctionCallContent functionCall = updates
            .SelectMany(u => u.Contents)
            .OfType<FunctionCallContent>()
            .Single();
        Assert.Equal("call_1", functionCall.CallId);
        Assert.Equal("NoArgsTool", functionCall.Name);
        Assert.Null(functionCall.Arguments);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithOverlappingToolCalls_ThrowsInvalidOperationExceptionAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ToolCallStartEvent { ToolCallId = "call_1", ToolCallName = "Tool1", ParentMessageId = "msg1" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "{}" },
            new ToolCallStartEvent { ToolCallId = "call_2", ToolCallName = "Tool2", ParentMessageId = "msg1" } // Second start before first ends
        ];

        // Act & Assert
        await Assert.ThrowsAsync<InvalidOperationException>(async () =>
        {
            await foreach (var _ in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
            {
                // Consume stream to trigger exception
            }
        });
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithMismatchedToolCallId_ThrowsInvalidOperationExceptionAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ToolCallStartEvent { ToolCallId = "call_1", ToolCallName = "Tool1", ParentMessageId = "msg1" },
            new ToolCallArgsEvent { ToolCallId = "call_2", Delta = "{}" } // Wrong call ID
        ];

        // Act & Assert
        await Assert.ThrowsAsync<InvalidOperationException>(async () =>
        {
            await foreach (var _ in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
            {
                // Consume stream to trigger exception
            }
        });
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithMismatchedToolCallEndId_ThrowsInvalidOperationExceptionAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ToolCallStartEvent { ToolCallId = "call_1", ToolCallName = "Tool1", ParentMessageId = "msg1" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "{}" },
            new ToolCallEndEvent { ToolCallId = "call_2" } // Wrong call ID
        ];

        // Act & Assert
        await Assert.ThrowsAsync<InvalidOperationException>(async () =>
        {
            await foreach (var _ in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
            {
                // Consume stream to trigger exception
            }
        });
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithMultipleSequentialToolCalls_ProcessesAllCorrectlyAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ToolCallStartEvent { ToolCallId = "call_1", ToolCallName = "Tool1", ParentMessageId = "msg1" },
            new ToolCallArgsEvent { ToolCallId = "call_1", Delta = "{\"arg1\":\"val1\"}" },
            new ToolCallEndEvent { ToolCallId = "call_1" },
            new ToolCallStartEvent { ToolCallId = "call_2", ToolCallName = "Tool2", ParentMessageId = "msg2" },
            new ToolCallArgsEvent { ToolCallId = "call_2", Delta = "{\"arg2\":\"val2\"}" },
            new ToolCallEndEvent { ToolCallId = "call_2" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        List<FunctionCallContent> functionCalls = updates
            .SelectMany(u => u.Contents)
            .OfType<FunctionCallContent>()
            .ToList();
        Assert.Equal(2, functionCalls.Count);
        Assert.Equal("call_1", functionCalls[0].CallId);
        Assert.Equal("Tool1", functionCalls[0].Name);
        Assert.Equal("call_2", functionCalls[1].CallId);
        Assert.Equal("Tool2", functionCalls[1].Name);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_ConvertsStateSnapshotEvent_ToDataContentWithJsonAsync()
    {
        // Arrange
        JsonElement stateSnapshot = JsonSerializer.SerializeToElement(new { counter = 42, status = "active" });
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new StateSnapshotEvent { Snapshot = stateSnapshot },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        ChatResponseUpdate stateUpdate = updates.First(u => u.Contents.Any(c => c is DataContent));
        Assert.Equal(ChatRole.Assistant, stateUpdate.Role);
        Assert.Equal("thread1", stateUpdate.ConversationId);
        Assert.Equal("run1", stateUpdate.ResponseId);

        DataContent dataContent = Assert.IsType<DataContent>(stateUpdate.Contents[0]);
        Assert.Equal("application/json", dataContent.MediaType);

        // Verify the JSON content
        string jsonText = System.Text.Encoding.UTF8.GetString(dataContent.Data.ToArray());
        JsonElement deserializedState = JsonElement.Parse(jsonText);
        Assert.Equal(42, deserializedState.GetProperty("counter").GetInt32());
        Assert.Equal("active", deserializedState.GetProperty("status").GetString());

        // Verify additional properties
        Assert.NotNull(stateUpdate.AdditionalProperties);
        Assert.True((bool)stateUpdate.AdditionalProperties["is_state_snapshot"]!);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithNullStateSnapshot_DoesNotEmitUpdateAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new StateSnapshotEvent { Snapshot = null },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.DoesNotContain(updates, u => u.Contents.Any(c => c is DataContent));
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithEmptyObjectStateSnapshot_EmitsDataContentAsync()
    {
        // Arrange
        JsonElement emptyState = JsonSerializer.SerializeToElement(new { });
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new StateSnapshotEvent { Snapshot = emptyState },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        ChatResponseUpdate stateUpdate = updates.First(u => u.Contents.Any(c => c is DataContent));
        DataContent dataContent = Assert.IsType<DataContent>(stateUpdate.Contents[0]);
        string jsonText = System.Text.Encoding.UTF8.GetString(dataContent.Data.ToArray());
        Assert.Equal("{}", jsonText);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithComplexStateSnapshot_PreservesJsonStructureAsync()
    {
        // Arrange
        var complexState = new
        {
            user = new { name = "Alice", age = 30 },
            items = new[] { "item1", "item2", "item3" },
            metadata = new { timestamp = "2024-01-01T00:00:00Z", version = 2 }
        };
        JsonElement stateSnapshot = JsonSerializer.SerializeToElement(complexState);
        List<BaseEvent> events =
        [
            new StateSnapshotEvent { Snapshot = stateSnapshot }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        ChatResponseUpdate stateUpdate = updates.First();
        DataContent dataContent = Assert.IsType<DataContent>(stateUpdate.Contents[0]);
        string jsonText = System.Text.Encoding.UTF8.GetString(dataContent.Data.ToArray());
        JsonElement roundTrippedState = JsonElement.Parse(jsonText);

        Assert.Equal("Alice", roundTrippedState.GetProperty("user").GetProperty("name").GetString());
        Assert.Equal(30, roundTrippedState.GetProperty("user").GetProperty("age").GetInt32());
        Assert.Equal(3, roundTrippedState.GetProperty("items").GetArrayLength());
        Assert.Equal("item1", roundTrippedState.GetProperty("items")[0].GetString());
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithStateSnapshotAndTextMessages_EmitsBothAsync()
    {
        // Arrange
        JsonElement state = JsonSerializer.SerializeToElement(new { step = 1 });
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new TextMessageStartEvent { MessageId = "msg1", Role = AGUIRoles.Assistant },
            new TextMessageContentEvent { MessageId = "msg1", Delta = "Processing..." },
            new TextMessageEndEvent { MessageId = "msg1" },
            new StateSnapshotEvent { Snapshot = state },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Contains(updates, u => u.Contents.Any(c => c is TextContent));
        Assert.Contains(updates, u => u.Contents.Any(c => c is DataContent));
    }

    #region State Delta Tests

    [Fact]
    public async Task AsChatResponseUpdatesAsync_ConvertsStateDeltaEvent_ToDataContentWithJsonPatchAsync()
    {
        // Arrange - Create JSON Patch operations (RFC 6902)
        JsonElement stateDelta = JsonSerializer.SerializeToElement(new object[]
        {
            new { op = "replace", path = "/counter", value = 43 },
            new { op = "add", path = "/newField", value = "test" }
        });
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new StateDeltaEvent { Delta = stateDelta },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        ChatResponseUpdate deltaUpdate = updates.First(u => u.Contents.Any(c => c is DataContent dc && dc.MediaType == "application/json-patch+json"));
        Assert.Equal(ChatRole.Assistant, deltaUpdate.Role);
        Assert.Equal("thread1", deltaUpdate.ConversationId);
        Assert.Equal("run1", deltaUpdate.ResponseId);

        DataContent dataContent = Assert.IsType<DataContent>(deltaUpdate.Contents[0]);
        Assert.Equal("application/json-patch+json", dataContent.MediaType);

        // Verify the JSON Patch content
        string jsonText = System.Text.Encoding.UTF8.GetString(dataContent.Data.ToArray());
        JsonElement deserializedDelta = JsonElement.Parse(jsonText);
        Assert.Equal(JsonValueKind.Array, deserializedDelta.ValueKind);
        Assert.Equal(2, deserializedDelta.GetArrayLength());

        // Verify first operation
        JsonElement firstOp = deserializedDelta[0];
        Assert.Equal("replace", firstOp.GetProperty("op").GetString());
        Assert.Equal("/counter", firstOp.GetProperty("path").GetString());
        Assert.Equal(43, firstOp.GetProperty("value").GetInt32());

        // Verify second operation
        JsonElement secondOp = deserializedDelta[1];
        Assert.Equal("add", secondOp.GetProperty("op").GetString());
        Assert.Equal("/newField", secondOp.GetProperty("path").GetString());
        Assert.Equal("test", secondOp.GetProperty("value").GetString());

        // Verify additional properties
        Assert.NotNull(deltaUpdate.AdditionalProperties);
        Assert.True((bool)deltaUpdate.AdditionalProperties["is_state_delta"]!);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithNullStateDelta_DoesNotEmitUpdateAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new StateDeltaEvent { Delta = null },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert - Only run started and finished should be present
        Assert.Equal(2, updates.Count);
        Assert.IsType<ChatResponseUpdate>(updates[0]); // Run started
        Assert.IsType<ChatResponseUpdate>(updates[1]); // Run finished
        Assert.DoesNotContain(updates, u => u.Contents.Any(c => c is DataContent));
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithEmptyStateDelta_EmitsUpdateAsync()
    {
        // Arrange - Empty JSON Patch array is valid
        JsonElement emptyDelta = JsonSerializer.SerializeToElement(Array.Empty<object>());
        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new StateDeltaEvent { Delta = emptyDelta },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Contains(updates, u => u.Contents.Any(c => c is DataContent dc && dc.MediaType == "application/json-patch+json"));
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithMultipleStateDeltaEvents_ConvertsAllAsync()
    {
        // Arrange
        JsonElement delta1 = JsonSerializer.SerializeToElement(new[] { new { op = "replace", path = "/counter", value = 1 } });
        JsonElement delta2 = JsonSerializer.SerializeToElement(new[] { new { op = "replace", path = "/counter", value = 2 } });
        JsonElement delta3 = JsonSerializer.SerializeToElement(new[] { new { op = "replace", path = "/counter", value = 3 } });

        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new StateDeltaEvent { Delta = delta1 },
            new StateDeltaEvent { Delta = delta2 },
            new StateDeltaEvent { Delta = delta3 },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        var deltaUpdates = updates.Where(u => u.Contents.Any(c => c is DataContent dc && dc.MediaType == "application/json-patch+json")).ToList();
        Assert.Equal(3, deltaUpdates.Count);
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_ConvertsDataContentWithJsonPatch_ToStateDeltaEventAsync()
    {
        // Arrange - Create a ChatResponseUpdate with JSON Patch DataContent
        JsonElement patchOps = JsonSerializer.SerializeToElement(new object[]
        {
            new { op = "remove", path = "/oldField" },
            new { op = "add", path = "/newField", value = "newValue" }
        });
        byte[] jsonBytes = JsonSerializer.SerializeToUtf8Bytes(patchOps);
        DataContent dataContent = new(jsonBytes, "application/json-patch+json");

        List<ChatResponseUpdate> updates =
        [
            new ChatResponseUpdate(ChatRole.Assistant, [dataContent])
            {
                MessageId = "msg1"
            }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        StateDeltaEvent? deltaEvent = outputEvents.OfType<StateDeltaEvent>().FirstOrDefault();
        Assert.NotNull(deltaEvent);
        Assert.NotNull(deltaEvent.Delta);
        Assert.Equal(JsonValueKind.Array, deltaEvent.Delta.Value.ValueKind);

        // Verify patch operations
        JsonElement delta = deltaEvent.Delta.Value;
        Assert.Equal(2, delta.GetArrayLength());
        Assert.Equal("remove", delta[0].GetProperty("op").GetString());
        Assert.Equal("/oldField", delta[0].GetProperty("path").GetString());
        Assert.Equal("add", delta[1].GetProperty("op").GetString());
        Assert.Equal("/newField", delta[1].GetProperty("path").GetString());
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithBothSnapshotAndDelta_EmitsBothEventsAsync()
    {
        // Arrange
        JsonElement snapshot = JsonSerializer.SerializeToElement(new { counter = 0 });
        byte[] snapshotBytes = JsonSerializer.SerializeToUtf8Bytes(snapshot);
        DataContent snapshotContent = new(snapshotBytes, "application/json");

        JsonElement delta = JsonSerializer.SerializeToElement(new[] { new { op = "replace", path = "/counter", value = 1 } });
        byte[] deltaBytes = JsonSerializer.SerializeToUtf8Bytes(delta);
        DataContent deltaContent = new(deltaBytes, "application/json-patch+json");

        List<ChatResponseUpdate> updates =
        [
            new ChatResponseUpdate(ChatRole.Assistant, [snapshotContent]) { MessageId = "msg1" },
            new ChatResponseUpdate(ChatRole.Assistant, [deltaContent]) { MessageId = "msg2" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        Assert.Contains(outputEvents, e => e is StateSnapshotEvent);
        Assert.Contains(outputEvents, e => e is StateDeltaEvent);
    }

    [Fact]
    public async Task StateDeltaEvent_RoundTrip_PreservesJsonPatchOperationsAsync()
    {
        // Arrange - Create complex JSON Patch with various operations
        JsonElement originalDelta = JsonSerializer.SerializeToElement(new object[]
        {
            new { op = "add", path = "/user/email", value = "test@example.com" },
            new { op = "remove", path = "/user/tempData" },
            new { op = "replace", path = "/user/lastLogin", value = "2025-11-09T12:00:00Z" },
            new { op = "move", from = "/user/oldAddress", path = "/user/previousAddress" },
            new { op = "copy", from = "/user/name", path = "/user/displayName" },
            new { op = "test", path = "/user/version", value = 2 }
        });

        List<BaseEvent> events =
        [
            new RunStartedEvent { ThreadId = "thread1", RunId = "run1" },
            new StateDeltaEvent { Delta = originalDelta },
            new RunFinishedEvent { ThreadId = "thread1", RunId = "run1" }
        ];

        // Act - Convert to ChatResponseUpdate and back to events
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        List<BaseEvent> roundTripEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            roundTripEvents.Add(evt);
        }

        // Assert
        StateDeltaEvent? roundTripDelta = roundTripEvents.OfType<StateDeltaEvent>().FirstOrDefault();
        Assert.NotNull(roundTripDelta);
        Assert.NotNull(roundTripDelta.Delta);

        JsonElement delta = roundTripDelta.Delta.Value;
        Assert.Equal(6, delta.GetArrayLength());

        // Verify each operation type
        Assert.Equal("add", delta[0].GetProperty("op").GetString());
        Assert.Equal("remove", delta[1].GetProperty("op").GetString());
        Assert.Equal("replace", delta[2].GetProperty("op").GetString());
        Assert.Equal("move", delta[3].GetProperty("op").GetString());
        Assert.Equal("copy", delta[4].GetProperty("op").GetString());
        Assert.Equal("test", delta[5].GetProperty("op").GetString());
    }

    #endregion State Delta Tests

    #region Reasoning Tests

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithReasoningMessageEndForWrongMessageId_ThrowsInvalidOperationExceptionAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ReasoningMessageStartEvent { MessageId = "reason1" },
            new ReasoningMessageContentEvent { MessageId = "reason1", Delta = "thinking..." },
            new ReasoningMessageEndEvent { MessageId = "reason2" } // Wrong message ID
        ];

        // Act & Assert
        await Assert.ThrowsAsync<InvalidOperationException>(async () =>
        {
            await foreach (var _ in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
            {
                // Consume stream to trigger exception
            }
        });
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithReasoningContent_EmitsCorrectReasoningEventSequenceAsync()
    {
        // Arrange
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("I need to think about this")]) { MessageId = "reason1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        Assert.IsType<RunStartedEvent>(outputEvents[0]);
        var reasoningStart = Assert.IsType<ReasoningStartEvent>(outputEvents[1]);
        var reasoningId = reasoningStart.MessageId;
        Assert.NotEqual("reason1", reasoningId);
        var reasoningMessageStart = Assert.IsType<ReasoningMessageStartEvent>(outputEvents[2]);
        var reasoningMessageId = reasoningMessageStart.MessageId;
        Assert.NotEqual(reasoningId, reasoningMessageId);
        var reasoningContent = Assert.IsType<ReasoningMessageContentEvent>(outputEvents[3]);
        Assert.Equal(reasoningMessageId, reasoningContent.MessageId);
        Assert.Equal("I need to think about this", reasoningContent.Delta);
        var reasoningMessageEnd = Assert.IsType<ReasoningMessageEndEvent>(outputEvents[4]);
        Assert.Equal(reasoningMessageId, reasoningMessageEnd.MessageId);
        var reasoningEnd = Assert.IsType<ReasoningEndEvent>(outputEvents[5]);
        Assert.Equal(reasoningId, reasoningEnd.MessageId);
        Assert.IsType<RunFinishedEvent>(outputEvents[6]);
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithMultipleReasoningDeltas_EmitsContentEventPerDeltaAsync()
    {
        // Arrange
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("First")]) { MessageId = "reason1" },
            new(ChatRole.Assistant, [new TextReasoningContent(" step")]) { MessageId = "reason1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        var contentEvents = outputEvents.OfType<ReasoningMessageContentEvent>().ToList();
        Assert.Equal(2, contentEvents.Count);
        Assert.Equal("First", contentEvents[0].Delta);
        Assert.Equal(" step", contentEvents[1].Delta);

        // Only one START/END pair
        Assert.Single(outputEvents.OfType<ReasoningStartEvent>());
        Assert.Single(outputEvents.OfType<ReasoningMessageStartEvent>());
        Assert.Single(outputEvents.OfType<ReasoningMessageEndEvent>());
        Assert.Single(outputEvents.OfType<ReasoningEndEvent>());
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithReasoningAndProtectedData_EmitsEncryptedValueEventAsync()
    {
        // Arrange
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("thinking") { ProtectedData = "encrypted-abc" }]) { MessageId = "reason1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        var reasoningMessageId = outputEvents.OfType<ReasoningMessageStartEvent>().Single().MessageId;
        Assert.NotEqual("reason1", reasoningMessageId);
        var encryptedEvent = outputEvents.OfType<ReasoningEncryptedValueEvent>().Single();
        Assert.Equal(reasoningMessageId, encryptedEvent.EntityId);
        Assert.Equal("encrypted-abc", encryptedEvent.EncryptedValue);
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithReasoningFollowedByText_EmitsBothEventSequencesAsync()
    {
        // Arrange
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("thinking")]) { MessageId = "reason1" },
            new(ChatRole.Assistant, [new TextContent("Hello")]) { MessageId = "msg1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        Assert.Contains(outputEvents, e => e is ReasoningStartEvent);
        Assert.Contains(outputEvents, e => e is ReasoningMessageContentEvent);
        Assert.Contains(outputEvents, e => e is ReasoningEndEvent);
        Assert.Contains(outputEvents, e => e is TextMessageStartEvent);
        Assert.Contains(outputEvents, e => e is TextMessageContentEvent);
        Assert.Contains(outputEvents, e => e is TextMessageEndEvent);
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithReasoningAndTextSharingSameMessageId_EmitsDistinctEventIdsAsync()
    {
        // Arrange
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("thinking")]) { MessageId = "shared1" },
            new(ChatRole.Assistant, [new TextContent("Hello")]) { MessageId = "shared1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        var reasoningId = outputEvents.OfType<ReasoningStartEvent>().Single().MessageId;
        var reasoningMessageId = outputEvents.OfType<ReasoningMessageStartEvent>().Single().MessageId;
        var textMessageId = outputEvents.OfType<TextMessageStartEvent>().Single().MessageId;
        Assert.NotEqual(reasoningId, reasoningMessageId);
        Assert.NotEqual(reasoningId, textMessageId);
        Assert.NotEqual(reasoningMessageId, textMessageId);
        Assert.Equal("shared1", textMessageId);
        Assert.All(outputEvents.OfType<ReasoningMessageContentEvent>(), e => Assert.Equal(reasoningMessageId, e.MessageId));
        Assert.Equal(reasoningMessageId, outputEvents.OfType<ReasoningMessageEndEvent>().Single().MessageId);
        Assert.Equal(reasoningId, outputEvents.OfType<ReasoningEndEvent>().Single().MessageId);
        Assert.All(outputEvents.OfType<TextMessageContentEvent>(), e => Assert.Equal("shared1", e.MessageId));
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithReasoningThenTextSharingSameMessageId_ClosesReasoningBlockBeforeTextStartAsync()
    {
        // Arrange
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("thinking")]) { MessageId = "shared1" },
            new(ChatRole.Assistant, [new TextContent("Hello")]) { MessageId = "shared1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        int reasoningMessageEndIndex = outputEvents.FindIndex(e => e is ReasoningMessageEndEvent);
        int reasoningEndIndex = outputEvents.FindIndex(e => e is ReasoningEndEvent);
        int textMessageStartIndex = outputEvents.FindIndex(e => e is TextMessageStartEvent);
        Assert.True(reasoningMessageEndIndex < textMessageStartIndex);
        Assert.True(reasoningEndIndex < textMessageStartIndex);
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithReasoningThenToolCallSharingSameMessageId_ClosesReasoningBlockBeforeToolCallStartAsync()
    {
        // Arrange
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("thinking about which tool to use")]) { MessageId = "shared1" },
            new(ChatRole.Assistant, [new FunctionCallContent("call-1", "GetWeather", new Dictionary<string, object?> { ["location"] = "Seattle" })]) { MessageId = "shared1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        int reasoningEndIndex = outputEvents.FindIndex(e => e is ReasoningEndEvent);
        int toolCallStartIndex = outputEvents.FindIndex(e => e is ToolCallStartEvent);
        Assert.True(reasoningEndIndex < toolCallStartIndex);
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithReasoningThenToolResultSharingSameMessageId_ClosesReasoningBlockBeforeToolResultAsync()
    {
        // Arrange
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("reflecting on result")]) { MessageId = "shared1" },
            new(ChatRole.Tool, [new FunctionResultContent("call-1", "72F and sunny")]) { MessageId = "shared1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        int reasoningEndIndex = outputEvents.FindIndex(e => e is ReasoningEndEvent);
        int toolCallResultIndex = outputEvents.FindIndex(e => e is ToolCallResultEvent);
        Assert.True(reasoningEndIndex < toolCallResultIndex);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithReasoningMessageSequence_ProducesTextReasoningContentPerDeltaAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ReasoningStartEvent { MessageId = "reason1" },
            new ReasoningMessageStartEvent { MessageId = "reason1" },
            new ReasoningMessageContentEvent { MessageId = "reason1", Delta = "First thought" },
            new ReasoningMessageContentEvent { MessageId = "reason1", Delta = " and more" },
            new ReasoningMessageEndEvent { MessageId = "reason1" },
            new ReasoningEndEvent { MessageId = "reason1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Equal(2, updates.Count);
        Assert.All(updates, u => Assert.Equal(ChatRole.Assistant, u.Role));
        Assert.All(updates, u => Assert.Equal("reason1", u.MessageId));
        var firstContent = Assert.IsType<TextReasoningContent>(updates[0].Contents[0]);
        Assert.Equal("First thought", firstContent.Text);
        var secondContent = Assert.IsType<TextReasoningContent>(updates[1].Contents[0]);
        Assert.Equal(" and more", secondContent.Text);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithReasoningStartAndEndEvents_DoNotProduceUpdatesAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ReasoningStartEvent { MessageId = "reason1" },
            new ReasoningEndEvent { MessageId = "reason1" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Empty(updates);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithReasoningEncryptedValueEvent_ProducesTextReasoningContentWithProtectedDataAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ReasoningEncryptedValueEvent { EntityId = "reason1", EncryptedValue = "secret-token" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Single(updates);
        Assert.Equal(ChatRole.Assistant, updates[0].Role);
        Assert.Equal("reason1", updates[0].MessageId);
        var content = Assert.IsType<TextReasoningContent>(updates[0].Contents[0]);
        Assert.Equal("secret-token", content.ProtectedData);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithReasoningMessageChunks_ProducesTextReasoningContentPerChunkAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ReasoningMessageChunkEvent { MessageId = "reason1", Delta = "chunk one" },
            new ReasoningMessageChunkEvent { MessageId = "reason1", Delta = " chunk two" },
            new ReasoningMessageChunkEvent { MessageId = "reason1", Delta = "" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Equal(2, updates.Count);
        Assert.All(updates, u => Assert.Equal(ChatRole.Assistant, u.Role));
        var firstContent = Assert.IsType<TextReasoningContent>(updates[0].Contents[0]);
        Assert.Equal("chunk one", firstContent.Text);
        var secondContent = Assert.IsType<TextReasoningContent>(updates[1].Contents[0]);
        Assert.Equal(" chunk two", secondContent.Text);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithReasoningMessageChunkEmptyDelta_ProducesNoUpdateAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ReasoningMessageChunkEvent { MessageId = "reason1", Delta = "" }
        ];

        // Act
        List<ChatResponseUpdate> updates = [];
        await foreach (ChatResponseUpdate update in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            updates.Add(update);
        }

        // Assert
        Assert.Empty(updates);
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithReasoningMessageStartWhileMessageInProgress_ThrowsInvalidOperationExceptionAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ReasoningMessageStartEvent { MessageId = "reason1" },
            new ReasoningMessageStartEvent { MessageId = "reason2" } // Overlapping start
        ];

        // Act & Assert
        await Assert.ThrowsAsync<InvalidOperationException>(async () =>
        {
            await foreach (var _ in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
            {
                // Consume stream to trigger exception
            }
        });
    }

    [Fact]
    public async Task AsChatResponseUpdatesAsync_WithReasoningMessageEndWithoutStart_ThrowsInvalidOperationExceptionAsync()
    {
        // Arrange
        List<BaseEvent> events =
        [
            new ReasoningMessageEndEvent { MessageId = "reason1" } // End without start
        ];

        // Act & Assert
        await Assert.ThrowsAsync<InvalidOperationException>(async () =>
        {
            await foreach (var _ in events.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
            {
                // Consume stream to trigger exception
            }
        });
    }

    [Fact]
    public async Task AsAGUIEventStreamAsync_WithProtectedDataOnly_EmitsEncryptedValueEventWithoutContentDeltaAsync()
    {
        // Arrange — TextReasoningContent with empty text but non-empty ProtectedData
        List<ChatResponseUpdate> updates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("") { ProtectedData = "encrypted-only" }]) { MessageId = "reason1" }
        ];

        // Act
        List<BaseEvent> outputEvents = [];
        await foreach (BaseEvent evt in updates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            outputEvents.Add(evt);
        }

        // Assert
        Assert.Contains(outputEvents, e => e is ReasoningStartEvent);
        Assert.Contains(outputEvents, e => e is ReasoningMessageStartEvent);
        Assert.DoesNotContain(outputEvents, e => e is ReasoningMessageContentEvent);
        var reasoningMessageId = outputEvents.OfType<ReasoningMessageStartEvent>().Single().MessageId;
        Assert.NotEqual("reason1", reasoningMessageId);
        var encryptedEvent = outputEvents.OfType<ReasoningEncryptedValueEvent>().Single();
        Assert.Equal(reasoningMessageId, encryptedEvent.EntityId);
        Assert.Equal("encrypted-only", encryptedEvent.EncryptedValue);
        Assert.Contains(outputEvents, e => e is ReasoningMessageEndEvent);
        Assert.Contains(outputEvents, e => e is ReasoningEndEvent);
    }

    [Fact]
    public async Task ReasoningContent_RoundTrip_OutboundThenInbound_PreservesTextAndProtectedDataAsync()
    {
        // Arrange
        List<ChatResponseUpdate> outboundUpdates =
        [
            new(ChatRole.Assistant, [new TextReasoningContent("I'm thinking") { ProtectedData = "enc-value" }]) { MessageId = "reason1" }
        ];

        // Act - outbound: ChatResponseUpdate → AGUI events
        List<BaseEvent> aguilEvents = [];
        await foreach (BaseEvent evt in outboundUpdates.ToAsyncEnumerableAsync().AsAGUIEventStreamAsync("thread1", "run1", AGUIJsonSerializerContext.Default.Options))
        {
            aguilEvents.Add(evt);
        }

        // Act - inbound: AGUI events → ChatResponseUpdate
        List<ChatResponseUpdate> inboundUpdates = [];
        await foreach (ChatResponseUpdate update in aguilEvents.ToAsyncEnumerableAsync().AsChatResponseUpdatesAsync(AGUIJsonSerializerContext.Default.Options))
        {
            inboundUpdates.Add(update);
        }

        // Assert
        var reasoningContents = inboundUpdates
            .SelectMany(u => u.Contents)
            .OfType<TextReasoningContent>()
            .ToList();

        Assert.Contains(reasoningContents, c => c.Text == "I'm thinking");
        Assert.Contains(reasoningContents, c => c.ProtectedData == "enc-value");
    }

    #endregion Reasoning Tests
}