fix low level issues

bincio/extract/metrics.py

@@ -237,19 +237,29 @@ def _fastest_time_for_distance(speed_1hz: list[float], target_km: float) -> Opti
 def _best_climb(ele_1hz: list[Optional[float]]) -> Optional[float]:
     """Maximum net elevation gain over any contiguous window (Kadane's on deltas).
 
-    Ignores samples where elevation is None.  Returns None if fewer than two
-    valid elevation samples exist.
+    None samples are treated as breaks between segments — the Kadane window is
+    reset to 0 at each gap so non-contiguous elevation data is never joined.
+    Returns None if fewer than two non-None samples exist.
     """
-    valid = [e for e in ele_1hz if e is not None]
-    if len(valid) < 2:
+    non_null = sum(1 for e in ele_1hz if e is not None)
+    if non_null < 2:
         return None
 
     max_gain = 0.0
     current = 0.0
-    for a, b in zip(valid, valid[1:]):
-        current = max(0.0, current + (b - a))
-        if current > max_gain:
-            max_gain = current
+    prev: Optional[float] = None
+
+    for e in ele_1hz:
+        if e is None:
+            # Gap — reset window so we don't bridge the discontinuity
+            current = 0.0
+            prev = None
+            continue
+        if prev is not None:
+            current = max(0.0, current + (e - prev))
+            if current > max_gain:
+                max_gain = current
+        prev = e
 
     return round(max_gain, 1) if max_gain > 0 else None