From 76c2aba14e4bdcdeb4828fcdcb7703c68e899b90 Mon Sep 17 00:00:00 2001
From: firestar5683 <168790843+firestar5683@users.noreply.github.com>
Date: Mon, 26 Oct 2026 13:36:59 -0500
Subject: [PATCH] Keep Lane Width Calculation Out of NumPy Cold Imports

---
 openpilot/starpilot/lateral/lane_tracking.py  | 10 ++++---
 .../lateral/tests/test_lane_centering.py      | 27 +++++++++++++++++++
 prebuilt.json                                 |  2 +-
 3 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/openpilot/starpilot/lateral/lane_tracking.py b/openpilot/starpilot/lateral/lane_tracking.py
index e253a46467..eb8176005a 100644
--- a/openpilot/starpilot/lateral/lane_tracking.py
+++ b/openpilot/starpilot/lateral/lane_tracking.py
@@ -93,7 +93,9 @@ class SingleLineTracker:
             raise ValueError
           slope = sum(float(np.interp(distance, x, np.gradient(y, x))) for x, y in valid_lines) * 0.5
           widths.append((right - left) / math.hypot(1.0, slope))
-        width = float(np.median(widths))
+        if not all(math.isfinite(value) for value in widths):
+          raise ValueError
+        width = sorted(widths)[1]
         if not 2.6 <= width <= 4.8:
           raise ValueError
         self.width, self.width_at, self.width_travel = width, self.clock, self.travel
@@ -137,7 +139,7 @@ class SingleLineTracker:
         self._clear_line()
         self.side = side
         self.acquired_at = self.clock
-        self.pending = max(self.MIN_CLEARANCE, float(np.median(distances)))
+        self.pending = max(self.MIN_CLEARANCE, sorted(distances)[1])
         if (
           not jump
           and self.width is not None
@@ -147,9 +149,9 @@ class SingleLineTracker:
           self.spacing = self.width * 0.5
       elif self.spacing is None and self.clock - self.acquired_at >= self.ACQUIRE_SECONDS:
         assert self.pending is not None
-        if abs(float(np.median(distances)) - self.pending) > 0.25:
+        if abs(sorted(distances)[1] - self.pending) > 0.25:
           self.acquired_at = self.clock
-          self.pending = max(self.MIN_CLEARANCE, float(np.median(distances)))
+          self.pending = max(self.MIN_CLEARANCE, sorted(distances)[1])
         else:
           self.spacing = self.pending
       self.last_good_at, self.last_near, self.last_slope = self.clock, near, slope
diff --git a/openpilot/starpilot/lateral/tests/test_lane_centering.py b/openpilot/starpilot/lateral/tests/test_lane_centering.py
index f741b19eb5..666a6c310b 100644
--- a/openpilot/starpilot/lateral/tests/test_lane_centering.py
+++ b/openpilot/starpilot/lateral/tests/test_lane_centering.py
@@ -49,6 +49,33 @@ def settled(controller, source, ticks=300):
 
 
 class TestLaneCentering(unittest.TestCase):
+  def test_lane_width_avoids_first_use_numpy_median_import(self):
+    from openpilot.starpilot.lateral.lane_tracking import SingleLineTracker
+    tracker = SingleLineTracker()
+    with patch.object(np, 'median', side_effect=AssertionError('No lazy masked-array import in Controls')):
+      result = tracker.target(model(), 1, 10.0, 0.01, 0.0)
+    self.assertFalse(result.blocked)
+    assert tracker.width is not None
+    self.assertAlmostEqual(tracker.width, 3.6, places=5)
+
+  def test_single_line_spacing_avoids_first_use_numpy_median_import(self):
+    from openpilot.starpilot.lateral.lane_tracking import SingleLineTracker
+    tracker = SingleLineTracker()
+    with patch.object(np, 'median', side_effect=AssertionError('No lazy masked-array import in Controls')):
+      for frame in range(8):
+        tracker.target(single(line=-1.7, edge=10.), frame, 20., .05, 0.)
+    assert tracker.spacing is not None
+    self.assertAlmostEqual(tracker.spacing, 1.7, places=5)
+
+  def test_lane_width_rejects_nonfinite_gradient_before_median(self):
+    from openpilot.starpilot.lateral.lane_tracking import SingleLineTracker
+    for value in (float('nan'), float('inf'), float('-inf')):
+      tracker = SingleLineTracker()
+      with patch.object(np, 'gradient', return_value=np.full(len(XS), value)):
+        result = tracker.target(model(), 1, 10.0, 0.01, 0.0)
+      self.assertTrue(result.blocked)
+      self.assertIsNone(tracker.width)
+
   def test_reader_cache_detects_mutation_samples_and_reset(self):
     from openpilot.starpilot.lateral import lane_centering as module
     builder = model()
diff --git a/prebuilt.json b/prebuilt.json
index a6e47740a9..f923d7c2d8 100644
--- a/prebuilt.json
+++ b/prebuilt.json
@@ -1 +1 @@
-{"protected_inventory_sha256": "efd11c6fa09ef1c09fd6c394aec7b482b63101c1009824054635ef9bac18cf4b", "schema_version": 1}
+{"protected_inventory_sha256": "7517fc683e66896ce2ee8d4f60c770b54ff6109d4bfaa9f7edd8ef0db6107134", "schema_version": 1}