fix(messenger): add scope leak safety in worker subscriber

If startSpan fires but neither endSpanWithSuccess nor endSpanOnError
fires (e.g. worker killed, unhandled error in another subscriber),
the OTel context scope leaks into subsequent messages.

Now startSpan checks for a lingering scope at the beginning of each
message and cleans it up: detaches the scope, marks the orphaned span
as ERROR, and ends it. This prevents context pollution across messages.

Author: gaelreyrol

src/Instrumentation/Symfony/Messenger/WorkerMessageEventSubscriber.php

@@ -56,6 +56,17 @@ public function startSpan(WorkerMessageReceivedEvent $event): void
             return;
         }
 
+        // Clean up any lingering scope from a previous message that was not
+        // properly ended (e.g. worker killed, unhandled error in another subscriber).
+        $previousScope = Context::storage()->scope();
+        if (null !== $previousScope) {
+            $previousScope->detach();
+            $orphanedSpan = Span::fromContext($previousScope->context());
+            $orphanedSpan->setStatus(StatusCode::STATUS_ERROR, 'Span was not properly ended');
+            $orphanedSpan->end();
+            $this->logger->warning(sprintf('Cleaned up orphaned span "%s"', $orphanedSpan->getContext()->getSpanId()));
+        }
+
         // ensure propagation from incoming trace
         $context = $this->propagator->extract($event->getEnvelope(), new TraceStampPropagator($this->logger));
 

tests/Functional/Instrumentation/Messenger/MessengerWorkerTracingTest.php

@@ -154,4 +154,27 @@ public function testWorkerMessageFailedWithHandlerFailedException(): void
             'exception.message' => 'Handler B failed',
         ]);
     }
+
+    public function testLingeringScopeIsCleanedOnNextMessage(): void
+    {
+        $envelope1 = new Envelope(new DummyMessage('first'));
+        $envelope2 = new Envelope(new DummyMessage('second'));
+
+        // First message starts a span but is never handled/failed
+        $this->eventDispatcher->dispatch(new WorkerMessageReceivedEvent($envelope1, 'main'));
+
+        // Second message arrives — should clean up the orphaned span
+        $this->eventDispatcher->dispatch(new WorkerMessageReceivedEvent($envelope2, 'main'));
+        $this->eventDispatcher->dispatch(new WorkerMessageHandledEvent($envelope2, 'main'));
+
+        self::assertSpansCount(2);
+
+        $orphanedSpan = self::getSpans()[0];
+        self::assertSpanName($orphanedSpan, 'main App\Message\DummyMessage');
+        self::assertSpanStatus($orphanedSpan, new StatusData(StatusCode::STATUS_ERROR, 'Span was not properly ended'));
+
+        $normalSpan = self::getSpans()[1];
+        self::assertSpanName($normalSpan, 'main App\Message\DummyMessage');
+        self::assertSpanStatus($normalSpan, StatusData::ok());
+    }
 }