diff --git a/docs/settings.md b/docs/settings.md
index cdbc5889..707cade8 100644
--- a/docs/settings.md
+++ b/docs/settings.md
@@ -206,6 +206,8 @@ Setting key: syncGuardEnabled
 
 When enabled on this device, the workspace temporarily blocks interaction after a large batch of incoming note changes is detected during CouchDB LiveSync startup or resume. Incoming changes continue to be received and applied while the workspace is protected. The overlay can be bypassed at any time, including when synchronisation fails or the remote is unavailable. The preference is device-local; it does not affect other synchronising devices.
 
+Both SyncGuard preferences are stored in device-local storage for this Vault, separately from the main plug-in settings. They are not transferred through Setup URIs. Existing values saved by earlier test builds are migrated to device-local storage when the plug-in starts.
+
 The threshold avoids interruption for ordinary small transfers. However, the number of changes cannot be known before they arrive: some notes may be updated before the guard activates. The guard is a user-interface aid, not an atomic Vault snapshot or a restriction on other plug-ins and external tools. It does not apply to other remote types or to ordinary live changes after the initial catch-up.
 
 #### Minimum received files to protect the workspace
diff --git a/src/modules/features/SettingDialogue/ObsidianLiveSyncSettingTab.declarative.unit.spec.ts b/src/modules/features/SettingDialogue/ObsidianLiveSyncSettingTab.declarative.unit.spec.ts
index 029741af..afe7986f 100644
--- a/src/modules/features/SettingDialogue/ObsidianLiveSyncSettingTab.declarative.unit.spec.ts
+++ b/src/modules/features/SettingDialogue/ObsidianLiveSyncSettingTab.declarative.unit.spec.ts
@@ -1,6 +1,7 @@
 import { MemoryValueStore } from "@vrtmrz/value-store";
 import { beforeEach, describe, expect, it, vi } from "vitest";
 import { DEFAULT_SETTINGS } from "@vrtmrz/livesync-commonlib/compat/common/types";
+import { DEFAULT_SYNC_GUARD_SETTINGS, type SyncGuardSettings } from "@/modules/services/ObsidianSettingService.ts";
 import type { SettingDefinitionGroup, SettingDefinitionItem, SettingDefinitionPage } from "obsidian";
 import type { PageFunctions } from "./SettingPane.ts";
 
@@ -152,6 +153,7 @@ type SettingsTabOptions = {
 };
 
 function createSettingsTab(options: SettingsTabOptions = {}): ObsidianLiveSyncSettingTab {
+    const syncGuardSettings: SyncGuardSettings = { ...DEFAULT_SYNC_GUARD_SETTINGS };
     const core = {
         settings: { ...DEFAULT_SETTINGS, useAdvancedMode: true },
         confirm: {
@@ -160,6 +162,10 @@ function createSettingsTab(options: SettingsTabOptions = {}): ObsidianLiveSyncSe
         services: {
             setting: {
                 deviceValues: new MemoryValueStore(),
+                syncGuardSettings,
+                setSyncGuardSetting: vi.fn(async (key: keyof SyncGuardSettings, value: boolean | number) => {
+                    Object.assign(syncGuardSettings, { [key]: value });
+                }),
                 getDeviceAndVaultName: vi.fn(() => ""),
                 saveSettingData: vi.fn(async () => undefined),
             },
@@ -179,8 +185,8 @@ function createSettingsTab(options: SettingsTabOptions = {}): ObsidianLiveSyncSe
     };
     const tab = new ObsidianLiveSyncSettingTab({} as never, plugin as never);
     Object.assign(tab, {
-        _editingSettings: { ...DEFAULT_SETTINGS, useAdvancedMode: true },
-        initialSettings: { ...DEFAULT_SETTINGS, useAdvancedMode: true },
+        _editingSettings: { ...DEFAULT_SETTINGS, ...syncGuardSettings, useAdvancedMode: true },
+        initialSettings: { ...DEFAULT_SETTINGS, ...syncGuardSettings, useAdvancedMode: true },
     });
     return tab;
 }
@@ -347,6 +353,39 @@ describe("ObsidianLiveSyncSettingTab native page lifecycle", () => {
         ).toEqual(["useAdvancedMode", "usePowerUserMode", "useEdgeCaseMode"]);
     });
 
+    it("persists declarative SyncGuard controls through Obsidian's local settings service", async () => {
+        const tab = createSettingsTab();
+        const setting = tab.services.setting as typeof tab.services.setting & {
+            setSyncGuardSetting: ReturnType<typeof vi.fn>;
+        };
+        const initialCoreSettings = { ...tab.core.settings };
+
+        await tab.setControlValue("syncGuardEnabled", true);
+        await tab.setControlValue("syncGuardMinimumFiles", 6);
+
+        expect(setting.setSyncGuardSetting).toHaveBeenNthCalledWith(1, "syncGuardEnabled", true);
+        expect(setting.setSyncGuardSetting).toHaveBeenNthCalledWith(2, "syncGuardMinimumFiles", 6);
+        expect(tab.getControlValue("syncGuardEnabled")).toBe(true);
+        expect(tab.getControlValue("syncGuardMinimumFiles")).toBe(6);
+        expect(tab.core.settings).toEqual(initialCoreSettings);
+        expect(setting.saveSettingData).not.toHaveBeenCalled();
+    });
+
+    it("refreshes active settings when local SyncGuard preferences change elsewhere", async () => {
+        const tab = createSettingsTab();
+        tab.isShown = true;
+        const refresh = vi.spyOn(tab, "requestPageRefresh").mockImplementation(() => undefined);
+        const setting = tab.services.setting as typeof tab.services.setting & { syncGuardSettings: SyncGuardSettings };
+        setting.syncGuardSettings.syncGuardEnabled = true;
+        setting.syncGuardSettings.syncGuardMinimumFiles = 13;
+
+        await tab.requestReload();
+
+        expect(tab.editingSettings.syncGuardEnabled).toBe(true);
+        expect(tab.editingSettings.syncGuardMinimumFiles).toBe(13);
+        expect(refresh).toHaveBeenCalledOnce();
+    });
+
     it("omits the old Setup child page and keeps standard General and Advanced pages native", () => {
         const tab = createSettingsTab();
         const pages = collectPages(tab.getSettingDefinitions());
diff --git a/src/modules/features/SettingDialogue/ObsidianLiveSyncSettingTab.ts b/src/modules/features/SettingDialogue/ObsidianLiveSyncSettingTab.ts
index a3c72a31..e5680d8e 100644
--- a/src/modules/features/SettingDialogue/ObsidianLiveSyncSettingTab.ts
+++ b/src/modules/features/SettingDialogue/ObsidianLiveSyncSettingTab.ts
@@ -77,6 +77,11 @@ import { createExtraMenuSettingSpecGroup, createGeneralSettingSpecGroups } from
 import { SetupManager } from "@/modules/features/SetupManager.ts";
 import { isP2PMainRemote } from "@/common/remoteConfiguration.ts";
 import { withOwnedRemoteResource } from "@/common/ownedRemoteResource.ts";
+import {
+    getSyncGuardSettings,
+    isSyncGuardSettingKey,
+    setSyncGuardSetting,
+} from "@/modules/services/ObsidianSettingService.ts";
 
 // For creating a document
 // const toc = new Set<string>();
@@ -138,6 +143,7 @@ export class ObsidianLiveSyncSettingTab extends PluginSettingTab {
             if (
                 this.isReconstructionRequiredSetting(k) ||
                 this.isConfigurationEncryptionSetting(k) ||
+                isSyncGuardSettingKey(k) ||
                 k in OnDialogSettingsDefault
             ) {
                 // //@ts-ignore
@@ -157,6 +163,10 @@ export class ObsidianLiveSyncSettingTab extends PluginSettingTab {
             (e) => this.isDirty(e) && !this.isReconstructionRequiredSetting(e)
         );
         await this.saveConfigurationEncryptionIfDirty(changedKeys);
+        for (const key of changedKeys.filter(isSyncGuardSettingKey)) {
+            await setSyncGuardSetting(this.services.setting, key, this.editingSettings[key]);
+            this.copySettingValue(this.initialSettings, this.editingSettings, key);
+        }
         this.applySetting(changedKeys);
         this.reloadAllSettings();
     }
@@ -177,6 +187,11 @@ export class ObsidianLiveSyncSettingTab extends PluginSettingTab {
         await this.saveConfigurationEncryptionIfDirty(appliedKeys);
         for (const k of appliedKeys) {
             if (this.isConfigurationEncryptionSetting(k)) continue;
+            if (isSyncGuardSettingKey(k)) {
+                await setSyncGuardSetting(this.services.setting, k, this.editingSettings[k]);
+                this.copySettingValue(this.initialSettings, this.editingSettings, k);
+                continue;
+            }
             if (k in OnDialogSettingsDefault) {
                 await this.saveLocalSetting(k as keyof OnDialogSettings);
                 this.copySettingValue(this.initialSettings, this.editingSettings, k);
@@ -307,7 +322,7 @@ export class ObsidianLiveSyncSettingTab extends PluginSettingTab {
         ret.configPassphrase = this.localConfigurationPassphrase;
         ret.preset = "";
         ret.deviceAndVaultName = this.services.setting.getDeviceAndVaultName();
-        return ret;
+        return { ...ret, ...getSyncGuardSettings(this.services.setting) };
     }
     computeAllLocalSettings(): Partial<OnDialogSettings> {
         const syncMode = this.editingSettings?.liveSync
@@ -375,7 +390,7 @@ export class ObsidianLiveSyncSettingTab extends PluginSettingTab {
             return;
         }
         const localSetting = this.reloadAllLocalSettings();
-        if (key in this.core.settings) {
+        if (isSyncGuardSettingKey(key) || key in this.core.settings) {
             if (key in localSetting) {
                 this.copySettingValue(this.initialSettings, localSetting, key);
                 this.copySettingValue(this.editingSettings, localSetting, key);
@@ -567,25 +582,25 @@ export class ObsidianLiveSyncSettingTab extends PluginSettingTab {
         const nativeTabIsShown =
             this.supportsDeclarativeSettings() && this.containerEl !== undefined && this.containerEl.isShown();
         if (this.isShown || nativeTabIsShown) {
-            const newConf = this.core.settings;
-            const keys = Object.keys(newConf) as (keyof ObsidianLiveSyncSettings)[];
+            const newConf = { ...this.core.settings, ...getSyncGuardSettings(this.services.setting) };
+            const keys = Object.keys(newConf) as AllSettingItemKey[];
             let hasLoaded = false;
             let catalogueVisibilityChanged = false;
             for (const k of keys) {
-                if (isObjectDifferent(newConf[k], this.initialSettings?.[k])) {
+                if (isObjectDifferent(Reflect.get(newConf, k), this.initialSettings?.[k])) {
                     // Something has changed
-                    if (this.isDirty(k as AllSettingItemKey)) {
+                    if (this.isDirty(k)) {
                         // And modified.
                         this.core.confirm.askInPopup(
                             `config-reloaded-${k}`,
                             $msg("obsidianLiveSyncSettingTab.msgSettingModified", {
-                                setting: getConfName(k as AllSettingItemKey),
+                                setting: getConfName(k),
                             }),
                             (anchor) => {
                                 anchor.text = $msg("obsidianLiveSyncSettingTab.optionHere");
                                 anchor.addEventListener("click", () => {
-                                    this.refreshSetting(k as AllSettingItemKey);
-                                    if (this.changesPageCatalogue(k as AllSettingItemKey)) {
+                                    this.refreshSetting(k);
+                                    if (this.changesPageCatalogue(k)) {
                                         this.requestCatalogueRefresh();
                                     } else {
                                         this.requestPageRefresh();
@@ -595,12 +610,12 @@ export class ObsidianLiveSyncSettingTab extends PluginSettingTab {
                         );
                     } else {
                         // not modified
-                        this.refreshSetting(k as AllSettingItemKey);
+                        this.refreshSetting(k);
                         if (k in OnDialogSettingsDefault) {
                             continue;
                         }
                         hasLoaded = true;
-                        if (this.changesPageCatalogue(k as AllSettingItemKey)) {
+                        if (this.changesPageCatalogue(k)) {
                             catalogueVisibilityChanged = true;
                         }
                     }
diff --git a/src/modules/features/SettingDialogue/settingConstants.ts b/src/modules/features/SettingDialogue/settingConstants.ts
index 495f8f76..a3a5c201 100644
--- a/src/modules/features/SettingDialogue/settingConstants.ts
+++ b/src/modules/features/SettingDialogue/settingConstants.ts
@@ -1,25 +1,50 @@
-export {
-    AllSettingDefault,
-    OnDialogSettingsDefault,
-    SettingInformation,
-} from "@vrtmrz/livesync-commonlib/compat/common/settingConstants";
-export type {
-    AllSettings,
-    AllSettingItemKey,
-    AllStringItemKey,
-    AllNumericItemKey,
-    AllBooleanItemKey,
-    OnDialogSettings,
-    ValueOf,
-} from "@vrtmrz/livesync-commonlib/compat/common/settingConstants";
+export { OnDialogSettingsDefault } from "@vrtmrz/livesync-commonlib/compat/common/settingConstants";
+export type { OnDialogSettings } from "@vrtmrz/livesync-commonlib/compat/common/settingConstants";
 
 import {
+    AllSettingDefault as CommonlibAllSettingDefault,
+    SettingInformation as CommonlibSettingInformation,
     getConfig as getCommonlibConfig,
     getConfName as getCommonlibConfName,
-    type AllSettingItemKey,
+    type AllSettings as CommonlibAllSettings,
+    type AllSettingItemKey as CommonlibAllSettingItemKey,
+    type AllStringItemKey as CommonlibAllStringItemKey,
+    type AllNumericItemKey as CommonlibAllNumericItemKey,
+    type AllBooleanItemKey as CommonlibAllBooleanItemKey,
 } from "@vrtmrz/livesync-commonlib/compat/common/settingConstants";
+import type { ConfigurationItem } from "@vrtmrz/livesync-commonlib/compat/common/types";
 import type { MessageTranslator } from "@vrtmrz/livesync-commonlib/context";
 import { translateLiveSyncMessage } from "@/common/translation";
+import {
+    DEFAULT_SYNC_GUARD_SETTINGS,
+    isSyncGuardSettingKey,
+    type SyncGuardSettingKey,
+    type SyncGuardSettings,
+} from "@/modules/services/ObsidianSettingService";
+
+export type AllSettings = Omit<CommonlibAllSettings, SyncGuardSettingKey> & SyncGuardSettings;
+export type AllStringItemKey = CommonlibAllStringItemKey;
+export type AllNumericItemKey = Exclude<CommonlibAllNumericItemKey, SyncGuardSettingKey> | "syncGuardMinimumFiles";
+export type AllBooleanItemKey = Exclude<CommonlibAllBooleanItemKey, SyncGuardSettingKey> | "syncGuardEnabled";
+export type AllSettingItemKey = Exclude<CommonlibAllSettingItemKey, SyncGuardSettingKey> | SyncGuardSettingKey;
+export type ValueOf<T extends AllSettingItemKey> = AllSettings[T];
+
+const syncGuardSettingInformation: Record<SyncGuardSettingKey, ConfigurationItem> = {
+    syncGuardEnabled: {
+        name: "Enable SyncGuard",
+        desc: "Enable device-local SyncGuard protection during synchronisation.",
+    },
+    syncGuardMinimumFiles: {
+        name: "SyncGuard minimum files",
+        desc: "Minimum number of Vault files required for SyncGuard protection to apply.",
+    },
+};
+
+export const AllSettingDefault = { ...CommonlibAllSettingDefault, ...DEFAULT_SYNC_GUARD_SETTINGS };
+export const SettingInformation: Partial<Record<AllSettingItemKey, ConfigurationItem>> = {
+    ...CommonlibSettingInformation,
+    ...syncGuardSettingInformation,
+};
 
 // Commonlib defaults `translate` to its English-only translator, so every caller which omits
 // it silently renders English regardless of `displayLanguage`. Default it to the LiveSync
@@ -28,10 +53,12 @@ import { translateLiveSyncMessage } from "@/common/translation";
 
 /** `getConfig` with the LiveSync catalogue applied by default. */
 export function getConfig(key: AllSettingItemKey, translate: MessageTranslator = translateLiveSyncMessage) {
-    return getCommonlibConfig(key, translate);
+    if (isSyncGuardSettingKey(key)) return syncGuardSettingInformation[key];
+    return getCommonlibConfig(key as CommonlibAllSettingItemKey, translate);
 }
 
 /** `getConfName` with the LiveSync catalogue applied by default. See `getConfig`. */
 export function getConfName(key: AllSettingItemKey, translate: MessageTranslator = translateLiveSyncMessage) {
-    return getCommonlibConfName(key, translate);
+    if (isSyncGuardSettingKey(key)) return syncGuardSettingInformation[key].name;
+    return getCommonlibConfName(key as CommonlibAllSettingItemKey, translate);
 }
diff --git a/src/modules/services/ObsidianSettingService.ts b/src/modules/services/ObsidianSettingService.ts
index 87b93b59..0eabbc69 100644
--- a/src/modules/services/ObsidianSettingService.ts
+++ b/src/modules/services/ObsidianSettingService.ts
@@ -9,12 +9,48 @@ import {
 } from "@vrtmrz/livesync-commonlib/compat/services/base/SettingService";
 import type { ObsidianServiceContext } from "@/modules/services/ObsidianServiceContext";
 
+export type SyncGuardSettings = {
+    syncGuardEnabled: boolean;
+    syncGuardMinimumFiles: number;
+};
+
+export type SyncGuardSettingKey = keyof SyncGuardSettings;
+
+export const DEFAULT_SYNC_GUARD_SETTINGS: Readonly<SyncGuardSettings> = {
+    syncGuardEnabled: false,
+    syncGuardMinimumFiles: 20,
+};
+
+export function isSyncGuardSettingKey(key: string): key is SyncGuardSettingKey {
+    return key === "syncGuardEnabled" || key === "syncGuardMinimumFiles";
+}
+
+/** Access the Obsidian host preferences from a service exposed through the shared hub type. */
+export function getSyncGuardSettings(setting: SettingService<ObsidianServiceContext>): Readonly<SyncGuardSettings> {
+    return (setting as ObsidianSettingService<ObsidianServiceContext>).syncGuardSettings;
+}
+
+export async function setSyncGuardSetting<K extends SyncGuardSettingKey>(
+    setting: SettingService<ObsidianServiceContext>,
+    key: K,
+    value: SyncGuardSettings[K]
+): Promise<void> {
+    await (setting as ObsidianSettingService<ObsidianServiceContext>).setSyncGuardSetting(key, value);
+}
+
 export function normaliseObsidianSettingsData(data: unknown): ObsidianLiveSyncSettings | undefined {
     if (typeof data !== "object" || data === null || Array.isArray(data)) return undefined;
     return data as ObsidianLiveSyncSettings;
 }
 
 export class ObsidianSettingService<T extends ObsidianServiceContext> extends SettingService<T> {
+    private _syncGuardSettings: SyncGuardSettings = { ...DEFAULT_SYNC_GUARD_SETTINGS };
+    private legacySyncGuardSettings: Partial<SyncGuardSettings> = {};
+
+    get syncGuardSettings(): Readonly<SyncGuardSettings> {
+        return this._syncGuardSettings;
+    }
+
     constructor(context: T, dependencies: SettingServiceDependencies) {
         super(context, dependencies);
         this.onSettingSaved.addHandler((settings) => {
@@ -26,10 +62,60 @@ export class ObsidianSettingService<T extends ObsidianServiceContext> extends Se
             return Promise.resolve(true);
         });
     }
+
+    override async loadSettings(): Promise<void> {
+        await super.loadSettings();
+        const storedEnabled = await this.config.getObject("syncGuardEnabled");
+        const storedMinimumFiles = await this.config.getObject("syncGuardMinimumFiles");
+        const enabled = typeof storedEnabled === "boolean" ? storedEnabled : this.legacySyncGuardSettings.syncGuardEnabled;
+        const minimumFiles =
+            typeof storedMinimumFiles === "number" && Number.isFinite(storedMinimumFiles) && storedMinimumFiles >= 1
+                ? storedMinimumFiles
+                : this.legacySyncGuardSettings.syncGuardMinimumFiles;
+
+        this._syncGuardSettings = {
+            syncGuardEnabled: enabled ?? DEFAULT_SYNC_GUARD_SETTINGS.syncGuardEnabled,
+            syncGuardMinimumFiles: minimumFiles ?? DEFAULT_SYNC_GUARD_SETTINGS.syncGuardMinimumFiles,
+        };
+        if (storedEnabled === undefined && enabled !== undefined) {
+            await this.config.setObject("syncGuardEnabled", enabled);
+        }
+        if (storedMinimumFiles === undefined && minimumFiles !== undefined) {
+            await this.config.setObject("syncGuardMinimumFiles", minimumFiles);
+        }
+    }
+
+    async setSyncGuardSetting<K extends SyncGuardSettingKey>(key: K, value: SyncGuardSettings[K]): Promise<void> {
+        if (key === "syncGuardMinimumFiles" && (typeof value !== "number" || !Number.isInteger(value) || value < 1)) {
+            throw new RangeError("SyncGuard minimum files must be a positive integer");
+        }
+        if (this._syncGuardSettings[key] === value) return;
+        await this.config.setObject(key, value);
+        this._syncGuardSettings = { ...this._syncGuardSettings, [key]: value };
+        this.context.events.emitEvent(EVENT_SETTING_SAVED, this.currentSettings());
+    }
+
     protected override async saveData(data: ObsidianLiveSyncSettings): Promise<void> {
-        return await this.context.liveSyncPlugin.saveData(data);
+        const persisted: Record<string, unknown> = { ...data };
+        delete persisted.syncGuardEnabled;
+        delete persisted.syncGuardMinimumFiles;
+        return await this.context.liveSyncPlugin.saveData(persisted);
     }
     protected override async loadData(): Promise<ObsidianLiveSyncSettings | undefined> {
-        return normaliseObsidianSettingsData(await this.context.liveSyncPlugin.loadData());
+        const data = normaliseObsidianSettingsData(await this.context.liveSyncPlugin.loadData());
+        if (!data) return undefined;
+        const persisted: Record<string, unknown> = { ...data };
+        const { syncGuardEnabled, syncGuardMinimumFiles } = persisted;
+        this.legacySyncGuardSettings = {
+            ...(typeof syncGuardEnabled === "boolean" ? { syncGuardEnabled } : {}),
+            ...(typeof syncGuardMinimumFiles === "number" &&
+            Number.isFinite(syncGuardMinimumFiles) &&
+            syncGuardMinimumFiles >= 1
+                ? { syncGuardMinimumFiles }
+                : {}),
+        };
+        delete persisted.syncGuardEnabled;
+        delete persisted.syncGuardMinimumFiles;
+        return persisted as unknown as ObsidianLiveSyncSettings;
     }
 }
diff --git a/src/modules/services/ObsidianSettingService.unit.spec.ts b/src/modules/services/ObsidianSettingService.unit.spec.ts
index 6df8404d..db7bfa2d 100644
--- a/src/modules/services/ObsidianSettingService.unit.spec.ts
+++ b/src/modules/services/ObsidianSettingService.unit.spec.ts
@@ -1,20 +1,28 @@
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import { createServiceContext } from "@vrtmrz/livesync-commonlib/context";
-import type { ObsidianLiveSyncSettings } from "@vrtmrz/livesync-commonlib/compat/common/types";
+import { DEFAULT_SETTINGS, type ObsidianLiveSyncSettings } from "@vrtmrz/livesync-commonlib/compat/common/types";
+import { EVENT_SETTING_SAVED } from "@vrtmrz/livesync-commonlib/compat/events/coreEvents";
 import type { IAPIService } from "@vrtmrz/livesync-commonlib/compat/services/base/IService";
 import { MemoryValueStore } from "@vrtmrz/value-store";
 import type { ObsidianServiceContext } from "@/modules/services/ObsidianServiceContext";
 import { normaliseObsidianSettingsData } from "./ObsidianSettingService.ts";
-import { ObsidianSettingService } from "./ObsidianSettingService.ts";
+import { getSyncGuardSettings, ObsidianSettingService, setSyncGuardSetting } from "./ObsidianSettingService.ts";
 
 function createSettingService(
     vaultName: string,
-    deviceValues: MemoryValueStore
+    deviceValues: MemoryValueStore,
+    savedData?: unknown,
+    saveData = vi.fn(async (_settings: unknown) => undefined)
 ): ObsidianSettingService<ObsidianServiceContext> {
     const context = createServiceContext() as unknown as ObsidianServiceContext;
+    context.liveSyncPlugin = {
+        loadData: vi.fn(async () => savedData),
+        saveData,
+    } as unknown as ObsidianServiceContext["liveSyncPlugin"];
     const APIService = {
         addLog: () => undefined,
         getSystemVaultName: () => vaultName,
+        getAppID: () => "test-app",
     } as unknown as IAPIService;
     return new ObsidianSettingService(context, { APIService, deviceValues });
 }
@@ -52,3 +60,99 @@ describe("normaliseObsidianSettingsData", () => {
         await expect(secondValues.getValue("second-vault-shared-key")).resolves.toBe("second config");
     });
 });
+
+describe("SyncGuard device-local settings", () => {
+    const savedSettings = { ...DEFAULT_SETTINGS, isConfigured: true, additionalSuffixOfDatabaseName: "" };
+
+    it("loads safe defaults when no local values were saved", async () => {
+        const setting = createSettingService("first-vault", new MemoryValueStore(), savedSettings);
+
+        await setting.loadSettings();
+
+        expect(getSyncGuardSettings(setting)).toEqual({ syncGuardEnabled: false, syncGuardMinimumFiles: 20 });
+    });
+
+    it("migrates preferences stored by earlier builds and excludes them from plugin data", async () => {
+        const localValues = new MemoryValueStore();
+        const saveData = vi.fn(async (_data: unknown) => undefined);
+        const setting = createSettingService(
+            "first-vault",
+            localValues,
+            { ...savedSettings, syncGuardEnabled: true, syncGuardMinimumFiles: 7 },
+            saveData
+        );
+
+        await setting.loadSettings();
+        await setting.saveSettingData();
+
+        expect(getSyncGuardSettings(setting)).toEqual({ syncGuardEnabled: true, syncGuardMinimumFiles: 7 });
+        await expect(setting.config.getObject("syncGuardEnabled")).resolves.toBe(true);
+        await expect(setting.config.getObject("syncGuardMinimumFiles")).resolves.toBe(7);
+        expect(saveData.mock.lastCall?.[0]).not.toHaveProperty("syncGuardEnabled");
+        expect(saveData.mock.lastCall?.[0]).not.toHaveProperty("syncGuardMinimumFiles");
+    });
+
+    it("keeps existing device-local values authoritative over legacy plugin data", async () => {
+        const localValues = new MemoryValueStore();
+        const setting = createSettingService(
+            "first-vault",
+            localValues,
+            { ...savedSettings, syncGuardEnabled: true, syncGuardMinimumFiles: 5 }
+        );
+        await localValues.setObject("first-vault--syncGuardEnabled", false);
+        await localValues.setObject("first-vault--syncGuardMinimumFiles", 30);
+
+        await setting.loadSettings();
+
+        expect(getSyncGuardSettings(setting)).toEqual({ syncGuardEnabled: false, syncGuardMinimumFiles: 30 });
+    });
+
+    it("restores saved preferences after recreating the service", async () => {
+        const localValues = new MemoryValueStore();
+        const first = createSettingService("first-vault", localValues, savedSettings);
+        await first.loadSettings();
+        await setSyncGuardSetting(first, "syncGuardEnabled", true);
+        await setSyncGuardSetting(first, "syncGuardMinimumFiles", 12);
+
+        const reloaded = createSettingService("first-vault", localValues, savedSettings);
+        await reloaded.loadSettings();
+
+        expect(getSyncGuardSettings(reloaded)).toEqual({ syncGuardEnabled: true, syncGuardMinimumFiles: 12 });
+    });
+
+    it("rejects invalid file thresholds without changing local settings", async () => {
+        const setting = createSettingService("first-vault", new MemoryValueStore(), savedSettings);
+        await setting.loadSettings();
+        const storedBefore = await setting.config.getObject("syncGuardMinimumFiles");
+
+        for (const invalid of [0, -1, 1.5, NaN, Infinity]) {
+            await expect(setSyncGuardSetting(setting, "syncGuardMinimumFiles", invalid)).rejects.toThrow(RangeError);
+        }
+
+        expect(getSyncGuardSettings(setting).syncGuardMinimumFiles).toBe(20);
+        await expect(setting.config.getObject("syncGuardMinimumFiles")).resolves.toBe(storedBefore);
+    });
+
+    it("persists edits only in this Vault's device store and notifies the guard", async () => {
+        const localValues = new MemoryValueStore();
+        const saveData = vi.fn(async (_data: unknown) => undefined);
+        const first = createSettingService("first-vault", localValues, savedSettings, saveData);
+        const second = createSettingService("second-vault", localValues, savedSettings);
+        await first.loadSettings();
+        await second.loadSettings();
+        const initialSaveCount = saveData.mock.calls.length;
+        const changed = vi.fn();
+        first.context.events.onEvent(EVENT_SETTING_SAVED, changed);
+
+        await setSyncGuardSetting(first, "syncGuardEnabled", true);
+        await setSyncGuardSetting(first, "syncGuardMinimumFiles", 8);
+        await setSyncGuardSetting(first, "syncGuardEnabled", true);
+
+        expect(getSyncGuardSettings(first)).toEqual({ syncGuardEnabled: true, syncGuardMinimumFiles: 8 });
+        expect(getSyncGuardSettings(second)).toEqual({ syncGuardEnabled: false, syncGuardMinimumFiles: 20 });
+        await expect(localValues.getObject("first-vault--syncGuardEnabled")).resolves.toBe(true);
+        await expect(localValues.getObject("first-vault--syncGuardMinimumFiles")).resolves.toBe(8);
+        expect(changed).toHaveBeenCalledTimes(2);
+        expect(saveData).toHaveBeenCalledTimes(initialSaveCount);
+    });
+});