Preserve sub-integer precision at trip end and BMW SOC fallback

Continuity check: also keep prediction when BMW is within rounding
(abs < 0.5), not just when BMW >= prediction. Prevents jump from
54.7% to 54% at trip end.

BMW SOC fallback: if existing last_magic_soc is within rounding of
BMW integer, keep the sub-integer value instead of overwriting.
Prevents jump after continuity window expires.

Author: renaudallard

custom_components/cardata/magic_soc.py

@@ -605,14 +605,19 @@ def get_magic_soc(self, vin: str, bmw_soc: float | None, mileage: float | None)
         if last_driving is not None:
             predicted_soc, saved_at = last_driving
             if (time.time() - saved_at) < DRIVING_SOC_CONTINUITY_SECONDS:
-                # Use last prediction if BMW SOC appears stale (higher or equal)
-                if bmw_soc is None or bmw_soc >= predicted_soc:
+                # Use last prediction if BMW SOC is stale (higher/equal) or
+                # within rounding of our sub-integer prediction
+                if bmw_soc is None or bmw_soc >= predicted_soc or abs(bmw_soc - predicted_soc) < 0.5:
                     self._last_magic_soc[vin] = predicted_soc
                     return predicted_soc
             # Expired or BMW sent fresh lower SOC — discard
             del self._last_driving_predicted_soc[vin]
 
         if bmw_soc is not None:
+            # Keep existing sub-integer prediction if BMW agrees within rounding
+            existing = self._last_magic_soc.get(vin)
+            if existing is not None and abs(bmw_soc - existing) < 0.5:
+                return existing
             self._last_magic_soc[vin] = bmw_soc
             return bmw_soc
         return self._last_magic_soc.get(vin)