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fix: ChatController naming consistency and streaming cancellation/error handling #1089

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Merged
BenjaminMichaelis merged 9 commits into from
May 16, 2026
Merged

fix: ChatController naming consistency and streaming cancellation/error handling #1089

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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
9038dbd
Harden forwarded headers trust configuration
BenjaminMichaelis May 16, 2026
58a00fe
Merge origin/main into copilot/fix-inconsistent-casing-ai-chat-service
BenjaminMichaelis May 16, 2026
7e45bac
Refine chat stream cancellation handling
BenjaminMichaelis May 16, 2026
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55 changes: 29 additions & 26 deletions EssentialCSharp.Web/Controllers/ChatController.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,13 +15,13 @@ 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 +46,7 @@ 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 +75,15 @@ 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 +94,7 @@ 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 +104,7 @@ 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 @@ -133,46 +133,49 @@ 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)
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{
LogChatStreamCancelled(_Logger, User.Identity?.Name);
}
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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);
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);
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}
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)
{
// 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.
}
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Fixed
}
}
catch (Exception ex) when (!Response.HasStarted)
{
LogChatStreamErrorBeforeResponseStarted(_Logger, ex, User.Identity?.Name);
Response.StatusCode = 500;
Response.ContentType = "application/json";
await Response.WriteAsJsonAsync(new { error = "Chat service unavailable" }, CancellationToken.None);
await Response.WriteAsJsonAsync(new { error = "Chat service unavailable" }, cancellationToken);
}
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)
{
Expand Down
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