diff --git a/src/stores/useModelStore.ts b/src/stores/useModelStore.ts
index 82680f3..62cc9f9 100644
--- a/src/stores/useModelStore.ts
+++ b/src/stores/useModelStore.ts
@@ -257,6 +257,9 @@ interface ModelStore {
   setGridAutoFollow: (b: boolean) => void;
   /** Nudge grid by delta meters and disable auto-follow. */
   nudgeGridY: (delta: number) => void;
+  /** When true, the next click on a model face sets grid Y to that point. */
+  gridCalibMode: boolean;
+  setGridCalibMode: (b: boolean) => void;
 
   wireframeColor: string;
   setWireframeColor: (color: string) => void;