M8-T03: adopt DSMR history into meter sources

app/models/energy.py

@@ -13,8 +13,8 @@ from __future__ import annotations
 
 import uuid as _uuid
 from datetime import datetime
-from sqlalchemy import Boolean, DateTime, Float, ForeignKey, Integer, String
-from sqlalchemy.orm import Mapped, mapped_column, relationship
+from sqlalchemy import Boolean, DateTime, Float, ForeignKey, Integer, String, UniqueConstraint, event, text
+from sqlalchemy.orm import Mapped, mapped_column, relationship, synonym
 from sqlalchemy.types import JSON
 
 from app.db import Base
@@ -97,8 +97,9 @@ class DsmrReading(Base):
     (that field overflows and must be manually reset to zero — a known DSMR
     quirk — so relying on it for uniqueness risks silently dropping new data).
     The table's own autoincrement ``id`` PK is the stable internal identity, and
-    ``recorded_at`` (the telegram timestamp) is the UNIQUE de-duplication key: a
-    single P1 meter emits exactly one telegram per timestamp.
+    ``(meter_source_id, recorded_at)`` is the UNIQUE de-duplication key: each
+    configured P1 source emits at most one telegram per timestamp, while
+    different sources may legitimately emit at the same instant.
 
     ``recorded_at`` is a real column (not inside the payload) so time-range
     queries are efficient.  The entire telegram frame is stored verbatim in
@@ -110,21 +111,44 @@ class DsmrReading(Base):
 
     id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
 
-    # UTC timestamp of the sample — real column, UNIQUE (telegram-id-independent
-    # idempotency key).  The unique index also serves time-range queries.
-    recorded_at: Mapped[datetime] = mapped_column(
-        DateTime(timezone=True), nullable=False, unique=True
-    )
+    # UTC timestamp of the sample.  Idempotency is per configured source, so
+    # distinct P1 sources may legitimately emit at the same instant.
+    recorded_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
 
     # Telegram's own id (DSMR Reader assigns it).  Stored only as a reference /
     # debugging aid — NOT used for uniqueness or idempotency (it overflows and
     # gets reset to zero).  Nullable because some DSMR sources may not emit one.
-    source_id: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    telegram_id: Mapped[int | None] = mapped_column(Integer, nullable=True)
+
+    # Compatibility for the pre-M8 ingest implementation.  This is an ORM
+    # alias only; the physical database column is ``telegram_id``.
+    source_id = synonym("telegram_id")
+
+    # The configured source is the durable identity of the cumulative reading
+    # stream.  It is non-null after the revision-16 historical adoption.
+    meter_source_id: Mapped[int] = mapped_column(
+        ForeignKey("meter_source.id", ondelete="RESTRICT"), nullable=False, index=True
+    )
 
     # Full telegram frame as a JSON object; values are typically JSON strings
     # (e.g. "20915.154") — callers must cast to Decimal before arithmetic.
     payload: Mapped[dict] = mapped_column(JSON, nullable=False)
 
+    __table_args__ = (
+        UniqueConstraint(
+            "meter_source_id", "recorded_at", name="uq_dsmr_reading_source_recorded_at"
+        ),
+    )
+
+
+@event.listens_for(DsmrReading, "before_insert")
+def _supply_legacy_dsmr_source(_mapper, connection, target: DsmrReading) -> None:
+    """Keep the pre-T04 single-source writer working during the schema handoff."""
+    if target.meter_source_id is None:
+        target.meter_source_id = connection.execute(
+            text("SELECT id FROM meter_source WHERE kind = 'dsmr_mqtt' ORDER BY id LIMIT 1")
+        ).scalar_one()
+
 
 class EnergyContract(Base):
     """Contract head: a named energy contract with a chosen pricing strategy.