M8-R03B: keep meter swap recompute in caller transaction

app/services/energy_cost.py

@@ -665,7 +665,9 @@ def compute_closed_periods(session: Session) -> int:
 # ---------------------------------------------------------------------------
 
 
-def recompute_range(session: Session, start: datetime, end: datetime) -> int:
+def recompute_range(
+    session: Session, start: datetime, end: datetime, *, commit: bool = True
+) -> int:
     """Recompute (overwrite) all 15-minute periods in ``[start, end)``.
 
     This is the *explicit opt-in* path for recovering from:
@@ -686,8 +688,11 @@ def recompute_range(session: Session, start: datetime, end: datetime) -> int:
     Parameters
     ----------
     session:
-        Active SQLAlchemy session.  The function commits after all periods
-        have been processed.
+        Active SQLAlchemy session.
+    commit:
+        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.
     start:
         Inclusive start datetime (floored to the nearest quarter-hour internally).
     end:
@@ -724,7 +729,8 @@ def recompute_range(session: Session, start: datetime, end: datetime) -> int:
                 )
         t0 += timedelta(minutes=_PERIOD_MINUTES)
 
-    session.commit()
+    if commit:
+        session.commit()
     logger.info(
         "recompute_range(%s, %s): wrote %d period(s).",
         start.isoformat(),