diff --git a/migrations/Version20260507210000.php b/migrations/Version20260507210000.php
new file mode 100644
index 0000000..607e21e
--- /dev/null
+++ b/migrations/Version20260507210000.php
@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+final class Version20260507210000 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return 'Add device.current_image_orientation so 304 cache check can detect orientation flips';
+    }
+
+    public function up(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE device ADD current_image_orientation VARCHAR(255) DEFAULT NULL');
+    }
+
+    public function down(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE device DROP COLUMN current_image_orientation');
+    }
+}
diff --git a/src/Controller/DeviceImageController.php b/src/Controller/DeviceImageController.php
index 05c808e..a8cd102 100644
--- a/src/Controller/DeviceImageController.php
+++ b/src/Controller/DeviceImageController.php
@@ -69,7 +69,10 @@ class DeviceImageController extends AbstractController
         }
 
         // 304: device already has this image — skip the binary transfer and redraw.
-        if ($image->getId() === $currentImageId) {
+        // Both the image and the orientation it was last rendered at must match;
+        // otherwise the device's cached .bin is stale and we must re-send.
+        if ($image->getId() === $currentImageId
+            && $device->getCurrentImageOrientation() === $device->getOrientation()) {
             $this->logger->info('device.poll.no_change', [
                 'device_id'   => $device->getId(),
                 'mac'         => $mac,
@@ -115,10 +118,17 @@ class DeviceImageController extends AbstractController
             return $r;
         }
 
+        // Record the orientation we're serving the image at so the next poll's
+        // 304 check can detect a flip and force a re-fetch. Flushed via the
+        // controller's EM (markSeen() above already dirties the row).
+        $device->setCurrentImageOrientation($device->getOrientation());
+        $em->flush();
+
         $this->logger->info('device.poll.served', [
             'device_id'   => $device->getId(),
             'mac'         => $mac,
             'image_id'    => $image->getId(),
+            'orientation' => $device->getOrientation()->value,
             'interval_ms' => $intervalMs,
             'bytes'       => filesize($binPath),
         ]);
diff --git a/src/Entity/Device.php b/src/Entity/Device.php
index e25f40e..fa2beb6 100644
--- a/src/Entity/Device.php
+++ b/src/Entity/Device.php
@@ -65,6 +65,15 @@ class Device
     #[ORM\Column(nullable: true)]
     private ?\DateTimeImmutable $lastSeenAt = null;
 
+    /**
+     * Orientation in effect when currentImage was last served as a 200 response.
+     * Used alongside currentImage's id to decide whether a poll can be answered
+     * with 304: if the device's orientation has flipped since, the cached image
+     * on-device is stale and we must re-send the freshly-rendered .bin.
+     */
+    #[ORM\Column(nullable: true, enumType: Orientation::class)]
+    private ?Orientation $currentImageOrientation = null;
+
     public function __construct()
     {
         $this->linkedAt = new \DateTimeImmutable();
@@ -110,4 +119,7 @@ class Device
 
     public function getLastSeenAt(): ?\DateTimeImmutable { return $this->lastSeenAt; }
     public function markSeen(): static { $this->lastSeenAt = new \DateTimeImmutable(); return $this; }
+
+    public function getCurrentImageOrientation(): ?Orientation { return $this->currentImageOrientation; }
+    public function setCurrentImageOrientation(?Orientation $o): static { $this->currentImageOrientation = $o; return $this; }
 }
diff --git a/tests/Functional/Controller/DeviceImageControllerTest.php b/tests/Functional/Controller/DeviceImageControllerTest.php
index f8e7706..6b30d0c 100644
--- a/tests/Functional/Controller/DeviceImageControllerTest.php
+++ b/tests/Functional/Controller/DeviceImageControllerTest.php
@@ -167,6 +167,9 @@ class DeviceImageControllerTest extends AppWebTestCase
         $imageId = $image->getId();
 
         $device->setLockedImage($image);
+        // Simulate the device having already received this image at the current
+        // orientation — the 304 path now requires this to match too.
+        $device->setCurrentImageOrientation(Orientation::Landscape);
         $this->em()->flush();
 
         $this->client->request('GET', '/api/device/' . self::MAC . '/image', [], [], [
@@ -176,6 +179,38 @@ class DeviceImageControllerTest extends AppWebTestCase
         $this->assertResponseStatusCodeSame(304);
     }
 
+    public function test_orientation_flip_returns_200_even_when_image_id_matches(): void
+    {
+        $setup   = $this->createTestSetup();
+        $device  = $setup['device'];
+        $image   = $setup['image'];
+        $imageId = $image->getId();
+
+        // Seed: device receives the image at landscape orientation.
+        $this->client->request('GET', '/api/device/' . self::MAC . '/image');
+        $this->assertResponseStatusCodeSame(200);
+
+        // User flips device to portrait and a portrait render is ready.
+        $this->em()->clear();
+        $device = $this->em()->find(Device::class, $setup['device']->getId());
+        $device->setOrientation(Orientation::Portrait);
+        $portraitAsset = (new RenderedAsset())
+            ->setImage($this->em()->find(Image::class, $imageId))
+            ->setDeviceModel(DeviceModel::V1)
+            ->setOrientation(Orientation::Portrait)
+            ->setStatus(RenderStatus::Ready)
+            ->setFilePath(self::BIN_PATH);
+        $this->em()->persist($portraitAsset);
+        $this->em()->flush();
+
+        // Same image ID, but device's stored orientation (landscape) no longer
+        // matches the device's current orientation (portrait) → must re-send.
+        $this->client->request('GET', '/api/device/' . self::MAC . '/image', [], [], [
+            'HTTP_X-Current-Image-Id' => (string) $imageId,
+        ]);
+        $this->assertResponseStatusCodeSame(200);
+    }
+
     public function test_poll_advances_current_image(): void
     {
         $setup    = $this->createTestSetup();