Optimize signal read paths and enforce score invariants

app/services/scoring_service.py

@@ -16,6 +16,7 @@ from datetime import datetime, timezone
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app.database import insert_for_session
 from app.exceptions import NotFoundError, ValidationError
 from app.models.score import CompositeScore, DimensionScore
 from app.models.ticker import Ticker
@@ -661,14 +662,23 @@ async def compute_dimension_score(
             # Can't compute — mark stale
             existing.is_stale = True
     elif score_val is not None:
-        dim = DimensionScore(
+        stmt = insert_for_session(db, DimensionScore).values(
             ticker_id=ticker.id,
             dimension=dimension,
             score=score_val,
             is_stale=False,
             computed_at=now,
         )
-        db.add(dim)
+        await db.execute(
+            stmt.on_conflict_do_update(
+                index_elements=["ticker_id", "dimension"],
+                set_={
+                    "score": stmt.excluded.score,
+                    "is_stale": False,
+                    "computed_at": stmt.excluded.computed_at,
+                },
+            )
+        )
 
     return score_val
 
@@ -738,25 +748,24 @@ async def compute_composite_score(
 
     # Persist composite score
     now = datetime.now(timezone.utc)
-    comp_result = await db.execute(
-        select(CompositeScore).where(CompositeScore.ticker_id == ticker.id)
+    stmt = insert_for_session(db, CompositeScore).values(
+        ticker_id=ticker.id,
+        score=composite,
+        is_stale=False,
+        weights_json=json.dumps(weights),
+        computed_at=now,
     )
-    existing = comp_result.scalar_one_or_none()
-
-    if existing is not None:
-        existing.score = composite
-        existing.is_stale = False
-        existing.weights_json = json.dumps(weights)
-        existing.computed_at = now
-    else:
-        comp = CompositeScore(
-            ticker_id=ticker.id,
-            score=composite,
-            is_stale=False,
-            weights_json=json.dumps(weights),
-            computed_at=now,
+    await db.execute(
+        stmt.on_conflict_do_update(
+            index_elements=["ticker_id"],
+            set_={
+                "score": stmt.excluded.score,
+                "is_stale": False,
+                "weights_json": stmt.excluded.weights_json,
+                "computed_at": stmt.excluded.computed_at,
+            },
         )
-        db.add(comp)
+    )
 
     return composite, missing