diff --git a/apps/web/src/components/DesktopRendererErrorBoundary.tsx b/apps/web/src/components/DesktopRendererErrorBoundary.tsx
index dd174fd8..a386be0c 100644
--- a/apps/web/src/components/DesktopRendererErrorBoundary.tsx
+++ b/apps/web/src/components/DesktopRendererErrorBoundary.tsx
@@ -63,9 +63,13 @@ export class DesktopRendererErrorBoundary extends React.Component<{ children: Re
           <div className="mb-4 flex h-11 w-11 items-center justify-center rounded-full bg-rose-50 text-xl text-rose-700">!</div>
           <h1 className="text-lg font-semibold">{zh ? "EdgeEver 页面出现异常" : "EdgeEver encountered a page error"}</h1>
           <p className="mt-2 text-sm leading-6 text-slate-600">
-            {zh
-              ? "问题已经记录到这台设备。你可以重新加载继续使用，并在提交前检查脱敏后的 GitHub Issue。"
-              : "The problem was recorded on this device. You can reload to continue and review the redacted GitHub Issue before submitting it."}
+            {desktop
+              ? (zh
+                  ? "问题已经记录到这台设备。你可以重新加载继续使用，并在提交前检查脱敏后的 GitHub Issue。"
+                  : "The problem was recorded on this device. You can reload to continue and review the redacted GitHub Issue before submitting it.")
+              : (zh
+                  ? "你可以重新加载继续使用。如果问题仍然出现，请检查浏览器控制台，并在提交 GitHub Issue 前移除敏感信息。"
+                  : "Reload to continue. If the problem persists, check the browser console and remove sensitive information before submitting a GitHub Issue.")}
           </p>
           <div className="mt-5 flex flex-wrap gap-3">
             <button
diff --git a/apps/web/src/hooks/useWorkspaceSyncLifecycle.ts b/apps/web/src/hooks/useWorkspaceSyncLifecycle.ts
index c8cfe3b0..7691d903 100644
--- a/apps/web/src/hooks/useWorkspaceSyncLifecycle.ts
+++ b/apps/web/src/hooks/useWorkspaceSyncLifecycle.ts
@@ -1,6 +1,7 @@
 import { useEffect, useRef } from "react";
 import { isBrowserOffline, verifyBrowserConnectivity } from "@/lib/network-status";
 import { SYNC_QUEUE_DEFERRED_EVENT } from "@/lib/sync-events";
+import { createClientUuid } from "@/lib/client-id";
 import {
   BACKGROUND_WORKSPACE_REFRESH_INTERVAL_MS,
   claimBackgroundRefreshLease,
@@ -30,7 +31,7 @@ export const useWorkspaceSyncLifecycle = ({
   const deferredSyncPendingRef = useRef(false);
   const runQueuedSyncRef = useRef(runQueuedSync);
   const refreshWorkspaceRef = useRef(refreshWorkspace);
-  const backgroundRefreshOwnerRef = useRef(crypto.randomUUID());
+  const backgroundRefreshOwnerRef = useRef(createClientUuid());
 
   useEffect(() => {
     refreshWorkspaceRef.current = refreshWorkspace;
diff --git a/apps/web/src/lib/api.ts b/apps/web/src/lib/api.ts
index c74e97a5..737ee1b9 100644
--- a/apps/web/src/lib/api.ts
+++ b/apps/web/src/lib/api.ts
@@ -39,6 +39,7 @@ import type {
 import { resolveInstanceUrlInput } from "@edgeever/shared";
 import type { MemoFilterMode, MemoSortMode } from "./app-helpers";
 import { readAiStreamingPreference } from "./ai-generation-preference";
+import { createClientUuid } from "./client-id";
 
 type ListNotebooksResponse = {
   notebooks: Notebook[];
@@ -227,10 +228,7 @@ export const saveDesktopApiBaseUrl = async (value: string) => {
 };
 
 const createWebDeviceId = () => {
-  const uuid = globalThis.crypto?.randomUUID?.();
-  return uuid
-    ? `web-${uuid}`
-    : `web-${Date.now().toString(36)}-${Math.random().toString(36).slice(2)}${Math.random().toString(36).slice(2)}`;
+  return `web-${createClientUuid()}`;
 };
 
 const getOrCreateWebDeviceId = () => {
diff --git a/apps/web/src/lib/client-id.test.mjs b/apps/web/src/lib/client-id.test.mjs
new file mode 100644
index 00000000..0f53bc84
--- /dev/null
+++ b/apps/web/src/lib/client-id.test.mjs
@@ -0,0 +1,32 @@
+import { strict as assert } from "node:assert";
+import { describe, it } from "node:test";
+import { createClientUuid } from "./client-id.ts";
+
+describe("createClientUuid", () => {
+  it("prefers the browser randomUUID implementation", () => {
+    const expected = "12345678-1234-4123-8123-123456789abc";
+    const cryptoApi = {
+      randomUUID: () => expected,
+      getRandomValues: () => {
+        throw new Error("getRandomValues should not be called");
+      },
+    };
+
+    assert.equal(createClientUuid(cryptoApi), expected);
+  });
+
+  it("creates an RFC 4122 v4 UUID when randomUUID is unavailable on HTTP", () => {
+    const cryptoApi = {
+      getRandomValues: (bytes) => {
+        bytes.fill(0xab);
+        return bytes;
+      },
+    };
+
+    assert.equal(createClientUuid(cryptoApi), "abababab-abab-4bab-abab-abababababab");
+  });
+
+  it("still returns a UUID when the Crypto API is unavailable", () => {
+    assert.match(createClientUuid(null), /^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/);
+  });
+});
diff --git a/apps/web/src/lib/client-id.ts b/apps/web/src/lib/client-id.ts
new file mode 100644
index 00000000..b3899441
--- /dev/null
+++ b/apps/web/src/lib/client-id.ts
@@ -0,0 +1,27 @@
+type ClientCrypto = Pick<Crypto, "getRandomValues"> & Partial<Pick<Crypto, "randomUUID">>;
+
+const fillWithPseudoRandomBytes = (bytes: Uint8Array) => {
+  for (let index = 0; index < bytes.length; index += 1) {
+    bytes[index] = Math.floor(Math.random() * 256);
+  }
+};
+
+export const createClientUuid = (cryptoApi: ClientCrypto | null | undefined = globalThis.crypto) => {
+  if (typeof cryptoApi?.randomUUID === "function") {
+    return cryptoApi.randomUUID();
+  }
+
+  const bytes = new Uint8Array(16);
+  if (typeof cryptoApi?.getRandomValues === "function") {
+    cryptoApi.getRandomValues(bytes);
+  } else {
+    fillWithPseudoRandomBytes(bytes);
+  }
+
+  // RFC 4122 version 4 and variant bits. getRandomValues remains available in
+  // browsers on plain-HTTP LAN origins where randomUUID is intentionally hidden.
+  bytes[6] = (bytes[6]! & 0x0f) | 0x40;
+  bytes[8] = (bytes[8]! & 0x3f) | 0x80;
+  const hex = Array.from(bytes, (value) => value.toString(16).padStart(2, "0"));
+  return `${hex.slice(0, 4).join("")}-${hex.slice(4, 6).join("")}-${hex.slice(6, 8).join("")}-${hex.slice(8, 10).join("")}-${hex.slice(10).join("")}`;
+};
diff --git a/apps/web/src/lib/local-mirror.ts b/apps/web/src/lib/local-mirror.ts
index aff7b08c..472575e1 100644
--- a/apps/web/src/lib/local-mirror.ts
+++ b/apps/web/src/lib/local-mirror.ts
@@ -5,6 +5,7 @@ import { localDb, selectNewestLocalDraft, type LocalDraft, type LocalMemo, type
 import { cacheLocalResourceBytes, localResourceUrl, removeCachedLocalResourceBytes } from "@/lib/local-resource-cache";
 import { isBrowserOffline } from "@/lib/network-status";
 import { parseTagsText } from "@/lib/utils";
+import { createClientUuid } from "@/lib/client-id";
 
 export type LocalMemoListParams = {
   notebookId?: string | null;
@@ -275,7 +276,7 @@ export const createLocalMemo = async (
   const contentMarkdown = input.contentMarkdown ?? docToMarkdown(contentJson);
   const contentText = docToText(contentJson);
   const memo: MemoDetail = {
-    id: `local_${crypto.randomUUID()}`,
+    id: `local_${createClientUuid()}`,
     notebookId: input.notebookId,
     title: input.title?.trim() || null,
     excerpt: createExcerpt(contentText),
@@ -460,7 +461,7 @@ export const deleteLocalResource = async (scope: string, resourceId: string) =>
 
 export const createLocalResource = async (scope: string, memoId: string, file: File) => {
   const now = new Date().toISOString();
-  const id = `local_resource_${crypto.randomUUID()}`;
+  const id = `local_resource_${createClientUuid()}`;
   const url = localResourceUrl(id);
   await cacheLocalResourceBytes(url, file);
   const resource: ResourceListItem = {
@@ -517,7 +518,7 @@ export const deleteLocalNotebook = async (scope: string, notebookId: string) =>
 export const createLocalNotebook = async (scope: string, input: { name: string; parentId?: string | null }) => {
   const now = new Date().toISOString();
   const notebook: Notebook = {
-    id: `local_${crypto.randomUUID()}`,
+    id: `local_${createClientUuid()}`,
     parentId: input.parentId ?? null,
     name: input.name.trim(),
     slug: null,
@@ -537,7 +538,7 @@ export const createLocalTemplate = async (scope: string, input: { name: string;
   const now = new Date().toISOString();
   const contentMarkdown = input.contentMarkdown ?? "";
   const template: MemoTemplate = {
-    id: `local_${crypto.randomUUID()}`,
+    id: `local_${createClientUuid()}`,
     name: input.name.trim(),
     description: input.description ?? null,
     title: input.title ?? null,
diff --git a/apps/web/src/lib/note-print.ts b/apps/web/src/lib/note-print.ts
index 1602b156..5870c1ec 100644
--- a/apps/web/src/lib/note-print.ts
+++ b/apps/web/src/lib/note-print.ts
@@ -2,6 +2,7 @@ import { DOMSerializer } from "@tiptap/pm/model";
 import type { Editor } from "@tiptap/react";
 import type { TiptapDoc } from "@edgeever/shared";
 import { getAppPagePath, getMessageTargetOrigin } from "@/lib/app-page-path";
+import { createClientUuid } from "@/lib/client-id";
 
 export const NOTE_PRINT_MESSAGE = "edgeever:note-print";
 export const NOTE_PRINT_READY_MESSAGE = "edgeever:note-print-ready";
@@ -44,7 +45,7 @@ export const openNotePrintPreview = (
   payload: Omit<NotePrintPayload, "type" | "token">,
   preopenedWindow?: Window,
 ) => {
-  const token = crypto.randomUUID();
+  const token = createClientUuid();
   let printWindow: Window | null = preopenedWindow ?? null;
 
   const handleMessage = (event: MessageEvent<NotePrintReadyMessage>) => {
diff --git a/apps/web/src/lib/sync-queue.ts b/apps/web/src/lib/sync-queue.ts
index c8f09fca..c87f64c0 100644
--- a/apps/web/src/lib/sync-queue.ts
+++ b/apps/web/src/lib/sync-queue.ts
@@ -31,6 +31,7 @@ import { getMemoSaveConflictInfo, parseMemoSaveConflictDetails } from "@/lib/mem
 import { getCachedLocalResourceBytes, removeCachedLocalResourceBytes } from "@/lib/local-resource-cache";
 import { isBrowserOffline } from "@/lib/network-status";
 import { parseTagsText } from "@/lib/utils";
+import { createClientUuid } from "@/lib/client-id";
 
 export type { SyncQueueSummary, SyncRunResult } from "@edgeever/shared";
 export type SyncQueueResult = MemoDetail | Notebook | MemoTemplate | Resource | null;
@@ -458,7 +459,7 @@ const claimQueueItem = (id: string) =>
       return null;
     }
 
-    const claimId = crypto.randomUUID();
+    const claimId = createClientUuid();
     const claimedItem: SyncQueueItem = {
       ...item,
       status: "syncing",