diff --git a/src/stores/useModelStore.ts b/src/stores/useModelStore.ts
index 48f3b8d..5589f7f 100644
--- a/src/stores/useModelStore.ts
+++ b/src/stores/useModelStore.ts
@@ -244,6 +244,23 @@ interface ModelStore {
   setMeasureMode: (on: boolean) => void;
   positionMode: boolean;
   setPositionMode: (on: boolean) => void;
+
+  // ── Selection (hide/isolate/export elements) ────────────
+  selectionMode: boolean;
+  setSelectionMode: (on: boolean) => void;
+  /** Keys: `${modelId}:${ifcId|name|uuid}` */
+  selectedElementKeys: Set<string>;
+  /** Hidden element keys, per-active-model file (persisted by fileName). */
+  hiddenElementKeys: Set<string>;
+  /** When non-null, only these keys are visible (isolation). */
+  isolatedElementKeys: Set<string> | null;
+  toggleElementSelection: (key: string) => void;
+  clearElementSelection: () => void;
+  hideSelectedElements: () => void;
+  isolateSelectedElements: () => void;
+  showAllElements: () => void;
+  /** Bump whenever visibility/selection state changes — viewer re-applies. */
+  visibilityNonce: number;
   measurePoints: MeasurePoint[];
   addMeasurePoint: (p: MeasurePoint) => void;
   undoLastMeasurePoint: () => void;