diff --git a/backend/routers/causal_lab.py b/backend/routers/causal_lab.py
index 58073b0..c192c28 100644
--- a/backend/routers/causal_lab.py
+++ b/backend/routers/causal_lab.py
@@ -885,19 +885,33 @@ def analyze_event(body: AnalyzeRequest):
         # Évaluation du graphe
         node_values = evaluate_graph(graph, inputs, body.coef_overrides or {})
 
-        # Lag effectif : max des lag_min/lag_days sur toutes les arêtes menant à un market_asset
-        edges     = graph.get("edges", [])
-        nodes_map = {n["id"]: n for n in graph.get("nodes", [])}
+        # Lag effectif : max sur toutes les arêtes du graphe
+        # (filtre output_ids optionnel mais peu fiable si types de nœuds non standards)
+        edges      = graph.get("edges", [])
+        nodes_map  = {n["id"]: n for n in graph.get("nodes", [])}
         output_ids = {n["id"] for n in graph.get("nodes", []) if n.get("type") in ("market_asset", "output")}
+
+        edges_to_output   = [e for e in edges if e.get("to") in output_ids]
+        edges_for_lag     = edges_to_output if edges_to_output else edges  # fallback : toutes arêtes
+
         effective_lag = max(
-            (e.get("lag_min", 0) or 0 for e in edges if e.get("to") in output_ids),
+            (e.get("lag_min", 0) or 0 for e in edges_for_lag),
             default=0,
         )
         effective_lag_days = max(
-            (e.get("lag_days", 0) or 0 for e in edges if e.get("to") in output_ids),
+            (e.get("lag_days", 0) or 0 for e in edges_for_lag),
             default=0,
         )
 
+        # Diagnostic : combien d'arêtes portent un lag_days > 0
+        edges_with_lag_days = sum(1 for e in edges if (e.get("lag_days") or 0) > 0)
+        lag_debug = {
+            "output_ids":           list(output_ids),
+            "edges_to_output":      len(edges_to_output),
+            "edges_with_lag_days":  edges_with_lag_days,
+            "used_all_edges":       not edges_to_output,
+        }
+
         # Instruments : utiliser tous ceux du template si aucun spécifié
         if body.instrument:
             instruments = list({body.instrument} | set(tmpl.get("instruments", [body.instrument])))
@@ -944,6 +958,7 @@ def analyze_event(body: AnalyzeRequest):
             "prices_mode":        prices.get("mode", "none"),
             "effective_lag_min":  effective_lag,
             "effective_lag_days": effective_lag_days,
+            "lag_debug":          lag_debug,
             "analyzed_at":        analyzed_at,
             "graph_json":         graph,   # structure complète pour visualisation frontend
         }
diff --git a/frontend/src/pages/MarketEvents.tsx b/frontend/src/pages/MarketEvents.tsx
index 94aa497..91c289a 100644
--- a/frontend/src/pages/MarketEvents.tsx
+++ b/frontend/src/pages/MarketEvents.tsx
@@ -402,6 +402,7 @@ function EventDetail({
     pricesMode?: string
     lagMin?: number
     lagDays?: number
+    lagDebug?: { output_ids: string[]; edges_to_output: number; edges_with_lag_days: number; used_all_edges: boolean }
   } | null>(null)
   const [graphData, setGraphData]     = useState<GraphData | null>(null)
 
@@ -557,6 +558,7 @@ function EventDetail({
         pricesMode: d.prices_mode,
         lagMin:     d.effective_lag_min,
         lagDays:    d.effective_lag_days,
+        lagDebug:   d.lag_debug,
       })
       if (d.graph_json?.nodes?.length) setGraphData(d.graph_json)
       await loadAnalyses()
@@ -878,6 +880,7 @@ function EventDetail({
               const lagMin  = anResult.lagMin ?? 0
               const lagDays = anResult.lagDays ?? 0
               const driftEntries = Object.entries(anResult.drift ?? {})
+              const dbg = anResult.lagDebug
               return (
                 <div className="bg-slate-900/70 border border-slate-700/40 rounded px-3 py-2 space-y-1.5 text-[10px] font-mono">
                   <div className="flex items-center gap-2 flex-wrap">
@@ -895,6 +898,15 @@ function EventDetail({
                     {mode !== 'intraday_5m' && lagDays === 0 && (
                       <span className="text-slate-600 italic">lag J = 0 (jour J)</span>
                     )}
+                    {dbg && dbg.used_all_edges && (
+                      <span className="text-yellow-500/80 italic">⚠ fallback edges (output_ids vides)</span>
+                    )}
+                    {dbg && (
+                      <span className="text-slate-600">
+                        edges→out: <span className="text-slate-400">{dbg.edges_to_output}</span>
+                        {' '}| edges lag_j: <span className="text-slate-400">{dbg.edges_with_lag_days}</span>
+                      </span>
+                    )}
                   </div>
                   {driftEntries.map(([inst, d]) => (
                     <div key={inst} className="flex items-center gap-2 flex-wrap border-t border-slate-800/60 pt-1.5">