feat: instrument model

backend/services/gauge_sync.py

@@ -247,12 +247,21 @@ _SUGGEST_FN = {
 
 # ── Public API ─────────────────────────────────────────────────────────────────
 
-def get_latest_gauges(conn) -> tuple[dict, str]:
-    """Retourne (gauges_dict, snapshot_date) depuis macro_regime_history."""
-    row = conn.execute(
-        "SELECT gauges_summary_json, timestamp FROM macro_regime_history "
-        "ORDER BY timestamp DESC LIMIT 1"
-    ).fetchone()
+def get_latest_gauges(conn, at_date: Optional[str] = None) -> tuple[dict, str]:
+    """Retourne (gauges_dict, snapshot_date) depuis macro_regime_history.
+    Si at_date fourni, retourne le snapshot le plus proche <= at_date."""
+    if at_date:
+        row = conn.execute(
+            "SELECT gauges_summary_json, timestamp FROM macro_regime_history "
+            "WHERE timestamp <= ? ORDER BY timestamp DESC LIMIT 1",
+            (at_date,)
+        ).fetchone()
+    else:
+        row = conn.execute(
+            "SELECT gauges_summary_json, timestamp FROM macro_regime_history "
+            "ORDER BY timestamp DESC LIMIT 1"
+        ).fetchone()
+
     if row:
         r = dict(row)
         gauges = json.loads(r.get("gauges_summary_json") or "{}")
@@ -261,10 +270,17 @@ def get_latest_gauges(conn) -> tuple[dict, str]:
             return gauges, date
 
     # Fallback : macro_gauge_snapshots
-    row2 = conn.execute(
-        "SELECT gauges_json, snapshot_date FROM macro_gauge_snapshots "
-        "ORDER BY snapshot_date DESC LIMIT 1"
-    ).fetchone()
+    if at_date:
+        row2 = conn.execute(
+            "SELECT gauges_json, snapshot_date FROM macro_gauge_snapshots "
+            "WHERE snapshot_date <= ? ORDER BY snapshot_date DESC LIMIT 1",
+            (at_date,)
+        ).fetchone()
+    else:
+        row2 = conn.execute(
+            "SELECT gauges_json, snapshot_date FROM macro_gauge_snapshots "
+            "ORDER BY snapshot_date DESC LIMIT 1"
+        ).fetchone()
     if row2:
         return json.loads(row2["gauges_json"] or "{}"), str(row2["snapshot_date"])