diff --git a/api/server/middleware/__tests__/requireJwtAuth.spec.js b/api/server/middleware/__tests__/requireJwtAuth.spec.js
index 6e1eba6a82..08f779fac0 100644
--- a/api/server/middleware/__tests__/requireJwtAuth.spec.js
+++ b/api/server/middleware/__tests__/requireJwtAuth.spec.js
@@ -71,6 +71,19 @@ jest.mock('@librechat/api', () => {
     recordRumProxyRequest: jest.fn(),
     getAuthFailureReasonCategory: actualApi.getAuthFailureReasonCategory,
     buildSafeAuthLogContext: actualApi.buildSafeAuthLogContext,
+    getValidOpenIdReuseUserId: (token) => {
+      if (!token || !process.env.JWT_REFRESH_SECRET) {
+        return null;
+      }
+      try {
+        const payload = require('jsonwebtoken').verify(token, process.env.JWT_REFRESH_SECRET);
+        return typeof payload === 'object' && payload != null && typeof payload.id === 'string'
+          ? payload.id
+          : null;
+      } catch {
+        return null;
+      }
+    },
     maybeRefreshCloudFrontAuthCookiesMiddleware: jest.fn((req, res, next) => next()),
     tenantContextMiddleware: (req, res, next) => {
       const context = {
diff --git a/api/server/middleware/requireJwtAuth.js b/api/server/middleware/requireJwtAuth.js
index 8457018320..251fef9958 100644
--- a/api/server/middleware/requireJwtAuth.js
+++ b/api/server/middleware/requireJwtAuth.js
@@ -1,5 +1,4 @@
 const cookies = require('cookie');
-const jwt = require('jsonwebtoken');
 const passport = require('passport');
 const { logger } = require('@librechat/data-schemas');
 const {
@@ -9,27 +8,12 @@ const {
   buildSafeAuthLogContext,
   maybeRefreshCloudFrontAuthCookiesMiddleware,
   recordRumProxyRequest,
+  getValidOpenIdReuseUserId,
 } = require('@librechat/api');
 
 const hasPassportStrategy = (strategy) =>
   typeof passport._strategy === 'function' && passport._strategy(strategy) != null;
 
-const getValidOpenIdReuseUserId = (parsedCookies) => {
-  const openidUserId = parsedCookies.openid_user_id;
-  if (!openidUserId || !process.env.JWT_REFRESH_SECRET) {
-    return null;
-  }
-
-  try {
-    const payload = jwt.verify(openidUserId, process.env.JWT_REFRESH_SECRET);
-    return typeof payload === 'object' && payload != null && typeof payload.id === 'string'
-      ? payload.id
-      : null;
-  } catch {
-    return null;
-  }
-};
-
 const getAuthenticatedUserId = (user) => user?.id?.toString?.() ?? user?._id?.toString?.();
 const refreshCloudFrontCookies =
   maybeRefreshCloudFrontAuthCookiesMiddleware ?? ((_req, _res, next) => next());
@@ -46,7 +30,7 @@ const getAuthStrategies = (req) => {
   const tokenProvider = parsedCookies.token_provider;
   const openidReuseEnabled = isEnabled(process.env.OPENID_REUSE_TOKENS);
   const openidJwtAvailable = openidReuseEnabled && hasPassportStrategy('openidJwt');
-  const openIdReuseUserId = getValidOpenIdReuseUserId(parsedCookies);
+  const openIdReuseUserId = getValidOpenIdReuseUserId(parsedCookies.openid_user_id);
   const useOpenIdJwt =
     tokenProvider === 'openid' && openidJwtAvailable && openIdReuseUserId != null;
 
diff --git a/api/strategies/openIdJwtStrategy.js b/api/strategies/openIdJwtStrategy.js
index 0bdf14b8b6..3606fe474b 100644
--- a/api/strategies/openIdJwtStrategy.js
+++ b/api/strategies/openIdJwtStrategy.js
@@ -1,6 +1,6 @@
 const cookies = require('cookie');
 const jwksRsa = require('jwks-rsa');
-const { logger } = require('@librechat/data-schemas');
+const { logger, getTenantId } = require('@librechat/data-schemas');
 const { CacheKeys, SystemRoles } = require('librechat-data-provider');
 const { Strategy: JwtStrategy, ExtractJwt } = require('passport-jwt');
 const {
@@ -12,6 +12,7 @@ const {
   buildAuthUserDocCacheKey,
   getAuthUserDocCacheMode,
   getCachedAuthUserDoc,
+  getValidOpenIdReuseUserId,
   invalidateCachedAuthUserDoc,
   setCachedAuthUserDoc,
   getHttpsProxyAgent,
@@ -55,6 +56,28 @@ const isOpenIdIssuerAllowed = (payload, openIdConfig) => {
 
 const getAuthUserDocCacheStore = () => getLogStores(CacheKeys.AUTH_USER_DOC);
 
+const getUserId = (user) => user?.id?.toString?.() ?? user?._id?.toString?.();
+
+const getAuthUserCacheScope = (tenantId, userId) => {
+  if (tenantId) {
+    return { tenantId };
+  }
+  if (userId) {
+    return { userId };
+  }
+  return {};
+};
+
+const isUserInAuthCacheScope = (user, { tenantId, userId }) => {
+  if (tenantId) {
+    return (user?.tenantId || undefined) === tenantId;
+  }
+  if (userId) {
+    return getUserId(user) === userId;
+  }
+  return !user?.tenantId;
+};
+
 /**
  * @function openIdJwtLogin
  * @param {import('openid-client').Configuration} openIdConfig - Configuration object for the JWT strategy.
@@ -108,10 +131,16 @@ const openIdJwtLogin = (openIdConfig) => {
         const authHeader = req.headers.authorization;
         const rawToken = authHeader?.replace('Bearer ', '');
         const openidIssuer = getOpenIdIssuer(payload, openIdConfig);
+        const tenantId = getTenantId();
+        const cookieHeader = req.headers.cookie;
+        const parsedCookies = cookieHeader ? cookies.parse(cookieHeader) : {};
+        const openIdReuseUserId = getValidOpenIdReuseUserId(parsedCookies.openid_user_id);
+        const authUserCacheScope = getAuthUserCacheScope(tenantId, openIdReuseUserId);
         const authUserCacheKey = buildAuthUserDocCacheKey({
           strategy: 'openid-jwt',
           subject: payload?.sub,
           issuer: openidIssuer,
+          ...authUserCacheScope,
         });
         const authUserCacheMode = getAuthUserDocCacheMode();
         const authUserCacheStore =
@@ -121,7 +150,10 @@ const openIdJwtLogin = (openIdConfig) => {
             ? await getCachedAuthUserDoc(authUserCacheStore, authUserCacheKey)
             : undefined;
 
-        const servedCachedUser = authUserCacheMode === 'on' && cachedUser;
+        const servedCachedUser =
+          authUserCacheMode === 'on' &&
+          cachedUser &&
+          isUserInAuthCacheScope(cachedUser, authUserCacheScope);
         const lookupResult = servedCachedUser
           ? { user: cachedUser, error: null, migration: false }
           : await findOpenIDUser({
@@ -167,7 +199,7 @@ const openIdJwtLogin = (openIdConfig) => {
                 userId: user.id,
                 cacheKey: authUserCacheKey,
               });
-            } else if (!servedCachedUser) {
+            } else if (!servedCachedUser && isUserInAuthCacheScope(user, authUserCacheScope)) {
               await setCachedAuthUserDoc(authUserCacheStore, authUserCacheKey, user);
             }
           }
@@ -180,8 +212,6 @@ const openIdJwtLogin = (openIdConfig) => {
 
           /** Fallback to cookies for backward compatibility */
           if (!accessToken || !refreshToken || !idToken) {
-            const cookieHeader = req.headers.cookie;
-            const parsedCookies = cookieHeader ? cookies.parse(cookieHeader) : {};
             accessToken = accessToken || parsedCookies.openid_access_token;
             idToken = idToken || parsedCookies.openid_id_token;
             refreshToken = refreshToken || parsedCookies.refreshToken;
diff --git a/api/strategies/openIdJwtStrategy.spec.js b/api/strategies/openIdJwtStrategy.spec.js
index 076fd99337..a1993aa5c7 100644
--- a/api/strategies/openIdJwtStrategy.spec.js
+++ b/api/strategies/openIdJwtStrategy.spec.js
@@ -9,6 +9,7 @@ const mockAuthUserDocCacheStore = {
   delete: jest.fn(),
 };
 const mockGetLogStores = jest.fn(() => mockAuthUserDocCacheStore);
+const mockGetTenantId = jest.fn();
 jest.mock('passport-jwt', () => ({
   Strategy: jest.fn((opts, verifyCallback) => {
     capturedStrategyOptions = opts;
@@ -27,6 +28,7 @@ jest.mock('https-proxy-agent', () => ({
 }));
 jest.mock('@librechat/data-schemas', () => ({
   logger: { info: jest.fn(), warn: jest.fn(), debug: jest.fn(), error: jest.fn() },
+  getTenantId: mockGetTenantId,
 }));
 jest.mock('@librechat/api', () => ({
   isEnabled: jest.fn(() => false),
@@ -37,6 +39,7 @@ jest.mock('@librechat/api', () => ({
   buildAuthUserDocCacheKey: jest.fn(() => 'auth-user-doc-key'),
   getAuthUserDocCacheMode: jest.fn(() => 'off'),
   getCachedAuthUserDoc: jest.fn(),
+  getValidOpenIdReuseUserId: jest.fn(),
   invalidateCachedAuthUserDoc: jest.fn(),
   setCachedAuthUserDoc: jest.fn(),
   getHttpsProxyAgent: jest.fn(() => undefined),
@@ -61,6 +64,7 @@ const {
   findOpenIDUser,
   getAuthUserDocCacheMode,
   getCachedAuthUserDoc,
+  getValidOpenIdReuseUserId,
   invalidateCachedAuthUserDoc,
   setCachedAuthUserDoc,
 } = require('@librechat/api');
@@ -68,6 +72,7 @@ const openIdJwtLogin = require('./openIdJwtStrategy');
 const { findUser, updateUser } = require('~/models');
 
 function resetAuthUserDocCacheMocks() {
+  mockGetTenantId.mockReturnValue(undefined);
   mockAuthUserDocCacheStore.get.mockResolvedValue(undefined);
   mockAuthUserDocCacheStore.set.mockResolvedValue(undefined);
   mockAuthUserDocCacheStore.delete.mockResolvedValue(undefined);
@@ -75,6 +80,7 @@ function resetAuthUserDocCacheMocks() {
   buildAuthUserDocCacheKey.mockReturnValue('auth-user-doc-key');
   getAuthUserDocCacheMode.mockReturnValue('off');
   getCachedAuthUserDoc.mockResolvedValue(undefined);
+  getValidOpenIdReuseUserId.mockReturnValue(null);
   invalidateCachedAuthUserDoc.mockResolvedValue(undefined);
   setCachedAuthUserDoc.mockResolvedValue(undefined);
 }
@@ -416,11 +422,13 @@ describe('openIdJwtStrategy – auth user document cache', () => {
   });
 
   it('uses the cached user document in on mode without a database lookup', async () => {
+    mockGetTenantId.mockReturnValue('tenant-a');
     const cachedUser = {
       _id: 'cached-user',
       role: SystemRoles.USER,
       provider: 'openid',
       email: 'cached@example.com',
+      tenantId: 'tenant-a',
     };
     getAuthUserDocCacheMode.mockReturnValue('on');
     getCachedAuthUserDoc.mockResolvedValue(cachedUser);
@@ -431,6 +439,7 @@ describe('openIdJwtStrategy – auth user document cache', () => {
       strategy: 'openid-jwt',
       subject: payload.sub,
       issuer: 'https://issuer.example.com',
+      tenantId: 'tenant-a',
     });
     expect(findOpenIDUser).not.toHaveBeenCalled();
     expect(user).toMatchObject({
@@ -458,6 +467,88 @@ describe('openIdJwtStrategy – auth user document cache', () => {
     expect(invalidateCachedAuthUserDoc).not.toHaveBeenCalled();
   });
 
+  it('rejects a cached user document from another tenant', async () => {
+    mockGetTenantId.mockReturnValue('tenant-b');
+    getAuthUserDocCacheMode.mockReturnValue('on');
+    getCachedAuthUserDoc.mockResolvedValue({
+      _id: 'tenant-a-user',
+      role: SystemRoles.ADMIN,
+      provider: 'openid',
+      email: 'cached@example.com',
+      tenantId: 'tenant-a',
+    });
+    findOpenIDUser.mockResolvedValue({
+      user: { ...baseUser, _id: { toString: () => 'tenant-b-user' }, tenantId: 'tenant-b' },
+      error: null,
+      migration: false,
+    });
+
+    const { user } = await invokeVerify(req, payload);
+
+    expect(buildAuthUserDocCacheKey).toHaveBeenCalledWith({
+      strategy: 'openid-jwt',
+      subject: payload.sub,
+      issuer: 'https://issuer.example.com',
+      tenantId: 'tenant-b',
+    });
+    expect(findOpenIDUser).toHaveBeenCalled();
+    expect(user).toMatchObject({ id: 'tenant-b-user', tenantId: 'tenant-b' });
+    expect(setCachedAuthUserDoc).toHaveBeenCalledWith(
+      mockAuthUserDocCacheStore,
+      'auth-user-doc-key',
+      expect.objectContaining({ id: 'tenant-b-user', tenantId: 'tenant-b' }),
+    );
+  });
+
+  it('uses the signed OpenID user id as cache scope before tenant context is available', async () => {
+    getAuthUserDocCacheMode.mockReturnValue('on');
+    getValidOpenIdReuseUserId.mockReturnValue('tenant-a-user');
+    getCachedAuthUserDoc.mockResolvedValue({
+      _id: 'tenant-a-user',
+      role: SystemRoles.USER,
+      provider: 'openid',
+      email: 'cached@example.com',
+      tenantId: 'tenant-a',
+    });
+
+    const { user } = await invokeVerify(
+      {
+        headers: {
+          authorization: 'Bearer tok',
+          cookie: 'openid_user_id=signed-user-id',
+        },
+        session: {},
+      },
+      payload,
+    );
+
+    expect(getValidOpenIdReuseUserId).toHaveBeenCalledWith('signed-user-id');
+    expect(buildAuthUserDocCacheKey).toHaveBeenCalledWith({
+      strategy: 'openid-jwt',
+      subject: payload.sub,
+      issuer: 'https://issuer.example.com',
+      userId: 'tenant-a-user',
+    });
+    expect(findOpenIDUser).not.toHaveBeenCalled();
+    expect(user).toMatchObject({ id: 'tenant-a-user', tenantId: 'tenant-a' });
+  });
+
+  it('does not cache a lookup result outside the active tenant scope', async () => {
+    mockGetTenantId.mockReturnValue('tenant-b');
+    getAuthUserDocCacheMode.mockReturnValue('on');
+    getCachedAuthUserDoc.mockResolvedValue(undefined);
+    findOpenIDUser.mockResolvedValue({
+      user: { ...baseUser, tenantId: 'tenant-a' },
+      error: null,
+      migration: false,
+    });
+
+    await invokeVerify(req, payload);
+
+    expect(findOpenIDUser).toHaveBeenCalled();
+    expect(setCachedAuthUserDoc).not.toHaveBeenCalled();
+  });
+
   it('invalidates instead of populating when login mutates the user', async () => {
     getAuthUserDocCacheMode.mockReturnValue('on');
     findOpenIDUser.mockResolvedValue({
diff --git a/packages/api/src/auth/index.ts b/packages/api/src/auth/index.ts
index 1932986e3b..f2b4b2adde 100644
--- a/packages/api/src/auth/index.ts
+++ b/packages/api/src/auth/index.ts
@@ -10,3 +10,4 @@ export * from './invite';
 export * from './codeapi';
 export * from './openidRoleSync';
 export * from './userDocCache';
+export * from './reuse';
diff --git a/packages/api/src/auth/reuse.spec.ts b/packages/api/src/auth/reuse.spec.ts
new file mode 100644
index 0000000000..b49b0ec9ba
--- /dev/null
+++ b/packages/api/src/auth/reuse.spec.ts
@@ -0,0 +1,18 @@
+import jwt from 'jsonwebtoken';
+import { getValidOpenIdReuseUserId } from './reuse';
+
+const secret = 'test-refresh-secret';
+
+describe('getValidOpenIdReuseUserId', () => {
+  it('returns the signed OpenID user id', () => {
+    const token = jwt.sign({ id: 'user-a' }, secret);
+
+    expect(getValidOpenIdReuseUserId(token, secret)).toBe('user-a');
+  });
+
+  it('rejects missing or invalid signed user ids', () => {
+    expect(getValidOpenIdReuseUserId(undefined, secret)).toBeNull();
+    expect(getValidOpenIdReuseUserId('invalid-token', secret)).toBeNull();
+    expect(getValidOpenIdReuseUserId(jwt.sign({ sub: 'user-a' }, secret), secret)).toBeNull();
+  });
+});
diff --git a/packages/api/src/auth/reuse.ts b/packages/api/src/auth/reuse.ts
new file mode 100644
index 0000000000..b5315aa23f
--- /dev/null
+++ b/packages/api/src/auth/reuse.ts
@@ -0,0 +1,19 @@
+import jwt from 'jsonwebtoken';
+
+export function getValidOpenIdReuseUserId(
+  openidUserId: string | undefined,
+  secret: string | undefined = process.env.JWT_REFRESH_SECRET,
+): string | null {
+  if (!openidUserId || !secret) {
+    return null;
+  }
+
+  try {
+    const payload = jwt.verify(openidUserId, secret);
+    return typeof payload === 'object' && payload != null && typeof payload.id === 'string'
+      ? payload.id
+      : null;
+  } catch {
+    return null;
+  }
+}
diff --git a/packages/api/src/auth/userDocCache.spec.ts b/packages/api/src/auth/userDocCache.spec.ts
index e052b77f33..4c70c438ab 100644
--- a/packages/api/src/auth/userDocCache.spec.ts
+++ b/packages/api/src/auth/userDocCache.spec.ts
@@ -86,28 +86,61 @@ describe('auth user document cache helpers', () => {
     expect(getAuthUserDocCacheMode()).toBe('off');
   });
 
-  it('builds stable keys from strategy, subject, issuer, and scope', () => {
+  it('builds stable keys from strategy, subject, issuer, tenant, user, and scope', () => {
     const key = buildAuthUserDocCacheKey({
       strategy: ' OpenID-JWT ',
       subject: 'subject-1',
       issuer: 'https://issuer.example.com/',
+      tenantId: 'Tenant-A',
+      userId: 'User-A',
       scope: ' Org-A ',
     });
     const equivalent = buildAuthUserDocCacheKey({
       strategy: 'openid-jwt',
       subject: 'subject-1',
       issuer: 'https://issuer.example.com',
+      tenantId: 'Tenant-A',
+      userId: 'User-A',
+      scope: 'org-a',
+    });
+    const otherTenant = buildAuthUserDocCacheKey({
+      strategy: 'openid-jwt',
+      subject: 'subject-1',
+      issuer: 'https://issuer.example.com',
+      tenantId: 'Tenant-B',
+      userId: 'User-A',
+      scope: 'org-a',
+    });
+    const caseVariantTenant = buildAuthUserDocCacheKey({
+      strategy: 'openid-jwt',
+      subject: 'subject-1',
+      issuer: 'https://issuer.example.com',
+      tenantId: 'tenant-a',
+      userId: 'User-A',
+      scope: 'org-a',
+    });
+    const otherUser = buildAuthUserDocCacheKey({
+      strategy: 'openid-jwt',
+      subject: 'subject-1',
+      issuer: 'https://issuer.example.com',
+      tenantId: 'Tenant-A',
+      userId: 'User-B',
       scope: 'org-a',
     });
     const otherScope = buildAuthUserDocCacheKey({
       strategy: 'openid-jwt',
       subject: 'subject-1',
       issuer: 'https://issuer.example.com',
+      tenantId: 'Tenant-A',
+      userId: 'User-A',
       scope: 'org-b',
     });
 
-    expect(key).toMatch(/^auth-user-doc:v1:/);
+    expect(key).toMatch(/^auth-user-doc:v2:/);
     expect(key).toBe(equivalent);
+    expect(key).not.toBe(otherTenant);
+    expect(key).not.toBe(caseVariantTenant);
+    expect(key).not.toBe(otherUser);
     expect(key).not.toBe(otherScope);
     expect(buildAuthUserDocCacheKey({ strategy: '', subject: 'subject-1' })).toBeUndefined();
     expect(buildAuthUserDocCacheKey({ strategy: 'openid-jwt' })).toBeUndefined();
@@ -115,7 +148,7 @@ describe('auth user document cache helpers', () => {
 
   it('sanitizes sensitive fields and remembers cache keys by user id', async () => {
     const store = makeStore();
-    const cacheKey = 'auth-user-doc:v1:key';
+    const cacheKey = 'auth-user-doc:v2:key';
     const userId = new Types.ObjectId();
 
     await setCachedAuthUserDoc(store, cacheKey, {
@@ -146,7 +179,7 @@ describe('auth user document cache helpers', () => {
 
     expect(store.set).toHaveBeenCalledWith(
       cacheKey,
-      expect.objectContaining({ version: 1, user: expect.any(Object) }),
+      expect.objectContaining({ version: 2, user: expect.any(Object) }),
       AUTH_USER_DOC_CACHE_TTL_MS,
     );
     expect(store.values.get(buildAuthUserDocReverseIndexKey(userId.toString()))).toEqual([
@@ -187,8 +220,8 @@ describe('auth user document cache helpers', () => {
 
   it('returns cached user documents only for the current cache version', async () => {
     const store = makeStore();
-    store.values.set('current', { version: 1, cachedAt: Date.now(), user: { id: 'user-1' } });
-    store.values.set('stale', { version: 0, cachedAt: Date.now(), user: { id: 'user-2' } });
+    store.values.set('current', { version: 2, cachedAt: Date.now(), user: { id: 'user-1' } });
+    store.values.set('stale', { version: 1, cachedAt: Date.now(), user: { id: 'user-2' } });
 
     await expect(getCachedAuthUserDoc(store, 'current')).resolves.toEqual({ id: 'user-1' });
     await expect(getCachedAuthUserDoc(store, 'stale')).resolves.toBeUndefined();
diff --git a/packages/api/src/auth/userDocCache.ts b/packages/api/src/auth/userDocCache.ts
index 95be55fd64..7a308e3823 100644
--- a/packages/api/src/auth/userDocCache.ts
+++ b/packages/api/src/auth/userDocCache.ts
@@ -4,7 +4,7 @@ import { AUTH_USER_DOC_BY_ID_PREFIX, CacheKeys } from 'librechat-data-provider';
 import type { IUser } from '@librechat/data-schemas';
 import { cacheConfig } from '~/cache/cacheConfig';
 
-const AUTH_USER_DOC_CACHE_VERSION = 1;
+const AUTH_USER_DOC_CACHE_VERSION = 2;
 export const AUTH_USER_DOC_CACHE_TTL_MS = 5000;
 
 export type AuthUserDocCacheMode = 'off' | 'on';
@@ -19,6 +19,8 @@ export interface AuthUserDocCacheKeyInput {
   strategy: string;
   subject?: string;
   issuer?: string;
+  tenantId?: string;
+  userId?: string;
   scope?: string;
 }
 
@@ -71,6 +73,10 @@ function normalizeKeyPart(value: string | undefined): string {
   return (value ?? '').trim().toLowerCase().replace(/\/+$/, '');
 }
 
+function normalizeExactKeyPart(value: string | undefined): string {
+  return (value ?? '').trim();
+}
+
 export function buildAuthUserDocCacheKey(input: AuthUserDocCacheKeyInput): string | undefined {
   const strategy = input.strategy.trim();
   const subject = input.subject?.trim();
@@ -84,6 +90,8 @@ export function buildAuthUserDocCacheKey(input: AuthUserDocCacheKeyInput): strin
         normalizeKeyPart(strategy),
         subject,
         normalizeKeyPart(input.issuer),
+        normalizeExactKeyPart(input.tenantId),
+        normalizeExactKeyPart(input.userId),
         normalizeKeyPart(input.scope),
       ].join('\0'),
     )