feat: causal lab — debug endpoint + error display in UI

backend/routers/causal_lab.py

@@ -320,6 +320,27 @@ class AnalyzeRequest(BaseModel):
 
 # ── Endpoints ─────────────────────────────────────────────────────────────────
 
+@router.get("/api/causal-lab/debug")
+def debug_causal():
+    """Endpoint de diagnostic — vérifie que causal_graphs est bien chargé."""
+    try:
+        from services.database import get_conn
+        from services.causal_graphs import BUILT_IN_TEMPLATES, init_tables, seed_templates
+        conn = get_conn()
+        init_tables(conn)
+        seed_templates(conn)
+        count = conn.execute("SELECT COUNT(*) FROM causal_graph_templates").fetchone()[0]
+        conn.close()
+        return {
+            "built_in_templates": len(BUILT_IN_TEMPLATES),
+            "db_templates": count,
+            "status": "ok",
+        }
+    except Exception as e:
+        import traceback
+        return {"status": "error", "error": str(e), "trace": traceback.format_exc()}
+
+
 @router.get("/api/causal-lab/templates")
 def list_templates(category: str = Query("")):
     try:
@@ -329,8 +350,11 @@ def list_templates(category: str = Query("")):
         _init(conn)
         data = get_templates(conn, category)
         conn.close()
+        print(f"[causal_lab] list_templates → {len(data)} templates (category={category!r})", flush=True)
         return data
     except Exception as e:
+        import traceback
+        print(f"[causal_lab] list_templates ERROR: {e}\n{traceback.format_exc()}", flush=True)
         logger.error(f"[causal_lab] list_templates: {e}")
         raise HTTPException(500, str(e))