fix stream error handling

src/Controller/AskSseController.php

@@ -40,6 +40,10 @@ final readonly class AskSseController
 
         return new StreamedResponse(
             function () use ($prompt, $clientId, $cookieResponse, $includeFullContext): void {
+                @set_time_limit(0);
+                @ini_set('output_buffering', 'off');
+                @ini_set('zlib.output_compression', '0');
+
                 while (ob_get_level() > 0) {
                     ob_end_flush();
                 }
@@ -49,7 +53,7 @@ final readonly class AskSseController
                 }
 
                 echo "retry: 3000\n\n";
-                flush();
+                $this->sendComment('stream-open');
 
                 if ($prompt === '') {
                     $this->sendEvent('error', 'Empty prompt');
@@ -59,6 +63,10 @@ final readonly class AskSseController
 
                 try {
                     foreach ($this->agentRunner->run($prompt, $clientId, $includeFullContext) as $chunk) {
+                        if (connection_aborted() === 1) {
+                            return;
+                        }
+
                         $chunk = str_replace(["\r\n", "\r"], "\n", $chunk);
                         $this->sendData($chunk);
                     }
@@ -77,12 +85,18 @@ final readonly class AskSseController
                 'Cache-Control' => 'no-cache, no-store, must-revalidate',
                 'Connection' => 'keep-alive',
                 'X-Accel-Buffering' => 'no',
+                'X-Content-Type-Options' => 'nosniff',
             ]
         );
     }
 
     private function sendData(string $data): void
     {
+        if ($data === '') {
+            $this->sendComment('keepalive');
+            return;
+        }
+
         $lines = explode("\n", $data);
 
         foreach ($lines as $line) {
@@ -90,7 +104,7 @@ final readonly class AskSseController
         }
 
         echo "\n\n";
-        flush();
+        $this->flushOutput();
     }
 
     private function sendEvent(string $event, string $data): void
@@ -99,6 +113,23 @@ final readonly class AskSseController
 
         echo "event: {$event}\n";
         echo "data: {$safe}\n\n";
-        flush();
+        $this->flushOutput();
+    }
+
+    private function sendComment(string $comment): void
+    {
+        $safe = str_replace(["\r", "\n"], ' ', $comment);
+
+        echo ': ' . $safe . "\n\n";
+        $this->flushOutput();
+    }
+
+    private function flushOutput(): void
+    {
+        if (function_exists('ob_flush')) {
+            @ob_flush();
+        }
+
+        @flush();
     }
 }