M8-T16: add thermal meter cost APIs

app/services/meter_cost.py

@@ -220,7 +220,14 @@ def compute_closed_periods(session: Session, *, now: datetime | None = None) ->
     return written
 
 
-def recompute_range(session: Session, start: datetime, end: datetime) -> int:
+def recompute_range(session: Session, start: datetime, end: datetime, *, commit: bool = True) -> int:
+    """Recompute a thermal range.
+
+    The historical service entry point remains self-committing for the scheduler
+    and direct callers.  HTTP callers pass ``commit=False`` so validation,
+    recomputation, response statistics, and the single commit share one
+    transaction owned by the route.
+    """
     cursor, end = floor_to_quarter(_utc(start)), _utc(end)
     now, written = datetime.now(UTC), 0
     while cursor < end:
@@ -229,7 +236,8 @@ def recompute_range(session: Session, start: datetime, end: datetime) -> int:
                 if compute_period(session, commodity, cursor, overwrite=True):
                     written += 1
         cursor += _PERIOD
-    session.commit()
+    if commit:
+        session.commit()
     return written
 
 
@@ -257,7 +265,9 @@ def summarize(session: Session, start: datetime, end: datetime, *, now: datetime
     final_day = timezone_service.local_date(end - timedelta(microseconds=1))
     final_day = min(final_day, _settled_end_date(now or datetime.now(UTC)))
     day = timezone_service.local_date(start)
-    fixed = Decimal("0")
+    fixed_breakdown: dict[str, Decimal] = {key: Decimal("0") for key in (
+        "heating_network", "metering", "delivery_set", "hot_water_network", "other"
+    )}
     versions = active_contract_versions(session, scope="thermal")
     while start < end and day <= final_day:
         day_start = datetime.combine(day, time.min, tzinfo=timezone_service.local_tz()).astimezone(UTC)
@@ -275,14 +285,14 @@ def summarize(session: Session, start: datetime, end: datetime, *, now: datetime
             if segment_start >= segment_end:
                 continue
             values = version.values["standing"]
-            annual = sum((_decimal(values.get(key, "0")) for key in (
-                "heating_network", "metering", "delivery_set", "hot_water_network", "other"
-            )), Decimal("0"))
             fraction = Decimal(str((segment_end - segment_start).total_seconds())) / local_day_seconds
-            fixed += annual / Decimal("365") * fraction
+            for key in fixed_breakdown:
+                fixed_breakdown[key] += _decimal(values.get(key, "0")) / Decimal("365") * fraction
         day += timedelta(days=1)
+    fixed = sum(fixed_breakdown.values(), Decimal("0"))
     return {
         "currency": good[0].currency if good else "EUR", "variable_cost": variable,
-        "fixed_cost": fixed, "total_cost": variable + fixed, "breakdown": breakdown,
+        "fixed_cost": fixed, "fixed_breakdown": fixed_breakdown,
+        "total_cost": variable + fixed, "breakdown": breakdown,
         "period_count": len(good), "degraded_count": len(rows) - len(good),
     }