diff --git a/phpstan.neon b/phpstan.neon
index 718611fbd..aef873d37 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -64,6 +64,7 @@ parameters:
           paths:
               - tests/unit/DurableLaravel/*
               - tests/unit/Bridge/Illuminate/*
+              - tests/integration/Temporal/Hosts/*
         # A test asserts at runtime what its types promise: an assertion PHPStan already proves is
         # still the check the test makes, and what keeps it from being a test without assertion.
         - identifier: staticMethod.alreadyNarrowedType
diff --git a/tests/integration/Temporal/Fixtures/HeartbeatActivities.php b/tests/integration/Temporal/Fixtures/HeartbeatActivities.php
new file mode 100644
index 000000000..0c2e4f22b
--- /dev/null
+++ b/tests/integration/Temporal/Fixtures/HeartbeatActivities.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace integration\Temporal\Fixtures;
+
+use Gplanchat\Durable\Attribute\AsActivityMethod;
+
+/**
+ * The activities that heartbeat, hosted by a framework's own activity worker rather than by the
+ * suite's `worker.php` (#518).
+ */
+interface HeartbeatActivities
+{
+    /** Heartbeats once a second for `$seconds`, then returns how many beats it sent. */
+    #[AsActivityMethod('heartbeat.for')]
+    public function heartbeatFor(int $seconds): int;
+
+    /**
+     * Heartbeats once a second until a heartbeat answers that the server asked for cancellation,
+     * then writes it to `$marker`: the test reads the file, since a cancelled activity's result
+     * reaches no one.
+     */
+    #[AsActivityMethod('heartbeat.until_cancelled')]
+    public function heartbeatUntilCancelled(string $marker): string;
+}
diff --git a/tests/integration/Temporal/Fixtures/HeartbeatingActivities.php b/tests/integration/Temporal/Fixtures/HeartbeatingActivities.php
new file mode 100644
index 000000000..4d7a7ac78
--- /dev/null
+++ b/tests/integration/Temporal/Fixtures/HeartbeatingActivities.php
@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace integration\Temporal\Fixtures;
+
+use Gplanchat\Durable\Port\ActivityHeartbeatSenderInterface;
+
+/**
+ * Takes its sender the way an application's activity does: injected by the host's container (#510).
+ */
+final class HeartbeatingActivities implements HeartbeatActivities
+{
+    private const MAX_SECONDS = 60;
+
+    public function __construct(private readonly ActivityHeartbeatSenderInterface $heartbeat) {}
+
+    public function heartbeatFor(int $seconds): int
+    {
+        for ($beat = 1; $beat <= $seconds; ++$beat) {
+            sleep(1);
+            $this->heartbeat->sendHeartbeat(['beat' => $beat]);
+        }
+
+        return $seconds;
+    }
+
+    public function heartbeatUntilCancelled(string $marker): string
+    {
+        for ($beat = 1; $beat <= self::MAX_SECONDS; ++$beat) {
+            sleep(1);
+            if ($this->heartbeat->sendHeartbeat(['beat' => $beat])) {
+                file_put_contents($marker, 'cancel-requested');
+
+                return 'cancelled';
+            }
+        }
+        file_put_contents($marker, 'never-cancelled');
+
+        return 'never cancelled';
+    }
+}
diff --git a/tests/integration/Temporal/Fixtures/IntegrationWorkflows.php b/tests/integration/Temporal/Fixtures/IntegrationWorkflows.php
index 779518323..dc1b4d18d 100644
--- a/tests/integration/Temporal/Fixtures/IntegrationWorkflows.php
+++ b/tests/integration/Temporal/Fixtures/IntegrationWorkflows.php
@@ -175,6 +175,35 @@ public static function registerWorkflows(WorkflowRegistry $registry): void
                 $env->childWorkflowStub(DoublerWorkflow::class)->run((int) ($input['value'] ?? 0)),
             )];
         });
+
+        // One attempt: an activity whose heartbeats never arrive fails on its heartbeat timeout
+        // instead of being retried until the test gives up (#518).
+        $registry->registerFactory('HeartbeatsThroughItsTimeout', static fn(array $input) => static fn(WorkflowEnvironment $env): array => [
+            'beats' => $env->await($env->activityStub(HeartbeatActivities::class, self::heartbeatOptions())->heartbeatFor((int) ($input['seconds'] ?? 30))),
+        ]);
+
+        // The deadline cancels the activity it outlives: the server records the request and hands
+        // it to the activity's next heartbeat (#518). The run then stays open for a few heartbeats:
+        // once it closes, a heartbeat hears "not found", not "cancel requested".
+        $registry->registerFactory('CancelsItsHeartbeatingActivity', static fn(array $input) => static function (WorkflowEnvironment $env) use ($input): array {
+            try {
+                $env->await($env->activityStub(HeartbeatActivities::class, self::heartbeatOptions())->heartbeatUntilCancelled((string) ($input['marker'] ?? '')), Duration::seconds(3));
+            } catch (DeadlineExceededException) {
+                $env->sleep(Duration::seconds(10));
+
+                return ['deadline' => true];
+            }
+
+            return ['deadline' => false];
+        });
+    }
+
+    private static function heartbeatOptions(): ActivityOptions
+    {
+        return new ActivityOptions(
+            RetryLimit::once(),
+            timeouts: ActivityTimeouts::attempt(Duration::seconds(60))->withHeartbeat(Duration::seconds(5)),
+        );
     }
 
     /** Exposed for {@see DoublerWorkflow}, which lives outside this class. */
diff --git a/tests/integration/Temporal/HeartbeatOnAHostTestCase.php b/tests/integration/Temporal/HeartbeatOnAHostTestCase.php
new file mode 100644
index 000000000..9c7d5a08f
--- /dev/null
+++ b/tests/integration/Temporal/HeartbeatOnAHostTestCase.php
@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+namespace integration\Temporal;
+
+use Temporal\Api\Common\V1\WorkflowExecution;
+use Temporal\Api\Enums\V1\WorkflowExecutionStatus;
+use Temporal\Api\Workflowservice\V1\DescribeWorkflowExecutionRequest;
+
+/**
+ * The heartbeat scenarios of #510 against a real server, with the activities hosted by a
+ * framework's activity worker rather than by this suite's own (#518). The workflows run on the
+ * suite's workflow worker; only the activity side changes host.
+ *
+ * The workers are killed in the parent's tearDown(), which runs whether the test passed or not.
+ */
+abstract class HeartbeatOnAHostTestCase extends TemporalServerTestCase
+{
+    private const MARKER_TIMEOUT_SECONDS = 30.0;
+
+    /** @var list<string> */
+    private array $markers = [];
+
+    protected function tearDown(): void
+    {
+        foreach ($this->markers as $marker) {
+            @unlink($marker);
+        }
+        parent::tearDown();
+    }
+
+    /**
+     * Thirty seconds of heartbeats, one a second, under a five-second heartbeat timeout and a single
+     * attempt: the activity completes only if its heartbeats reach the server through the sender its
+     * host injected. With the no-op sender, the server times it out after five seconds and the run
+     * never completes (until #544 it did not even fail: the bounded wait below reports it).
+     */
+    public function testAHeartbeatingActivityOutlivesItsHeartbeatTimeout(): void
+    {
+        self::assertSame(['beats' => 30], $this->runWithin('HeartbeatsThroughItsTimeout', ['seconds' => 30], 90.0));
+    }
+
+    /**
+     * The workflow's deadline cancels the activity it outlives; the server hands the request to the
+     * activity's next heartbeat, and sendHeartbeat() returns true.
+     */
+    public function testACancellationRequestedByTheServerReachesSendHeartbeat(): void
+    {
+        $marker = $this->markers[] = sys_get_temp_dir() . '/durable-heartbeat-' . bin2hex(random_bytes(6));
+
+        self::assertSame(['deadline' => true], $this->runWithin('CancelsItsHeartbeatingActivity', ['marker' => $marker], 60.0));
+
+        $deadline = microtime(true) + self::MARKER_TIMEOUT_SECONDS;
+        while (!is_file($marker) && microtime(true) < $deadline) {
+            usleep(250_000);
+        }
+        self::assertFileExists($marker, \sprintf('No heartbeat of the %s-hosted activity reported the cancellation within %.0f s.', $this->activityWorkerRole(), self::MARKER_TIMEOUT_SECONDS));
+        self::assertSame('cancel-requested', file_get_contents($marker));
+    }
+
+    /**
+     * Starts the workflow and returns its result, failing after `$seconds` of wall-clock time: the
+     * status is read with a describe, which does not block, and the result only once the run closed.
+     *
+     * @param array<string, mixed> $input
+     */
+    private function runWithin(string $workflowType, array $input, float $seconds): mixed
+    {
+        $executionId = $this->startWorkflow($workflowType, $input);
+        $request = new DescribeWorkflowExecutionRequest([
+            'namespace' => $this->connection->namespace->name(),
+            'execution' => new WorkflowExecution(['workflow_id' => $this->workflowId($executionId)]),
+        ]);
+
+        $deadline = microtime(true) + $seconds;
+        do {
+            $status = $this->client->DescribeWorkflowExecution($request, [], ['timeout' => 5_000_000])->getWorkflowExecutionInfo()?->getStatus();
+            if (WorkflowExecutionStatus::WORKFLOW_EXECUTION_STATUS_RUNNING !== $status) {
+                return $this->workflowClient()->pollForCompletion($executionId, 0, 1);
+            }
+            usleep(250_000);
+        } while (microtime(true) < $deadline);
+
+        self::fail(\sprintf('The %s run did not close within %.0f s; its activities are hosted by the %s worker.', $workflowType, $seconds, $this->activityWorkerRole()));
+    }
+}
diff --git a/tests/integration/Temporal/Hosts/laravel-activity.php b/tests/integration/Temporal/Hosts/laravel-activity.php
new file mode 100644
index 000000000..d0239065b
--- /dev/null
+++ b/tests/integration/Temporal/Hosts/laravel-activity.php
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * The Temporal activity worker as a Laravel application gets it: `DurableServiceProvider` on a bare
+ * container with `backend: temporal`, the activities resolved from that container, so the sender
+ * they inject is the provider's (#510, #518). The loop is `durable:temporal-worker --role=activity`
+ * with `--max-time`: illuminate/console is not a root dependency, so the command itself cannot run.
+ *
+ * DURABLE_HEARTBEAT=noop hands the activities the no-op sender instead, to show the heartbeat test
+ * red. Only this script reads it: nothing under src/ knows it.
+ *
+ * Required by worker.php, whose arguments it reads: <address> <namespace> <taskQueue> <role> [transport].
+ */
+
+use Gplanchat\Bridge\Temporal\Worker\TemporalActivityWorker;
+use Gplanchat\Durable\Activity\NullActivityHeartbeatSender;
+use Gplanchat\Durable\Activity\PayloadToContractMethodInvoker;
+use Gplanchat\Durable\Laravel\DurableServiceProvider;
+use Gplanchat\Durable\Port\ActivityHeartbeatSenderInterface;
+use Gplanchat\Durable\RegistryActivityExecutor;
+use Illuminate\Container\Container;
+use integration\Temporal\Fixtures\HeartbeatActivities;
+use integration\Temporal\Fixtures\HeartbeatingActivities;
+
+$arguments = $_SERVER['argv'] ?? null;
+if (!\is_array($arguments) || !isset($arguments[1], $arguments[2], $arguments[3])) {
+    fwrite(\STDERR, "Usage: worker.php <address> <namespace> <taskQueue> <role> [transport]\n");
+
+    exit(1);
+}
+[$address, $namespace, $taskQueue] = [$arguments[1], $arguments[2], $arguments[3]];
+$transport = $arguments[5] ?? 'auto';
+
+$dsn = \sprintf(
+    'temporal://%s?namespace=%s&journal_task_queue=%3$s&workflow_task_queue=%3$s&activity_task_queue=%3$s&transport=%4$s',
+    $address,
+    rawurlencode($namespace),
+    rawurlencode($taskQueue),
+    rawurlencode($transport),
+);
+
+$app = new Container();
+$app->instance('config', new ArrayObject(['durable' => ['backend' => 'temporal', 'temporal' => ['dsn' => $dsn]]], ArrayObject::ARRAY_AS_PROPS));
+(new DurableServiceProvider($app))->register();
+
+if ('noop' === getenv('DURABLE_HEARTBEAT')) {
+    $app->instance(ActivityHeartbeatSenderInterface::class, new NullActivityHeartbeatSender());
+}
+$activities = $app->make(HeartbeatingActivities::class);
+$executor = $app->make(RegistryActivityExecutor::class);
+foreach ((new ReflectionClass(HeartbeatActivities::class))->getMethods() as $method) {
+    $name = $method->getAttributes(Gplanchat\Durable\Attribute\AsActivityMethod::class)[0]->newInstance()->name;
+    $executor->register($name, new PayloadToContractMethodInvoker($activities, HeartbeatActivities::class, $method->getName()));
+}
+
+$worker = $app->make(TemporalActivityWorker::class);
+$deadline = microtime(true) + (float) (getenv('DURABLE_HOST_WORKER_MAX_TIME') ?: 180);
+while (microtime(true) < $deadline) {
+    try {
+        $worker->pollOnce();
+    } catch (Throwable $e) {
+        fwrite(STDERR, 'laravel activity worker: ' . $e::class . ': ' . $e->getMessage() . "\n");
+    }
+}
diff --git a/tests/integration/Temporal/Hosts/magento-activity.php b/tests/integration/Temporal/Hosts/magento-activity.php
new file mode 100644
index 000000000..0177415bb
--- /dev/null
+++ b/tests/integration/Temporal/Hosts/magento-activity.php
@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * The Temporal activity worker as the Magento module gets it: `RuntimeFactory::activityWorker()`,
+ * with the shared sender `di.xml` hands the activities (#510, #518). The factory is plain PHP, so
+ * it runs here without a Mage-OS install; what Magento adds around it is the ObjectManager and the
+ * `bin/magento` command that turns this loop.
+ *
+ * DURABLE_HEARTBEAT=noop hands the activities the no-op sender instead, to show the heartbeat test
+ * red. Only this script reads it: nothing under src/ knows it.
+ *
+ * Required by worker.php, whose arguments it reads: <address> <namespace> <taskQueue> <role> [transport].
+ */
+
+use Gplanchat\Durable\Activity\NullActivityHeartbeatSender;
+use Gplanchat\DurableModule\Runtime\RuntimeFactory;
+use Gplanchat\DurableModule\Runtime\SharedActivityHeartbeatSender;
+use integration\Temporal\Fixtures\HeartbeatingActivities;
+
+$arguments = $_SERVER['argv'] ?? null;
+if (!\is_array($arguments) || !isset($arguments[1], $arguments[2], $arguments[3])) {
+    fwrite(\STDERR, "Usage: worker.php <address> <namespace> <taskQueue> <role> [transport]\n");
+
+    exit(1);
+}
+[$address, $namespace, $taskQueue] = [$arguments[1], $arguments[2], $arguments[3]];
+$transport = $arguments[5] ?? 'auto';
+
+$dsn = \sprintf(
+    'temporal://%s?namespace=%s&journal_task_queue=%3$s&workflow_task_queue=%3$s&activity_task_queue=%3$s&transport=%4$s',
+    $address,
+    rawurlencode($namespace),
+    rawurlencode($taskQueue),
+    rawurlencode($transport),
+);
+
+$shared = new SharedActivityHeartbeatSender();
+$factory = new RuntimeFactory(
+    activityHandlers: [new HeartbeatingActivities('noop' === getenv('DURABLE_HEARTBEAT') ? new NullActivityHeartbeatSender() : $shared)],
+    temporalDsn: $dsn,
+    heartbeat: $shared,
+);
+
+$worker = $factory->activityWorker();
+$deadline = microtime(true) + (float) (getenv('DURABLE_HOST_WORKER_MAX_TIME') ?: 180);
+while (microtime(true) < $deadline) {
+    try {
+        $worker->pollOnce();
+    } catch (Throwable $e) {
+        fwrite(STDERR, 'magento activity worker: ' . $e::class . ': ' . $e->getMessage() . "\n");
+    }
+}
diff --git a/tests/integration/Temporal/LaravelHostedHeartbeatTest.php b/tests/integration/Temporal/LaravelHostedHeartbeatTest.php
new file mode 100644
index 000000000..ca64f0f7f
--- /dev/null
+++ b/tests/integration/Temporal/LaravelHostedHeartbeatTest.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace integration\Temporal;
+
+/**
+ * The heartbeat scenarios with the activities hosted by the Laravel integration's activity worker
+ * (see Hosts/laravel-activity.php).
+ */
+final class LaravelHostedHeartbeatTest extends HeartbeatOnAHostTestCase
+{
+    protected function activityWorkerRole(): string
+    {
+        return 'laravel-activity';
+    }
+}
diff --git a/tests/integration/Temporal/MagentoHostedHeartbeatTest.php b/tests/integration/Temporal/MagentoHostedHeartbeatTest.php
new file mode 100644
index 000000000..19d73f1fc
--- /dev/null
+++ b/tests/integration/Temporal/MagentoHostedHeartbeatTest.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace integration\Temporal;
+
+/**
+ * The heartbeat scenarios with the activities hosted by the Magento integration's activity worker
+ * (see Hosts/magento-activity.php).
+ */
+final class MagentoHostedHeartbeatTest extends HeartbeatOnAHostTestCase
+{
+    protected function activityWorkerRole(): string
+    {
+        return 'magento-activity';
+    }
+}
diff --git a/tests/integration/Temporal/TemporalServerTestCase.php b/tests/integration/Temporal/TemporalServerTestCase.php
index 5e4fc9896..18db185a1 100644
--- a/tests/integration/Temporal/TemporalServerTestCase.php
+++ b/tests/integration/Temporal/TemporalServerTestCase.php
@@ -68,7 +68,15 @@ protected function setUp(): void
         $this->client = WorkflowServiceClientFactory::create($this->connection);
 
         $this->spawnWorker('workflow');
-        $this->spawnWorker('activity');
+        $this->spawnWorker($this->activityWorkerRole());
+    }
+
+    /**
+     * Who hosts the activities: this suite's own worker by default, or a framework's (#518).
+     */
+    protected function activityWorkerRole(): string
+    {
+        return 'activity';
     }
 
     public static function transportFromEnv(): string
diff --git a/tests/integration/Temporal/worker.php b/tests/integration/Temporal/worker.php
index d58da85d4..90fb0c1c5 100644
--- a/tests/integration/Temporal/worker.php
+++ b/tests/integration/Temporal/worker.php
@@ -42,6 +42,14 @@
 );
 $client = WorkflowServiceClientFactory::create($connection);
 
+// An activity worker a framework builds, not this script: the host's container wires the sender
+// its activities inject (#518).
+if (\in_array($role, ['laravel-activity', 'magento-activity'], true)) {
+    require __DIR__ . '/Hosts/' . $role . '.php';
+
+    exit(0);
+}
+
 if ('workflow' === $role) {
     $registry = new WorkflowRegistry();
     IntegrationWorkflows::registerWorkflows($registry);