diff --git a/account/sql/20251001-migrate_to_uuid.md b/account/sql/20251001-migrate_to_uuid.md
new file mode 100644
index 0000000..2a775de
--- /dev/null
+++ b/account/sql/20251001-migrate_to_uuid.md
@@ -0,0 +1,68 @@
+# 前置准备
+
+1. 确认扩展
+登录 PostgreSQL，执行： \dx 看看是否已经有 uuid-ossp 或 pgcrypto。
+如果没有，就执行： 
+
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+或者：
+CREATE EXTENSION IF NOT EXISTS "pgcrypto";
+
+
+⚠️ 推荐用 pgcrypto（函数是 gen_random_uuid()），更现代；
+如果你已经用了 uuid-ossp，脚本里的 uuid_generate_v4() 就能直接用。
+
+2. 备份数据库
+
+这是最关键的保险：
+
+pg_dump -U <user> -d <dbname> > backup_before_uuid.sql
+
+3. 执行迁移
+
+假设你的 schema 在 schema.sql 文件里，迁移脚本在 migrate_to_uuid.sql 文件里。
+
+执行： psql -U <user> -d <dbname> -f migrate_to_uuid.sql
+
+
+这个脚本会做三步：
+
+- 新增 uuid 列，填充数据。
+- 新建 user_uuid 外键字段，保持和旧 id 外键并存。
+- 删除旧的 id、user_id，把 uuid 设为主键。
+
+4. 验证结果
+
+迁移后，进入数据库： psql -U <user> -d <dbname>
+
+查看表结构：
+
+\d users
+\d identities
+\d sessions
+
+
+应该看到：
+
+users(uuid PRIMARY KEY, username, password, email, created_at …)
+identities(uuid PRIMARY KEY, user_uuid REFERENCES users(uuid), provider, external_id …)
+sessions(uuid PRIMARY KEY, user_uuid REFERENCES users(uuid), token, expires_at …)
+
+再验证外键是否正确：
+
+SELECT constraint_name, table_name, column_name, foreign_table_name
+FROM information_schema.key_column_usage
+WHERE table_schema = 'public';
+
+回滚策略
+
+如果迁移出错，可以用之前的备份恢复：
+
+psql -U <user> -d <dbname> < backup_before_uuid.sql
+
+总结：
+
+先启用扩展
+再运行迁移脚本
+验证新表结构和外键
+保留备份，随时可回滚
diff --git a/account/sql/20251001-migrate_to_uuid.sql b/account/sql/20251001-migrate_to_uuid.sql
new file mode 100644
index 0000000..2d6b7f3
--- /dev/null
+++ b/account/sql/20251001-migrate_to_uuid.sql
@@ -0,0 +1,117 @@
+------------------------------------------------
+-- STEP 0: 启用 UUID 扩展
+------------------------------------------------
+-- 两种方式任选其一，推荐 pgcrypto（更现代）
+-- 如果数据库还没装扩展，可以先运行 CREATE EXTENSION
+
+-- 方式一：使用 uuid-ossp
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+
+-- 方式二：使用 pgcrypto
+-- CREATE EXTENSION IF NOT EXISTS "pgcrypto";
+
+-- 注意：
+-- uuid-ossp 用 uuid_generate_v4()
+-- pgcrypto 用 gen_random_uuid()
+
+------------------------------------------------
+-- STEP 1: 平滑迁移（添加 UUID 字段并建立外键）
+------------------------------------------------
+
+-- ========== Users ==========
+ALTER TABLE users
+    ADD COLUMN IF NOT EXISTS uuid UUID DEFAULT uuid_generate_v4();
+
+UPDATE users SET uuid = uuid_generate_v4() WHERE uuid IS NULL;
+
+ALTER TABLE users
+    ALTER COLUMN uuid SET NOT NULL;
+
+ALTER TABLE users
+    ADD CONSTRAINT users_uuid_unique UNIQUE (uuid);
+
+-- ========== Identities ==========
+ALTER TABLE identities
+    ADD COLUMN IF NOT EXISTS uuid UUID DEFAULT uuid_generate_v4();
+
+UPDATE identities SET uuid = uuid_generate_v4() WHERE uuid IS NULL;
+
+ALTER TABLE identities
+    ALTER COLUMN uuid SET NOT NULL;
+
+ALTER TABLE identities
+    ADD CONSTRAINT identities_uuid_unique UNIQUE (uuid);
+
+-- 新增 user_uuid 外键字段
+ALTER TABLE identities
+    ADD COLUMN IF NOT EXISTS user_uuid UUID;
+
+UPDATE identities i
+SET user_uuid = u.uuid
+FROM users u
+WHERE i.user_id = u.id;
+
+ALTER TABLE identities
+    ALTER COLUMN user_uuid SET NOT NULL;
+
+ALTER TABLE identities
+    ADD CONSTRAINT identities_user_uuid_fk FOREIGN KEY (user_uuid) REFERENCES users(uuid) ON DELETE CASCADE;
+
+-- ========== Sessions ==========
+ALTER TABLE sessions
+    ADD COLUMN IF NOT EXISTS uuid UUID DEFAULT uuid_generate_v4();
+
+UPDATE sessions SET uuid = uuid_generate_v4() WHERE uuid IS NULL;
+
+ALTER TABLE sessions
+    ALTER COLUMN uuid SET NOT NULL;
+
+ALTER TABLE sessions
+    ADD CONSTRAINT sessions_uuid_unique UNIQUE (uuid);
+
+-- 新增 user_uuid 外键字段
+ALTER TABLE sessions
+    ADD COLUMN IF NOT EXISTS user_uuid UUID;
+
+UPDATE sessions s
+SET user_uuid = u.uuid
+FROM users u
+WHERE s.user_id = u.id;
+
+ALTER TABLE sessions
+    ALTER COLUMN user_uuid SET NOT NULL;
+
+ALTER TABLE sessions
+    ADD CONSTRAINT sessions_user_uuid_fk FOREIGN KEY (user_uuid) REFERENCES users(uuid) ON DELETE CASCADE;
+
+
+------------------------------------------------
+-- STEP 2: 清理（彻底切换到 UUID 主键）
+------------------------------------------------
+
+-- 删除原有的主键约束
+ALTER TABLE users DROP CONSTRAINT users_pkey;
+ALTER TABLE identities DROP CONSTRAINT identities_pkey;
+ALTER TABLE sessions DROP CONSTRAINT sessions_pkey;
+
+-- 删除旧的 id 外键
+ALTER TABLE identities DROP CONSTRAINT IF EXISTS identities_user_id_fkey;
+ALTER TABLE sessions DROP CONSTRAINT IF EXISTS sessions_user_id_fkey;
+
+-- 设置 uuid 为新的主键
+ALTER TABLE users ADD CONSTRAINT users_pkey PRIMARY KEY (uuid);
+ALTER TABLE identities ADD CONSTRAINT identities_pkey PRIMARY KEY (uuid);
+ALTER TABLE sessions ADD CONSTRAINT sessions_pkey PRIMARY KEY (uuid);
+
+-- 删除旧的 id 字段
+ALTER TABLE users DROP COLUMN id;
+ALTER TABLE identities DROP COLUMN id;
+ALTER TABLE sessions DROP COLUMN id;
+
+-- 删除旧的 user_id 外键字段
+ALTER TABLE identities DROP COLUMN user_id;
+ALTER TABLE sessions DROP COLUMN user_id;
+
+------------------------------------------------
+-- Done: 所有表都只用 UUID 作为主键/外键
+------------------------------------------------
diff --git a/account/sql/schema.sql b/account/sql/schema.sql
index a3b4524..5fe3970 100644
--- a/account/sql/schema.sql
+++ b/account/sql/schema.sql
@@ -1,5 +1,10 @@
+-- 启用扩展（只需执行一次）
+CREATE EXTENSION IF NOT EXISTS "uuid-ossp";
+-- 或者：CREATE EXTENSION IF NOT EXISTS "pgcrypto";
+
 CREATE TABLE IF NOT EXISTS users (
-    id SERIAL PRIMARY KEY,
+    id SERIAL UNIQUE, -- 保留自增 id 作为内部用途
+    uuid UUID PRIMARY KEY DEFAULT uuid_generate_v4(), -- 业务主键
     username TEXT NOT NULL UNIQUE,
     password TEXT NOT NULL,
     email TEXT,
@@ -7,16 +12,18 @@ CREATE TABLE IF NOT EXISTS users (
 );
 
 CREATE TABLE IF NOT EXISTS identities (
-    id SERIAL PRIMARY KEY,
-    user_id INTEGER REFERENCES users(id) ON DELETE CASCADE,
+    id SERIAL UNIQUE,
+    uuid UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    user_id UUID REFERENCES users(uuid) ON DELETE CASCADE,
     provider TEXT NOT NULL,
     external_id TEXT NOT NULL,
     UNIQUE(provider, external_id)
 );
 
 CREATE TABLE IF NOT EXISTS sessions (
-    id SERIAL PRIMARY KEY,
-    user_id INTEGER REFERENCES users(id) ON DELETE CASCADE,
+    id SERIAL UNIQUE,
+    uuid UUID PRIMARY KEY DEFAULT uuid_generate_v4(),
+    user_id UUID REFERENCES users(uuid) ON DELETE CASCADE,
     token TEXT NOT NULL,
     expires_at TIMESTAMPTZ NOT NULL
 );