diff --git a/AGENTS.md b/AGENTS.md
index b27fdf1..66c97b8 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -4,11 +4,12 @@
 - 默认中文维护项目文档、commit、issue 和 PR；代码与上游 API 名称保留英文。
 - 项目使用 Java 与 Spring；Native 是交付约束，不是可选优化，不引入 Kotlin。
 - 日常变更先通过适用的 JVM 测试，不要求每轮执行耗时的 Native 编译与测试；Native 仍为交付目标，在阶段性验收或兼容性风险变化时集中验证。未执行的验证明确报告。
-- 按 DDD 组织 authentication 上下文：领域拥有 User/UserRepository 与认证事务规则，应用层编排，基础设施实现 AD 仓储，Web 仅处理传输与会话；领域和应用层不依赖 Spring/Servlet/LDAP。
+- 按 DDD 组织 authentication 上下文：领域拥有 User/UserRepository，应用层编排目录认证与读取，基础设施实现 AD 仓储与 Security Provider，Web 仅渲染页面；领域和应用层不依赖 Spring/Servlet/LDAP。
 - 用户仓储复用本次用户 bind 的连接，不新增只读服务账号；连接限于当前用例，不保留密码或连接在 HTTP session 中。
 - 选型演示在真实接入后删除，不将演示入口、状态机、验证码或开关保留为应用功能。
 - 只实现当前任务范围。Hydra 负责签发，首轮 AD 负责身份和组，本服务独立于 Ayatori。
-- 不把 LDAP 密码成功当成完整 MFA 成功；所有因素绑定同一主体与认证事务。
+- React 只替换 Spring Security 默认登录 UI；表单认证、SecurityContext、因素状态、会话轮换与退出交给框架，不自建登录状态机。
+- LDAP 密码成功可以建立仅含密码因素的 SecurityContext，但不等于完整 MFA 或 Hydra 授权；受保护操作必须检查所需因素。
 - 不提交凭据、MFA secret、生产配置秘密或包含上述内容的测试输出。
 - 生产部署配置属于 homelab-infra；本仓库初始化不授权切换现役登录入口。
 - 文档区分计划、实现、Native 实测和人类验收，禁止将代码存在当成部署证据。
diff --git a/README.md b/README.md
index cb074d6..a278a2c 100644
--- a/README.md
+++ b/README.md
@@ -75,27 +75,30 @@ JVM、AOT、Native 测试及原生应用 HTTP 检查已通过，实测范围与
 当前限界上下文为 `authentication`，使用 DDD 分层，依赖向领域内部收敛：
 
 ```text
-interfaces/web → application → domain
+interfaces/web → infrastructure/security（principal）+ domain
+infrastructure/security → application → domain
 infrastructure/ad → application/port + domain
 configuration → 装配上述实现
 ```
 
-- `authentication/domain`：`User`、`UserRepository`、`LoginTransaction`；稳定主体、组成员关系、
-  登录步骤与期限属于领域模型，不依赖 Spring、Servlet、LDAP 或持久化注解。
-- `authentication/application`：登录用例，编排密码认证、用户仓储查询与事务推进；
+- `authentication/domain`：`User`、`UserRepository`；稳定主体与组成员关系属于领域模型，不依赖 Spring、Servlet、LDAP 或持久化注解。
+- `authentication/application`：`VerifyPassword` 用例，编排密码认证与同连接用户仓储查询；
   `port` 描述密码认证及其用户仓储会话，不暴露 `DirContext`。
 - `authentication/infrastructure/ad`：AD bind、Spring Data LDAP 用户仓储、LDAP 实体与领域映射。
   使用同一次用户 bind 的连接，查询结束关闭，不新增服务账号，不保存用户密码。
-- `authentication/interfaces/web`：HTTP、CSRF、会话存取和页面数据转换；不定义认证状态规则。
+- `authentication/infrastructure/security`：Provider 将目录用户转换为仅含密码因素的认证结果。
+- `authentication/interfaces/web`：登录页面与上下文转换；不处理密码 POST、认证会话或退出。
 - `configuration`：Spring 组件装配、安全链、静态资源和 Native hints。
 - `frontend/src`：入口、页面、表单组件和页面数据契约分别维护，只包含真实登录流程。
 
-测试分别覆盖领域规则、应用用例、AD 仓储和 Web 行为，LDAP 夹具集中在测试 `support` 包。
+测试覆盖应用用例、AD 仓储和完整 Spring Security 过滤器链，LDAP 夹具集中在测试 `support` 包。
 界面采用 React + Vite，Spring 在 HTML 中内联当前步骤上下文，浏览器原生表单 POST，
-由服务端决定下一页。不增加前端路由器、模板引擎或 Node 运行服务。
+表单由 Spring Security `formLogin` 处理，框架维护因素、SecurityContext、会话轮换和退出。
+React 只替换默认登录 UI，不增加前端路由器、模板引擎或 Node 运行服务。
 
 ## AD 第一因素接入
 
 真实入口为 `/signin`，默认关闭且要求 HTTPS。密码验证通过后显示 AD 身份与直接所属组，
-停在等待 MFA 状态，不建立完整登录身份或接受 Hydra challenge。
+保存仅含 `FACTOR_PASSWORD` 的认证结果，停在等待 MFA 状态。待 MFA 页要求十分钟内的密码因素；
+其他应用入口暂时全部拒绝，不能凭密码因素接受 Hydra challenge。监控 Basic 认证使用独立无状态安全链。
 配置、组语义、HTTPS 与验收边界见 [AD 接入](docs/ad-login.md)。
diff --git a/docs/ad-login.md b/docs/ad-login.md
index 37771f9..21e1327 100644
--- a/docs/ad-login.md
+++ b/docs/ad-login.md
@@ -4,14 +4,15 @@
 随后由 Spring Data LDAP 仓储复用这条已认证连接查询用户与组。
 不使用额外目录服务账号，不写入 AD，不复制 Authelia 的绑定密码。
 
-领域仓储接口为 `UserRepository`，`User` 与 `LoginTransaction` 为领域模型。应用层以
+领域仓储接口为 `UserRepository`，`User` 为领域模型。`VerifyPassword` 应用用例以
 try-with-resources 管理已认证用户仓储会话；基础设施的 `AdUserRepository` 通过
 `SimpleLdapRepository<AdUserEntry>`、`LdapTemplate`、ODM 实现读取与转换，关闭后不可继续查询。
 `AdUserEntry` 的 LDAP 注解不会进入领域对象。
 
 成功后重定向到 `/signin/mfa`，显示目录账号、objectGUID、邮箱、直接所属组及组 DN。
-**这是密码因素验收页面，MFA 尚未接入，不是完整登录成功。** 不创建 Spring Security
-认证上下文，不调用 Hydra，不替换现役 Go/Authelia/Gitea 登录链路。
+**这是密码因素验收页面，MFA 尚未接入，不是完整登录成功。** Spring Security 保存
+仅含 `FACTOR_PASSWORD` 的认证结果；其余应用请求使用 `denyAll`，不调用 Hydra，
+不替换现役 Go/Authelia/Gitea 登录链路。
 
 ## 目录和组语义
 
@@ -82,13 +83,20 @@ AD 根范围查询可能返回 DomainDnsZones/ForestDnsZones 等分区 referral
 
 ## 状态与操作
 
-原生表单 POST 带 Spring CSRF token；服务端决定下一页。密码成功后轮换 session ID，
-只保存目录身份快照和十分钟期限，不保存密码；重启或“退出并重新验证”清除事务。
-页面禁止缓存，内联 JSON 转义 HTML 结束标记。失败页面不披露目录内部异常。
+React 只渲染登录页面与待 MFA 页面，原生表单 POST 由 Spring Security `formLogin`
+接收。`DirectoryAuthenticationProvider` 调用目录用例并返回不含密码的 principal 和
+带签发时间的 `FACTOR_PASSWORD`；目录组只保留在身份快照中，不映射为本服务权限。
+框架负责 CSRF、成功/失败跳转、SecurityContext 持久化、session ID 轮换以及 POST logout。
+`/signin/restart` 是框架 logout 地址；不再维护 LoginTransaction 或另一份浏览器认证状态。
 
-当前每个 session 只保留一份事务，多标签页会共享状态。两秒提交间隔仅用于同事务的
-重复提交，不是账号/IP 限流；此 PoC 仅供受控 LAN/Tailscale 验收，生产发布前仍需完善
-入口限流、审计、MFA、Hydra 事务和恢复策略。
+待 MFA 页通过框架的 `validDuration` 要求密码因素在十分钟内完成，过期后需要重新认证。
+这不是完整登录会话的过期策略。MFA 与 Hydra 尚未实现，其余应用入口当前拒绝所有访问。
+`/actuator/**` 使用独立无状态 Basic 安全链，人类密码因素不能用于读取监控端点，
+监控账号也不能借 Basic 进入人类登录流程。
+
+移除原来事务内的两秒提交间隔；它不是有效的账号/IP 限流。此 PoC 仍仅供受控
+LAN/Tailscale 验收，生产发布前需完善入口限流、审计、MFA、Hydra challenge 和恢复策略。
+页面禁止缓存，内联 JSON 转义 HTML 结束标记。错误页面只显示统一消息。
 
 基础存活检查使用 `/actuator/health/liveness`。Boot 自动配置的 LDAP 健康项并未连接这里
 按用户 bind 创建的仓储连接，不能把该项当作此认证路径的可用性验证。
@@ -96,18 +104,18 @@ AD 根范围查询可能返回 DomainDnsZones/ForestDnsZones 等分区 referral
 ## 本轮验证边界
 
 隔离测试使用真实 TLS、LDAP bind 和搜索，校验正确/错误密码、未知账号、AD 账号状态
-子码、GUID 字节序、组名、错误 TLS 主机名、CSRF、HTTPS、会话轮换、超时和密码成功后
-仍未完整认证。UnboundID 的 UPN bind 与 AD 子码由测试拦截器模拟，不能替代 Samba AD。
+子码、GUID 字节序、组名、错误 TLS 主机名、CSRF、HTTPS、会话轮换、因素过期和密码成功后
+仍不能访问受保护应用入口。UnboundID 的 UPN bind 与 AD 子码由测试拦截器模拟，不能替代 Samba AD。
 测试证书、私钥与账号全为虚构夹具，不用于实际部署。
 
-2026-09-25：DDD/Spring Data LDAP 版本通过 20 项 JVM 测试和 `bootJar` 构建，
-包含同一次 bind 连接完成仓储查询、用例结束关闭连接、领域规则及监控集成。
-开发 HTTPS 实例已更新为该版本。此前 JVM 使用受信 CA 完成 Samba AD RootDSE 查询。
+2026-09-27：Spring Security 重构通过 18 项 JVM 测试和 `bootJar` 构建，覆盖
+密码因素的保存与有效期、会话轮换、退出、未完成 MFA 的访问限制，以及监控安全链隔离。
+此前 JVM 使用受信 CA 完成 Samba AD RootDSE 查询。
 浏览器已检查登录表单渲染、真实 CSRF 原生 POST 和失败后清空密码；只使用在访问 AD 前
 即拒绝的合成外域用户名，不尝试猜测人类密码。浏览器回归共 1 项通过，包含移动端布局。
 复现：`IAM_AD_URL=https://验收域名:端口 npm --prefix frontend run test:browser -- ad-login.spec.ts`。
 重构前，维护者已在 HTTPS 页面完成真实密码验证，成功到达待 MFA 页面，并反馈目录标识、邮箱与
 六个直接所属组的查询结果。该验收覆盖 Samba AD 第一因素与属性读取，不表示 MFA、
-嵌套组/主组等价性或 Hydra 登录已完成。Spring Data LDAP 重构后的真实人类复验仍待反馈。
+嵌套组/主组等价性或 Hydra 登录已完成。Spring Security 重构后的真实人类复验仍待反馈。
 不在聊天、命令行或日志中传递人类密码。
 新增 AD 路径尚未进行 Native 测试，不能复用旧 UI 原型的 Native 结论。
diff --git a/src/main/java/top/ddupan/iam/login/authentication/application/SignInService.java b/src/main/java/top/ddupan/iam/login/authentication/application/SignInService.java
deleted file mode 100644
index c3985e6..0000000
--- a/src/main/java/top/ddupan/iam/login/authentication/application/SignInService.java
+++ /dev/null
@@ -1,50 +0,0 @@
-package top.ddupan.iam.login.authentication.application;
-
-import java.time.Clock;
-import java.util.UUID;
-import top.ddupan.iam.login.authentication.application.port.PasswordAuthenticator;
-import top.ddupan.iam.login.authentication.domain.UserRepository;
-import top.ddupan.iam.login.authentication.application.port.PasswordVerificationException;
-import top.ddupan.iam.login.authentication.domain.LoginTransaction;
-
-/** Coordinates the first-factor use case. HTTP/session/LDAP details stay in adapters. */
-public final class SignInService {
-    public enum PasswordResult { ACCEPTED, REJECTED, EXPIRED, WRONG_STEP, RETRY_LATER }
-    private final PasswordAuthenticator authenticator;
-    private final Clock clock;
-    private final boolean enabled;
-
-    public SignInService(PasswordAuthenticator authenticator, Clock clock, boolean enabled) {
-        this.authenticator = authenticator;
-        this.clock = clock;
-        this.enabled = enabled;
-    }
-
-    public boolean enabled() { return enabled; }
-    public LoginTransaction start() { return LoginTransaction.start(UUID.randomUUID(), clock.instant()); }
-    public boolean expired(LoginTransaction transaction) { return transaction.expiredAt(clock.instant()); }
-
-    public PasswordResult submitPassword(LoginTransaction transaction, String username, String password) {
-        if (!enabled) throw new IllegalStateException("Human sign-in is disabled");
-        var attempt = transaction.beginPasswordAttempt(clock.instant());
-        if (attempt != LoginTransaction.Attempt.ALLOWED) {
-            return switch (attempt) {
-                case EXPIRED -> PasswordResult.EXPIRED;
-                case WRONG_STEP -> PasswordResult.WRONG_STEP;
-                case RETRY_LATER -> PasswordResult.RETRY_LATER;
-                case ALLOWED -> throw new IllegalStateException("Unexpected attempt result");
-            };
-        }
-        try (var session = authenticator.authenticate(username, password)) {
-            var identity = session.users().findByLoginName(session.loginName());
-            if (identity.isEmpty()) return PasswordResult.REJECTED;
-            // A slow directory response must not revive an expired transaction.
-            var verifiedAt = clock.instant();
-            if (transaction.expiredAt(verifiedAt)) return PasswordResult.EXPIRED;
-            transaction.passwordVerified(identity.orElseThrow(), verifiedAt);
-            return PasswordResult.ACCEPTED;
-        } catch (PasswordVerificationException | UserRepository.AccessFailure ex) {
-            return PasswordResult.REJECTED;
-        }
-    }
-}
diff --git a/src/main/java/top/ddupan/iam/login/authentication/application/VerifyPassword.java b/src/main/java/top/ddupan/iam/login/authentication/application/VerifyPassword.java
new file mode 100644
index 0000000..c4363fa
--- /dev/null
+++ b/src/main/java/top/ddupan/iam/login/authentication/application/VerifyPassword.java
@@ -0,0 +1,22 @@
+package top.ddupan.iam.login.authentication.application;
+
+import top.ddupan.iam.login.authentication.application.port.PasswordAuthenticator;
+import top.ddupan.iam.login.authentication.application.port.PasswordVerificationException;
+import top.ddupan.iam.login.authentication.application.port.PasswordVerificationException.Reason;
+import top.ddupan.iam.login.authentication.domain.User;
+
+/** Resolves the user through the same authenticated directory connection. */
+public final class VerifyPassword {
+    private final PasswordAuthenticator authenticator;
+
+    public VerifyPassword(PasswordAuthenticator authenticator) {
+        this.authenticator = authenticator;
+    }
+
+    public User verify(String username, String password) {
+        try (var session = authenticator.authenticate(username, password)) {
+            return session.users().findByLoginName(session.loginName())
+                .orElseThrow(() -> new PasswordVerificationException(Reason.REJECTED));
+        }
+    }
+}
diff --git a/src/main/java/top/ddupan/iam/login/authentication/domain/LoginTransaction.java b/src/main/java/top/ddupan/iam/login/authentication/domain/LoginTransaction.java
deleted file mode 100644
index 5048b81..0000000
--- a/src/main/java/top/ddupan/iam/login/authentication/domain/LoginTransaction.java
+++ /dev/null
@@ -1,56 +0,0 @@
-package top.ddupan.iam.login.authentication.domain;
-
-import java.time.Duration;
-import java.time.Instant;
-import java.util.Objects;
-import java.util.UUID;
-
-/** Owns first-factor ordering, lifetime and the identity to which further factors must bind. */
-public final class LoginTransaction {
-    private static final Duration LIFETIME = Duration.ofMinutes(10);
-    private static final Duration ATTEMPT_INTERVAL = Duration.ofSeconds(2);
-
-    public enum Step { PASSWORD_REQUIRED, MFA_REQUIRED }
-    public enum Attempt { ALLOWED, EXPIRED, WRONG_STEP, RETRY_LATER }
-
-    private final UUID id;
-    private Step step = Step.PASSWORD_REQUIRED;
-    private Instant expiresAt;
-    private Instant retryAfter = Instant.MIN;
-    private User identity;
-
-    private LoginTransaction(UUID id, Instant now) {
-        this.id = Objects.requireNonNull(id);
-        this.expiresAt = now.plus(LIFETIME);
-    }
-
-    public static LoginTransaction start(UUID id, Instant now) {
-        return new LoginTransaction(id, now);
-    }
-
-    public Attempt beginPasswordAttempt(Instant now) {
-        if (expiredAt(now)) return Attempt.EXPIRED;
-        if (step != Step.PASSWORD_REQUIRED) return Attempt.WRONG_STEP;
-        if (now.isBefore(retryAfter)) return Attempt.RETRY_LATER;
-        retryAfter = now.plus(ATTEMPT_INTERVAL);
-        return Attempt.ALLOWED;
-    }
-
-    public void passwordVerified(User identity, Instant now) {
-        if (expiredAt(now) || step != Step.PASSWORD_REQUIRED) {
-            throw new IllegalStateException("Password verification is not allowed in this transaction state");
-        }
-        this.identity = Objects.requireNonNull(identity);
-        this.step = Step.MFA_REQUIRED;
-        this.expiresAt = now.plus(LIFETIME);
-    }
-
-    public UUID id() { return id; }
-    public Step step() { return step; }
-    public boolean expiredAt(Instant now) { return !now.isBefore(expiresAt); }
-
-    public User identity() {
-        if (identity == null) throw new IllegalStateException("No verified identity yet");
-        return identity;
-    }
-}
diff --git a/src/main/java/top/ddupan/iam/login/authentication/infrastructure/security/DirectoryAuthenticationProvider.java b/src/main/java/top/ddupan/iam/login/authentication/infrastructure/security/DirectoryAuthenticationProvider.java
new file mode 100644
index 0000000..e177365
--- /dev/null
+++ b/src/main/java/top/ddupan/iam/login/authentication/infrastructure/security/DirectoryAuthenticationProvider.java
@@ -0,0 +1,44 @@
+package top.ddupan.iam.login.authentication.infrastructure.security;
+
+import java.util.List;
+import org.springframework.security.authentication.AuthenticationProvider;
+import org.springframework.security.authentication.BadCredentialsException;
+import org.springframework.security.authentication.InternalAuthenticationServiceException;
+import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.security.core.Authentication;
+import org.springframework.security.core.authority.FactorGrantedAuthority;
+import top.ddupan.iam.login.authentication.application.VerifyPassword;
+import top.ddupan.iam.login.authentication.application.port.PasswordVerificationException;
+import top.ddupan.iam.login.authentication.domain.UserRepository;
+
+/** Bridges directory authentication into Spring Security's form-login lifecycle. */
+public final class DirectoryAuthenticationProvider implements AuthenticationProvider {
+    private final VerifyPassword passwords;
+
+    public DirectoryAuthenticationProvider(VerifyPassword passwords) {
+        this.passwords = passwords;
+    }
+
+    @Override
+    public Authentication authenticate(Authentication request) {
+        try {
+            var user = passwords.verify(request.getName(),
+                request.getCredentials() instanceof String password ? password : null);
+            // Directory groups remain profile data, not local application authorities.
+            return UsernamePasswordAuthenticationToken.authenticated(new DirectoryPrincipal(user), null,
+                List.of(FactorGrantedAuthority.fromAuthority(FactorGrantedAuthority.PASSWORD_AUTHORITY)));
+        } catch (PasswordVerificationException ex) {
+            if (ex.reason() == PasswordVerificationException.Reason.UNAVAILABLE) {
+                throw new InternalAuthenticationServiceException("Directory unavailable");
+            }
+            throw new BadCredentialsException("Unable to verify credentials");
+        } catch (UserRepository.AccessFailure ex) {
+            throw new InternalAuthenticationServiceException("Directory unavailable");
+        }
+    }
+
+    @Override
+    public boolean supports(Class<?> authentication) {
+        return UsernamePasswordAuthenticationToken.class.equals(authentication);
+    }
+}
diff --git a/src/main/java/top/ddupan/iam/login/authentication/infrastructure/security/DirectoryPrincipal.java b/src/main/java/top/ddupan/iam/login/authentication/infrastructure/security/DirectoryPrincipal.java
new file mode 100644
index 0000000..01e1ee4
--- /dev/null
+++ b/src/main/java/top/ddupan/iam/login/authentication/infrastructure/security/DirectoryPrincipal.java
@@ -0,0 +1,12 @@
+package top.ddupan.iam.login.authentication.infrastructure.security;
+
+import org.springframework.security.core.AuthenticatedPrincipal;
+import top.ddupan.iam.login.authentication.domain.User;
+
+/** An immutable directory snapshot; never contains credentials or connections. */
+public record DirectoryPrincipal(User user) implements AuthenticatedPrincipal {
+    @Override
+    public String getName() {
+        return user.id().authority() + ":" + user.id().value();
+    }
+}
diff --git a/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/BrowserSignInState.java b/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/BrowserSignInState.java
deleted file mode 100644
index 49ea262..0000000
--- a/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/BrowserSignInState.java
+++ /dev/null
@@ -1,12 +0,0 @@
-package top.ddupan.iam.login.authentication.interfaces.web;
-
-import top.ddupan.iam.login.authentication.domain.LoginTransaction;
-
-/** HTTP-session storage plus presentation feedback. Authentication rules live in the aggregate. */
-final class BrowserSignInState {
-    final LoginTransaction transaction;
-    String username = "";
-    String error = "";
-
-    BrowserSignInState(LoginTransaction transaction) { this.transaction = transaction; }
-}
diff --git a/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/PageRenderer.java b/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/PageRenderer.java
index e738fd6..d057063 100644
--- a/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/PageRenderer.java
+++ b/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/PageRenderer.java
@@ -27,6 +27,6 @@ public class PageRenderer {
             .replace(">", "\\u003e").replace("&", "\\u0026")
             .replace("\u2028", "\\u2028").replace("\u2029", "\\u2029");
         return ResponseEntity.ok().header("Cache-Control", "no-store")
-            .contentType(MediaType.TEXT_HTML).body(shell.replace(SLOT, safe));
+            .contentType(new MediaType(MediaType.TEXT_HTML, StandardCharsets.UTF_8)).body(shell.replace(SLOT, safe));
     }
 }
diff --git a/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/SignInAvailabilityFilter.java b/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/SignInAvailabilityFilter.java
new file mode 100644
index 0000000..9dd8b64
--- /dev/null
+++ b/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/SignInAvailabilityFilter.java
@@ -0,0 +1,35 @@
+package top.ddupan.iam.login.authentication.interfaces.web;
+
+import java.io.IOException;
+import jakarta.servlet.FilterChain;
+import jakarta.servlet.ServletException;
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpServletResponse;
+import org.springframework.web.filter.OncePerRequestFilter;
+
+/** Rejects disabled or plaintext sign-in before any credentials reach authentication. */
+public final class SignInAvailabilityFilter extends OncePerRequestFilter {
+    private final boolean enabled;
+
+    public SignInAvailabilityFilter(boolean enabled) {
+        this.enabled = enabled;
+    }
+
+    @Override
+    protected boolean shouldNotFilter(HttpServletRequest request) {
+        String path = request.getServletPath();
+        if (path.isEmpty()) path = request.getRequestURI().substring(request.getContextPath().length());
+        return !path.equals("/signin") && !path.startsWith("/signin/");
+    }
+
+    @Override
+    protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,
+            FilterChain chain) throws ServletException, IOException {
+        if (!enabled || !request.isSecure()) {
+            response.setHeader("Cache-Control", "no-store");
+            response.setStatus(enabled ? 426 : 404);
+            return;
+        }
+        chain.doFilter(request, response);
+    }
+}
diff --git a/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/SignInController.java b/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/SignInController.java
index 576f7ee..5a8b411 100644
--- a/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/SignInController.java
+++ b/src/main/java/top/ddupan/iam/login/authentication/interfaces/web/SignInController.java
@@ -1,118 +1,44 @@
 package top.ddupan.iam.login.authentication.interfaces.web;
 
-import jakarta.servlet.http.HttpServletRequest;
-import jakarta.servlet.http.HttpSession;
 import java.util.Map;
-import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
+import org.springframework.security.core.annotation.AuthenticationPrincipal;
 import org.springframework.security.web.csrf.CsrfToken;
 import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestParam;
 import org.springframework.web.bind.annotation.RestController;
-import org.springframework.web.server.ResponseStatusException;
-import top.ddupan.iam.login.authentication.application.SignInService;
-import top.ddupan.iam.login.authentication.domain.LoginTransaction.Step;
 import top.ddupan.iam.login.authentication.domain.User.GroupMembership;
+import top.ddupan.iam.login.authentication.infrastructure.security.DirectoryPrincipal;
 
-/** Translates browser requests and use-case outcomes; no directory or authentication policy here. */
+/** Renders Spring Security's login pages; form processing belongs to the security filters. */
 @RestController
 public class SignInController {
-    static final String STATE = SignInController.class.getName() + ".state";
-    private final SignInService signIn;
     private final PageRenderer renderer;
 
-    public SignInController(SignInService signIn, PageRenderer renderer) {
-        this.signIn = signIn;
+    public SignInController(PageRenderer renderer) {
         this.renderer = renderer;
     }
 
     @GetMapping(value = "/signin", produces = MediaType.TEXT_HTML_VALUE)
-    ResponseEntity<String> page(HttpServletRequest request, CsrfToken csrf) {
-        requireAvailable(request);
-        var session = request.getSession();
-        synchronized (session) {
-            var state = state(session);
-            if (state.transaction.step() == Step.MFA_REQUIRED) return redirect("/signin/mfa");
-            return renderer.render(Map.of("step", "password", "name", state.username,
-                "error", state.error, "action", "/signin/password", "csrf", csrf(csrf)));
-        }
-    }
-
-    @PostMapping("/signin/password")
-    ResponseEntity<String> password(HttpServletRequest request,
-            @RequestParam(defaultValue = "") String username,
-            @RequestParam(defaultValue = "") String password) {
-        requireAvailable(request);
-        var session = request.getSession(false);
-        if (session == null) throw new ResponseStatusException(HttpStatus.CONFLICT);
-        synchronized (session) {
-            var state = (BrowserSignInState) session.getAttribute(STATE);
-            if (state == null) return redirect("/signin");
-            state.username = username.length() <= 256 ? username : "";
-            return switch (signIn.submitPassword(state.transaction, username, password)) {
-                case ACCEPTED -> {
-                    request.changeSessionId();
-                    state.error = "";
-                    yield redirect("/signin/mfa");
-                }
-                case REJECTED -> {
-                    state.error = "无法验证账号，请检查凭据与账号状态，或稍后重试。";
-                    yield redirect("/signin");
-                }
-                case EXPIRED, WRONG_STEP -> redirect("/signin");
-                case RETRY_LATER -> throw new ResponseStatusException(HttpStatus.TOO_MANY_REQUESTS);
-            };
-        }
+    ResponseEntity<String> page(@RequestParam(required = false) String error, CsrfToken csrf) {
+        return renderer.render(Map.of("step", "password", "name", "",
+            "error", error == null ? "" : "无法验证账号，请检查凭据与账号状态，或稍后重试。",
+            "action", "/signin/password", "csrf", csrf(csrf)));
     }
 
     @GetMapping(value = "/signin/mfa", produces = MediaType.TEXT_HTML_VALUE)
-    ResponseEntity<String> pending(HttpServletRequest request, CsrfToken csrf) {
-        requireAvailable(request);
-        var session = request.getSession(false);
-        if (session == null) return redirect("/signin");
-        synchronized (session) {
-            var state = state(session);
-            if (state.transaction.step() != Step.MFA_REQUIRED) return redirect("/signin");
-            var user = state.transaction.identity();
-            return renderer.render(Map.of("step", "mfa-pending", "name", user.displayName(),
-                "error", "", "action", "/signin/restart", "csrf", csrf(csrf),
-                "identity", Map.of("username", user.username(), "subjectId", user.id().value(),
-                    "email", user.email(),
-                    "groups", user.memberships().stream().map(GroupMembership::name).toList(),
-                    "groupDns", user.memberships().stream().map(GroupMembership::externalId).toList())));
-        }
-    }
-
-    @PostMapping("/signin/restart")
-    ResponseEntity<String> restart(HttpServletRequest request) {
-        requireAvailable(request);
-        var session = request.getSession(false);
-        if (session != null) session.invalidate();
-        return redirect("/signin");
-    }
-
-    private void requireAvailable(HttpServletRequest request) {
-        if (!signIn.enabled()) throw new ResponseStatusException(HttpStatus.NOT_FOUND);
-        if (!request.isSecure()) throw new ResponseStatusException(HttpStatus.UPGRADE_REQUIRED, "HTTPS required");
-    }
-
-    private BrowserSignInState state(HttpSession session) {
-        var state = (BrowserSignInState) session.getAttribute(STATE);
-        if (state == null || signIn.expired(state.transaction)) {
-            state = new BrowserSignInState(signIn.start());
-            session.setAttribute(STATE, state);
-        }
-        return state;
+    ResponseEntity<String> pending(@AuthenticationPrincipal DirectoryPrincipal principal, CsrfToken csrf) {
+        var user = principal.user();
+        return renderer.render(Map.of("step", "mfa-pending", "name", user.displayName(),
+            "error", "", "action", "/signin/restart", "csrf", csrf(csrf),
+            "identity", Map.of("username", user.username(), "subjectId", user.id().value(),
+                "email", user.email(),
+                "groups", user.memberships().stream().map(GroupMembership::name).toList(),
+                "groupDns", user.memberships().stream().map(GroupMembership::externalId).toList())));
     }
 
     private static Map<String, String> csrf(CsrfToken token) {
         return Map.of("name", token.getParameterName(), "value", token.getToken());
     }
-
-    private static ResponseEntity<String> redirect(String location) {
-        return ResponseEntity.status(HttpStatus.SEE_OTHER).header("Location", location)
-            .header("Cache-Control", "no-store").build();
-    }
 }
diff --git a/src/main/java/top/ddupan/iam/login/configuration/AuthenticationConfiguration.java b/src/main/java/top/ddupan/iam/login/configuration/AuthenticationConfiguration.java
index a4369ad..0c432d2 100644
--- a/src/main/java/top/ddupan/iam/login/configuration/AuthenticationConfiguration.java
+++ b/src/main/java/top/ddupan/iam/login/configuration/AuthenticationConfiguration.java
@@ -1,6 +1,5 @@
 package top.ddupan.iam.login.configuration;
 
-import java.time.Clock;
 import javax.naming.directory.DirContext;
 import javax.naming.ldap.LdapContext;
 import org.springframework.aot.hint.RuntimeHints;
@@ -11,9 +10,8 @@ import org.springframework.ldap.core.DirContextProxy;
 import top.ddupan.iam.login.authentication.infrastructure.ad.AdUserEntry;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
-import top.ddupan.iam.login.authentication.application.SignInService;
+import top.ddupan.iam.login.authentication.application.VerifyPassword;
 import top.ddupan.iam.login.authentication.application.port.PasswordAuthenticator;
-import top.ddupan.iam.login.authentication.infrastructure.ad.AdProperties;
 
 /** Composition root: dependencies point inward, framework wiring stays outside the model. */
 @Configuration(proxyBeanMethods = false)
@@ -21,8 +19,8 @@ import top.ddupan.iam.login.authentication.infrastructure.ad.AdProperties;
 @ImportRuntimeHints(AuthenticationConfiguration.DirectoryHints.class)
 class AuthenticationConfiguration {
     @Bean
-    SignInService signInService(PasswordAuthenticator authenticator, AdProperties properties) {
-        return new SignInService(authenticator, Clock.systemUTC(), properties.enabled());
+    VerifyPassword verifyPassword(PasswordAuthenticator authenticator) {
+        return new VerifyPassword(authenticator);
     }
     static class DirectoryHints implements RuntimeHintsRegistrar {
         @Override
diff --git a/src/main/java/top/ddupan/iam/login/configuration/SecurityConfiguration.java b/src/main/java/top/ddupan/iam/login/configuration/SecurityConfiguration.java
index 7375039..48d4241 100644
--- a/src/main/java/top/ddupan/iam/login/configuration/SecurityConfiguration.java
+++ b/src/main/java/top/ddupan/iam/login/configuration/SecurityConfiguration.java
@@ -1,19 +1,68 @@
 package top.ddupan.iam.login.configuration;
 
+import java.time.Duration;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.annotation.Order;
+import org.springframework.http.HttpStatus;
+import org.springframework.security.authentication.ProviderManager;
+import org.springframework.security.authorization.AuthorizationManagerFactories;
 import org.springframework.security.config.Customizer;
 import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.authorization.EnableMultiFactorAuthentication;
 import org.springframework.security.web.SecurityFilterChain;
+import org.springframework.security.web.access.intercept.RequestAuthorizationContext;
+import org.springframework.security.web.authentication.HttpStatusEntryPoint;
+import org.springframework.security.web.authentication.LoginUrlAuthenticationEntryPoint;
+import org.springframework.security.web.csrf.CsrfFilter;
+import org.springframework.security.web.servlet.util.matcher.PathPatternRequestMatcher;
+import top.ddupan.iam.login.authentication.application.VerifyPassword;
+import top.ddupan.iam.login.authentication.infrastructure.ad.AdProperties;
+import top.ddupan.iam.login.authentication.infrastructure.security.DirectoryAuthenticationProvider;
+import top.ddupan.iam.login.authentication.interfaces.web.SignInAvailabilityFilter;
 
 @Configuration(proxyBeanMethods = false)
+@EnableMultiFactorAuthentication(authorities = {})
 class SecurityConfiguration {
+    // Operational Basic authentication is isolated from human first-factor authentication.
     @Bean
-    SecurityFilterChain security(HttpSecurity http) throws Exception {
-        return http.authorizeHttpRequests(auth -> auth
-                .requestMatchers("/error", "/signin", "/signin/**", "/assets/**", "/actuator/health/**").permitAll()
+    @Order(1)
+    SecurityFilterChain management(HttpSecurity http) throws Exception {
+        return http.securityMatcher("/actuator/**")
+            .authorizeHttpRequests(auth -> auth
+                .requestMatchers("/actuator/health/**").permitAll()
                 .anyRequest().authenticated())
+            .securityContext(context -> context.securityContextRepository(
+                new org.springframework.security.web.context.NullSecurityContextRepository()))
+            .sessionManagement(session -> session.sessionCreationPolicy(
+                org.springframework.security.config.http.SessionCreationPolicy.STATELESS))
             .httpBasic(Customizer.withDefaults())
+            .build();
+    }
+
+    @Bean
+    @Order(2)
+    SecurityFilterChain browser(HttpSecurity http, VerifyPassword passwords, AdProperties ad) throws Exception {
+        var passwordFactor = AuthorizationManagerFactories.<RequestAuthorizationContext>multiFactor()
+            .requireFactor(factor -> factor.passwordAuthority().validDuration(Duration.ofMinutes(10)))
+            .build();
+        return http
+            .authenticationManager(new ProviderManager(new DirectoryAuthenticationProvider(passwords)))
+            .addFilterBefore(new SignInAvailabilityFilter(ad.enabled()), CsrfFilter.class)
+            .authorizeHttpRequests(auth -> auth
+                .requestMatchers("/error", "/signin", "/signin/password", "/assets/**").permitAll()
+                .requestMatchers("/signin/mfa").access(passwordFactor.authenticated())
+                // No complete MFA or Hydra acceptance exists yet. Fail closed until those are implemented.
+                .anyRequest().denyAll())
+            .formLogin(form -> form.loginPage("/signin").loginProcessingUrl("/signin/password")
+                .defaultSuccessUrl("/signin/mfa", true).failureUrl("/signin?error"))
+            .logout(logout -> logout.logoutUrl("/signin/restart").logoutSuccessUrl("/signin"))
+            .exceptionHandling(exceptions -> exceptions
+                .defaultAuthenticationEntryPointFor(new LoginUrlAuthenticationEntryPoint("/signin"),
+                    PathPatternRequestMatcher.withDefaults().matcher("/signin/**"))
+                .defaultAuthenticationEntryPointFor(new HttpStatusEntryPoint(HttpStatus.UNAUTHORIZED),
+                    org.springframework.security.web.util.matcher.AnyRequestMatcher.INSTANCE))
+            .requestCache(cache -> cache.disable())
             .headers(headers -> headers.contentSecurityPolicy(csp -> csp.policyDirectives(
                 "default-src 'self'; script-src 'self'; style-src 'self'; img-src 'self' data:; "
                 + "object-src 'none'; base-uri 'none'; form-action 'self'; frame-ancestors 'none'")))
diff --git a/src/test/java/top/ddupan/iam/login/IamLoginApplicationTests.java b/src/test/java/top/ddupan/iam/login/IamLoginApplicationTests.java
index d97fc0e..fa16d00 100644
--- a/src/test/java/top/ddupan/iam/login/IamLoginApplicationTests.java
+++ b/src/test/java/top/ddupan/iam/login/IamLoginApplicationTests.java
@@ -47,6 +47,9 @@ class IamLoginApplicationTests {
     @Test
     void signInIsDisabledUntilDirectoryIsConfigured() throws Exception {
         mvc.perform(get("/signin").secure(true)).andExpect(status().isNotFound());
+        mvc.perform(org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post("/signin/password")
+            .secure(true).with(org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors.csrf()))
+            .andExpect(status().isNotFound());
     }
 
     @Test
diff --git a/src/test/java/top/ddupan/iam/login/authentication/application/SignInServiceTests.java b/src/test/java/top/ddupan/iam/login/authentication/application/SignInServiceTests.java
deleted file mode 100644
index fe58d75..0000000
--- a/src/test/java/top/ddupan/iam/login/authentication/application/SignInServiceTests.java
+++ /dev/null
@@ -1,107 +0,0 @@
-package top.ddupan.iam.login.authentication.application;
-
-import java.time.Clock;
-import java.time.Instant;
-import java.time.ZoneId;
-import java.time.ZoneOffset;
-import java.util.List;
-import java.util.Optional;
-import java.util.concurrent.atomic.AtomicInteger;
-import org.junit.jupiter.api.Test;
-import top.ddupan.iam.login.authentication.application.port.AuthenticatedUserSession;
-import top.ddupan.iam.login.authentication.application.port.PasswordVerificationException;
-import top.ddupan.iam.login.authentication.domain.LoginTransaction;
-import top.ddupan.iam.login.authentication.domain.User;
-import top.ddupan.iam.login.authentication.domain.UserRepository;
-import static org.assertj.core.api.Assertions.*;
-
-class SignInServiceTests {
-    static final User ALICE = new User(new User.UserId("directory", "alice-id"), "alice", "Alice", "", List.of());
-
-    @Test
-    void verifiesPasswordThenReadsTheBoundUserAndClosesTheRepositoryScope() {
-        var scope = new Scope(name -> {
-            assertThat(name).isEqualTo("alice@directory");
-            return Optional.of(ALICE);
-        });
-        var service = new SignInService((username, password) -> scope, new TestClock(), true);
-        var transaction = service.start();
-        assertThat(service.submitPassword(transaction, "alice", "secret")).isEqualTo(SignInService.PasswordResult.ACCEPTED);
-        assertThat(scope.closed).isTrue();
-        assertThat(transaction.step()).isEqualTo(LoginTransaction.Step.MFA_REQUIRED);
-        assertThat(transaction.identity()).isEqualTo(ALICE);
-    }
-
-    @Test
-    void failedAuthenticationDoesNotAdvanceTheTransaction() {
-        var service = new SignInService((username, password) -> {
-            throw new PasswordVerificationException(PasswordVerificationException.Reason.REJECTED);
-        }, new TestClock(), true);
-        var transaction = service.start();
-        assertThat(service.submitPassword(transaction, "alice", "wrong")).isEqualTo(SignInService.PasswordResult.REJECTED);
-        assertThat(transaction.step()).isEqualTo(LoginTransaction.Step.PASSWORD_REQUIRED);
-    }
-
-    @Test
-    void missingUserDoesNotAuthenticateAndStillClosesTheScope() {
-        var scope = new Scope(name -> Optional.empty());
-        var service = new SignInService((username, password) -> scope, new TestClock(), true);
-        var transaction = service.start();
-        assertThat(service.submitPassword(transaction, "alice", "secret")).isEqualTo(SignInService.PasswordResult.REJECTED);
-        assertThat(scope.closed).isTrue();
-        assertThat(transaction.step()).isEqualTo(LoginTransaction.Step.PASSWORD_REQUIRED);
-    }
-
-    @Test
-    void expiredAndRepeatedAttemptsDoNotCallTheDirectory() {
-        var calls = new AtomicInteger();
-        var clock = new TestClock();
-        var service = new SignInService((username, password) -> {
-            calls.incrementAndGet();
-            throw new PasswordVerificationException(PasswordVerificationException.Reason.REJECTED);
-        }, clock, true);
-        var transaction = service.start();
-        service.submitPassword(transaction, "alice", "wrong");
-        assertThat(service.submitPassword(transaction, "alice", "wrong")).isEqualTo(SignInService.PasswordResult.RETRY_LATER);
-        clock.now = clock.now.plusSeconds(600);
-        assertThat(service.submitPassword(transaction, "alice", "wrong")).isEqualTo(SignInService.PasswordResult.EXPIRED);
-        assertThat(calls.get()).isEqualTo(1);
-    }
-
-    @Test
-    void aSlowRepositoryCannotReviveAnExpiredTransaction() {
-        var clock = new TestClock();
-        var scope = new Scope(name -> { clock.now = clock.now.plusSeconds(600); return Optional.of(ALICE); });
-        var service = new SignInService((username, password) -> scope, clock, true);
-        var transaction = service.start();
-        assertThat(service.submitPassword(transaction, "alice", "secret")).isEqualTo(SignInService.PasswordResult.EXPIRED);
-        assertThat(transaction.step()).isEqualTo(LoginTransaction.Step.PASSWORD_REQUIRED);
-        assertThat(scope.closed).isTrue();
-    }
-
-    @Test
-    void repositoryFailureClosesTheScopeWithoutPromotingIdentity() {
-        var scope = new Scope(name -> { throw new UserRepository.AccessFailure(); });
-        var service = new SignInService((username, password) -> scope, new TestClock(), true);
-        var transaction = service.start();
-        assertThat(service.submitPassword(transaction, "alice", "secret")).isEqualTo(SignInService.PasswordResult.REJECTED);
-        assertThat(transaction.step()).isEqualTo(LoginTransaction.Step.PASSWORD_REQUIRED);
-        assertThat(scope.closed).isTrue();
-    }
-
-    private static final class Scope implements AuthenticatedUserSession {
-        private final UserRepository users;
-        boolean closed;
-        Scope(UserRepository users) { this.users = users; }
-        @Override public String loginName() { return "alice@directory"; }
-        @Override public UserRepository users() { return users; }
-        @Override public void close() { closed = true; }
-    }
-
-    private static final class TestClock extends Clock {
-        Instant now = Instant.parse("2026-01-01T00:00:00Z");
-        @Override public Instant instant() { return now; }
-        @Override public ZoneId getZone() { return ZoneOffset.UTC; }
-        @Override public Clock withZone(ZoneId zone) { return Clock.fixed(now, zone); }
-    }
-}
diff --git a/src/test/java/top/ddupan/iam/login/authentication/application/VerifyPasswordTests.java b/src/test/java/top/ddupan/iam/login/authentication/application/VerifyPasswordTests.java
new file mode 100644
index 0000000..729b91c
--- /dev/null
+++ b/src/test/java/top/ddupan/iam/login/authentication/application/VerifyPasswordTests.java
@@ -0,0 +1,49 @@
+package top.ddupan.iam.login.authentication.application;
+
+import java.util.List;
+import java.util.Optional;
+import org.junit.jupiter.api.Test;
+import top.ddupan.iam.login.authentication.application.port.AuthenticatedUserSession;
+import top.ddupan.iam.login.authentication.application.port.PasswordVerificationException;
+import top.ddupan.iam.login.authentication.domain.User;
+import top.ddupan.iam.login.authentication.domain.UserRepository;
+import static org.assertj.core.api.Assertions.*;
+
+class VerifyPasswordTests {
+    static final User ALICE = new User(new User.UserId("directory", "alice-id"), "alice", "Alice", "", List.of());
+
+    @Test
+    void readsTheBoundUserAndClosesTheConnection() {
+        var scope = new Scope(name -> {
+            assertThat(name).isEqualTo("alice@directory");
+            return Optional.of(ALICE);
+        });
+        assertThat(new VerifyPassword((username, password) -> scope).verify("alice", "secret")).isEqualTo(ALICE);
+        assertThat(scope.closed).isTrue();
+    }
+
+    @Test
+    void missingUserClosesTheConnectionAndRejectsAuthentication() {
+        var scope = new Scope(name -> Optional.empty());
+        assertThatThrownBy(() -> new VerifyPassword((u, p) -> scope).verify("alice", "secret"))
+            .isInstanceOf(PasswordVerificationException.class);
+        assertThat(scope.closed).isTrue();
+    }
+
+    @Test
+    void repositoryFailureStillClosesTheConnection() {
+        var scope = new Scope(name -> { throw new UserRepository.AccessFailure(); });
+        assertThatThrownBy(() -> new VerifyPassword((u, p) -> scope).verify("alice", "secret"))
+            .isInstanceOf(UserRepository.AccessFailure.class);
+        assertThat(scope.closed).isTrue();
+    }
+
+    private static final class Scope implements AuthenticatedUserSession {
+        private final UserRepository users;
+        boolean closed;
+        Scope(UserRepository users) { this.users = users; }
+        @Override public String loginName() { return "alice@directory"; }
+        @Override public UserRepository users() { return users; }
+        @Override public void close() { closed = true; }
+    }
+}
diff --git a/src/test/java/top/ddupan/iam/login/authentication/domain/LoginTransactionTests.java b/src/test/java/top/ddupan/iam/login/authentication/domain/LoginTransactionTests.java
deleted file mode 100644
index 1586e01..0000000
--- a/src/test/java/top/ddupan/iam/login/authentication/domain/LoginTransactionTests.java
+++ /dev/null
@@ -1,44 +0,0 @@
-package top.ddupan.iam.login.authentication.domain;
-
-import java.time.Instant;
-import java.util.List;
-import java.util.UUID;
-import org.junit.jupiter.api.Test;
-import static org.assertj.core.api.Assertions.*;
-
-class LoginTransactionTests {
-    static final Instant NOW = Instant.parse("2026-01-01T00:00:00Z");
-    static final User ALICE = new User(new User.UserId("directory", "alice-id"), "alice", "Alice", "", List.of());
-
-    @Test
-    void passwordVerificationBindsIdentityAndOnlyAdvancesToMfa() {
-        var transaction = LoginTransaction.start(UUID.randomUUID(), NOW);
-        assertThat(transaction.beginPasswordAttempt(NOW)).isEqualTo(LoginTransaction.Attempt.ALLOWED);
-        transaction.passwordVerified(ALICE, NOW);
-        assertThat(transaction.step()).isEqualTo(LoginTransaction.Step.MFA_REQUIRED);
-        assertThat(transaction.identity()).isEqualTo(ALICE);
-        assertThat(transaction.beginPasswordAttempt(NOW.plusSeconds(3))).isEqualTo(LoginTransaction.Attempt.WRONG_STEP);
-        var bob = new User(new User.UserId("directory", "bob-id"), "bob", "Bob", "", List.of());
-        assertThatThrownBy(() -> transaction.passwordVerified(bob, NOW.plusSeconds(3)))
-            .isInstanceOf(IllegalStateException.class);
-        assertThat(transaction.identity()).isEqualTo(ALICE);
-    }
-
-    @Test
-    void expiredTransactionsCannotAcceptAPasswordResult() {
-        var transaction = LoginTransaction.start(UUID.randomUUID(), NOW);
-        assertThat(transaction.beginPasswordAttempt(NOW.plusSeconds(600))).isEqualTo(LoginTransaction.Attempt.EXPIRED);
-        assertThatThrownBy(() -> transaction.passwordVerified(ALICE, NOW.plusSeconds(600)))
-            .isInstanceOf(IllegalStateException.class);
-    }
-
-    @Test
-    void attemptsAreSeparatedWithoutAdvancingAuthentication() {
-        var transaction = LoginTransaction.start(UUID.randomUUID(), NOW);
-        assertThat(transaction.beginPasswordAttempt(NOW)).isEqualTo(LoginTransaction.Attempt.ALLOWED);
-        assertThat(transaction.beginPasswordAttempt(NOW.plusSeconds(1))).isEqualTo(LoginTransaction.Attempt.RETRY_LATER);
-        assertThat(transaction.beginPasswordAttempt(NOW.plusSeconds(2))).isEqualTo(LoginTransaction.Attempt.ALLOWED);
-        assertThat(transaction.step()).isEqualTo(LoginTransaction.Step.PASSWORD_REQUIRED);
-        assertThatThrownBy(transaction::identity).isInstanceOf(IllegalStateException.class);
-    }
-}
diff --git a/src/test/java/top/ddupan/iam/login/authentication/interfaces/web/SignInIntegrationTests.java b/src/test/java/top/ddupan/iam/login/authentication/interfaces/web/SignInIntegrationTests.java
index 1463adf..7798312 100644
--- a/src/test/java/top/ddupan/iam/login/authentication/interfaces/web/SignInIntegrationTests.java
+++ b/src/test/java/top/ddupan/iam/login/authentication/interfaces/web/SignInIntegrationTests.java
@@ -10,6 +10,11 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.webmvc.test.autoconfigure.AutoConfigureMockMvc;
 import org.springframework.http.MediaType;
+import java.time.Instant;
+import java.util.List;
+import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
+import org.springframework.security.core.authority.FactorGrantedAuthority;
+import org.springframework.security.core.context.SecurityContext;
 import org.springframework.mock.web.MockHttpSession;
 import org.springframework.test.context.DynamicPropertyRegistry;
 import org.springframework.test.context.DynamicPropertySource;
@@ -20,8 +25,10 @@ import static org.springframework.test.web.servlet.request.MockMvcRequestBuilder
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
 
 /** Real LDAPS sockets and Spring Data LDAP; AD bind/subcode semantics are simulated. */
-@SpringBootTest(properties = {"iam.ad.enabled=true", "iam.ad.domain=example.test", "iam.ad.base-dn=dc=example,dc=test"})
+@SpringBootTest(properties = {"iam.ad.enabled=true", "iam.ad.domain=example.test", "iam.ad.base-dn=dc=example,dc=test",
+    "management.otlp.metrics.export.enabled=false", "spring.security.user.name=fixture-monitor", "spring.security.user.password=fixture-monitor-password"})
 @AutoConfigureMockMvc
+@org.springframework.boot.micrometer.metrics.test.autoconfigure.AutoConfigureMetrics
 @ImportRuntimeHints(SignInIntegrationTests.FixtureHints.class)
 class SignInIntegrationTests {
     static class FixtureHints implements RuntimeHintsRegistrar {
@@ -67,9 +74,12 @@ class SignInIntegrationTests {
             .andReturn().getResponse().getContentAsString();
         assertThat(html).contains("mfa-pending", "gitea-admins", "\\u003c/script\\u003e")
             .doesNotContain("fixture-password", "</script><script>attack()");
-        assertThat(session.getAttribute("SPRING_SECURITY_CONTEXT")).isNull();
+        var authentication = ((SecurityContext) session.getAttribute("SPRING_SECURITY_CONTEXT")).getAuthentication();
+        assertThat(authentication.isAuthenticated()).isTrue();
+        assertThat(authentication.getCredentials()).isNull();
+        assertThat(authentication.getAuthorities()).extracting("authority").containsExactly("FACTOR_PASSWORD");
         mvc.perform(get("/").secure(true).session(session).accept(MediaType.APPLICATION_JSON))
-            .andExpect(status().isUnauthorized());
+            .andExpect(status().isForbidden());
 
     }
 
@@ -79,12 +89,68 @@ class SignInIntegrationTests {
         mvc.perform(get("/signin").secure(true).session(session));
         mvc.perform(post("/signin/password").secure(true).session(session).with(csrf())
             .param("username", "alice").param("password", "wrong"))
-            .andExpect(redirectedUrl("/signin"));
-        var state = (BrowserSignInState) session.getAttribute(SignInController.STATE);
-        assertThat(state.transaction.step()).isEqualTo(top.ddupan.iam.login.authentication.domain.LoginTransaction.Step.PASSWORD_REQUIRED);
-        assertThat(state.error).isNotBlank().doesNotContain("LDAP", "wrong");
+            .andExpect(redirectedUrl("/signin?error"));
+        assertThat(session.getAttribute("SPRING_SECURITY_CONTEXT")).isNull();
+        mvc.perform(get("/signin").secure(true).param("error", "").session(session))
+            .andExpect(content().string(org.hamcrest.Matchers.containsString("无法验证账号")));
         mvc.perform(post("/signin/restart").secure(true).session(session).with(csrf()))
             .andExpect(redirectedUrl("/signin"));
         assertThat(session.isInvalid()).isTrue();
     }
+    @Test
+    void plaintextPasswordPostCannotReachDirectory() throws Exception {
+        int before = Directory.INSTANCE.binds.get();
+        mvc.perform(post("/signin/password").with(csrf()).param("username", "alice")
+            .param("password", "fixture-password")).andExpect(status().isUpgradeRequired());
+        assertThat(Directory.INSTANCE.binds.get()).isEqualTo(before);
+    }
+
+    @Test
+    void expiredPasswordFactorCannotOpenPendingPage() throws Exception {
+        var session = login();
+        var context = (SecurityContext) session.getAttribute("SPRING_SECURITY_CONTEXT");
+        var previous = context.getAuthentication();
+        context.setAuthentication(UsernamePasswordAuthenticationToken.authenticated(previous.getPrincipal(), null,
+            List.of(FactorGrantedAuthority.withAuthority(FactorGrantedAuthority.PASSWORD_AUTHORITY)
+                .issuedAt(Instant.now().minusSeconds(601)).build())));
+        mvc.perform(get("/signin/mfa").secure(true).session(session))
+            .andExpect(status().is3xxRedirection());
+    }
+
+    @Test
+    void directorySessionCannotScrapeManagementAndLogoutClearsAuthentication() throws Exception {
+        var session = login();
+        mvc.perform(get("/actuator/prometheus").secure(true).session(session))
+            .andExpect(status().isUnauthorized());
+        mvc.perform(post("/signin/restart").session(session).with(csrf()))
+            .andExpect(status().isUpgradeRequired());
+        assertThat(session.isInvalid()).isFalse();
+        mvc.perform(post("/signin/restart").secure(true).session(session))
+            .andExpect(status().isForbidden());
+        mvc.perform(post("/signin/restart").secure(true).session(session).with(csrf()))
+            .andExpect(redirectedUrl("/signin"));
+        assertThat(session.isInvalid()).isTrue();
+        mvc.perform(get("/signin/mfa").secure(true)).andExpect(status().is3xxRedirection());
+    }
+
+    @Test
+    void managementBasicCredentialsCannotAuthenticateBrowserLogin() throws Exception {
+        mvc.perform(get("/actuator/prometheus").secure(true).with(
+            org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors
+                .httpBasic("fixture-monitor", "fixture-monitor-password")))
+            .andExpect(status().isOk());
+        mvc.perform(get("/signin/mfa").secure(true).with(
+            org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors
+                .httpBasic("fixture-monitor", "fixture-monitor-password")))
+            .andExpect(status().is3xxRedirection());
+    }
+
+    private MockHttpSession login() throws Exception {
+        var session = new MockHttpSession();
+        mvc.perform(post("/signin/password").secure(true).session(session).with(csrf())
+            .param("username", "alice").param("password", "fixture-password"))
+            .andExpect(redirectedUrl("/signin/mfa"));
+        return session;
+    }
+
 }