diff --git a/apps/api/routers/auth.py b/apps/api/routers/auth.py
index e36f0d0..4495835 100755
--- a/apps/api/routers/auth.py
+++ b/apps/api/routers/auth.py
@@ -1,18 +1,24 @@
-"""Development-only token issuance.
+"""Auth endpoints: dev-token / refresh / logout (FR-ACC-05 双令牌会话).
 
-**This is not the V1 auth design.** FR-ACC-01/04/05 require 华为账号登录、手机号
-验证码、双令牌与服务端可撤销的 refresh token. This endpoint exists so the
-vertical slice can be exercised end to end, and it refuses to run unless
-``DEV_AUTH_ENABLED`` is true and the environment is local/dev.
+登出语义 = 撤销 ``id_session`` 会话，**refresh token 立即失效**。access JWT
+无状态、15 分钟 TTL：登出后旧 access 在其 TTL 内仍有效的残留窗口是 V1 已知
+且接受的设计权衡（要即时失效就得引入黑名单或极短 TTL，V1 不做）——
+「登出后旧令牌立即失效」的验收对象是 refresh 令牌与会话。
+
+明确不做（防止后人误判「漏了」）：华为账号登录（T-P1-12，等资质）、手机验证码
+（T-P1-12b，等短信通道）、游客/合并/注销。dev-token 端点不是正式鉴权设计，
+仅为纵向切片与联调服务：``DEV_AUTH_ENABLED`` + 本地环境双开关才放行。
 """
 
 from __future__ import annotations
 
 from fastapi import APIRouter
 
-from apps.api.deps import IdentityServiceDep, SettingsDep
-from apps.api.schemas import DevTokenRequest, DevTokenResponse
-from packages.identity.service import DEV_PROVIDER
+from apps.api.deps import CurrentUserId, IdentityServiceDep, SettingsDep
+from apps.api.schemas import DevTokenRequest
+from packages.identity.schemas import LogoutRequest, RefreshRequest, TokenPairResponse
+from packages.identity.service import DEV_PROVIDER, SessionIssued
+from packages.shared.config import Settings
 from packages.shared.errors import AppError, ErrorCode
 from packages.shared.response import ok
 from packages.shared.security import create_access_token
@@ -20,7 +26,34 @@ from packages.shared.security import create_access_token
 router = APIRouter(prefix="/auth", tags=["auth"])
 
 
-@router.post("/dev-token", summary="[dev only] Issue an access token for testing")
+def _access_token(settings: Settings, user_id: int) -> str:
+    return create_access_token(
+        user_id=user_id,
+        secret=settings.jwt_secret,
+        algorithm=settings.jwt_algorithm,
+        ttl_seconds=settings.jwt_access_ttl_seconds,
+        issuer=settings.jwt_issuer,
+    )
+
+
+def _token_pair(
+    settings: Settings, access_token: str, issued: SessionIssued
+) -> dict[str, str | int]:
+    """dev-token 与 refresh 共用的双令牌响应。
+
+    旧字段名 ``access_token/token_type/expires_in/user_id`` 一字不改
+    （smoke.sh 与既有测试依赖），只新增 ``refresh_token/refresh_expires_in``。
+    """
+    return TokenPairResponse(
+        access_token=access_token,
+        refresh_token=issued.refresh_token,
+        expires_in=settings.jwt_access_ttl_seconds,
+        refresh_expires_in=settings.refresh_token_ttl_seconds,
+        user_id=str(issued.user_id),
+    ).model_dump()
+
+
+@router.post("/dev-token", summary="[dev only] Issue a token pair for testing")
 async def dev_token(
     payload: DevTokenRequest,
     settings: SettingsDep,
@@ -34,17 +67,28 @@ async def dev_token(
         union_id=payload.device_key,
         register_source="dev",
     )
-    token = create_access_token(
-        user_id=user.user_id,
-        secret=settings.jwt_secret,
-        algorithm=settings.jwt_algorithm,
-        ttl_seconds=settings.jwt_access_ttl_seconds,
-        issuer=settings.jwt_issuer,
-    )
-    return ok(
-        DevTokenResponse(
-            access_token=token,
-            expires_in=settings.jwt_access_ttl_seconds,
-            user_id=str(user.user_id),
-        ).model_dump()
-    )
+    issued = await identity.issue_session(user.user_id)
+    return ok(_token_pair(settings, _access_token(settings, user.user_id), issued))
+
+
+@router.post("/refresh", summary="Rotate a refresh token into a new token pair")
+async def refresh(
+    payload: RefreshRequest,
+    settings: SettingsDep,
+    identity: IdentityServiceDep,
+) -> dict[str, object]:
+    issued = await identity.rotate(payload.refresh_token)
+    return ok(_token_pair(settings, _access_token(settings, issued.user_id), issued))
+
+
+@router.post("/logout", summary="Revoke the session bound to this refresh token")
+async def logout(
+    payload: LogoutRequest,
+    # CurrentUserId 只做鉴权门槛（不带 access 的登出请求一律 40100），
+    # 撤销仍以 refresh_token 定位会话，不信任 token 里的 user_id。
+    user_id: CurrentUserId,
+    identity: IdentityServiceDep,
+) -> dict[str, object]:
+    revoked = await identity.revoke(payload.refresh_token)
+    # 幂等登出：查无此 token 或已撤销都返回 revoked=false，不报错
+    return ok({"revoked": revoked})
diff --git a/packages/identity/repo.py b/packages/identity/repo.py
index 3f322cf..73dcde3 100755
--- a/packages/identity/repo.py
+++ b/packages/identity/repo.py
@@ -2,10 +2,12 @@
 
 from __future__ import annotations
 
+from datetime import UTC, datetime
+
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from packages.shared.models import Consent, User, UserIdentity
+from packages.shared.models import Consent, User, UserIdentity, UserSession
 
 
 async def get_user(session: AsyncSession, user_id: int) -> User | None:
@@ -36,3 +38,57 @@ def add_identity(session: AsyncSession, identity: UserIdentity) -> UserIdentity:
 def add_consent(session: AsyncSession, consent: Consent) -> Consent:
     session.add(consent)
     return consent
+
+
+async def find_session_by_hash(session: AsyncSession, token_hash: str) -> UserSession | None:
+    # UNIQUE(refresh_token_hash) 保证至多一行，scalar_one_or_none 即可
+    result = await session.execute(
+        select(UserSession).where(UserSession.refresh_token_hash == token_hash)
+    )
+    return result.scalar_one_or_none()
+
+
+def add_session(session: AsyncSession, user_session: UserSession) -> UserSession:
+    session.add(user_session)
+    return user_session
+
+
+async def revoke_session(session: AsyncSession, session_id: int) -> bool:
+    """撤销单条会话。返回 False = 该行不存在或已被撤销。
+
+    WHERE 里带 ``revoked = false`` 再 FOR UPDATE（照 billing.repo 的
+    lock_or_create_quota 模式）：两个并发请求拿着同一 refresh 轮换时，
+    后到者等先到者提交后重估条件、匹配 0 行返回 False——调用方据此按
+    「已撤销/重放」处理，无需自己加锁。
+    """
+    result = await session.execute(
+        select(UserSession)
+        .where(UserSession.session_id == session_id, UserSession.revoked.is_(False))
+        .with_for_update()
+    )
+    row = result.scalar_one_or_none()
+    if row is None:
+        return False
+    row.revoked = True
+    row.revoked_at = datetime.now(UTC)
+    return True
+
+
+async def revoke_all_sessions(session: AsyncSession, user_id: int) -> int:
+    """撤销某用户全部会话（logout-all）。返回实际撤销的行数。
+
+    V1 先备着：对应 FR 后续的「退出全部设备」，本批次不接路由，留实现是为了
+    把「会话可撤销」的数据通路一次铺好。
+    """
+    result = await session.execute(
+        select(UserSession)
+        .where(UserSession.user_id == user_id, UserSession.revoked.is_(False))
+        .with_for_update()
+    )
+    now = datetime.now(UTC)
+    revoked_count = 0
+    for row in result.scalars():
+        row.revoked = True
+        row.revoked_at = now
+        revoked_count += 1
+    return revoked_count
diff --git a/packages/identity/schemas.py b/packages/identity/schemas.py
new file mode 100755
index 0000000..725f076
--- /dev/null
+++ b/packages/identity/schemas.py
@@ -0,0 +1,36 @@
+"""identity 域的请求/响应模型（T4：双令牌会话，FR-ACC-05）。
+
+``apps/api/schemas.py`` 是本批次的共享禁改文件，refresh/logout 的契约模型
+放在域内这里，由 ``apps/api/routers/auth.py`` 引用；wire 响应仍只是统一
+信封 (架构文档 §9.2) 里的 ``data`` 部分。
+"""
+
+from __future__ import annotations
+
+from pydantic import BaseModel, Field
+
+#: 生成端 token_urlsafe(48) 恒为 64 字符；上限放宽到 128 容忍未来换编码。
+_REFRESH_TOKEN_MAX_LENGTH = 128
+
+
+class RefreshRequest(BaseModel):
+    refresh_token: str = Field(min_length=1, max_length=_REFRESH_TOKEN_MAX_LENGTH)
+
+
+class LogoutRequest(BaseModel):
+    refresh_token: str = Field(min_length=1, max_length=_REFRESH_TOKEN_MAX_LENGTH)
+
+
+class TokenPairResponse(BaseModel):
+    """dev-token 与 /auth/refresh 共用的双令牌响应。
+
+    旧字段名 ``access_token/token_type/expires_in/user_id`` 保持不变
+    （smoke.sh 与既有测试依赖），新增 ``refresh_token/refresh_expires_in``。
+    """
+
+    access_token: str
+    refresh_token: str
+    token_type: str = "Bearer"
+    expires_in: int = Field(description="access token 有效期（秒）")
+    refresh_expires_in: int = Field(description="refresh token 有效期（秒）")
+    user_id: str = Field(description="雪花 ID 以字符串返回，避免 JS 精度丢失")
diff --git a/packages/identity/service.py b/packages/identity/service.py
index 696f80e..4a283c7 100755
--- a/packages/identity/service.py
+++ b/packages/identity/service.py
@@ -5,25 +5,47 @@ import-linter enforces this (contract "identity must not depend on any other
 business domain").
 
 V1 scope still missing here: 华为账号登录 (FR-ACC-01)、手机号验证码 (FR-ACC-04)、
-双令牌与撤销 (FR-ACC-05)、游客合并 (FR-ACC-03)、注销 (FR-ACC-09)、未成年判定
-(FR-ACC-11). See packages/identity/README.md.
+游客合并 (FR-ACC-03)、注销 (FR-ACC-09)、未成年判定 (FR-ACC-11). See
+packages/identity/README.md. 双令牌与撤销 (FR-ACC-05) 已由 refresh 会话补齐
+(`issue_session`/`rotate`/`revoke`)。
 """
 
 from __future__ import annotations
 
-from datetime import UTC, datetime
+from dataclasses import dataclass
+from datetime import UTC, datetime, timedelta
 
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from packages.domain.ids import next_id
 from packages.identity import repo
+from packages.identity.tokens import generate_refresh_token, hash_refresh_token
+from packages.shared.config import get_settings
 from packages.shared.errors import AppError, ErrorCode
-from packages.shared.models import Consent, User, UserIdentity
+from packages.shared.logging import get_logger
+from packages.shared.models import Consent, User, UserIdentity, UserSession
+
+logger = get_logger(__name__)
 
 #: Provider used by the dev-only token endpoint. Never valid in prod.
 DEV_PROVIDER = "dev"
 
 
+@dataclass(frozen=True, slots=True)
+class SessionIssued:
+    """一次 refresh 签发的结果。
+
+    ``refresh_token`` 明文只在本对象里短暂存在，由调用方直接下发给客户端；
+    服务端只留 ``session_id``（撤销句柄）与 ``expires_at``。``user_id`` 供
+    /auth/refresh 换发 access JWT 使用——refresh 本身不携带任何可解码信息。
+    """
+
+    session_id: int
+    user_id: int
+    refresh_token: str
+    expires_at: datetime
+
+
 class IdentityService:
     def __init__(self, session: AsyncSession) -> None:
         self._session = session
@@ -98,3 +120,81 @@ class IdentityService:
         )
         await self._session.flush()
         return consent
+
+    # --- refresh 会话（FR-ACC-05）-------------------------------------------
+
+    async def issue_session(self, user_id: int) -> SessionIssued:
+        """登录成功后签发新 refresh 会话。
+
+        先 ``get_user``：已注销/被禁用的账号不得再拿新会话（防已注销用户续签）。
+        TTL 在用时读进程级配置而非构造器注入——``apps/api/deps.py``（共享禁改
+        文件）构造本 service 时拿不到 Settings；测试借 ``get_settings.cache_clear()``
+        注入 TTL 即可命中过期分支。
+        """
+        await self.get_user(user_id)
+        return await self._create_session(user_id)
+
+    async def rotate(self, refresh_token: str) -> SessionIssued:
+        """一次性轮换：旧 refresh 用过即死，成功则当场换发新 token。
+
+        旧行撤销与新行创建发生在**同一事务**（调用方 apps/api/deps.session_dep
+        统一 commit）：半途失败两者一起回滚，不会出现「旧 token 已死、新 token
+        未生」把用户锁在门外，也不会出现双活会话。
+        """
+        token_hash = hash_refresh_token(refresh_token)
+        row = await repo.find_session_by_hash(self._session, token_hash)
+        if row is None:
+            raise AppError(ErrorCode.REFRESH_TOKEN_INVALID)
+        if row.revoked:
+            # 重放检测：已撤销的 refresh 又出现了（可能是被盗用的副本，也可能是
+            # 客户端重试）。V1 只告警 + 拒绝；RFC 6819 的完整做法是撤销整个
+            # token 家族（家族连坐），留作 V2 硬化项。
+            logger.warning("refresh_reuse_detected", user_id=row.user_id)
+            raise AppError(ErrorCode.SESSION_REVOKED)
+        now = datetime.now(UTC)
+        if row.expire_at < now:
+            # 过期行顺手标记撤销，别让死会话一直可查。注意：HTTP 路径上这个
+            # 写入会随 401 的统一回滚一起丢失（仅事务内标记），落库与否不影响
+            # 判定本身——过期的行本来也不可能再通过校验。
+            row.revoked = True
+            row.revoked_at = now
+            await self._session.flush()
+            raise AppError(ErrorCode.REFRESH_TOKEN_EXPIRED)
+        await self.get_user(row.user_id)  # 防已注销用户续签
+        if not await repo.revoke_session(self._session, row.session_id):
+            # 并发轮换：另一请求刚撤销了这一行（revoke_session 的 WHERE 守卫
+            # 只放行第一个），后到者按重放处理。
+            raise AppError(ErrorCode.SESSION_REVOKED)
+        return await self._create_session(row.user_id)
+
+    async def revoke(self, refresh_token: str) -> bool:
+        """登出：撤销该 refresh 对应的会话。
+
+        查无此 token 或已撤销都返回 False 而不报错——登出必须幂等，客户端
+        重试不应收到 4xx。
+        """
+        token_hash = hash_refresh_token(refresh_token)
+        row = await repo.find_session_by_hash(self._session, token_hash)
+        if row is None:
+            return False
+        return await repo.revoke_session(self._session, row.session_id)
+
+    async def _create_session(self, user_id: int) -> SessionIssued:
+        token = generate_refresh_token()
+        expires_at = datetime.now(UTC) + timedelta(seconds=get_settings().refresh_token_ttl_seconds)
+        row = repo.add_session(
+            self._session,
+            UserSession(
+                session_id=next_id(),
+                user_id=user_id,
+                refresh_token_hash=hash_refresh_token(token),
+                expire_at=expires_at,
+            ),
+        )
+        await self._session.flush()
+        return SessionIssued(
+            session_id=row.session_id,
+            user_id=user_id,
+            refresh_token=token,
+            expires_at=row.expire_at,
+        )
diff --git a/packages/identity/tokens.py b/packages/identity/tokens.py
new file mode 100755
index 0000000..498d7c7
--- /dev/null
+++ b/packages/identity/tokens.py
@@ -0,0 +1,30 @@
+"""Opaque refresh tokens (FR-ACC-05, 架构文档 §6.2 id_session / §9.1).
+
+为什么是 opaque 随机串而不是 JWT：refresh 的核心价值就是「服务端可单条撤销」
+(FR-ACC-05)，无状态 JWT 天生做不到撤销——除非引入黑名单，而黑名单本身就是把
+状态搬回服务端，那不如直接用查表就能撤销的 opaque 令牌。
+
+库里只存 sha256 哈希而非明文：查库校验时重算一次哈希即可比对，而泄漏数据库
+不等于泄漏令牌——sha256 不可逆，拿到哈希换不出新 access。
+
+本模块是纯函数（无 IO、无配置），方便穷举式单测。
+"""
+
+from __future__ import annotations
+
+import hashlib
+import secrets
+
+#: token_urlsafe(48) 输出 64 个 URL 安全字符，携带 384 bit 熵，
+#: 暴力枚举哈希空间在计算上不可行。
+_TOKEN_BYTES = 48
+
+
+def generate_refresh_token() -> str:
+    """生成新 refresh token。明文只在签发瞬间出现一次，此后系统内只见哈希。"""
+    return secrets.token_urlsafe(_TOKEN_BYTES)
+
+
+def hash_refresh_token(token: str) -> str:
+    """sha256 hex（64 字符，与 id_session.refresh_token_hash 列宽一致）。"""
+    return hashlib.sha256(token.encode()).hexdigest()
diff --git a/tests/integration/test_auth_refresh.py b/tests/integration/test_auth_refresh.py
new file mode 100755
index 0000000..5fbf2c6
--- /dev/null
+++ b/tests/integration/test_auth_refresh.py
@@ -0,0 +1,145 @@
+"""Refresh token 链路（FR-ACC-05）—— 真实 PostgreSQL，auth 用例不涉及 LLM。
+
+与 test_vertical_slice.py 不同：这里不替换 LLM provider（没人会调到它），
+只验证 dev-token → refresh 轮换 → logout 撤销的会话生命周期。
+"""
+
+from __future__ import annotations
+
+import os
+import uuid
+from collections.abc import AsyncIterator
+from typing import Any
+
+import httpx
+import pytest
+
+
+def _infra_available() -> bool:
+    return bool(os.getenv("MEIDA_RUN_INTEGRATION"))
+
+
+pytestmark = [
+    pytest.mark.integration,
+    pytest.mark.skipif(
+        not _infra_available(),
+        reason="set MEIDA_RUN_INTEGRATION=1 with PostgreSQL and Redis running",
+    ),
+]
+
+
+@pytest.fixture
+async def client() -> AsyncIterator[httpx.AsyncClient]:
+    from apps.api.main import create_app
+    from packages.shared.config import get_settings
+
+    app = create_app(get_settings())
+    transport = httpx.ASGITransport(app=app)
+    async with (
+        httpx.AsyncClient(transport=transport, base_url="http://test") as http,
+        app.router.lifespan_context(app),
+    ):
+        yield http
+
+
+async def _dev_token(client: httpx.AsyncClient) -> dict[str, Any]:
+    """每个用例用独立 device_key，避免共享用户状态互相污染。"""
+    resp = await client.post(
+        "/v1/auth/dev-token", json={"device_key": f"t4-{uuid.uuid4().hex[:8]}"}
+    )
+    assert resp.status_code == 200
+    body = resp.json()
+    assert body["code"] == 0
+    data = body["data"]
+    # 兼容性：旧字段名一字不改，新字段在场
+    assert data["access_token"]
+    assert data["expires_in"] > 0
+    assert data["user_id"]
+    assert data["refresh_token"]
+    return data
+
+
+async def test_refresh_rotates_and_new_access_calls_quota(client: httpx.AsyncClient) -> None:
+    pair = await _dev_token(client)
+
+    resp = await client.post("/v1/auth/refresh", json={"refresh_token": pair["refresh_token"]})
+    assert resp.status_code == 200
+    assert resp.json()["code"] == 0
+    data = resp.json()["data"]
+    # 轮换的核心契约是 refresh 换新（随机串必不同）。access JWT 不比不等：
+    # 同一用户同一秒签发时 claims 完全一致，token 字节级相同是正常现象，
+    # 断言不等只会让用例变成秒边界的掷硬币。
+    assert data["refresh_token"] != pair["refresh_token"]
+    assert data["refresh_expires_in"] > 0
+
+    quota = await client.get(
+        "/v1/quota", headers={"Authorization": f"Bearer {data['access_token']}"}
+    )
+    assert quota.status_code == 200
+    assert quota.json()["code"] == 0
+
+
+async def test_old_refresh_is_single_use(client: httpx.AsyncClient) -> None:
+    pair = await _dev_token(client)
+
+    first = await client.post("/v1/auth/refresh", json={"refresh_token": pair["refresh_token"]})
+    assert first.status_code == 200
+
+    second = await client.post("/v1/auth/refresh", json={"refresh_token": pair["refresh_token"]})
+    assert second.status_code == 401
+    assert second.json()["code"] == 40105
+
+
+async def test_logout_revokes_the_session(client: httpx.AsyncClient) -> None:
+    pair = await _dev_token(client)
+    headers = {"Authorization": f"Bearer {pair['access_token']}"}
+
+    out = await client.post(
+        "/v1/auth/logout", json={"refresh_token": pair["refresh_token"]}, headers=headers
+    )
+    assert out.status_code == 200
+    assert out.json()["data"] == {"revoked": True}
+
+    # 幂等登出：同一 token 再登出一次不报错，revoked=false
+    again = await client.post(
+        "/v1/auth/logout", json={"refresh_token": pair["refresh_token"]}, headers=headers
+    )
+    assert again.status_code == 200
+    assert again.json()["data"] == {"revoked": False}
+
+    refreshed = await client.post("/v1/auth/refresh", json={"refresh_token": pair["refresh_token"]})
+    assert refreshed.status_code == 401
+    assert refreshed.json()["code"] == 40105
+
+
+async def test_forged_refresh_token_is_rejected(client: httpx.AsyncClient) -> None:
+    resp = await client.post("/v1/auth/refresh", json={"refresh_token": "forged-" + "x" * 32})
+    assert resp.status_code == 401
+    assert resp.json()["code"] == 40103
+
+
+async def test_expired_refresh_token_reports_40104() -> None:
+    """TTL=0 注入过期路径：签发即过期，refresh 必须走 40104 而非 40103/40105。"""
+    from apps.api.main import create_app
+    from packages.shared.config import get_settings
+
+    with pytest.MonkeyPatch.context() as mp:
+        mp.setenv("REFRESH_TOKEN_TTL_SECONDS", "0")
+        get_settings.cache_clear()
+        app = create_app(get_settings())
+        try:
+            transport = httpx.ASGITransport(app=app)
+            async with (
+                httpx.AsyncClient(transport=transport, base_url="http://test") as http,
+                app.router.lifespan_context(app),
+            ):
+                pair = await _dev_token(http)
+                assert pair["refresh_expires_in"] == 0
+                resp = await http.post(
+                    "/v1/auth/refresh", json={"refresh_token": pair["refresh_token"]}
+                )
+                assert resp.status_code == 401
+                assert resp.json()["code"] == 40104
+        finally:
+            # 恢复进程级配置缓存：打补丁的 Settings 不能泄漏给后续用例
+            get_settings.cache_clear()
diff --git a/tests/unit/test_refresh_tokens.py b/tests/unit/test_refresh_tokens.py
new file mode 100755
index 0000000..f6a131a
--- /dev/null
+++ b/tests/unit/test_refresh_tokens.py
@@ -0,0 +1,58 @@
+"""refresh token 纯函数（packages/identity/tokens.py）。
+
+无 IO、无配置：token 长度/字符域/唯一性、哈希稳定性与不可逆性在这里穷举，
+服务层的轮换/撤销语义由 tests/integration/test_auth_refresh.py 用真实 PG 验证。
+"""
+
+from __future__ import annotations
+
+import string
+
+from packages.identity.tokens import generate_refresh_token, hash_refresh_token
+
+#: token_urlsafe 的字母表：base64url（含 ``-`` ``_``），无 ``+`` ``/`` ``=``
+_URLSAFE_ALPHABET = frozenset(string.ascii_letters + string.digits + "_-")
+
+
+def test_token_has_fixed_length() -> None:
+    # 48 字节 → base64 无填充恒 64 字符；长度恒定才好做列宽与日志脱敏
+    assert len(generate_refresh_token()) == 64
+
+
+def test_token_stays_within_urlsafe_alphabet() -> None:
+    # 必须能原样放进 JSON / URL / Header，不引入需要转义的字符
+    tokens = [generate_refresh_token() for _ in range(50)]
+    assert all(set(token) <= _URLSAFE_ALPHABET for token in tokens)
+
+
+def test_tokens_are_unique() -> None:
+    tokens = [generate_refresh_token() for _ in range(100)]
+    assert len(set(tokens)) == len(tokens)
+
+
+def test_hash_is_stable() -> None:
+    # 校验路径 = 重算一次哈希再比对，稳定性是查库成立的前提
+    token = generate_refresh_token()
+    assert hash_refresh_token(token) == hash_refresh_token(token)
+
+
+def test_hash_is_lowercase_sha256_hex() -> None:
+    digest = hash_refresh_token("abc")
+    # sha256 恒 64 个小写 hex 字符，与 id_session.refresh_token_hash varchar(64) 对齐
+    assert len(digest) == 64
+    assert digest == digest.lower()
+    assert set(digest) <= set(string.digits + "abcdef")
+
+
+def test_hash_is_not_the_plaintext_token() -> None:
+    # 不可逆（≠原文）：库里存的是哈希，泄漏数据库换不回可用令牌
+    token = generate_refresh_token()
+    digest = hash_refresh_token(token)
+    assert digest != token
+    assert token not in digest
+
+
+def test_different_tokens_hash_differently() -> None:
+    assert hash_refresh_token(generate_refresh_token()) != hash_refresh_token(
+        generate_refresh_token()
+    )