diff --git a/src/sentry/class_map/RuntimeContextManager.php b/src/sentry/class_map/RuntimeContextManager.php
index 640f35e89..ad3b44c18 100644
--- a/src/sentry/class_map/RuntimeContextManager.php
+++ b/src/sentry/class_map/RuntimeContextManager.php
@@ -26,6 +26,8 @@
  * - The manager keeps a lazily initialized global context as fallback.
  * - startContext() creates an isolated runtime context for the current
  *   execution key when no context is active yet.
+ * - startContext() only takes effect inside a coroutine; in non-coroutine
+ *   environments it is a no-op and the global fallback context is used.
  * - endContext() flushes context resources and removes that context.
  *
  * @internal
@@ -120,6 +122,13 @@ public function hasActiveContext(): bool
      */
     public function startContext(): void
     {
+        // The main coroutine (non-coroutine environment, Coroutine::id() <= 0)
+        // uses a process-level context store that is not reaped together with
+        // a coroutine, so falling back to the global context is safer there.
+        if (\Hyperf\Engine\Coroutine::id() <= 0) {
+            return;
+        }
+
         $executionContextKey = $this->getExecutionContextKey();
 
         if ($this->hasActiveContextForExecutionContextKey($executionContextKey)) {
@@ -279,8 +288,11 @@ private function generateRuntimeContextId(): string
 
     private function getExecutionContextKey(): string
     {
-        // All supported runtime modes currently use a process-local execution key.
-        return self::PROCESS_EXECUTION_CONTEXT_KEY;
+        // The key is scoped per coroutine so execution context mappings cannot
+        // leak across coroutines or linger on the main coroutine. CoArrayObject
+        // already stores values per current coroutine, so normal behavior is
+        // unchanged.
+        return \sprintf('%s.%d', self::PROCESS_EXECUTION_CONTEXT_KEY, \Hyperf\Engine\Coroutine::id());
     }
 
     private function getGlobalContext(): RuntimeContext
diff --git a/tests/Sentry/RuntimeContextLifecycleTest.php b/tests/Sentry/RuntimeContextLifecycleTest.php
new file mode 100644
index 000000000..6f4205b74
--- /dev/null
+++ b/tests/Sentry/RuntimeContextLifecycleTest.php
@@ -0,0 +1,137 @@
+<?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 FriendsOfHyperf\CoPHPUnit\Attributes\NonCoroutine;
+use FriendsOfHyperf\Tests\TestCase;
+use Mockery;
+use Sentry\ClientInterface;
+use Sentry\Options;
+use Sentry\State\HubInterface;
+use Sentry\State\RuntimeContextManager;
+use Sentry\Transport\Result;
+use Sentry\Transport\ResultStatus;
+use Swoole\Coroutine;
+use Swoole\Coroutine\Channel;
+
+// The SDK class is replaced via Hyperf's class_map injection at runtime, which
+// is not active in the test process, so load the replacement file explicitly
+// to exercise the coroutine-aware implementation under test.
+require_once __DIR__ . '/../../src/sentry/class_map/RuntimeContextManager.php';
+
+/**
+ * @internal
+ */
+class RuntimeContextLifecycleTest extends TestCase
+{
+    public function testStartAndEndContextInsideCoroutine(): void
+    {
+        $manager = $this->createRuntimeContextManager();
+
+        $manager->startContext();
+
+        $this->assertTrue($manager->hasActiveContext());
+
+        $manager->endContext();
+
+        $this->assertFalse($manager->hasActiveContext());
+    }
+
+    #[NonCoroutine]
+    public function testStartContextIsIgnoredOnMainCoroutine(): void
+    {
+        $this->assertSame(-1, Coroutine::getCid());
+
+        $manager = $this->createRuntimeContextManager();
+
+        $manager->startContext();
+
+        // The main coroutine uses a process-level context store that is never
+        // reaped, so startContext() is a no-op and the global fallback is used.
+        $this->assertFalse($manager->hasActiveContext());
+        $this->assertSame('global', $manager->getCurrentContext()->getId());
+    }
+
+    public function testContextsAreIsolatedAcrossCoroutines(): void
+    {
+        $manager = $this->createRuntimeContextManager();
+        $channelA = new Channel(1);
+        $channelB = new Channel(1);
+        $result = [];
+
+        Coroutine::create(function () use ($manager, $channelA, &$result): void {
+            $manager->startContext();
+            $result['a_id'] = $manager->getCurrentContext()->getId();
+            $result['a_active'] = $manager->hasActiveContext();
+            $channelA->push('started');
+            $channelA->pop(); // Wait for the "end A" signal.
+            $manager->endContext();
+            $result['a_active_after_end'] = $manager->hasActiveContext();
+            $channelA->push('done');
+        });
+
+        Coroutine::create(function () use ($manager, $channelB, &$result): void {
+            $manager->startContext();
+            $result['b_id'] = $manager->getCurrentContext()->getId();
+            $result['b_active'] = $manager->hasActiveContext();
+            $channelB->push('started');
+            $channelB->pop(); // Wait for the "A ended" signal.
+            $result['b_active_after_a_end'] = $manager->hasActiveContext();
+            $channelB->push('done');
+        });
+
+        $channelA->pop(); // A started.
+        $channelB->pop(); // B started.
+
+        $this->assertNotSame($result['a_id'], $result['b_id']);
+        $this->assertTrue($result['a_active']);
+        $this->assertTrue($result['b_active']);
+
+        $channelA->push('end');
+        $channelA->pop(); // A finished ending its context.
+
+        $channelB->push('check');
+        $channelB->pop(); // B verified its own context is still active.
+
+        $this->assertFalse($result['a_active_after_end']);
+        $this->assertTrue($result['b_active_after_a_end']);
+    }
+
+    public function testStartContextIsIdempotentWithinSameCoroutine(): void
+    {
+        $manager = $this->createRuntimeContextManager();
+
+        $manager->startContext();
+        $firstId = $manager->getCurrentContext()->getId();
+        $manager->startContext();
+
+        // A nested start for the same execution key is a no-op.
+        $this->assertSame($firstId, $manager->getCurrentContext()->getId());
+        $this->assertTrue($manager->hasActiveContext());
+
+        $manager->endContext();
+
+        $this->assertFalse($manager->hasActiveContext());
+    }
+
+    private function createRuntimeContextManager(): RuntimeContextManager
+    {
+        $client = Mockery::mock(ClientInterface::class);
+        $client->shouldReceive('getOptions')->andReturn(new Options());
+        $client->shouldReceive('flush')->andReturn(new Result(ResultStatus::success()));
+
+        $hub = Mockery::mock(HubInterface::class);
+        $hub->shouldReceive('getClient')->andReturn($client);
+
+        return new RuntimeContextManager($hub);
+    }
+}