diff --git a/web/src/features/auth/LoginPage.tsx b/web/src/features/auth/LoginPage.tsx
index 034da3c6..82aa3846 100644
--- a/web/src/features/auth/LoginPage.tsx
+++ b/web/src/features/auth/LoginPage.tsx
@@ -4,7 +4,7 @@ import { Link, Navigate, useNavigate } from 'react-router-dom';
 
 import { Icon } from '@/app/Icon';
 import { PasswordInput } from '@/features/auth/components/PasswordInput';
-import { BASE_APP_NAME } from '@/lib/config';
+import { BASE_APP_NAME, FIXED_TENANT_CODE } from '@/lib/config';
 import { getTinode, loginBasic } from '@/lib/tinode/connection';
 import { loginErrorMessage, validateCredentialsMessage } from '@/lib/tinode/errors';
 import { useSessionStore } from '@/stores/session';
@@ -25,7 +25,7 @@ export function LoginPage() {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [error]);
 
-  if (!tenant) {
+  if (!tenant || tenant.code !== FIXED_TENANT_CODE) {
     // Read tenant before touching getTinode() -- getTinode() lazily creates and PERMANENTLY caches
     // the singleton off whatever tenant is in the store at that moment (or a hardcoded fallback
     // host if there's none yet); calling it here first would risk creating that singleton against
@@ -73,10 +73,7 @@ export function LoginPage() {
       </div>
 
       <div className="flex flex-1 flex-col bg-white px-6 py-8">
-        <Link to="/tenant" className="flex items-center gap-1 text-sm text-text-secondary no-underline">
-          <Icon name="arrow_back_ios_new" className="text-[16px]" />
-          切换企业
-        </Link>
+        <div className="text-sm text-text-secondary">企业码：{FIXED_TENANT_CODE}</div>
 
         <div className="flex flex-1 flex-col items-center justify-center">
           <form onSubmit={submit} className="flex w-full max-w-[380px] flex-col gap-4">
diff --git a/web/src/features/auth/TenantEntryPage.tsx b/web/src/features/auth/TenantEntryPage.tsx
index 0dc2a4a5..51978773 100644
--- a/web/src/features/auth/TenantEntryPage.tsx
+++ b/web/src/features/auth/TenantEntryPage.tsx
@@ -6,7 +6,7 @@ import { Link, useNavigate } from 'react-router-dom';
 import { Icon } from '@/app/Icon';
 import { ImApiError } from '@/lib/api/client';
 import { resolveTenant } from '@/lib/api/tenant';
-import { BASE_APP_NAME } from '@/lib/config';
+import { BASE_APP_NAME, FIXED_TENANT_CODE } from '@/lib/config';
 import { resetTinode } from '@/lib/tinode/connection';
 import { requestConfirm } from '@/stores/confirmDialog';
 import { parseWebsocketEndpoint, useSessionStore } from '@/stores/session';
@@ -17,13 +17,12 @@ export function TenantEntryPage() {
   const setTenant = useSessionStore((s) => s.setTenant);
   const setMyUserId = useSessionStore((s) => s.setMyUserId);
   const myUserId = useSessionStore((s) => s.myUserId);
-  const [code, setCode] = useState('');
   const [error, setError] = useState('');
   const [submitting, setSubmitting] = useState(false);
 
   const submit = async (e: React.FormEvent) => {
     e.preventDefault();
-    if (!code.trim() || submitting) return;
+    if (submitting) return;
     // Reachable by navigating back here while already logged in (no route guard keeps an
     // authenticated user out of /tenant) -- resetTinode() below would otherwise silently tear down
     // that live session with no warning at all. `myUserId` alone isn't enough: it's an in-memory
@@ -33,11 +32,11 @@ export function TenantEntryPage() {
     // RequireAuth.tsx, which is the ONLY place that re-populates `myUserId` from that token, and it
     // never mounts for this route. Checking the token directly closes that gap.
     const hasLiveSession = myUserId || sessionStorage.getItem('im-session-token');
-    if (hasLiveSession && !(await requestConfirm({ message: '切换企业将退出当前登录，确定继续吗？' }))) return;
+    if (hasLiveSession && !(await requestConfirm({ message: '重新进入将退出当前登录，确定继续吗？' }))) return;
     setSubmitting(true);
     setError('');
     try {
-      const res = await resolveTenant(code.trim());
+      const res = await resolveTenant(FIXED_TENANT_CODE);
       const { host, secure } = parseWebsocketEndpoint(res.endpoints.websocket);
       // Without this, switching tenants mid-session silently keeps talking to the OLD tenant's
       // host: getTinode() lazily creates one singleton and reuses it forever once created, and
@@ -73,7 +72,7 @@ export function TenantEntryPage() {
 
   return (
     <div className="relative flex h-dvh w-full items-center justify-center bg-surface-page px-6">
-      <Link to="/enterprise-register" state={{ tenantCodeHint: code.trim() }} className="absolute right-6 top-6 text-sm text-accent no-underline">
+      <Link to="/enterprise-register" state={{ tenantCodeHint: FIXED_TENANT_CODE }} className="absolute right-6 top-6 text-sm text-accent no-underline">
         企业注册
       </Link>
       <form onSubmit={submit} className="flex w-full max-w-[380px] flex-col gap-5">
@@ -90,22 +89,21 @@ export function TenantEntryPage() {
         <label className="flex h-[50px] items-center gap-2 rounded-lg bg-surface-input px-3.5 has-focus:border has-focus:border-focus-border has-focus:shadow-focus-ring">
           <Icon name="business" className="text-[20px] text-focus-border" />
           <input
-            value={code}
-            onChange={(e) => setCode(e.target.value)}
-            placeholder="请输入企业码"
-            maxLength={64}
-            className="w-full bg-transparent text-[15px] outline-none"
+            value={FIXED_TENANT_CODE}
+            readOnly
+            aria-label="企业码"
+            className="w-full cursor-not-allowed bg-transparent text-[15px] text-text-secondary outline-none"
           />
         </label>
         <button
           type="submit"
-          disabled={!code.trim() || submitting}
+          disabled={submitting}
           className="h-[50px] rounded-lg bg-btn text-base font-medium text-white shadow-btn disabled:bg-btn-disabled disabled:shadow-none"
         >
           {submitting ? '进入中…' : '进入企业'}
         </button>
       </form>
-      <Link to="/feedback" state={{ tenantCodeHint: code.trim() }} className="absolute bottom-8 text-sm text-accent no-underline">
+      <Link to="/feedback" state={{ tenantCodeHint: FIXED_TENANT_CODE }} className="absolute bottom-8 text-sm text-accent no-underline">
         遇到问题？
       </Link>
     </div>
diff --git a/web/src/lib/config.ts b/web/src/lib/config.ts
index 0d0d650f..077b0594 100644
--- a/web/src/lib/config.ts
+++ b/web/src/lib/config.ts
@@ -5,6 +5,9 @@
 /** User-visible product name. */
 export const BASE_APP_NAME = '迅工捷使';
 
+/** This deployment serves a single enterprise; users cannot switch tenants. */
+export const FIXED_TENANT_CODE = 'default';
+
 /** Name used in the Tinode client's User-Agent string. */
 export const APP_NAME = `MeetingIM/${__APP_VERSION__}`;
 
diff --git a/web/tests/fixed-tenant.test.mjs b/web/tests/fixed-tenant.test.mjs
new file mode 100644
index 00000000..581d3578
--- /dev/null
+++ b/web/tests/fixed-tenant.test.mjs
@@ -0,0 +1,24 @@
+import assert from 'node:assert/strict';
+import { readFile } from 'node:fs/promises';
+import test from 'node:test';
+
+const source = (path) => readFile(new URL(`../${path}`, import.meta.url), 'utf8');
+
+test('tenant entry is permanently fixed to default', async () => {
+  const config = await source('src/lib/config.ts');
+  const entry = await source('src/features/auth/TenantEntryPage.tsx');
+
+  assert.match(config, /FIXED_TENANT_CODE = 'default'/);
+  assert.match(entry, /value=\{FIXED_TENANT_CODE\}/);
+  assert.match(entry, /readOnly/);
+  assert.match(entry, /resolveTenant\(FIXED_TENANT_CODE\)/);
+  assert.doesNotMatch(entry, /setCode/);
+});
+
+test('login page exposes no tenant switch and rejects stale tenant state', async () => {
+  const login = await source('src/features/auth/LoginPage.tsx');
+
+  assert.match(login, /tenant\.code !== FIXED_TENANT_CODE/);
+  assert.match(login, /企业码：\{FIXED_TENANT_CODE\}/);
+  assert.doesNotMatch(login, />\s*切换企业\s*</);
+});