diff --git a/src/sentry/class_map/RuntimeContextManager.php b/src/sentry/class_map/RuntimeContextManager.php
index 640f35e89..c84ab29e2 100644
--- a/src/sentry/class_map/RuntimeContextManager.php
+++ b/src/sentry/class_map/RuntimeContextManager.php
@@ -34,6 +34,14 @@ final class RuntimeContextManager
 {
     private const PROCESS_EXECUTION_CONTEXT_KEY = 'sentry.process.execution_context';
 
+    /**
+     * Default flush timeout (seconds) used when endContext() is called without an explicit
+     * timeout. 0 means "do not wait": the transport drains its channel asynchronously and
+     * endContext() returns as soon as possible, so a full channel can never block the
+     * coroutine from terminating.
+     */
+    private const DEFAULT_FLUSH_TIMEOUT = 0;
+
     /**
      * @var HubInterface
      */
@@ -146,7 +154,9 @@ public function endContext(?int $timeout = null): void
         $runtimeContextId = $this->executionContextToRuntimeContext[$executionContextKey];
         unset($this->executionContextToRuntimeContext[$executionContextKey]);
 
-        $this->removeContextById($runtimeContextId, $timeout);
+        // Resolve the effective flush timeout here so that callers that omit it
+        // (e.g. SentrySdk::endContext()) can never block indefinitely; see DEFAULT_FLUSH_TIMEOUT.
+        $this->removeContextById($runtimeContextId, $timeout ?? self::DEFAULT_FLUSH_TIMEOUT);
     }
 
     private function createContextForExecutionContextKey(string $executionContextKey): void
@@ -165,6 +175,9 @@ private function removeContextById(string $runtimeContextId, ?int $timeout = nul
         }
 
         $runtimeContext = $this->activeContexts[$runtimeContextId];
+        // Release the context BEFORE flushing (intentional order): even when a flush segment
+        // below throws or times out, the context is already freed and the coroutine can
+        // terminate without leaking request state. Flushing is best-effort only.
         unset($this->activeContexts[$runtimeContextId]);
         // Remove any key mappings that may still reference this context.
         $this->removeExecutionContextMappingsForRuntimeContext($runtimeContextId);
@@ -176,6 +189,10 @@ private function removeContextById(string $runtimeContextId, ?int $timeout = nul
 
     private function flushRuntimeContextResources(RuntimeContext $runtimeContext, ?int $timeout, LoggerInterface $logger): void
     {
+        // Resolve the effective timeout once for every flush segment below. The context has
+        // already been released by the caller, so any failing/timing-out segment does not
+        // affect context release; each segment stays isolated in its own try/catch.
+        $timeout = $timeout ?? self::DEFAULT_FLUSH_TIMEOUT;
         $hub = $runtimeContext->getHub();
 
         // captureEvent can throw before transport send (for example from scope event processors
diff --git a/tests/Sentry/RuntimeContextManagerTest.php b/tests/Sentry/RuntimeContextManagerTest.php
new file mode 100644
index 000000000..58c24c4cb
--- /dev/null
+++ b/tests/Sentry/RuntimeContextManagerTest.php
@@ -0,0 +1,88 @@
+<?php
+
+declare(strict_types=1);
+/**
+ * This file is part of friendsofhyperf/components.
+ *
+ * @link     https://github.com/friendsofhyperf/components
+ * @document https://github.com/friendsofhyperf/components/blob/main/README.md
+ * @contact  huangdijia@gmail.com
+ */
+
+namespace FriendsOfHyperf\Tests\Sentry;
+
+use RuntimeException;
+use Sentry\ClientInterface;
+use Sentry\Options;
+use Sentry\State\HubInterface;
+use Sentry\State\RuntimeContextManager;
+use Sentry\Transport\Result;
+use Sentry\Transport\ResultStatus;
+
+// Load the component's class_map replacement for the SDK class (the same file the
+// ConfigProvider registers via the container class_map), so these tests exercise the
+// coroutine-safe implementation instead of the raw SDK class.
+require_once __DIR__ . '/../../src/sentry/class_map/RuntimeContextManager.php';
+
+beforeEach(function () {
+    // Mock hub + client so the RuntimeContextManager constructor never resolves the container
+    // ($baseHub->getClient() returns a truthy mock client).
+    $this->client = $this->createMock(ClientInterface::class);
+    $this->client->method('getOptions')->willReturn(new Options());
+    $this->client->method('captureEvent')->willReturn(null);
+
+    $this->baseHub = $this->createMock(HubInterface::class);
+    $this->baseHub->method('getClient')->willReturn($this->client);
+});
+
+test('startContext creates an isolated hub and marks the context active', function () {
+    // Tests run inside a coroutine via FriendsOfHyperf\Tests\TestCase, so the
+    // CoArrayObject-backed manager has a clean per-coroutine context here.
+    $manager = new RuntimeContextManager($this->baseHub);
+    $manager->startContext();
+
+    expect($manager->hasActiveContext())->toBeTrue();
+    expect($manager->getCurrentContext()->getHub())->not->toBe($this->baseHub);
+});
+
+test('endContext forwards the flush timeout to the client', function () {
+    $received = [];
+    $this->client->method('flush')->willReturnCallback(static function (?int $timeout) use (&$received) {
+        $received[] = $timeout;
+
+        return new Result(ResultStatus::success());
+    });
+
+    $manager = new RuntimeContextManager($this->baseHub);
+
+    $manager->startContext();
+    $manager->endContext(1500);
+    expect($received)->toBe([1500]);
+
+    $manager->startContext();
+    $manager->endContext(null);
+    expect($received)->toBe([1500, 0]);
+});
+
+test('endContext does not throw when the client flush throws and still releases the context', function () {
+    $this->client->method('flush')->willThrowException(new RuntimeException('transport unavailable'));
+
+    $manager = new RuntimeContextManager($this->baseHub);
+    $manager->startContext();
+
+    $manager->endContext();
+
+    expect($manager->hasActiveContext())->toBeFalse();
+});
+
+test('startContext is idempotent for the current execution key', function () {
+    $manager = new RuntimeContextManager($this->baseHub);
+
+    $manager->startContext();
+    $firstId = $manager->getCurrentContext()->getId();
+
+    $manager->startContext();
+    $secondId = $manager->getCurrentContext()->getId();
+
+    expect($secondId)->toBe($firstId);
+});