diff --git a/src/stores/useModelStore.ts b/src/stores/useModelStore.ts
index 2927e44..7f76df5 100644
--- a/src/stores/useModelStore.ts
+++ b/src/stores/useModelStore.ts
@@ -143,6 +143,9 @@ export interface Measurement {
   kind?: 'distance' | 'hole' | 'edge';
   /** Optional pre-formatted label (e.g. "Ø 12.5"). When absent, UI formats distanceMM. */
   label?: string;
+  /** Model the measurement belongs to. When set, pointA/pointB are stored in that
+   *  model's local frame so the measurement follows the model when repositioned. */
+  modelId?: string;
 }
 
 export interface HoverInfo {