feat(scoring): composite recency decay and severity weights persisted in DB [FASE-5.1]

backend/app/routers/snapshots.py

@@ -21,6 +21,7 @@ from app.services.snapshot_service import (
     create_snapshot,
     compare_snapshots,
     cleanup_old_snapshots,
+    get_coverage_evolution,
     serialize_snapshot_summary,
     list_snapshots as list_snapshots_svc,
     get_snapshot_or_raise,
@@ -82,6 +83,21 @@ def create_snapshot_endpoint(
     return serialize_snapshot_summary(snapshot)
 
 
+# ---------------------------------------------------------------------------
+# GET /snapshots/evolution — Coverage trend over time
+# ---------------------------------------------------------------------------
+
+
+@router.get("/evolution")
+def coverage_evolution(
+    months: int = Query(12, ge=1, le=36),
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """Return coverage snapshots for trend charts (last *months* months)."""
+    return get_coverage_evolution(db, months=months)
+
+
 # ---------------------------------------------------------------------------
 # GET /snapshots/compare — Compare two snapshots
 # ---------------------------------------------------------------------------