Skip to content

Fix ChatController naming consistency and streaming cancellation/error handling #1089

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Copilot wants to merge 6 commits into
base: main
Choose a base branch
from
+69 −29
Open

Fix ChatController naming consistency and streaming cancellation/error handling #1089

Changes from all commits
Commits
Show all changes
6 commits
Select commit Hold shift + click to select a range
89fe09b
Initial plan
Copilot May 13, 2026
4e9b2f6
Fix ChatController streaming cancellation handling
Copilot May 13, 2026
8397a8d
Potential fix for pull request finding 'Generic catch clause'
BenjaminMichaelis May 13, 2026
223a9bf
Fix chat stream cancellation and write error handling
Copilot May 13, 2026
ae6bf10
Document expected chat response write suppression
Copilot May 13, 2026
f2ca026
Relax stream cancellation filter after response start
Copilot May 14, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
98 changes: 69 additions & 29 deletions EssentialCSharp.Web/Controllers/ChatController.cs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
using System.IO;
using System.Security.Claims;
using System.Text.Json;
using EssentialCSharp.Chat.Common.Services;
Expand All @@ -15,13 +16,13 @@ namespace EssentialCSharp.Web.Controllers;
[IgnoreAntiforgeryToken]
public partial class ChatController : ControllerBase
{
private readonly AIChatService _AiChatService;
private readonly AIChatService _AIChatService;
private readonly ResponseIdValidationService _ResponseIdValidationService;
private readonly ILogger<ChatController> _Logger;

public ChatController(ILogger<ChatController> logger, AIChatService aiChatService, ResponseIdValidationService responseIdValidationService)
{
_AiChatService = aiChatService;
_AIChatService = aiChatService;
_ResponseIdValidationService = responseIdValidationService;
_Logger = logger;
}
Expand All @@ -46,7 +47,7 @@ public async Task<IActionResult> SendMessage([FromBody] ChatMessageRequest reque

try
{
var (response, responseId) = await _AiChatService.GetChatCompletion(
var (response, responseId) = await _AIChatService.GetChatCompletion(
prompt: request.Message,
previousResponseId: previousResponseId,
enableContextualSearch: request.EnableContextualSearch,
Expand Down Expand Up @@ -75,15 +76,15 @@ public async Task StreamMessage([FromBody] ChatMessageRequest request, Cancellat
if (string.IsNullOrEmpty(request.Message))
{
Response.StatusCode = 400;
await Response.WriteAsJsonAsync(new { error = "Message cannot be empty." }, CancellationToken.None);
await Response.WriteAsJsonAsync(new { error = "Message cannot be empty." }, cancellationToken);
return;
}

var userId = User.FindFirstValue(ClaimTypes.NameIdentifier);
if (string.IsNullOrEmpty(userId))
{
Response.StatusCode = 401;
await Response.WriteAsJsonAsync(new { error = "Unauthorized." }, CancellationToken.None);
await Response.WriteAsJsonAsync(new { error = "Unauthorized." }, cancellationToken);
return;
}

Expand All @@ -94,7 +95,7 @@ public async Task StreamMessage([FromBody] ChatMessageRequest request, Cancellat
if (!_ResponseIdValidationService.ValidateResponseId(userId, previousResponseId))
{
Response.StatusCode = 400;
await Response.WriteAsJsonAsync(new { error = "Invalid conversation context." }, CancellationToken.None);
await Response.WriteAsJsonAsync(new { error = "Invalid conversation context." }, cancellationToken);
return;
}

Expand All @@ -104,7 +105,7 @@ public async Task StreamMessage([FromBody] ChatMessageRequest request, Cancellat

try
{
await foreach (var (text, responseId) in _AiChatService.GetChatCompletionStream(
await foreach (var (text, responseId) in _AIChatService.GetChatCompletionStream(
prompt: request.Message,
previousResponseId: previousResponseId,
enableContextualSearch: request.EnableContextualSearch,
Expand Down Expand Up @@ -133,53 +134,92 @@ public async Task StreamMessage([FromBody] ChatMessageRequest request, Cancellat
await Response.WriteAsync("data: [DONE]\n\n", cancellationToken);
await Response.Body.FlushAsync(cancellationToken);
}
catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested || HttpContext.RequestAborted.IsCancellationRequested)
catch (OperationCanceledException) when (Response.HasStarted || cancellationToken.IsCancellationRequested || HttpContext.RequestAborted.IsCancellationRequested)
{
LogChatStreamCancelled(_Logger, User.Identity?.Name);
}
catch (ConversationContextLimitExceededException) when (!Response.HasStarted)
{
Response.StatusCode = 400;
Response.ContentType = "application/json";
await Response.WriteAsJsonAsync(new { error = "This conversation has grown too long. Please start a new one.", errorCode = "context_limit_exceeded" }, CancellationToken.None);
}
catch (ConversationContextLimitExceededException ex)
{
LogChatStreamErrorMidStream(_Logger, ex, User.Identity?.Name);
try
if (!Response.HasStarted)
{
await Response.WriteAsync("data: {\"type\":\"error\",\"message\":\"This conversation has grown too long. Please start a new one.\",\"errorCode\":\"context_limit_exceeded\"}\n\n", CancellationToken.None);
await Response.Body.FlushAsync(CancellationToken.None);
if (cancellationToken.IsCancellationRequested || HttpContext.RequestAborted.IsCancellationRequested)
return;

Response.StatusCode = 400;
Response.ContentType = "application/json";
try
{
await Response.WriteAsJsonAsync(new { error = "This conversation has grown too long. Please start a new one.", errorCode = "context_limit_exceeded" }, cancellationToken);
}
catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested || HttpContext.RequestAborted.IsCancellationRequested)
{
// Best-effort write during an aborted request — no response body can be delivered.
}
catch (IOException) when (HttpContext.RequestAborted.IsCancellationRequested)
{
// Expected client disconnect while attempting a best-effort error response write.
}
catch (ObjectDisposedException) when (HttpContext.RequestAborted.IsCancellationRequested)
{
// Response stream can already be disposed after an abrupt client disconnect.
}
}
catch (Exception)
else
{
// Best-effort write to an already-streaming response. Kestrel can throw
// IOException (connection reset), OperationCanceledException, or
// ObjectDisposedException on abrupt client disconnect — swallow all to
// avoid masking the original exception.
LogChatStreamErrorMidStream(_Logger, ex, User.Identity?.Name);
try
{
await Response.WriteAsync("data: {\"type\":\"error\",\"message\":\"This conversation has grown too long. Please start a new one.\",\"errorCode\":\"context_limit_exceeded\"}\n\n", cancellationToken);
await Response.Body.FlushAsync(cancellationToken);
}
catch (Exception writeException) when (writeException is IOException or OperationCanceledException or ObjectDisposedException)
{
// Best-effort write to an already-streaming response. Kestrel can throw
// IOException (connection reset), OperationCanceledException, or
// ObjectDisposedException on abrupt client disconnect — swallow expected
// transport/disconnect exceptions to avoid masking the original exception.
}
}
}
catch (Exception ex) when (!Response.HasStarted)
{
LogChatStreamErrorBeforeResponseStarted(_Logger, ex, User.Identity?.Name);
if (cancellationToken.IsCancellationRequested || HttpContext.RequestAborted.IsCancellationRequested)
return;

Response.StatusCode = 500;
Response.ContentType = "application/json";
await Response.WriteAsJsonAsync(new { error = "Chat service unavailable" }, CancellationToken.None);
try
{
await Response.WriteAsJsonAsync(new { error = "Chat service unavailable" }, cancellationToken);
}
catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested || HttpContext.RequestAborted.IsCancellationRequested)
{
// Best-effort write during an aborted request — no response body can be delivered.
}
catch (IOException) when (HttpContext.RequestAborted.IsCancellationRequested)
{
// Expected client disconnect while attempting a best-effort error response write.
}
catch (ObjectDisposedException) when (HttpContext.RequestAborted.IsCancellationRequested)
{
// Response stream can already be disposed after an abrupt client disconnect.
}
}
catch (Exception ex)
{
LogChatStreamErrorMidStream(_Logger, ex, User.Identity?.Name);
try
{
await Response.WriteAsync("data: {\"type\":\"error\",\"message\":\"Stream interrupted\"}\n\n", CancellationToken.None);
await Response.Body.FlushAsync(CancellationToken.None);
await Response.WriteAsync("data: {\"type\":\"error\",\"message\":\"Stream interrupted\"}\n\n", cancellationToken);
await Response.Body.FlushAsync(cancellationToken);
}
catch (Exception)
catch (Exception writeException) when (writeException is IOException or OperationCanceledException or ObjectDisposedException)
{
// Best-effort write to an already-streaming response. Kestrel can throw
// IOException (connection reset), OperationCanceledException, or
// ObjectDisposedException on abrupt client disconnect — swallow all to
// avoid masking the original exception.
// ObjectDisposedException on abrupt client disconnect — swallow expected
// transport/disconnect exceptions to avoid masking the original exception.
}
}
}
Expand Down