M8-R08: add atomic meter close and binding transfer

app/services/energy_cost.py

@@ -666,7 +666,7 @@ def compute_closed_periods(session: Session) -> int:
 
 
 def recompute_range(
-    session: Session, start: datetime, end: datetime, *, commit: bool = True
+    session: Session, start: datetime, end: datetime, *, commit: bool = True, strict: bool = False
 ) -> int:
     """Recompute (overwrite) all 15-minute periods in ``[start, end)``.
 
@@ -693,6 +693,11 @@ def recompute_range(
         When true (the default), commit after all periods have been processed.
         Callers composing this recompute with other writes may pass false and
         own the surrounding transaction themselves.
+    strict:
+        When true, propagate a failed period computation to the caller.  This
+        is for lifecycle transactions which must roll back their meter/binding
+        mutation together with the cost recompute.  The default remains
+        best-effort for existing background and standalone callers.
     start:
         Inclusive start datetime (floored to the nearest quarter-hour internally).
     end:
@@ -723,6 +728,8 @@ def recompute_range(
                 if did_write:
                     written += 1
             except Exception:
+                if strict:
+                    raise
                 logger.exception(
                     "recompute_range: unexpected error for t0=%s — continuing.",
                     t0.isoformat(),