diff --git a/src/__tests__/store/libraryStore.test.ts b/src/__tests__/store/libraryStore.test.ts
new file mode 100644
index 0000000..797386b
--- /dev/null
+++ b/src/__tests__/store/libraryStore.test.ts
@@ -0,0 +1,147 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { useLibraryStore } from "@/store/libraryStore";
+import { useStorageStore } from "@/store/storageStore";
+import { notifyError } from "@/utils/notifications";
+import { safeStoreLoad } from "@/utils/tauri";
+
+const mocks = vi.hoisted(() => ({
+  isTauri: true,
+  storeData: new Map<string, unknown>(),
+  storeLoadPaths: [] as string[],
+  storeSets: [] as Array<[string, unknown]>,
+  storeSaves: 0,
+  failStoreLoad: false,
+}));
+
+vi.mock("@/utils/tauri", () => ({
+  isTauri: vi.fn(() => mocks.isTauri),
+  isMobile: vi.fn(() => false),
+  safeInvoke: vi.fn(async () => undefined),
+  safeStoreLoad: vi.fn(async (path: string) => {
+    mocks.storeLoadPaths.push(path);
+    if (mocks.failStoreLoad) throw new Error("settings store unavailable");
+    return {
+      get: async <T>(key: string): Promise<T | null> => (mocks.storeData.get(key) as T) ?? null,
+      set: async (key: string, value: unknown) => {
+        mocks.storeData.set(key, value);
+        mocks.storeSets.push([key, value]);
+      },
+      save: async () => {
+        mocks.storeSaves += 1;
+      },
+      clear: async () => {
+        mocks.storeData.clear();
+      },
+      onKeyChange: () => () => {},
+      onChange: () => () => {},
+    };
+  }),
+}));
+
+vi.mock("@/utils/notifications", () => ({
+  notifyError: vi.fn(async (_title: string, _message: string) => {}),
+  notifySuccess: vi.fn(async () => {}),
+  notifyInfo: vi.fn(async () => {}),
+}));
+
+const eInkClasses = () => document.documentElement.classList.contains("e-ink");
+
+describe("e-ink display setting load (#115)", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    mocks.isTauri = true;
+    mocks.storeData.clear();
+    mocks.storeLoadPaths.length = 0;
+    mocks.storeSets.length = 0;
+    mocks.storeSaves = 0;
+    mocks.failStoreLoad = false;
+    useLibraryStore.setState({ eInkMode: false });
+    useStorageStore.setState({ offlineStoragePath: "" });
+    document.documentElement.classList.remove("e-ink");
+  });
+
+  it("applies the persisted e-ink preference and the DOM class", async () => {
+    mocks.storeData.set("e_ink_mode", true);
+
+    await useLibraryStore.getState().loadSettings();
+
+    expect(useLibraryStore.getState().eInkMode).toBe(true);
+    expect(eInkClasses()).toBe(true);
+    expect(notifyError).not.toHaveBeenCalled();
+  });
+
+  it("leaves e-ink off when the preference is not persisted", async () => {
+    mocks.storeData.set("e_ink_mode", false);
+
+    await useLibraryStore.getState().loadSettings();
+
+    expect(useLibraryStore.getState().eInkMode).toBe(false);
+    expect(eInkClasses()).toBe(false);
+  });
+
+  it("routes a load failure through notifyError and keeps defaults", async () => {
+    mocks.failStoreLoad = true;
+    useLibraryStore.setState({ eInkMode: true });
+    document.documentElement.classList.add("e-ink");
+
+    await expect(useLibraryStore.getState().loadSettings()).resolves.toBeUndefined();
+
+    expect(notifyError).toHaveBeenCalledWith(
+      "Settings Error",
+      "Failed to load e-ink display settings.",
+    );
+    // Defaults still apply: the optimistic e-ink value is not introduced.
+    expect(useLibraryStore.getState().eInkMode).toBe(true);
+    expect(eInkClasses()).toBe(true);
+  });
+});
+
+describe("e-ink display setting save (#115)", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    mocks.isTauri = true;
+    mocks.storeData.clear();
+    mocks.storeLoadPaths.length = 0;
+    mocks.storeSets.length = 0;
+    mocks.storeSaves = 0;
+    mocks.failStoreLoad = false;
+    useLibraryStore.setState({ eInkMode: false });
+    useStorageStore.setState({ offlineStoragePath: "" });
+    document.documentElement.classList.remove("e-ink");
+  });
+
+  it("updates state and DOM optimistically before persisting", async () => {
+    await useLibraryStore.getState().setEInkMode(true);
+
+    expect(useLibraryStore.getState().eInkMode).toBe(true);
+    expect(eInkClasses()).toBe(true);
+    expect(vi.mocked(safeStoreLoad)).toHaveBeenCalledWith("shelfsync_settings.json");
+    expect(mocks.storeSets).toContainEqual(["e_ink_mode", true]);
+    expect(mocks.storeSaves).toBeGreaterThan(0);
+    expect(notifyError).not.toHaveBeenCalled();
+  });
+
+  it("turns off the DOM class when e-ink is disabled", async () => {
+    document.documentElement.classList.add("e-ink");
+    useLibraryStore.setState({ eInkMode: true });
+
+    await useLibraryStore.getState().setEInkMode(false);
+
+    expect(useLibraryStore.getState().eInkMode).toBe(false);
+    expect(eInkClasses()).toBe(false);
+  });
+
+  it("routes a save failure through notifyError while keeping optimistic state", async () => {
+    mocks.failStoreLoad = true;
+
+    await expect(useLibraryStore.getState().setEInkMode(true)).resolves.toBeUndefined();
+
+    expect(useLibraryStore.getState().eInkMode).toBe(true);
+    expect(eInkClasses()).toBe(true);
+    expect(notifyError).toHaveBeenCalledWith(
+      "Settings Error",
+      "Failed to save e-ink display setting.",
+    );
+    expect(mocks.storeSaves).toBe(0);
+  });
+});
diff --git a/src/store/libraryStore.ts b/src/store/libraryStore.ts
index a8d19c3..3a215fd 100644
--- a/src/store/libraryStore.ts
+++ b/src/store/libraryStore.ts
@@ -1,5 +1,6 @@
 import { create } from "zustand";
 import { useStorageStore } from "@/store/storageStore";
+import { notifyError } from "@/utils/notifications";
 import { safeStoreLoad } from "@/utils/tauri";
 
 const STORE_PATH = "shelfsync_settings.json";
@@ -29,7 +30,9 @@ export const useLibraryStore = create<LibraryState>((set) => ({
       const store = await safeStoreLoad(STORE_PATH);
       await store.set("e_ink_mode", enabled);
       await store.save();
-    } catch (_) {}
+    } catch (_) {
+      notifyError("Settings Error", "Failed to save e-ink display setting.");
+    }
   },
 
   loadSettings: async () => {
@@ -47,6 +50,7 @@ export const useLibraryStore = create<LibraryState>((set) => ({
       }
     } catch (_) {
       // Settings load failure is non-fatal; defaults apply.
+      notifyError("Settings Error", "Failed to load e-ink display settings.");
     }
   },
 }));