refactor(vo): address final review — accurate docstring + update_depth_hint tests

Final review findings (Important):
- I1: e2e test docstring overclaimed — harness always uses ORBVisualOdometry.
  Rewrite docstring to describe the actual scope: smoke test + ORB regression
  guard. Wiring Mono-Depth wrapper through the harness is a sprint 2 task.
- I2: update_depth_hint had no tests. Add 2 tests: clamp at 1.0m for bogus
  values, and verify next compute_relative_pose uses the updated scale.
- I3: add TODO marker for sprint 2 deduplication with CuVSLAMVisualOdometry.

No behavior change — only docstrings, TODO markers, and test coverage.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/gps_denied/core/vo.py

@@ -395,6 +395,9 @@ class CuVSLAMVisualOdometry(ISequentialVisualOdometry):
 # ---------------------------------------------------------------------------
 # CuVSLAMMonoDepthVisualOdometry — cuVSLAM Mono-Depth mode (sprint 1 production)
 # ---------------------------------------------------------------------------
+# TODO(sprint 2): collapse duplicated SDK-load / _init_tracker scaffolding with
+# CuVSLAMVisualOdometry once Inertial mode is removed. Kept separate for sprint 1
+# so the Inertial → Mono-Depth migration is reversible.
 
 # Reference altitude used to normalise ORB unit-scale translation in dev/CI.
 # At this altitude the ORB unit vector is scaled to match expected metric displacement.

tests/e2e/test_euroc.py

@@ -115,19 +115,27 @@ async def test_euroc_mh01_gps_rmse_within_ceiling(euroc_mh01_root: Path):
 @pytest.mark.needs_dataset
 @pytest.mark.asyncio
 async def test_euroc_mh01_mono_depth_within_ceiling(euroc_mh01_root: Path):
-    """Mono-Depth backend ATE on EuRoC — regression guard for VO migration.
+    """CuVSLAMMonoDepthVisualOdometry instantiation smoke test + ORB-pipeline regression guard.
 
-    Verifies CuVSLAMMonoDepthVisualOdometry._compute_via_orb_scaled produces
-    metric translations consistent with the baseline ORB pipeline when
-    depth_hint_m scale equals the calibrated VO_SCALE_M.
+    Scope of this test:
+      1. SMOKE: CuVSLAMMonoDepthVisualOdometry constructs with EuRoC-typical
+         depth_hint and camera params without raising.
+      2. REGRESSION GUARD: runs the existing ORB-based harness (which uses
+         ORBVisualOdometry() directly — see src/gps_denied/testing/harness.py)
+         with the calibrated VO_SCALE_M and asserts ATE stays under 0.5 m.
 
-    EuRoC indoor != production outdoor nadir. Poor ATE here is not a blocker
-    for production. Test documents baseline and prevents unexpected regression.
+    NOT in scope (deliberately): this test does NOT exercise
+    CuVSLAMMonoDepthVisualOdometry through the pipeline. The E2EHarness
+    currently hardcodes ORBVisualOdometry(); wiring the Mono-Depth wrapper
+    through the harness is a sprint 2 task. The scale-math invariant is
+    covered by test_mono_depth_depth_hint_scales_translation in test_vo.py.
+
+    EuRoC indoor != production outdoor nadir. Baseline ATE 0.2046m documented.
     """
     from gps_denied.core.vo import CuVSLAMMonoDepthVisualOdometry
     from gps_denied.schemas import CameraParameters
 
-    # Sanity: class instantiates and reports metric scale.
+    # (1) Smoke test — class instantiates with EuRoC-typical params.
     cam = CameraParameters(
         focal_length=16.0, sensor_width=23.2, sensor_height=17.4,
         resolution_width=752, resolution_height=480,
@@ -137,8 +145,7 @@ async def test_euroc_mh01_mono_depth_within_ceiling(euroc_mh01_root: Path):
     )
     assert vo._depth_hint_m == EUROC_MH01_MONO_DEPTH_HINT_M
 
-    # Full e2e using the calibrated scale — pipeline-equivalent to baseline
-    # ORB until cuVSLAM SDK lands on Jetson.
+    # (2) Regression guard — ORB pipeline baseline stays under 0.5m ATE.
     adapter = EuRoCAdapter(euroc_mh01_root)
     harness = E2EHarness(
         adapter, max_frames=EUROC_MH01_MAX_FRAMES, vo_scale_m=EUROC_MH01_VO_SCALE_M,

tests/test_vo.py

@@ -301,3 +301,43 @@ def test_mono_depth_create_vo_backend_selects_it():
     from gps_denied.core.vo import CuVSLAMMonoDepthVisualOdometry, create_vo_backend
     vo = create_vo_backend(prefer_mono_depth=True, depth_hint_m=600.0)
     assert isinstance(vo, CuVSLAMMonoDepthVisualOdometry)
+
+
+def test_mono_depth_update_depth_hint_clamps_below_one():
+    """update_depth_hint clamps bogus/negative barometer values to minimum 1.0m."""
+    from gps_denied.core.vo import CuVSLAMMonoDepthVisualOdometry
+    vo = CuVSLAMMonoDepthVisualOdometry(depth_hint_m=600.0)
+    vo.update_depth_hint(-5.0)
+    assert vo._depth_hint_m == 1.0
+    vo.update_depth_hint(0.0)
+    assert vo._depth_hint_m == 1.0
+    vo.update_depth_hint(0.5)
+    assert vo._depth_hint_m == 1.0
+
+
+def test_mono_depth_update_depth_hint_affects_subsequent_scale():
+    """update_depth_hint changes scale used by next compute_relative_pose call."""
+    from unittest.mock import patch
+    from gps_denied.core.vo import CuVSLAMMonoDepthVisualOdometry, ORBVisualOdometry
+    from gps_denied.schemas.vo import RelativePose
+
+    cam = CameraParameters(
+        focal_length=16.0, sensor_width=23.2, sensor_height=17.4,
+        resolution_width=640, resolution_height=480,
+    )
+    img = np.zeros((480, 640), dtype=np.uint8)
+    unit_pose = RelativePose(
+        translation=np.array([1.0, 0.0, 0.0]),
+        rotation=np.eye(3),
+        confidence=1.0, inlier_count=100, total_matches=100,
+        tracking_good=True, scale_ambiguous=True,
+    )
+
+    with patch.object(ORBVisualOdometry, "compute_relative_pose", return_value=unit_pose):
+        vo = CuVSLAMMonoDepthVisualOdometry(depth_hint_m=600.0)
+        pose_before = vo.compute_relative_pose(img, img, cam)
+        vo.update_depth_hint(1200.0)
+        pose_after = vo.compute_relative_pose(img, img, cam)
+
+    assert np.allclose(pose_before.translation, [1.0, 0.0, 0.0])  # 600/600 = 1.0x
+    assert np.allclose(pose_after.translation, [2.0, 0.0, 0.0])   # 1200/600 = 2.0x