diff --git a/src/core/auth/jwt.test.ts b/src/core/auth/jwt.test.ts
new file mode 100644
index 00000000..f8869537
--- /dev/null
+++ b/src/core/auth/jwt.test.ts
@@ -0,0 +1,28 @@
+import { describe, expect, it } from 'vitest'
+import { decodeJwtClaims } from './jwt'
+
+function token(payload: string) {
+  return `header.${Buffer.from(payload).toString('base64url')}.signature`
+}
+
+describe('JWT claim decoding', () => {
+  it.each(['2110664514823360515', '"2110664514823360515"'])('preserves the exact account ID encoded as %s', userId => {
+    const claims = decodeJwtClaims(token(`{"user_id":${userId},"app_code":"PLATFORM","exp":1792060000,"iat":1792058200}`))
+    expect(claims.user_id).toBe('2110664514823360515')
+    expect(claims.exp).toBe(1792060000)
+    expect(claims).toHaveProperty('iat', 1792058200)
+  })
+
+  it('retains safe numeric IDs and ordinary claims', () => {
+    expect(decodeJwtClaims(token('{"user_id":123,"username":"operator","roles":["ADMIN"],"exp":1}')))
+      .toEqual({ user_id: 123, username: 'operator', roles: ['ADMIN'], exp: 1 })
+  })
+
+  it.each(['', 'header..signature'])('rejects a missing payload: %s', value => {
+    expect(() => decodeJwtClaims(value)).toThrow('登录响应中的 accessToken 格式无效')
+  })
+
+  it.each(['header.%.signature', token('{"user_id":2110664514823360515,')])('rejects malformed encoding or JSON: %s', value => {
+    expect(() => decodeJwtClaims(value)).toThrow('登录响应中的 accessToken 无法解析')
+  })
+})
diff --git a/src/core/auth/jwt.ts b/src/core/auth/jwt.ts
index 87465ebf..f104d1e0 100644
--- a/src/core/auth/jwt.ts
+++ b/src/core/auth/jwt.ts
@@ -1,3 +1,5 @@
+import { parseJsonWithSafeIntegers } from '@chongchong/shared'
+
 export interface PlatformJwtClaims {
   user_id?: string | number
   username?: string
@@ -19,7 +21,7 @@ export function decodeJwtClaims(token: string): PlatformJwtClaims {
   const payload = token.split('.')[1]
   if (!payload) throw new Error('登录响应中的 accessToken 格式无效')
   try {
-    return JSON.parse(decodeBase64Url(payload)) as PlatformJwtClaims
+    return parseJsonWithSafeIntegers(decodeBase64Url(payload)) as PlatformJwtClaims
   } catch {
     throw new Error('登录响应中的 accessToken 无法解析')
   }
diff --git a/src/modules/appointment-calendar/WorkCommandForm.auth.test.ts b/src/modules/appointment-calendar/WorkCommandForm.auth.test.ts
new file mode 100644
index 00000000..42705ca7
--- /dev/null
+++ b/src/modules/appointment-calendar/WorkCommandForm.auth.test.ts
@@ -0,0 +1,73 @@
+import { flushPromises, mount } from '@vue/test-utils'
+import { createPinia, setActivePinia } from 'pinia'
+import { afterEach, beforeEach, expect, it, vi } from 'vitest'
+import { http } from '@/shared/api/http'
+import WorkCommandForm from './WorkCommandForm.vue'
+import { submitWorkCommand } from './workApi'
+import { followAction, workDetail, workItem } from './work.test-support'
+import { useAuthStore } from '@/core/auth/auth'
+
+vi.mock('@/core/auth/platformAuthorization', () => ({ listCurrentPlatformPermissionCodes: vi.fn().mockResolvedValue(['platform:appointment:followup']) }))
+vi.mock('@/core/access/accessPreview', () => ({ useAccessPreviewStore: () => ({ can: () => true }) }))
+vi.mock('element-plus', () => ({ ElMessage: { warning: vi.fn(), success: vi.fn() }, ElMessageBox: { confirm: vi.fn() } }))
+vi.mock('./workApi', async original => ({ ...await original<typeof import('./workApi')>(), submitWorkCommand: vi.fn() }))
+
+function token(userId: string, exp = Math.floor(Date.now() / 1000) + 1800) {
+  // Keep the numeric JSON literal intact; constructing a JS number would lose precision before decoding.
+  const payload = `{"user_id":${userId},"username":"test_operator","app_code":"PLATFORM","exp":${exp}}`
+  return `header.${Buffer.from(payload).toString('base64url')}.signature`
+}
+
+beforeEach(() => {
+  const values = new Map<string, string>()
+  vi.stubGlobal('localStorage', {
+    getItem: (key: string) => values.get(key) ?? null,
+    setItem: (key: string, value: string) => values.set(key, value),
+    removeItem: (key: string) => values.delete(key),
+  })
+  setActivePinia(createPinia())
+  vi.mocked(submitWorkCommand).mockResolvedValue({ item: workItem(), affectedWorkItemKeys: [] })
+})
+afterEach(() => { vi.restoreAllMocks(); vi.unstubAllGlobals() })
+
+it.each([
+  ['login', '2110664514823360515'], ['login', '"2110664514823360515"'],
+  ['restore', '2110664514823360515'], ['restore', '"2110664514823360515"'],
+])('preserves the %s session ID through the real follow-up form for JSON %s', async (mode, userId) => {
+  const accessToken = token(userId)
+  if (mode === 'restore') {
+    localStorage.setItem('cc-admin-token', accessToken)
+    localStorage.setItem('cc-admin-permission-codes', '[]')
+  }
+  const auth = useAuthStore()
+  if (mode === 'login') {
+    vi.spyOn(http, 'post').mockResolvedValue({ code: '200', data: { accessToken, refreshToken: 'test-refresh', expiresIn: 1800, refreshExpiresIn: 604800 } })
+    await auth.login('test_operator', 'test-password')
+  }
+  expect(auth.user?.id).toBe('2110664514823360515')
+  expect(auth.isAuthenticated).toBe(true)
+  const wrapper = mount(WorkCommandForm, {
+    props: { detail: workDetail({ item: workItem({ owner: null }) }), action: followAction, refreshing: false },
+    global: {
+      provide: { 'appointment-work-leave-guard': () => () => undefined },
+      stubs: { ElButton: { template: '<button><slot /></button>' }, LoadErrorState: true, ApiErrorMeta: true },
+    },
+  })
+  try {
+    expect((wrapper.get('select').element as HTMLSelectElement).value).toBe('2110664514823360515')
+    await wrapper.get('textarea').setValue('已联系负责人')
+    await wrapper.get('form').trigger('submit')
+    await flushPromises()
+    expect(submitWorkCommand).toHaveBeenCalledWith('work-delivery-1', expect.objectContaining({
+      command: 'SAVE_FOLLOWUP', payload: { ownerId: '2110664514823360515', followupDate: '2026-10-15', note: '已联系负责人' },
+    }))
+  } finally { wrapper.unmount() }
+})
+
+it.each([token('2110664514823360515', 1), 'header.%.signature'])('does not restore an expired or malformed token: %s', accessToken => {
+  localStorage.setItem('cc-admin-token', accessToken)
+  const auth = useAuthStore()
+  expect(auth.user).toBeNull()
+  expect(auth.isAuthenticated).toBe(false)
+  expect(localStorage.getItem('cc-admin-token')).toBeNull()
+})