diff --git a/src/main.test.ts b/src/main.test.ts
new file mode 100644
index 0000000..768759f
--- /dev/null
+++ b/src/main.test.ts
@@ -0,0 +1,166 @@
+import { afterEach, beforeEach, describe, expect, test, vi } from "vitest";
+import ObsyncPlugin from "./main";
+
+vi.mock("obsidian", () => ({
+  App: class {},
+  Notice: class {
+    hide(): void {}
+  },
+  Platform: {
+    isAndroidApp: false,
+    isIosApp: false,
+    isTablet: false,
+  },
+  Plugin: class {},
+  PluginSettingTab: class {},
+  requestUrl: vi.fn(),
+  TFile: class {},
+  TFolder: class {},
+}));
+
+describe("auto sync scheduling", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+    vi.stubGlobal("window", {
+      clearTimeout: globalThis.clearTimeout,
+      setTimeout: globalThis.setTimeout,
+    });
+  });
+
+  afterEach(() => {
+    vi.useRealTimers();
+    vi.unstubAllGlobals();
+    vi.restoreAllMocks();
+  });
+
+  test("does not schedule when auto sync is disabled", async () => {
+    const plugin = createPlugin({ autoSync: false });
+
+    plugin.queueAutoSync(0);
+    await vi.runAllTimersAsync();
+
+    expect(plugin.syncNow).not.toHaveBeenCalled();
+  });
+
+  test("skips scheduled sync when auto sync is disabled before the timer fires", async () => {
+    const plugin = createPlugin();
+
+    plugin.queueAutoSync();
+    plugin.settings.autoSync = false;
+    await vi.advanceTimersByTimeAsync(2_000);
+
+    expect(plugin.syncNow).not.toHaveBeenCalled();
+  });
+
+  test("skips when connection settings are incomplete", async () => {
+    const plugin = createPlugin({ secretAccessKey: "" });
+
+    plugin.queueAutoSync(0);
+    await vi.runAllTimersAsync();
+
+    expect(plugin.syncNow).not.toHaveBeenCalled();
+  });
+
+  test("debounces repeated file-change triggers into one sync", async () => {
+    const plugin = createPlugin();
+
+    plugin.queueAutoSync();
+    await vi.advanceTimersByTimeAsync(1_000);
+    plugin.queueAutoSync();
+    await vi.advanceTimersByTimeAsync(1_000);
+    plugin.queueAutoSync();
+    await vi.advanceTimersByTimeAsync(1_999);
+
+    expect(plugin.syncNow).not.toHaveBeenCalled();
+
+    await vi.advanceTimersByTimeAsync(1);
+
+    expect(plugin.syncNow).toHaveBeenCalledTimes(1);
+  });
+
+  test("runs one follow-up sync when triggered during an active sync", async () => {
+    const plugin = createPlugin();
+    let finishSync: (() => void) | undefined;
+    plugin.syncNow.mockImplementationOnce(() => new Promise<void>((resolve) => {
+      finishSync = resolve;
+    }));
+
+    const firstRun = plugin.runAutoSync();
+    await Promise.resolve();
+
+    void plugin.runAutoSync();
+    expect(plugin.syncNow).toHaveBeenCalledTimes(1);
+
+    finishSync?.();
+    await firstRun;
+    await vi.advanceTimersByTimeAsync(2_000);
+
+    expect(plugin.syncNow).toHaveBeenCalledTimes(2);
+  });
+
+  test("does not run queued follow-up if auto sync is disabled while syncing", async () => {
+    const plugin = createPlugin();
+    let finishSync: (() => void) | undefined;
+    plugin.syncNow.mockImplementationOnce(() => new Promise<void>((resolve) => {
+      finishSync = resolve;
+    }));
+
+    const firstRun = plugin.runAutoSync();
+    await Promise.resolve();
+
+    void plugin.runAutoSync();
+    plugin.settings.autoSync = false;
+    finishSync?.();
+    await firstRun;
+    await vi.runAllTimersAsync();
+
+    expect(plugin.syncNow).toHaveBeenCalledTimes(1);
+  });
+});
+
+function createPlugin(settings: Partial<TestSettings> = {}): TestPlugin {
+  const plugin = Object.create(ObsyncPlugin.prototype) as TestPlugin;
+  plugin.settings = {
+    endpoint: "https://example.com",
+    bucket: "vault",
+    region: "auto",
+    accessKeyId: "key",
+    secretAccessKey: "secret",
+    rootPrefix: "obsync/v1",
+    accountKey: "default",
+    vaultKey: "vault",
+    vaultId: "vlt_test",
+    deviceId: "dev_test",
+    deviceName: "Mac",
+    syncIntervalMinutes: 5,
+    autoSync: true,
+    syncState: { files: {} },
+    ...settings,
+  };
+  plugin.syncNow = vi.fn(async () => {});
+  return plugin;
+}
+
+type TestPlugin = {
+  settings: TestSettings;
+  queueAutoSync: (delayMs?: number) => void;
+  runAutoSync: () => Promise<void>;
+  syncNow: ReturnType<typeof vi.fn<() => Promise<void>>>;
+};
+
+interface TestSettings {
+  endpoint: string;
+  bucket: string;
+  region: string;
+  accessKeyId: string;
+  secretAccessKey: string;
+  rootPrefix: string;
+  accountKey: string;
+  vaultKey: string;
+  vaultId: string;
+  deviceId: string;
+  deviceName: string;
+  syncIntervalMinutes: number;
+  autoSync: boolean;
+  syncState: { files: Record<string, unknown> };
+}
diff --git a/src/main.ts b/src/main.ts
index b7c2f3c..55e0d28 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,4 +1,4 @@
-import { App, Notice, Platform, Plugin, PluginSettingTab, requestUrl, TFile, TFolder } from "obsidian";
+import { App, Notice, Platform, Plugin, PluginSettingTab, requestUrl, type TAbstractFile, TFile, TFolder } from "obsidian";
 import { createApp, reactive, type App as VueApp } from "vue";
 import { createRandomId, createVaultId, normalizeKey } from "./core/ids";
 import SettingsApp from "./settings/SettingsApp.vue";
@@ -55,8 +55,13 @@ const DEFAULT_SETTINGS: ObsyncSettings = {
   },
 };
 
+const AUTO_SYNC_DEBOUNCE_MS = 2_000;
+
 export default class ObsyncPlugin extends Plugin {
   settings: ObsyncSettings = DEFAULT_SETTINGS;
+  private autoSyncTimer: number | null = null;
+  private autoSyncRunning = false;
+  private autoSyncQueued = false;
 
   async onload(): Promise<void> {
     await this.loadSettings();
@@ -87,6 +92,7 @@ export default class ObsyncPlugin extends Plugin {
     });
 
     this.addSettingTab(new ObsyncSettingTab(this.app, this));
+    this.registerAutoSyncTriggers();
   }
 
   async syncNow(): Promise<void> {
@@ -154,6 +160,76 @@ export default class ObsyncPlugin extends Plugin {
     (leftRibbonActions ?? iconEl.parentElement)?.append(iconEl);
   }
 
+  private registerAutoSyncTriggers(): void {
+    this.app.workspace.onLayoutReady(() => {
+      this.queueAutoSync(0);
+    });
+
+    this.registerDomEvent(window, "focus", () => {
+      this.queueAutoSync();
+    });
+
+    this.registerDomEvent(document, "visibilitychange", () => {
+      if (!document.hidden) {
+        this.queueAutoSync();
+      }
+    });
+
+    const queueFileSync = (file: TAbstractFile) => {
+      if (file instanceof TFile) {
+        this.queueAutoSync();
+      }
+    };
+
+    this.registerEvent(this.app.vault.on("create", queueFileSync));
+    this.registerEvent(this.app.vault.on("modify", queueFileSync));
+    this.registerEvent(this.app.vault.on("delete", queueFileSync));
+    this.registerEvent(this.app.vault.on("rename", queueFileSync));
+  }
+
+  private queueAutoSync(delayMs = AUTO_SYNC_DEBOUNCE_MS): void {
+    if (!this.settings.autoSync) {
+      return;
+    }
+
+    if (this.autoSyncTimer !== null) {
+      window.clearTimeout(this.autoSyncTimer);
+    }
+
+    this.autoSyncTimer = window.setTimeout(() => {
+      this.autoSyncTimer = null;
+      void this.runAutoSync();
+    }, delayMs);
+  }
+
+  private async runAutoSync(): Promise<void> {
+    if (!this.settings.autoSync || !this.hasConnectionSettings()) {
+      return;
+    }
+
+    if (this.autoSyncRunning) {
+      this.autoSyncQueued = true;
+      return;
+    }
+
+    this.autoSyncRunning = true;
+
+    try {
+      await this.syncNow();
+    } finally {
+      this.autoSyncRunning = false;
+
+      if (this.autoSyncQueued) {
+        this.autoSyncQueued = false;
+        this.queueAutoSync();
+      }
+    }
+  }
+
+  private hasConnectionSettings(): boolean {
+    return Boolean(this.settings.endpoint && this.settings.bucket && this.settings.accessKeyId && this.settings.secretAccessKey);
+  }
+
   async loadSettings(): Promise<void> {
     const loaded = await this.loadData();
     this.settings = Object.assign({}, DEFAULT_SETTINGS, loaded);