diff --git a/src/stores/cytoscapeStore.ts b/src/stores/cytoscapeStore.ts
index 8de21bc..599073d 100644
--- a/src/stores/cytoscapeStore.ts
+++ b/src/stores/cytoscapeStore.ts
@@ -26,8 +26,8 @@ export interface Node {
 }
 
 export interface NodePositions {
-  [direction: string]: {
-    [graphId: string]: Node[];
+  [graphId: string]: {
+    [direction: string]: Node[];
   }
 }
 
@@ -51,16 +51,10 @@ export const useCytoscapeStore = defineStore('cytoscapeStore', {
       if (!this.nodePositions[this.currentGraphId][direction]) {
         this.nodePositions[this.currentGraphId][direction] = [];
       }
-      // If this graph's data was previously stored in localStorage
-      if (localStorage.getItem(SAVE_KEY_NAME)) {
-        const nodeToSave = this.nodePositions[this.currentGraphId][direction]
-          .find(node => node.id === nodeId);
-        if (nodeToSave) {
-          nodeToSave.position = position;
-        } else {
-          this.nodePositions[this.currentGraphId][direction]
-            .push({ id: nodeId, position: position });
-        }
+      const nodeToSave = this.nodePositions[this.currentGraphId][direction]
+        .find(node => node.id === nodeId);
+      if (nodeToSave) {
+        nodeToSave.position = position;
       } else {
         this.nodePositions[this.currentGraphId][direction]
           .push({ id: nodeId, position: position });
diff --git a/tests/stores/cytoscapeStoreSaveNodePosition.test.js b/tests/stores/cytoscapeStoreSaveNodePosition.test.js
new file mode 100644
index 0000000..1ad6bbf
--- /dev/null
+++ b/tests/stores/cytoscapeStoreSaveNodePosition.test.js
@@ -0,0 +1,63 @@
+// The Lucia project.
+// Copyright 2026-2026 DSP, inc.  All rights reserved.
+// Authors:
+//   imacat.yang@dsp.im (imacat), 2026/07/04
+
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { setActivePinia, createPinia } from "pinia";
+import { useCytoscapeStore } from "@/stores/cytoscapeStore";
+
+// Mock localStorage since jsdom's localStorage is limited
+const localStorageMock = (() => {
+  let store = {};
+  return {
+    getItem: vi.fn((key) => store[key] || null),
+    setItem: vi.fn((key, value) => {
+      store[key] = value;
+    }),
+    removeItem: vi.fn((key) => {
+      delete store[key];
+    }),
+    clear: vi.fn(() => {
+      store = {};
+    }),
+  };
+})();
+Object.defineProperty(globalThis, "localStorage", {
+  value: localStorageMock,
+});
+
+describe("cytoscapeStore saveNodePosition without stored data", () => {
+  let store;
+
+  beforeEach(() => {
+    setActivePinia(createPinia());
+    store = useCytoscapeStore();
+    localStorageMock.clear();
+    vi.clearAllMocks();
+    // Keep localStorage empty for SAVE_KEY_NAME throughout, as when
+    // storage is unavailable or cleared externally between saves.
+    localStorageMock.getItem.mockReturnValue(null);
+  });
+
+  it("does not duplicate a node saved twice without stored data", () => {
+    store.setCurrentGraphId("graph1");
+    store.saveNodePosition("node1", { x: 10, y: 20 }, "TB");
+    store.saveNodePosition("node1", { x: 30, y: 40 }, "TB");
+    expect(store.nodePositions["graph1"]["TB"]).toHaveLength(1);
+    expect(store.nodePositions["graph1"]["TB"][0]).toEqual({
+      id: "node1",
+      position: { x: 30, y: 40 },
+    });
+  });
+
+  it("adds separate entries for different nodes", () => {
+    store.setCurrentGraphId("graph1");
+    store.saveNodePosition("node1", { x: 10, y: 20 }, "TB");
+    store.saveNodePosition("node2", { x: 30, y: 40 }, "TB");
+    expect(store.nodePositions["graph1"]["TB"]).toEqual([
+      { id: "node1", position: { x: 10, y: 20 } },
+      { id: "node2", position: { x: 30, y: 40 } },
+    ]);
+  });
+});