diff --git a/src/stores/useModelStore.ts b/src/stores/useModelStore.ts
index c4f771e..34afc02 100644
--- a/src/stores/useModelStore.ts
+++ b/src/stores/useModelStore.ts
@@ -133,6 +133,15 @@ interface ModelStore {
   showGrid: boolean;
   setShowGrid: (show: boolean) => void;
 
+  /** World Y position of the grid plane (meters). */
+  gridY: number;
+  setGridY: (y: number) => void;
+  /** When true, grid follows the bottom of the loaded model automatically. */
+  gridAutoFollow: boolean;
+  setGridAutoFollow: (b: boolean) => void;
+  /** Nudge grid by delta meters and disable auto-follow. */
+  nudgeGridY: (delta: number) => void;
+
   wireframeColor: string;
   setWireframeColor: (color: string) => void;