diff --git a/observe/describe.py b/observe/describe.py
index 07f712ac3..befcaff89 100644
--- a/observe/describe.py
+++ b/observe/describe.py
@@ -28,10 +28,8 @@ from enum import Enum
 from pathlib import Path
 from typing import List, Optional
 
-import av
 from PIL import Image
 
-from observe.aruco import detect_markers, mask_convey_region, polygon_area
 from observe.extract import DEFAULT_MAX_EXTRACTIONS, select_frames_for_extraction
 from observe.utils import get_segment_key
 from think.callosum import callosum_send
@@ -222,6 +220,14 @@ class VideoProcessor:
         # Cache for the last qualified frame hash
         last_hash: Optional[int] = None
 
+        # Imports deferred: av (PyAV) and cv2 (via observe.aruco) bundle
+        # mismatched libavdevice majors. Keeping them out of module scope
+        # avoids the macOS ObjC duplicate-class warning on every caller that
+        # only needs CATEGORIES (see observe/screen.py).
+        import av
+
+        from observe.aruco import detect_markers, mask_convey_region, polygon_area
+
         try:
             with av.open(str(self.video_path)) as container:
                 stream = container.streams.video[0]
diff --git a/tests/test_describe_lazy_imports.py b/tests/test_describe_lazy_imports.py
new file mode 100644
index 000000000..1487b104a
--- /dev/null
+++ b/tests/test_describe_lazy_imports.py
@@ -0,0 +1,22 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright (c) 2026 sol pbc
+
+import sys
+
+
+def test_importing_categories_does_not_load_av_or_cv2(monkeypatch):
+    for mod in (
+        "av",
+        "cv2",
+        "observe.aruco",
+        "observe.describe",
+        "observe.screen",
+    ):
+        monkeypatch.delitem(sys.modules, mod, raising=False)
+
+    from observe.describe import CATEGORIES
+
+    assert isinstance(CATEGORIES, dict)
+    assert len(CATEGORIES) > 0
+    assert "av" not in sys.modules
+    assert "cv2" not in sys.modules