diff --git a/packages/shared/src/audit/audit-actions.spec.ts b/packages/shared/src/audit/audit-actions.spec.ts
new file mode 100644
index 0000000..a2f9442
--- /dev/null
+++ b/packages/shared/src/audit/audit-actions.spec.ts
@@ -0,0 +1,124 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  AUDIT_ACTION_CATALOG,
+  AUDIT_ACTION_CODES,
+  AUDIT_CATEGORIES,
+  AUDIT_CATEGORY_KEYS,
+  AUDIT_TARGET_TYPES,
+  auditActionMeta,
+  auditCategoryLabel,
+  isKnownAuditAction,
+} from './audit-actions.js';
+
+/** A1–A4 已落地的 36 个 @Audit(...) code（A5 起必须全部可在目录中查到中文名） */
+const EXISTING_AUDIT_CODES = [
+  'catalog.dict_item.create',
+  'catalog.dict_item.update',
+  'catalog.dict_type.create',
+  'catalog.dict_type.delete',
+  'catalog.dict_type.status',
+  'catalog.dict_type.update',
+  'client.customer.apply_industry_pack',
+  'client.customer.create',
+  'client.customer.groups',
+  'client.customer.status',
+  'client.customer.transfer',
+  'client.customer.update',
+  'client.customer_field.apply',
+  'client.customer_field.approve',
+  'client.customer_group.create',
+  'client.customer_group.delete',
+  'client.customer_group.members',
+  'client.customer_group.update',
+  'client.industry.create',
+  'client.industry.delete',
+  'client.industry.status',
+  'client.industry.update',
+  'identity.auth.change-password',
+  'identity.department.create',
+  'identity.department.disable',
+  'identity.department.enable',
+  'identity.department.update',
+  'identity.role.create',
+  'identity.role.delete',
+  'identity.role.update',
+  'identity.user.create',
+  'identity.user.disable',
+  'identity.user.enable',
+  'identity.user.transfer_customers',
+  'identity.user.update',
+  'platform.system_config.update',
+] as const;
+
+const NEW_AUDIT_CODES = [
+  'identity.auth.login',
+  'identity.auth.logout',
+  'audit.log.view',
+  'audit.export',
+  'audit.export.download',
+  'sensitive.cost.view',
+  'sensitive.asset_pack.view',
+] as const;
+
+describe('审计动作目录（A5-BE-02）', () => {
+  it('36 个既有 @Audit code 与 A5 新增 code 全部登记', () => {
+    expect(EXISTING_AUDIT_CODES).toHaveLength(36);
+    for (const code of [...EXISTING_AUDIT_CODES, ...NEW_AUDIT_CODES]) {
+      expect(isKnownAuditAction(code)).toBe(true);
+      expect(AUDIT_ACTION_CATALOG[code]?.code).toBe(code);
+    }
+  });
+
+  it('目录条目分类 / 目标类型 / 中文名合法', () => {
+    const categoryKeys = new Set<string>(AUDIT_CATEGORY_KEYS);
+    const targetTypes = new Set<string>(AUDIT_TARGET_TYPES);
+    for (const code of AUDIT_ACTION_CODES) {
+      const meta = AUDIT_ACTION_CATALOG[code];
+      expect(meta).toBeDefined();
+      if (meta === undefined) continue;
+      expect(meta.label.trim().length).toBeGreaterThan(0);
+      expect(categoryKeys.has(meta.category)).toBe(true);
+      if (meta.targetType !== undefined) {
+        expect(targetTypes.has(meta.targetType)).toBe(true);
+      }
+    }
+  });
+
+  it('权限变更 / 客户 / 字典 / 配置 / 导出 / 敏感访问分类正确', () => {
+    expect(auditActionMeta('identity.role.update').category).toBe('permission');
+    expect(auditActionMeta('client.customer.create').category).toBe('client');
+    expect(auditActionMeta('catalog.dict_item.update').category).toBe('catalog');
+    expect(auditActionMeta('platform.system_config.update').category).toBe('config');
+    expect(auditActionMeta('audit.export').category).toBe('export');
+    expect(auditActionMeta('audit.log.view').category).toBe('sensitive');
+    expect(auditActionMeta('audit.log.view').sensitive).toBe(true);
+    expect(auditActionMeta('identity.auth.login').category).toBe('auth');
+  });
+
+  it('未知 code 兜底 label = code、分类 other，不抛错', () => {
+    const meta = auditActionMeta('unknown.action.code');
+    expect(meta.label).toBe('unknown.action.code');
+    expect(meta.category).toBe('other');
+    expect(meta.targetType).toBeUndefined();
+    expect(auditCategoryLabel('other')).toBe('其他');
+    expect(auditCategoryLabel('not-exist')).toBe('not-exist');
+  });
+
+  it('分类目录包含 9 类业务分类 + 兜底，key 唯一', () => {
+    expect(AUDIT_CATEGORIES).toHaveLength(10);
+    expect(new Set(AUDIT_CATEGORIES.map((item) => item.key)).size).toBe(10);
+    expect(AUDIT_CATEGORIES.map((item) => item.key)).toEqual([
+      'auth',
+      'permission',
+      'client',
+      'catalog',
+      'config',
+      'export',
+      'task',
+      'asset',
+      'sensitive',
+      'other',
+    ]);
+  });
+});
diff --git a/packages/shared/src/audit/audit-actions.ts b/packages/shared/src/audit/audit-actions.ts
new file mode 100644
index 0000000..2bf0779
--- /dev/null
+++ b/packages/shared/src/audit/audit-actions.ts
@@ -0,0 +1,413 @@
+/**
+ * 审计动作目录（A5-BE-02 / 工程规范 08 LOG-12）
+ *
+ * - `AUDIT_CATEGORIES`：审计分类（前端筛选与色彩映射），共 9 类业务分类 + 1 类兜底；
+ * - `AUDIT_ACTION_CATALOG`：动作 code → 中文名 / 分类 / 默认 targetType / 是否敏感；
+ * - 动作中文名与分类**只在本文件维护**，`audit_logs` 表只存 code，避免字典漂移。
+ *
+ * 约束：新增 `@Audit('...')` 必须同步登记本目录，否则会走兜底（label = code），
+ * `audit-actions.spec.ts` 会扫描源码断言一致性。
+ */
+
+export const AUDIT_CATEGORIES = [
+  { key: 'auth', label: '登录与会话' },
+  { key: 'permission', label: '权限与角色' },
+  { key: 'client', label: '客户与行业' },
+  { key: 'catalog', label: '字典' },
+  { key: 'config', label: '系统配置' },
+  { key: 'export', label: '导出' },
+  { key: 'task', label: '任务' },
+  { key: 'asset', label: '资产' },
+  { key: 'sensitive', label: '敏感访问' },
+  /** 未知动作的兜底分类（新增动作未登记时使用，避免前端筛选出现空分类） */
+  { key: 'other', label: '其他' },
+] as const;
+
+export type AuditCategoryKey = (typeof AUDIT_CATEGORIES)[number]['key'];
+
+export const AUDIT_CATEGORY_KEYS = AUDIT_CATEGORIES.map((item) => item.key) as [
+  AuditCategoryKey,
+  ...AuditCategoryKey[],
+];
+
+const AUDIT_CATEGORY_LABEL_MAP: ReadonlyMap<string, string> = new Map(
+  AUDIT_CATEGORIES.map((item) => [item.key, item.label]),
+);
+
+export function auditCategoryLabel(category: string): string {
+  return AUDIT_CATEGORY_LABEL_MAP.get(category) ?? category;
+}
+
+/** 统一对象类型白名单（target_type），前端按此渲染对象列；未登记类型只做文本展示 */
+export const AUDIT_TARGET_TYPES = [
+  'user',
+  'department',
+  'role',
+  'customer',
+  'industry',
+  'customer_group',
+  'customer_field',
+  'dict_type',
+  'dict_item',
+  'system_config',
+  'audit_log',
+  'audit_export',
+  /** B1 / A6 预留 */
+  'asset',
+  'task',
+] as const;
+
+export type AuditTargetType = (typeof AUDIT_TARGET_TYPES)[number];
+
+export interface AuditActionMeta {
+  code: string;
+  label: string;
+  category: AuditCategoryKey;
+  /** 未显式声明时由拦截器按请求参数 / Service patchAudit 决定 */
+  targetType?: AuditTargetType;
+  /** 敏感访问（查看成本 / 资产包 / 审计等），需额外留痕与前端提示 */
+  sensitive?: boolean;
+}
+
+/**
+ * 动作目录：覆盖 A1–A4 已落地的 36 个 `@Audit(...)` code，
+ * 并登记 A5 新增（登录 / 登出 / 审计查看 / 审计导出 / 导出下载）与后续批次预留项。
+ */
+export const AUDIT_ACTION_CATALOG: Readonly<Record<string, AuditActionMeta>> = {
+  // ---------------- 登录与会话 ----------------
+  'identity.auth.login': {
+    code: 'identity.auth.login',
+    label: '登录',
+    category: 'auth',
+    targetType: 'user',
+    sensitive: true,
+  },
+  'identity.auth.logout': {
+    code: 'identity.auth.logout',
+    label: '登出',
+    category: 'auth',
+    targetType: 'user',
+  },
+  'identity.auth.change-password': {
+    code: 'identity.auth.change-password',
+    label: '修改密码',
+    category: 'auth',
+    targetType: 'user',
+    sensitive: true,
+  },
+
+  // ---------------- 权限与角色 / 组织 ----------------
+  'identity.role.create': {
+    code: 'identity.role.create',
+    label: '新建角色',
+    category: 'permission',
+    targetType: 'role',
+  },
+  'identity.role.update': {
+    code: 'identity.role.update',
+    label: '编辑角色',
+    category: 'permission',
+    targetType: 'role',
+  },
+  'identity.role.delete': {
+    code: 'identity.role.delete',
+    label: '删除角色',
+    category: 'permission',
+    targetType: 'role',
+  },
+  'identity.user.create': {
+    code: 'identity.user.create',
+    label: '新建用户',
+    category: 'permission',
+    targetType: 'user',
+  },
+  'identity.user.update': {
+    code: 'identity.user.update',
+    label: '编辑用户',
+    category: 'permission',
+    targetType: 'user',
+  },
+  'identity.user.disable': {
+    code: 'identity.user.disable',
+    label: '停用用户',
+    category: 'permission',
+    targetType: 'user',
+  },
+  'identity.user.enable': {
+    code: 'identity.user.enable',
+    label: '启用用户',
+    category: 'permission',
+    targetType: 'user',
+  },
+  'identity.user.transfer_customers': {
+    code: 'identity.user.transfer_customers',
+    label: '转交客户',
+    category: 'client',
+    targetType: 'customer',
+  },
+  'identity.department.create': {
+    code: 'identity.department.create',
+    label: '新建部门',
+    category: 'permission',
+    targetType: 'department',
+  },
+  'identity.department.update': {
+    code: 'identity.department.update',
+    label: '编辑部门',
+    category: 'permission',
+    targetType: 'department',
+  },
+  'identity.department.disable': {
+    code: 'identity.department.disable',
+    label: '停用部门',
+    category: 'permission',
+    targetType: 'department',
+  },
+  'identity.department.enable': {
+    code: 'identity.department.enable',
+    label: '启用部门',
+    category: 'permission',
+    targetType: 'department',
+  },
+
+  // ---------------- 客户与行业 ----------------
+  'client.customer.create': {
+    code: 'client.customer.create',
+    label: '新建客户',
+    category: 'client',
+    targetType: 'customer',
+  },
+  'client.customer.update': {
+    code: 'client.customer.update',
+    label: '编辑客户',
+    category: 'client',
+    targetType: 'customer',
+  },
+  'client.customer.status': {
+    code: 'client.customer.status',
+    label: '变更客户状态',
+    category: 'client',
+    targetType: 'customer',
+  },
+  'client.customer.transfer': {
+    code: 'client.customer.transfer',
+    label: '转交客户负责人',
+    category: 'client',
+    targetType: 'customer',
+  },
+  'client.customer.groups': {
+    code: 'client.customer.groups',
+    label: '调整客户组归属',
+    category: 'client',
+    targetType: 'customer',
+  },
+  'client.customer.apply_industry_pack': {
+    code: 'client.customer.apply_industry_pack',
+    label: '套用行业资产包',
+    category: 'client',
+    targetType: 'customer',
+  },
+  'client.customer_field.apply': {
+    code: 'client.customer_field.apply',
+    label: '申请客户字段',
+    category: 'client',
+    targetType: 'customer_field',
+  },
+  'client.customer_field.approve': {
+    code: 'client.customer_field.approve',
+    label: '审批客户字段',
+    category: 'client',
+    targetType: 'customer_field',
+    sensitive: true,
+  },
+  'client.industry.create': {
+    code: 'client.industry.create',
+    label: '新建行业',
+    category: 'client',
+    targetType: 'industry',
+  },
+  'client.industry.update': {
+    code: 'client.industry.update',
+    label: '编辑行业',
+    category: 'client',
+    targetType: 'industry',
+  },
+  'client.industry.status': {
+    code: 'client.industry.status',
+    label: '变更行业状态',
+    category: 'client',
+    targetType: 'industry',
+  },
+  'client.industry.delete': {
+    code: 'client.industry.delete',
+    label: '删除行业',
+    category: 'client',
+    targetType: 'industry',
+  },
+  'client.customer_group.create': {
+    code: 'client.customer_group.create',
+    label: '新建客户组',
+    category: 'client',
+    targetType: 'customer_group',
+  },
+  'client.customer_group.update': {
+    code: 'client.customer_group.update',
+    label: '编辑客户组',
+    category: 'client',
+    targetType: 'customer_group',
+  },
+  'client.customer_group.delete': {
+    code: 'client.customer_group.delete',
+    label: '删除客户组',
+    category: 'client',
+    targetType: 'customer_group',
+  },
+  'client.customer_group.members': {
+    code: 'client.customer_group.members',
+    label: '调整客户组成员',
+    category: 'client',
+    targetType: 'customer_group',
+  },
+
+  // ---------------- 字典 ----------------
+  'catalog.dict_type.create': {
+    code: 'catalog.dict_type.create',
+    label: '新建字典类型',
+    category: 'catalog',
+    targetType: 'dict_type',
+  },
+  'catalog.dict_type.update': {
+    code: 'catalog.dict_type.update',
+    label: '编辑字典类型',
+    category: 'catalog',
+    targetType: 'dict_type',
+  },
+  'catalog.dict_type.status': {
+    code: 'catalog.dict_type.status',
+    label: '变更字典类型状态',
+    category: 'catalog',
+    targetType: 'dict_type',
+  },
+  'catalog.dict_type.delete': {
+    code: 'catalog.dict_type.delete',
+    label: '删除字典类型',
+    category: 'catalog',
+    targetType: 'dict_type',
+  },
+  'catalog.dict_item.create': {
+    code: 'catalog.dict_item.create',
+    label: '新建字典条目',
+    category: 'catalog',
+    targetType: 'dict_item',
+  },
+  'catalog.dict_item.update': {
+    code: 'catalog.dict_item.update',
+    label: '编辑字典条目',
+    category: 'catalog',
+    targetType: 'dict_item',
+  },
+
+  // ---------------- 系统配置 ----------------
+  'platform.system_config.update': {
+    code: 'platform.system_config.update',
+    label: '保存系统配置',
+    category: 'config',
+    targetType: 'system_config',
+  },
+
+  // ---------------- 审计与导出（A5） ----------------
+  'audit.log.view': {
+    code: 'audit.log.view',
+    label: '查看审计日志',
+    category: 'sensitive',
+    targetType: 'audit_log',
+    sensitive: true,
+  },
+  'audit.export': {
+    code: 'audit.export',
+    label: '导出审计日志',
+    category: 'export',
+    targetType: 'audit_export',
+  },
+  'audit.export.download': {
+    code: 'audit.export.download',
+    label: '下载审计导出文件',
+    category: 'export',
+    targetType: 'audit_export',
+  },
+
+  // ---------------- 后续批次预留（B1 资产 / A6 任务） ----------------
+  'asset.create': {
+    code: 'asset.create',
+    label: '上传资产',
+    category: 'asset',
+    targetType: 'asset',
+  },
+  'asset.update': {
+    code: 'asset.update',
+    label: '编辑资产',
+    category: 'asset',
+    targetType: 'asset',
+  },
+  'asset.disable': {
+    code: 'asset.disable',
+    label: '停用资产',
+    category: 'asset',
+    targetType: 'asset',
+  },
+  'asset.delete': {
+    code: 'asset.delete',
+    label: '删除资产',
+    category: 'asset',
+    targetType: 'asset',
+  },
+  'task.submit': { code: 'task.submit', label: '提交任务', category: 'task', targetType: 'task' },
+  'task.cancel': { code: 'task.cancel', label: '取消任务', category: 'task', targetType: 'task' },
+  'task.retry': { code: 'task.retry', label: '重试任务', category: 'task', targetType: 'task' },
+  'task.finished': {
+    code: 'task.finished',
+    label: '任务完成',
+    category: 'task',
+    targetType: 'task',
+  },
+  'task.failed': { code: 'task.failed', label: '任务失败', category: 'task', targetType: 'task' },
+
+  // ---------------- 敏感访问（A5 预留，成本 / 资产包接口就绪后接入） ----------------
+  'sensitive.cost.view': {
+    code: 'sensitive.cost.view',
+    label: '查看成本数据',
+    category: 'sensitive',
+    sensitive: true,
+  },
+  'sensitive.asset_pack.view': {
+    code: 'sensitive.asset_pack.view',
+    label: '查看客户资产包',
+    category: 'sensitive',
+    sensitive: true,
+  },
+};
+
+export const AUDIT_ACTION_CODES: readonly string[] = Object.keys(AUDIT_ACTION_CATALOG);
+
+const AUDIT_ACTION_META_MAP: ReadonlyMap<string, AuditActionMeta> = new Map(
+  Object.entries(AUDIT_ACTION_CATALOG),
+);
+
+/**
+ * 取动作元数据；未登记 code 兜底：label 用 code 本身、分类 `other`。
+ * 兜底不抛错，保证新增动作忘登记时审计写入不被阻塞。
+ */
+export function auditActionMeta(code: string): AuditActionMeta {
+  return (
+    AUDIT_ACTION_META_MAP.get(code) ?? {
+      code,
+      label: code,
+      category: 'other',
+      sensitive: false,
+    }
+  );
+}
+
+export function isKnownAuditAction(code: string): boolean {
+  return AUDIT_ACTION_META_MAP.has(code);
+}
diff --git a/packages/shared/src/audit/audit-diff.spec.ts b/packages/shared/src/audit/audit-diff.spec.ts
new file mode 100644
index 0000000..361de4b
--- /dev/null
+++ b/packages/shared/src/audit/audit-diff.spec.ts
@@ -0,0 +1,79 @@
+import { describe, expect, it } from 'vitest';
+
+import { buildAuditDiff } from './audit-diff.js';
+
+describe('审计前后值 diff（A5-BE-03）', () => {
+  it('顶层字段新增 / 删除 / 修改', () => {
+    expect(
+      buildAuditDiff({ name: '旧名', status: 'ACTIVE' }, { name: '新名', remark: '备注' }),
+    ).toEqual([
+      { path: 'name', label: null, before: '旧名', after: '新名', kind: 'changed' },
+      { path: 'status', label: null, before: 'ACTIVE', after: null, kind: 'removed' },
+      { path: 'remark', label: null, before: null, after: '备注', kind: 'added' },
+    ]);
+  });
+
+  it('对象只展开一层（a.b），值相等不产生行', () => {
+    expect(
+      buildAuditDiff(
+        { dataScope: { type: 'all', targetIds: [] }, name: '客户' },
+        { dataScope: { type: 'department', targetIds: [] }, name: '客户' },
+      ),
+    ).toEqual([
+      { path: 'dataScope.type', label: null, before: 'all', after: 'department', kind: 'changed' },
+    ]);
+  });
+
+  it('数组按元素 index 展开（新增 / 删除 / 修改）', () => {
+    expect(buildAuditDiff({ specs: ['1080x1920'] }, { specs: ['1080x1920', '1080x1080'] })).toEqual(
+      [{ path: 'specs[1]', label: null, before: null, after: '1080x1080', kind: 'added' }],
+    );
+    expect(buildAuditDiff({ tags: ['a', 'b'] }, { tags: ['a'] })).toEqual([
+      { path: 'tags[1]', label: null, before: 'b', after: null, kind: 'removed' },
+    ]);
+    expect(buildAuditDiff({ tags: ['a', 'b'] }, { tags: ['a', 'c'] })).toEqual([
+      { path: 'tags[1]', label: null, before: 'b', after: 'c', kind: 'changed' },
+    ]);
+  });
+
+  it('权限点数组按增删语义（顺序变化不误报）', () => {
+    const rows = buildAuditDiff(
+      { permissions: ['script:read', 'user:view'] },
+      { permissions: ['user:view', 'role:view'] },
+    );
+    expect(rows).toEqual([
+      { path: 'permissions', label: null, before: 'script:read', after: null, kind: 'removed' },
+      { path: 'permissions', label: null, before: null, after: 'role:view', kind: 'added' },
+    ]);
+
+    const reordered = buildAuditDiff(
+      { specialPermissions: ['audit:read', 'audit:export'] },
+      { specialPermissions: ['audit:export', 'audit:read'] },
+    );
+    expect(reordered).toEqual([]);
+  });
+
+  it('对象数组按 index 展开为子字段路径', () => {
+    expect(
+      buildAuditDiff(
+        { fields: [{ code: 'a', name: '旧' }] },
+        { fields: [{ code: 'a', name: '新' }] },
+      ),
+    ).toEqual([
+      { path: 'fields[0].name', label: null, before: '旧', after: '新', kind: 'changed' },
+    ]);
+  });
+
+  it('before / after 全空或无变化返回空数组；支持标签映射', () => {
+    expect(buildAuditDiff(null, null)).toEqual([]);
+    expect(buildAuditDiff({}, {})).toEqual([]);
+    expect(buildAuditDiff({ a: 1 }, { a: 1 })).toEqual([]);
+    expect(buildAuditDiff(null, { name: '新增' })).toEqual([
+      { path: 'name', label: null, before: null, after: '新增', kind: 'added' },
+    ]);
+
+    expect(buildAuditDiff({ name: '旧' }, { name: '新' }, { name: '名称' })).toEqual([
+      { path: 'name', label: '名称', before: '旧', after: '新', kind: 'changed' },
+    ]);
+  });
+});
diff --git a/packages/shared/src/audit/audit-diff.ts b/packages/shared/src/audit/audit-diff.ts
new file mode 100644
index 0000000..e7ad07c
--- /dev/null
+++ b/packages/shared/src/audit/audit-diff.ts
@@ -0,0 +1,209 @@
+/**
+ * 审计前后值 diff（A5-BE-03 / 工程规范 08）
+ *
+ * 纯函数，前后端可共用：输入 before / after（JSON 值），输出可读的扁平变更行。
+ * 口径：
+ * - 顶层字段逐键比较；对象字段只展开一层（`a.b`），避免深层噪音；
+ * - 数组默认按元素索引展开（`a[0]`）；
+ * - 权限点数组（键名含 permission 或元素形如 `module:action`）按集合增删语义输出，
+ *   避免顺序变化被误报成大量改动；
+ * - 缺失字段 → added / removed，值变化 → changed。
+ */
+import { z } from 'zod';
+
+export const auditDiffKindSchema = z.enum(['added', 'removed', 'changed']);
+export type AuditDiffKind = z.infer<typeof auditDiffKindSchema>;
+
+export interface AuditDiffRow {
+  /** 字段路径，如 `name` / `dataScope.type` / `permissions` / `specs[0]` */
+  path: string;
+  /** 可选中文字段名（由调用方提供字典映射；默认 null） */
+  label: string | null;
+  before: unknown;
+  after: unknown;
+  kind: AuditDiffKind;
+}
+
+export const auditDiffRowSchema = z.object({
+  path: z.string().min(1),
+  label: z.string().nullable(),
+  before: z.unknown().nullable(),
+  after: z.unknown().nullable(),
+  kind: auditDiffKindSchema,
+});
+
+function isPlainObject(value: unknown): value is Record<string, unknown> {
+  return typeof value === 'object' && value !== null && !Array.isArray(value);
+}
+
+function sortKeys(value: unknown): unknown {
+  if (Array.isArray(value)) {
+    return value.map((item) => sortKeys(item));
+  }
+  if (!isPlainObject(value)) {
+    return value;
+  }
+  const sorted: Record<string, unknown> = {};
+  for (const key of Object.keys(value).sort()) {
+    sorted[key] = sortKeys(value[key]);
+  }
+  return sorted;
+}
+
+/** 结构化相等：忽略对象键顺序，undefined 与缺失视为相同 */
+function isEqualJson(left: unknown, right: unknown): boolean {
+  if (left === undefined && right === undefined) return true;
+  return JSON.stringify(sortKeys(left)) === JSON.stringify(sortKeys(right));
+}
+
+function isPermissionKey(key: string): boolean {
+  return key.toLowerCase().includes('permission');
+}
+
+function looksLikePermissionCodes(value: readonly unknown[]): boolean {
+  return value.length > 0 && value.every((item) => typeof item === 'string' && item.includes(':'));
+}
+
+/** 数组是否按集合增删语义比较（权限点数组） */
+function isSetLikeArray(
+  key: string,
+  before: readonly unknown[],
+  after: readonly unknown[],
+): boolean {
+  return (
+    isPermissionKey(key) || looksLikePermissionCodes(before) || looksLikePermissionCodes(after)
+  );
+}
+
+function pushRow(
+  rows: AuditDiffRow[],
+  path: string,
+  before: unknown,
+  after: unknown,
+  kind: AuditDiffKind,
+): void {
+  rows.push({
+    path,
+    label: null,
+    before: before === undefined ? null : before,
+    after: after === undefined ? null : after,
+    kind,
+  });
+}
+
+function diffObject(
+  rows: AuditDiffRow[],
+  path: string,
+  before: Record<string, unknown>,
+  after: Record<string, unknown>,
+): void {
+  const keys = [...Object.keys(before), ...Object.keys(after).filter((key) => !(key in before))];
+  for (const key of keys) {
+    const childPath = path.length === 0 ? key : `${path}.${key}`;
+    const hasBefore = key in before;
+    const hasAfter = key in after;
+    if (!hasBefore) {
+      pushRow(rows, childPath, undefined, after[key], 'added');
+      continue;
+    }
+    if (!hasAfter) {
+      pushRow(rows, childPath, before[key], undefined, 'removed');
+      continue;
+    }
+    diffValue(rows, childPath, key, before[key], after[key]);
+  }
+}
+
+function diffArray(
+  rows: AuditDiffRow[],
+  path: string,
+  key: string,
+  before: readonly unknown[],
+  after: readonly unknown[],
+): void {
+  if (isSetLikeArray(key, before, after)) {
+    const beforeSet = new Set(before.map((item) => JSON.stringify(sortKeys(item))));
+    const afterSet = new Set(after.map((item) => JSON.stringify(sortKeys(item))));
+    for (const item of before) {
+      if (!afterSet.has(JSON.stringify(sortKeys(item)))) {
+        pushRow(rows, path, item, undefined, 'removed');
+      }
+    }
+    for (const item of after) {
+      if (!beforeSet.has(JSON.stringify(sortKeys(item)))) {
+        pushRow(rows, path, undefined, item, 'added');
+      }
+    }
+    return;
+  }
+  const length = Math.max(before.length, after.length);
+  for (let index = 0; index < length; index += 1) {
+    const childPath = `${path}[${String(index)}]`;
+    const hasBefore = index < before.length;
+    const hasAfter = index < after.length;
+    if (!hasBefore) {
+      pushRow(rows, childPath, undefined, after[index], 'added');
+      continue;
+    }
+    if (!hasAfter) {
+      pushRow(rows, childPath, before[index], undefined, 'removed');
+      continue;
+    }
+    const beforeItem = before[index];
+    const afterItem = after[index];
+    if (isPlainObject(beforeItem) && isPlainObject(afterItem)) {
+      diffObject(rows, childPath, beforeItem, afterItem);
+    } else if (!isEqualJson(beforeItem, afterItem)) {
+      pushRow(rows, childPath, beforeItem, afterItem, 'changed');
+    }
+  }
+}
+
+function diffValue(
+  rows: AuditDiffRow[],
+  path: string,
+  key: string,
+  before: unknown,
+  after: unknown,
+): void {
+  if (isPlainObject(before) && isPlainObject(after)) {
+    // 对象只展开一层，避免深层 diff 噪音
+    diffObject(rows, path, before, after);
+    return;
+  }
+  if (Array.isArray(before) && Array.isArray(after)) {
+    diffArray(rows, path, key, before, after);
+    return;
+  }
+  if (!isEqualJson(before, after)) {
+    pushRow(rows, path, before, after, 'changed');
+  }
+}
+
+/**
+ * 生成前后值 diff。before / after 可为 null / undefined（如仅新增或仅删除），
+ * 返回空数组表示无变化。
+ */
+export function buildAuditDiff(
+  before: unknown,
+  after: unknown,
+  labels?: Readonly<Record<string, string>>,
+): AuditDiffRow[] {
+  const rows: AuditDiffRow[] = [];
+  if (isPlainObject(before) && isPlainObject(after)) {
+    diffObject(rows, '', before, after);
+  } else if (isPlainObject(before)) {
+    diffObject(rows, '', before, {});
+  } else if (isPlainObject(after)) {
+    diffObject(rows, '', {}, after);
+  } else if (!isEqualJson(before, after)) {
+    pushRow(rows, '$', before, after, 'changed');
+  }
+  if (labels === undefined) {
+    return rows;
+  }
+  return rows.map((row) => {
+    const label = labels[row.path];
+    return label === undefined ? row : { ...row, label };
+  });
+}
diff --git a/packages/shared/src/config/system-configs.ts b/packages/shared/src/config/system-configs.ts
index ddb7a53..1f2da5b 100644
--- a/packages/shared/src/config/system-configs.ts
+++ b/packages/shared/src/config/system-configs.ts
@@ -13,6 +13,7 @@ export const SYSTEM_CONFIG_GROUP_KEYS = [
   'notify',
   'limits',
   'threshold',
+  'audit',
 ] as const;
 
 export type SystemConfigGroupKey = (typeof SYSTEM_CONFIG_GROUP_KEYS)[number];
@@ -44,6 +45,12 @@ export const SYSTEM_CONFIG_GROUPS: readonly {
     description: '爆量判定、审核超时与质量告警',
     sortOrder: 60,
   },
+  {
+    key: 'audit',
+    name: '审计与日志',
+    description: '审计保留期、导出上限与运行日志平台入口',
+    sortOrder: 70,
+  },
 ];
 
 export type SystemConfigInputType = 'text' | 'number' | 'boolean' | 'pattern';
@@ -451,6 +458,52 @@ export const SYSTEM_CONFIG_DEFINITIONS: readonly SystemConfigDefinition[] = [
     public: false,
     sortOrder: 260,
   },
+
+  // 审计与日志（A5）
+  {
+    key: 'audit.retention_months',
+    group: 'audit',
+    label: '审计日志保留期',
+    description: '审计日志在线保留的最短月数；归档任务按该值执行（QT-10 最终值待确认）',
+    impact:
+      '影响审计可检索范围与归档策略；PRD Q-08 要求 ≥ 12 个月，归档只做只读搬迁、不删除审计数据',
+    type: 'number',
+    defaultValue: 12,
+    unit: '个月',
+    min: 12,
+    max: 60,
+    editable: true,
+    public: false,
+    sortOrder: 270,
+  },
+  {
+    key: 'audit.export_max_rows',
+    group: 'audit',
+    label: '审计导出单次行数上限',
+    description: '单次异步导出的最大行数，超出部分截断并在导出任务上标记 truncated',
+    impact: '影响导出文件体积与导出耗时；截断后需缩小筛选条件重新导出',
+    type: 'number',
+    defaultValue: 50000,
+    unit: '条',
+    min: 1000,
+    max: 200000,
+    editable: true,
+    public: true,
+    sortOrder: 280,
+  },
+  {
+    key: 'audit.logs_platform_url',
+    group: 'audit',
+    label: '运行日志平台地址',
+    description: '后台「运行日志」入口跳转的 Grafana / Loki 地址；只存链接，不含任何密钥',
+    impact: '仅影响前端跳转链接；运行日志不入业务库（工程规范 08）',
+    type: 'text',
+    defaultValue: '',
+    maxLength: 500,
+    editable: true,
+    public: true,
+    sortOrder: 290,
+  },
 ];
 
 const DEFINITION_MAP: ReadonlyMap<string, SystemConfigDefinition> = new Map(
@@ -518,6 +571,10 @@ export function validateSystemConfigValue(
   }
   const text = value.trim();
   if (text.length === 0) {
+    // 允许默认值为空串的文本项（如 audit.logs_platform_url：未配置日志平台时为空）
+    if (definition.defaultValue === '') {
+      return { ok: true, value: '' };
+    }
     return { ok: false, message: '配置值不能为空' };
   }
   if (definition.type === 'pattern') {
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index 8fd81f0..397f148 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -1,3 +1,5 @@
+export * from './audit/audit-actions.js';
+export * from './audit/audit-diff.js';
 export * from './config/system-configs.js';
 export * from './constants.js';
 export * from './errors/api-error.js';
@@ -5,6 +7,7 @@ export * from './errors/codes.js';
 export * from './naming.js';
 export * from './permissions.js';
 export * from './schemas/api.js';
+export * from './schemas/audit.js';
 export * from './schemas/client.js';
 export * from './schemas/common.js';
 export * from './schemas/config.js';
diff --git a/packages/shared/src/schemas/audit.spec.ts b/packages/shared/src/schemas/audit.spec.ts
new file mode 100644
index 0000000..01ce363
--- /dev/null
+++ b/packages/shared/src/schemas/audit.spec.ts
@@ -0,0 +1,109 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  auditExportCreateSchema,
+  auditExportJobSchema,
+  auditLogDetailSchema,
+  auditLogItemSchema,
+  auditLogListQuerySchema,
+  auditLogListResponseSchema,
+} from './audit.js';
+
+const ITEM = {
+  id: '01HZZZZZZZZZZZZZZZZZZZZZZZ',
+  occurred_at: '2026-11-04T08:00:00.000Z',
+  actor_id: '01HZZZZZZZZZZZZZZZZZZZZZZY',
+  actor_name: '江岚',
+  actor_account: 'jiang.lan',
+  action_code: 'client.customer.update',
+  action_label: '编辑客户',
+  category: 'client',
+  category_label: '客户与行业',
+  target_type: 'customer',
+  target_id: '01HZZZZZZZZZZZZZZZZZZZZZZX',
+  target_name: '花间集',
+  customer_id: '01HZZZZZZZZZZZZZZZZZZZZZZX',
+  customer_name: '花间集',
+  result: 'success' as const,
+  http_method: 'PATCH',
+  http_path: '/api/v1/customers/01HZZZZZZZZZZZZZZZZZZZZZZX',
+  trace_id: 'trace-0001',
+  ip: '127.0.0.1',
+  duration_ms: 12,
+  error_code: null,
+  error_message: null,
+  change_count: 1,
+  has_before: true,
+  has_after: true,
+};
+
+describe('审计日志契约（A5-BE-03）', () => {
+  it('列表 query：默认 limit=20、数字强制转换、未知枚举拒绝', () => {
+    const parsed = auditLogListQuerySchema.parse({});
+    expect(parsed.limit).toBe(20);
+    expect(auditLogListQuerySchema.parse({ limit: '50' }).limit).toBe(50);
+    expect(
+      auditLogListQuerySchema.parse({
+        actor: '江岚',
+        result: 'failure',
+        from: '2026-11-01T00:00:00.000Z',
+        to: '2026-11-05T00:00:00.000Z',
+      }).result,
+    ).toBe('failure');
+    expect(() => auditLogListQuerySchema.parse({ result: 'unknown' })).toThrow();
+    expect(() => auditLogListQuerySchema.parse({ limit: 101 })).toThrow();
+    expect(() => auditLogListQuerySchema.parse({ customer_id: 'not-ulid' })).toThrow();
+  });
+
+  it('列表项可解析；详情在列表基础上增加前后值与 diff', () => {
+    expect(auditLogItemSchema.parse(ITEM).action_label).toBe('编辑客户');
+    const detail = {
+      ...ITEM,
+      user_agent: 'Mozilla/5.0',
+      reason: '客户更名',
+      before: { name: '旧名' },
+      after: { name: '花间集' },
+      changes: null,
+      diff: [{ path: 'name', label: null, before: '旧名', after: '花间集', kind: 'changed' }],
+    };
+    expect(auditLogDetailSchema.parse(detail).diff).toHaveLength(1);
+    expect(
+      auditLogListResponseSchema.parse({ items: [ITEM], next_cursor: null }).items,
+    ).toHaveLength(1);
+  });
+
+  it('导出创建：format 默认 csv、filters 默认空对象、拒绝未知字段', () => {
+    expect(auditExportCreateSchema.parse({}).format).toBe('csv');
+    expect(auditExportCreateSchema.parse({ filters: { result: 'failure' } }).filters.result).toBe(
+      'failure',
+    );
+    expect(() => auditExportCreateSchema.parse({ format: 'json' })).toThrow();
+    expect(() => auditExportCreateSchema.parse({ extra: true })).toThrow();
+  });
+
+  it('导出任务：进度 0–100、状态枚举、行数字段', () => {
+    const job = {
+      id: '01HZZZZZZZZZZZZZZZZZZZZZZW',
+      status: 'running',
+      format: 'csv',
+      filters: { result: 'success' },
+      total_rows: 10,
+      row_count: null,
+      processed_rows: 5,
+      truncated: false,
+      progress: 50,
+      file_size: null,
+      error_message: null,
+      requested_at: '2026-11-04T08:00:00.000Z',
+      started_at: '2026-11-04T08:00:01.000Z',
+      finished_at: null,
+      expires_at: null,
+      download_count: 0,
+      last_downloaded_at: null,
+      download_token: null,
+    };
+    expect(auditExportJobSchema.parse(job).status).toBe('running');
+    expect(() => auditExportJobSchema.parse({ ...job, status: 'cancelled' })).toThrow();
+    expect(() => auditExportJobSchema.parse({ ...job, progress: 101 })).toThrow();
+  });
+});
diff --git a/packages/shared/src/schemas/audit.ts b/packages/shared/src/schemas/audit.ts
new file mode 100644
index 0000000..d19d032
--- /dev/null
+++ b/packages/shared/src/schemas/audit.ts
@@ -0,0 +1,179 @@
+/**
+ * 审计日志共享契约（A5-BE-03）
+ *
+ * 依据：PRD §5.4.6 / R-05；技术架构 §5.4.5 / §6.3；开发计划 A5-BE-03 / §7.5。
+ * - 列表 query 用 snake_case（C-01），body 用 camelCase；
+ * - 列表只返回摘要与变更字段数，before / after / changes 仅在详情返回；
+ * - 导出为异步任务，创建后立即返回 queued，进度用 job 查询。
+ */
+import { z } from 'zod';
+
+import { AUDIT_CATEGORY_KEYS } from '../audit/audit-actions.js';
+import { auditDiffRowSchema } from '../audit/audit-diff.js';
+import { isoDateTimeSchema, ulidSchema } from './common.js';
+
+export const auditCategorySchema = z.enum(AUDIT_CATEGORY_KEYS);
+
+export const auditResultSchema = z.enum(['success', 'failure']);
+export type AuditResult = z.infer<typeof auditResultSchema>;
+
+export const auditExportStatusSchema = z.enum(['queued', 'running', 'succeeded', 'failed']);
+export type AuditExportStatus = z.infer<typeof auditExportStatusSchema>;
+
+export const auditExportFormatSchema = z.enum(['csv']);
+
+/** 列表 / 导出共用筛选条件（query 与 body.filters 同一口径，全部 snake_case） */
+export const auditLogFilterSchema = z.object({
+  /** 操作人：匹配 actor_id 精确 / 姓名 / 账号包含 */
+  actor: z.string().trim().min(1).max(64).optional(),
+  customer_id: ulidSchema.optional(),
+  action_code: z.string().trim().min(1).max(64).optional(),
+  category: auditCategorySchema.optional(),
+  target_type: z.string().trim().min(1).max(64).optional(),
+  target_id: z.string().trim().min(1).max(128).optional(),
+  result: auditResultSchema.optional(),
+  from: isoDateTimeSchema.optional(),
+  to: isoDateTimeSchema.optional(),
+  /** 关键字：对象名 / 对象 id / 请求路径 / 原因 包含 */
+  keyword: z.string().trim().min(1).max(100).optional(),
+});
+
+export type AuditLogFilter = z.infer<typeof auditLogFilterSchema>;
+
+export const auditLogListQuerySchema = auditLogFilterSchema.extend({
+  cursor: z.string().min(1).max(512).optional(),
+  limit: z.coerce.number().int().min(1).max(100).default(20),
+});
+
+export type AuditLogListQuery = z.infer<typeof auditLogListQuerySchema>;
+
+/** 列表摘要：不含 before / after / changes，只给变更字段数 */
+export const auditLogItemSchema = z.object({
+  id: ulidSchema,
+  occurred_at: isoDateTimeSchema,
+  actor_id: z.string().nullable(),
+  actor_name: z.string().nullable(),
+  actor_account: z.string().nullable(),
+  action_code: z.string().min(1),
+  action_label: z.string().min(1),
+  category: z.string().min(1),
+  category_label: z.string().min(1),
+  target_type: z.string().nullable(),
+  target_id: z.string().nullable(),
+  target_name: z.string().nullable(),
+  customer_id: z.string().nullable(),
+  customer_name: z.string().nullable(),
+  result: auditResultSchema,
+  http_method: z.string().nullable(),
+  http_path: z.string().nullable(),
+  trace_id: z.string().nullable(),
+  ip: z.string().nullable(),
+  duration_ms: z.number().int().nullable(),
+  error_code: z.string().nullable(),
+  error_message: z.string().nullable(),
+  change_count: z.number().int().nonnegative(),
+  has_before: z.boolean(),
+  has_after: z.boolean(),
+});
+
+export type AuditLogItem = z.infer<typeof auditLogItemSchema>;
+
+/** 详情：含 before / after / changes / diff / UA / 原因 */
+export const auditLogDetailSchema = auditLogItemSchema.extend({
+  user_agent: z.string().nullable(),
+  reason: z.string().nullable(),
+  before: z.unknown().nullable(),
+  after: z.unknown().nullable(),
+  changes: z.unknown().nullable(),
+  diff: z.array(auditDiffRowSchema),
+});
+
+export type AuditLogDetail = z.infer<typeof auditLogDetailSchema>;
+
+export const auditLogListResponseSchema = z.object({
+  items: z.array(auditLogItemSchema),
+  next_cursor: z.string().nullable(),
+});
+
+export type AuditLogListResponse = z.infer<typeof auditLogListResponseSchema>;
+
+/** 服务端动作目录（筛选下拉与中文名映射） */
+export const auditActionCatalogItemSchema = z.object({
+  code: z.string().min(1),
+  label: z.string().min(1),
+  category: z.string().min(1),
+  category_label: z.string().min(1),
+  target_type: z.string().nullable(),
+  sensitive: z.boolean(),
+});
+
+export type AuditActionCatalogItem = z.infer<typeof auditActionCatalogItemSchema>;
+
+export const auditLogActionsResponseSchema = z.object({
+  items: z.array(auditActionCatalogItemSchema),
+  categories: z.array(
+    z.object({
+      key: z.string().min(1),
+      label: z.string().min(1),
+    }),
+  ),
+});
+
+export type AuditLogActionsResponse = z.infer<typeof auditLogActionsResponseSchema>;
+
+/** 导出创建入参：format 暂只支持 csv */
+export const auditExportCreateSchema = z
+  .object({
+    format: auditExportFormatSchema.default('csv'),
+    filters: auditLogFilterSchema.default({}),
+  })
+  .strict();
+
+export type AuditExportCreateInput = z.input<typeof auditExportCreateSchema>;
+export type AuditExportCreateParsed = z.output<typeof auditExportCreateSchema>;
+
+export const auditExportCreateResponseSchema = z.object({
+  id: ulidSchema,
+  status: z.literal('queued'),
+});
+
+export type AuditExportCreateResponse = z.infer<typeof auditExportCreateResponseSchema>;
+
+/** 导出任务（进度用 processed_rows / total_rows 计算，前端不猜状态） */
+export const auditExportJobSchema = z.object({
+  id: ulidSchema,
+  status: auditExportStatusSchema,
+  format: auditExportFormatSchema,
+  filters: auditLogFilterSchema,
+  total_rows: z.number().int().nonnegative().nullable(),
+  row_count: z.number().int().nonnegative().nullable(),
+  processed_rows: z.number().int().nonnegative().nullable(),
+  truncated: z.boolean(),
+  progress: z.number().min(0).max(100),
+  file_size: z.number().int().nonnegative().nullable(),
+  error_message: z.string().nullable(),
+  requested_at: isoDateTimeSchema,
+  started_at: isoDateTimeSchema.nullable(),
+  finished_at: isoDateTimeSchema.nullable(),
+  expires_at: isoDateTimeSchema.nullable(),
+  download_count: z.number().int().nonnegative(),
+  last_downloaded_at: isoDateTimeSchema.nullable(),
+  /** 成功任务返回短时效 HMAC 下载 token（前端拼 /exports/:id/download?token=） */
+  download_token: z.string().nullable(),
+});
+
+export type AuditExportJob = z.infer<typeof auditExportJobSchema>;
+
+export const auditExportListResponseSchema = z.object({
+  items: z.array(auditExportJobSchema),
+  next_cursor: z.string().nullable(),
+});
+
+export type AuditExportListResponse = z.infer<typeof auditExportListResponseSchema>;
+
+export const auditExportListQuerySchema = z.object({
+  cursor: z.string().min(1).max(512).optional(),
+  limit: z.coerce.number().int().min(1).max(100).default(20),
+});
+
+export type AuditExportListQuery = z.infer<typeof auditExportListQuerySchema>;
diff --git a/packages/shared/src/schemas/config.spec.ts b/packages/shared/src/schemas/config.spec.ts
index 5d7c2ac..d9d4928 100644
--- a/packages/shared/src/schemas/config.spec.ts
+++ b/packages/shared/src/schemas/config.spec.ts
@@ -29,6 +29,44 @@ describe('系统配置契约（A4-BE-02 / R-26）', () => {
     expect(systemConfigDefinition('limit.customer.gen_field')?.public).toBe(true);
     expect(systemConfigDefinition('platform.page.default_limit')?.public).toBe(true);
     expect(systemConfigDefinition('naming.script.pattern')?.public).toBe(false);
+    // A5：导出上限前端可读，保留期与日志平台地址按权限控制
+    expect(systemConfigDefinition('audit.export_max_rows')?.public).toBe(true);
+    expect(systemConfigDefinition('audit.retention_months')?.public).toBe(false);
+    expect(systemConfigDefinition('audit.logs_platform_url')?.public).toBe(true);
+  });
+
+  it('A5 审计分组与 3 项配置（保留期 / 导出上限 / 运行日志入口）', () => {
+    const groupKeys = SYSTEM_CONFIG_GROUPS.map((group) => group.key);
+    expect(groupKeys).toContain('audit');
+    expect(groupKeys.indexOf('audit')).toBe(groupKeys.length - 1);
+    const auditDefaults = SYSTEM_CONFIG_DEFINITIONS.filter(
+      (definition) => definition.group === 'audit',
+    );
+    expect(auditDefaults).toHaveLength(3);
+    expect(systemConfigDefinition('audit.retention_months')).toMatchObject({
+      type: 'number',
+      defaultValue: 12,
+      min: 12,
+      max: 60,
+    });
+    expect(systemConfigDefinition('audit.export_max_rows')).toMatchObject({
+      type: 'number',
+      defaultValue: 50000,
+      min: 1000,
+      max: 200000,
+    });
+    expect(systemConfigDefinition('audit.logs_platform_url')).toMatchObject({
+      type: 'text',
+      defaultValue: '',
+      maxLength: 500,
+    });
+    // 空串是合法的默认值（未配置日志平台），但非空项仍禁止保存空串
+    const url = systemConfigDefinition('audit.logs_platform_url');
+    expect(url).toBeDefined();
+    if (url === undefined) return;
+    expect(validateSystemConfigValue(url, '').ok).toBe(true);
+    expect(validateSystemConfigValue(url, 'https://grafana.example.com').ok).toBe(true);
+    expect(validateSystemConfigValue(url, 'x'.repeat(501)).ok).toBe(false);
   });
 
   it('数字边界与布尔类型校验', () => {