fix: BUG-21 GPS-speed fallback in server route replay

server/modules/db.py

@@ -617,9 +617,20 @@ def get_trip_route(device_id, trip_id):
         lon = float(p[2])
         speed = p[3] or 0
         raw_odo = p[4]
+        speed_source = "obd" if speed > 0 else "gps"
+        # Mirror the Pi's route_points GPS-speed fallback: when OBD speed is
+        # missing (adapter dropout), derive speed from the previous point's
+        # movement so the replay doesn't flatline at 0 km/h while the car moves.
+        if speed <= 0 and prev is not None:
+            seconds = (p[0] - prev[2]).total_seconds()
+            if seconds > 0:
+                dist_km = hav(prev[0], prev[1], lat, lon)
+                seg_speed = dist_km / seconds * 3600
+                if seg_speed <= 220 and dist_km * 1000 >= 8:
+                    speed = seg_speed
         if prev is not None:
             cumulative += hav(prev[0], prev[1], lat, lon)
-        prev = (lat, lon)
+        prev = (lat, lon, p[0])
         if raw_odo is not None and float(raw_odo) > 0:
             odometer = float(raw_odo)
         else:
@@ -628,10 +639,10 @@ def get_trip_route(device_id, trip_id):
             "datetime": p[0].isoformat(),
             "latitude": lat,
             "longitude": lon,
-            "speed": speed,
+            "speed": round(speed, 1),
             # Mirror the Pi's route_points: OBD speed when we have it,
             # otherwise the point is sourced from GPS.
-            "speed_source": "obd" if speed > 0 else "gps",
+            "speed_source": speed_source,
             "odometer": round(odometer, 1),
         })
     return {