feat(backend): add root cause calculation

backend/cmd/main.go

@@ -218,15 +218,25 @@ func main() {
 			jobsGroup.GET("/metrics", jobsHandlers.GetJobMetrics)
 		}
 
-		// Service dependency graph (requires admin permission)
+		// Service dependency graph
 		graphGroup := v1.Group("/graph")
-		graphGroup.Use(auth.AuthMiddleware(), handlers.RequireAdmin())
+		graphGroup.Use(auth.AuthMiddleware())
 		{
-			graphGroup.GET("", graphHandlers.GetYAML)
-			graphGroup.PUT("", graphHandlers.UpdateYAML)
-			graphGroup.GET("/order", graphHandlers.StartupOrder)
-			graphGroup.GET("/cycle", graphHandlers.CycleCheck)
-			graphGroup.GET("/failure", graphHandlers.GetFailureRootCause)
+			// Read-only endpoints: GET (require view)
+			graphView := graphGroup.Group("")
+			graphView.Use(handlers.RequireView())
+			{
+				graphView.GET("", graphHandlers.GetYAML)
+				graphView.GET("/order", graphHandlers.StartupOrder)
+				graphView.GET("/cycle", graphHandlers.CycleCheck)
+				graphView.GET("/failure", graphHandlers.GetFailureRootCause)
+			}
+			// Write endpoints: PUT (require admin)
+			graphAdmin := graphGroup.Group("")
+			graphAdmin.Use(handlers.RequireAdmin())
+			{
+				graphAdmin.PUT("", graphHandlers.UpdateYAML)
+			}
 		}
 
 		// Agent registration