fix(k1): harden live handoff and camera recovery

tests/test_xgrids_camera_gateway.py

@@ -801,6 +801,16 @@ def test_preview_queue_enforces_exact_fragment_byte_and_age_bounds() -> None:
     assert age_bounded.offer(("media", b"too-old")) is False
 
 
+def test_preview_queue_survives_measured_ui_pause() -> None:
+    now = [100.0]
+    preview_queue = _CameraPreviewSegmentQueue(clock=lambda: now[0])
+
+    assert preview_queue.offer(("media", b"first")) is True
+    now[0] += 3.2
+
+    assert preview_queue.offer(("media", b"next")) is True
+
+
 def test_camera_router_closes_lagging_preview_with_explicit_private_code(
     tmp_path: Path,
     monkeypatch: pytest.MonkeyPatch,