diff --git a/AGENTS.md b/AGENTS.md
index 5920986..f6f28fb 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -59,14 +59,20 @@ docker-compose up -d                   # AgentKit + Redis + PostgreSQL
 ### Request Flow
 
 ```
-User Input -> CostAwareRouter (3-layer)
-  Layer 0: RegexRules (~0ms, 0 tokens) -> DIRECT_CHAT
-  Layer 1: HeuristicClassifier (~0ms) / LLM quick_classify (~500ms, ~100 tokens)
-  Layer 1.5: SemanticRouter (vector similarity, optional)
-  Layer 2: Capability matching / Vickrey Auction
-  -> ExecutionMode: DIRECT_CHAT / REACT / SKILL_REACT / TEAM_COLLAB
+User Input
+  ├─ @board prefix -> BoardRouter (experts/board_router.py) -> BoardOrchestrator (multi-round discussion)
+  ├─ @team prefix  -> ExpertTeamRouter (experts/router.py) -> TeamOrchestrator (pipeline collaboration)
+  └─ otherwise     -> RequestPreprocessor (chat/request_preprocessor.py)
+       Layer 0: @skill:xxx prefix -> explicit skill selection (SKILL_REACT or skill's configured mode)
+       Layer 1: Trivial-input regex (~0ms, 0 tokens) -> DIRECT_CHAT
+                (greetings, identity, factual Q&A, math, translation; guarded by _TOOL_CONTEXT_RE)
+       Default: -> REACT (LLM decides tool usage autonomously in the agent loop)
+  -> ExecutionMode: DIRECT_CHAT / REACT / SKILL_REACT / REWOO / REFLEXION / PLAN_EXEC / TEAM_COLLAB
+     (chat handler currently supports DIRECT_CHAT, REACT, SKILL_REACT; others raise "not yet supported")
 ```
 
+**Note**: The old 3-layer `CostAwareRouter` (with `RegexRules` / `HeuristicClassifier` / `SemanticRouter` / `Vickrey Auction`) has been replaced by `RequestPreprocessor`. The `IntentRouter` (`router/intent.py`) exists but is not wired into the chat flow. `AuctionHouse` with Vickrey auction lives in `marketplace/auction.py` (marketplace subsystem, not routing).
+
 ### Agent Hierarchy
 
 ```
diff --git a/docs/plans/2026-06-21-001-fix-p0-security-and-quality-optimization-plan.md b/docs/plans/2026-06-21-001-fix-p0-security-and-quality-optimization-plan.md
new file mode 100644
index 0000000..3f26da9
--- /dev/null
+++ b/docs/plans/2026-06-21-001-fix-p0-security-and-quality-optimization-plan.md
@@ -0,0 +1,240 @@
+---
+title: "fix: P0 安全修复与代码质量优化"
+status: active
+date: 2026-06-21
+type: fix
+origin: ocr 代码审查 + 全面项目质量评估报告
+---
+
+# P0 安全修复与代码质量优化计划
+
+## Summary
+
+基于 open-code-review 对 auth 功能分支的审查（9 文件 15 评论）和全面项目质量评估，本计划修复 4 个 P0 级安全/Bug 问题、1 个文档不一致问题、1 个核心 UX 缺失，并补强集成测试覆盖。所有修复均有明确的代码证据和 ocr 审查评论支撑。
+
+## Problem Frame
+
+ocr 审查发现 whoami 冷启动路径存在 2 个安全漏洞（被禁用用户绕过 + 令牌放大风险），1 个数据不一致 Bug（list_active_by_provider 未过滤过期会话），1 个测试崩溃 Bug（asyncio.run 在事件循环内）。此外，CLAUDE.md/AGENTS.md 中路由系统描述与实际实现严重不匹配，前端缺少基础的"停止生成"功能。
+
+## Requirements
+
+- R1: whoami 冷启动必须检查 `is_active`，被禁用用户不能获取新 access token
+- R2: whoami 冷启动必须实现 refresh token 轮换，防止令牌放大攻击
+- R3: `list_active_by_provider` 必须过滤过期会话，与 docstring 承诺一致
+- R4: 集成测试中 `asyncio.run()` 必须修复，跨用户撤销测试必须可运行
+- R5: CLAUDE.md/AGENTS.md 路由系统描述必须与 RequestPreprocessor 实际实现匹配
+- R6: 前端聊天界面必须支持"停止生成"功能，用户可中途取消 LLM 输出
+- R7: 集成测试必须补齐 ocr 指出的覆盖缺口（404 边界、密码修改端到端、会话撤销验证）
+
+## Key Technical Decisions
+
+### KTD-1: whoami 冷启动 refresh token 处理策略
+
+**决策**: 采用方案 B — 仅签发短期 access token，不创建新 refresh token。
+
+**理由**: 客户端已有有效 refresh token，冷启动只需 access token 即可恢复会话。调用 `svc.rotate()` 会增加复杂度且改变客户端持有的 refresh token，而方案 B 更简单、安全（原 refresh token 仍受重用检测保护）。不调用 `create_token_pair`，改为单独签发 access token。
+
+### KTD-2: 停止生成的实现方式
+
+**决策**: 前端通过 WebSocket 发送 `cancel` 消息（协议已定义），后端通过 CancellationToken 取消正在执行的 Agent 任务。
+
+**理由**: WebSocket 协议中已有 `cancel` 消息类型（见 AGENTS.md），后端 BaseAgent 已实现 CancellationToken 协作式取消。只需前端添加按钮和发送逻辑，无需新增后端端点。
+
+## Scope Boundaries
+
+### In Scope
+
+- whoami 冷启动安全修复（is_active + token 策略）
+- list_active_by_provider 过滤修复
+- asyncio.run 测试修复 + 集成测试补强
+- CLAUDE.md/AGENTS.md 路由文档更新
+- 前端"停止生成"按钮
+
+### Deferred to Follow-Up Work
+
+- 多模态输入支持（C1，需独立计划）
+- 用户反馈机制 thumbs up/down（C3，需独立计划）
+- Prompt Caching（C9，需 LLM Gateway 改造）
+- 多租户隔离逻辑（C7，需独立计划）
+- `: Any` 类型清理（213 处，大规模重构）
+- 吞异常清理（109 处，需逐文件审查）
+- LLM 模块测试覆盖（0.06 比率，需独立计划）
+
+---
+
+## Implementation Units
+
+### U1. 修复 whoami 冷启动安全漏洞
+
+**Goal**: 修复 whoami 冷启动路径的 2 个安全漏洞：缺失 is_active 检查 + 令牌放大风险。
+
+**Requirements**: R1, R2
+
+**Dependencies**: 无
+
+**Files**:
+- Modify: `src/agentkit/server/routes/auth.py`（whoami 路由）
+- Modify: `src/agentkit/server/auth/jwt_utils.py`（如需新增单独签发 access token 的函数）
+- Test: `tests/integration/auth/test_auth_routes.py`
+
+**Approach**:
+1. 在 whoami 路由中，将 `if row is None` 改为 `if row is None or not bool(row["is_active"])`，返回 401
+2. 移除冷启动路径中的 `create_token_pair` 调用，改为仅签发 access token（使用 jwt_utils 中现有的 access token 创建逻辑）
+3. 不创建新 refresh token，不调用 `svc.rotate()`，客户端保留原 refresh token
+
+**Patterns to follow**: `/auth/refresh` 路由中的 `is_active` 检查模式（auth.py 第 514 行）
+
+**Test scenarios**:
+- **Happy path**: 被禁用用户（is_active=0）用 refresh token 调用 whoami → 401
+- **Happy path**: 活跃用户用 refresh token 调用 whoami → 200 + 新 access token + 无新 refresh token
+- **Edge case**: 活跃用户用 access token 调用 whoami → 200 + access_token 为 None（行为不变）
+- **Error path**: 不存在的用户 ID（token 被篡改）→ 401
+
+**Verification**: `pytest tests/integration/auth/test_auth_routes.py::TestWhoamiColdStart -v` 全部通过
+
+---
+
+### U2. 修复 list_active_by_provider 过滤过期会话
+
+**Goal**: 使 SQL 查询与 docstring 承诺一致，过滤掉已过期的会话。
+
+**Requirements**: R3
+
+**Dependencies**: 无
+
+**Files**:
+- Modify: `src/agentkit/server/auth/session_service.py`（list_active_by_provider 方法）
+- Test: `tests/unit/auth/test_session_service.py`
+
+**Approach**:
+1. 在 SQL 查询中添加 `AND expires_at > ?` 条件
+2. 传入当前 UTC 时间的 ISO 格式字符串作为参数
+3. 需要在方法顶部导入 `datetime, timezone`（如未导入）
+
+**Patterns to follow**: `list_all` 方法中的 SQL 构造模式
+
+**Test scenarios**:
+- **Happy path**: 有 1 个活跃会话 + 1 个过期会话 → 仅返回活跃会话
+- **Happy path**: 所有会话均过期 → 返回空列表
+- **Edge case**: 无会话 → 返回空列表
+- **Edge case**: 会话 expires_at 恰好等于当前时间 → 不返回（边界 > 而非 >=）
+
+**Verification**: `pytest tests/unit/auth/test_session_service.py -k list_active_by_provider -v` 通过
+
+---
+
+### U3. 修复 asyncio.run 测试崩溃 + 补强集成测试
+
+**Goal**: 修复 test_revoke_other_user_session_returns_404 中的 asyncio.run 崩溃，并补齐 ocr 指出的 6 个测试覆盖缺口。
+
+**Requirements**: R4, R7
+
+**Dependencies**: U1
+
+**Files**:
+- Modify: `tests/integration/auth/test_auth_routes.py`
+- Modify: `tests/integration/auth/test_admin_routes.py`
+
+**Approach**:
+1. 将 `_login_sync_create_user` 改为 `async def`，调用方 `test_revoke_other_user_session_returns_404` 也改为 `async def`
+2. 移除未使用的 `auth_db_with_admin` fixture
+3. 补充测试：
+   - `test_non_admin_cannot_list_all_sessions`（admin 路由 403 测试）
+   - `test_revoke_session_belonging_to_different_user_returns_404`（admin 撤销不匹配用户会话）
+   - `test_admin_list_sessions_for_nonexistent_user_returns_404`
+   - `test_admin_revoke_nonexistent_session_returns_404`
+   - 密码修改测试：验证当前会话存活 + 用新密码登录
+   - 会话撤销测试：撤销后用原 token 调用 whoami → 401
+   - 全局会话列表：验证两个用户都会出现
+
+**Patterns to follow**: 现有 `test_admin_routes.py` 中的测试模式
+
+**Test scenarios**:
+- **Happy path**: asyncio 修复后 test_revoke_other_user_session_returns_404 正常运行
+- **Happy path**: 所有新增测试通过
+- **Error path**: 非管理员访问 /admin/sessions → 403
+- **Error path**: admin 撤销不存在会话 → 404
+- **Integration**: 密码修改 → 旧密码登录失败 → 新密码登录成功
+
+**Verification**: `pytest tests/integration/auth/ -v` 全部通过，无崩溃
+
+---
+
+### U4. 更新路由系统文档
+
+**Goal**: 使 CLAUDE.md 和 AGENTS.md 中的路由系统描述与实际 RequestPreprocessor 实现匹配。
+
+**Requirements**: R5
+
+**Dependencies**: 无
+
+**Files**:
+- Modify: `CLAUDE.md`（Request Flow 部分）
+- Modify: `AGENTS.md`（Request Flow 部分）
+
+**Approach**:
+1. 将 Request Flow 部分从 "CostAwareRouter (3-layer)" 改为 "RequestPreprocessor (2-layer)"
+2. 更新层级描述：
+   - Layer 0: `@skill:xxx` 前缀 → 显式技能选择
+   - Layer 1: 正则快速路径（问候/闲聊/身份/知识/算术/翻译）→ DIRECT_CHAT
+   - Layer 2: 其他全部 → REACT（LLM 在 agent loop 中自主决策）
+3. 移除对 HeuristicClassifier、SemanticRouter、Capability matching、Vickrey Auction 的描述
+4. 添加设计决策说明（引用 request_preprocessor.py docstring 中的 rationale）
+5. 更新 ExecutionMode 描述（移除 TEAM_COLLAB 从路由层触发，改为 @team 前缀触发）
+
+**Patterns to follow**: `src/agentkit/chat/request_preprocessor.py` 的 docstring
+
+**Test scenarios**:
+- **Test expectation**: none — 纯文档变更，无行为变化
+
+**Verification**: 文档中不再出现 "CostAwareRouter"、"HeuristicClassifier"、"SemanticRouter"（作为当前架构描述），grep 确认
+
+---
+
+### U5. 前端添加"停止生成"按钮
+
+**Goal**: 用户可在 LLM 长输出时中途取消生成。
+
+**Requirements**: R6
+
+**Dependencies**: 无
+
+**Files**:
+- Modify: `src/agentkit/server/frontend/src/components/chat/ChatInput.vue`（添加停止按钮）
+- Modify: `src/agentkit/server/frontend/src/stores/chat.ts`（添加 cancel 状态和发送逻辑）
+- Test: `src/agentkit/server/frontend/src/components/chat/__tests__/ChatInput.test.ts`（如存在）
+
+**Approach**:
+1. 在 chat store 中添加 `isGenerating` 状态（true 时显示停止按钮，false 时显示发送按钮）
+2. 添加 `cancelGeneration()` action，通过 WebSocket 发送 `cancel` 消息
+3. 在 ChatInput 组件中，根据 `isGenerating` 切换按钮：发送按钮 ↔ 停止按钮
+4. 停止按钮点击时调用 `cancelGeneration()`
+5. 收到 `final_answer` 或 `error` 事件时，自动将 `isGenerating` 置为 false
+
+**Patterns to follow**: 现有 ChatInput.vue 中发送按钮的实现模式
+
+**Test scenarios**:
+- **Happy path**: 空闲状态显示发送按钮，生成中显示停止按钮
+- **Happy path**: 点击停止按钮 → 发送 cancel 消息 → isGenerating 变为 false
+- **Edge case**: 生成中输入框禁用或允许继续输入（取决于现有 UX 模式）
+- **Integration**: 收到 final_answer 后 isGenerating 自动重置
+
+**Verification**: `npm run typecheck` 通过，手动验证按钮切换和取消功能
+
+---
+
+## Risks & Dependencies
+
+| 风险 | 影响 | 缓解措施 |
+|------|------|----------|
+| U1 修改 whoami 可能影响现有冷启动流程 | 中 | 集成测试覆盖所有 whoami 场景 |
+| U5 修改 chat store 可能影响 WebSocket 状态机 | 中 | 仅添加状态，不修改现有流转 |
+| U4 文档更新可能遗漏其他引用 CostAwareRouter 的位置 | 低 | grep 全仓库搜索 CostAwareRouter |
+
+## System-Wide Impact
+
+- **U1**: 影响 whoami 端点行为，前端 auth store 的冷启动流程需验证兼容性
+- **U2**: 影响 admin 会话查询结果，数据更准确
+- **U3**: 仅测试代码，无生产影响
+- **U4**: 仅文档，无代码影响
+- **U5**: 影响聊天 UI 交互，需验证 WebSocket cancel 消息处理
diff --git a/src/agentkit/server/auth/jwt_utils.py b/src/agentkit/server/auth/jwt_utils.py
index 35d16e9..77244da 100644
--- a/src/agentkit/server/auth/jwt_utils.py
+++ b/src/agentkit/server/auth/jwt_utils.py
@@ -203,6 +203,59 @@ def create_token_pair(
     )
 
 
+def create_access_token(
+    user_id: str,
+    username: str,
+    role: str,
+    secret: str,
+    *,
+    session_id: str | None = None,
+    now: datetime | None = None,
+) -> str:
+    """Create a single signed access JWT (no refresh token).
+
+    Used by ``/auth/whoami`` cold-start to issue a fresh access token
+    without creating a new refresh token (the client already has one).
+    This avoids the token-amplification risk of ``create_token_pair``
+    which would silently discard the new refresh token.
+
+    Args:
+        user_id: Subject (user id) — stored as ``sub``.
+        username: Username claim.
+        role: Role claim.
+        secret: HS256 signing secret.
+        session_id: Server-side session id. When provided, the token
+            carries ``sid`` and ``jti`` claims.
+        now: Override the issued-at time (for testing).
+
+    Returns:
+        The signed access token string.
+    """
+    if not secret:
+        raise ValueError("JWT secret must not be empty")
+
+    issued_at = now or datetime.now(timezone.utc)
+    access_exp = issued_at + ACCESS_TOKEN_TTL
+    jti = str(uuid.uuid4()) if session_id else None
+
+    access_payload: dict[str, Any] = {
+        "sub": user_id,
+        "username": username,
+        "role": role,
+        "type": "access",
+        "iat": int(issued_at.timestamp()),
+        "exp": int(access_exp.timestamp()),
+    }
+    if session_id:
+        access_payload["sid"] = session_id
+        access_payload["jti"] = jti
+
+    access_token = jwt.encode(access_payload, secret, algorithm=JWT_ALGORITHM)
+    if isinstance(access_token, bytes):
+        access_token = access_token.decode("utf-8")
+    return access_token
+
+
 def verify_token(
     token: str,
     secret: str,
diff --git a/src/agentkit/server/auth/session_service.py b/src/agentkit/server/auth/session_service.py
index 75f640f..1ea2dd9 100644
--- a/src/agentkit/server/auth/session_service.py
+++ b/src/agentkit/server/auth/session_service.py
@@ -209,14 +209,15 @@ class SessionService:
         Supports the future "show me all OIDC sessions" admin view.
         Only non-revoked, non-expired sessions are returned.
         """
+        now_iso = datetime.now(timezone.utc).isoformat()
         sql = (
             "SELECT * FROM auth_sessions "
-            "WHERE auth_provider = ? AND revoked = 0 "
+            "WHERE auth_provider = ? AND revoked = 0 AND expires_at > ? "
             "ORDER BY created_at DESC"
         )
         async with aiosqlite.connect(str(self._db_path)) as db:
             db.row_factory = aiosqlite.Row
-            cursor = await db.execute(sql, (auth_provider,))
+            cursor = await db.execute(sql, (auth_provider, now_iso))
             rows = await cursor.fetchall()
         return [_row_to_info(r) for r in rows]
 
diff --git a/src/agentkit/server/frontend/src/components/chat/ChatInput.vue b/src/agentkit/server/frontend/src/components/chat/ChatInput.vue
index ffb7fda..884c9c3 100644
--- a/src/agentkit/server/frontend/src/components/chat/ChatInput.vue
+++ b/src/agentkit/server/frontend/src/components/chat/ChatInput.vue
@@ -40,6 +40,7 @@
         class="chat-input__textarea"
       />
       <a-button
+        v-if="!isGenerating"
         type="primary"
         :disabled="!canSend"
         :loading="disabled"
@@ -48,6 +49,14 @@
       >
         <template #icon><SendOutlined /></template>
       </a-button>
+      <a-button
+        v-else
+        danger
+        @click="handleStop"
+        class="chat-input__stop"
+      >
+        <template #icon><PoweroffOutlined /></template>
+      </a-button>
     </div>
     <div class="chat-input__footer">
       <div class="chat-input__footer-left">
@@ -120,7 +129,7 @@
 <script setup lang="ts">
 import { ref, computed, onMounted, onUnmounted, type Component } from 'vue'
 import { Input as AInput, Button as AButton, Select as ASelect } from 'ant-design-vue'
-import { SendOutlined, TeamOutlined, UsergroupAddOutlined, PaperClipOutlined } from '@ant-design/icons-vue'
+import { SendOutlined, TeamOutlined, UsergroupAddOutlined, PaperClipOutlined, PoweroffOutlined } from '@ant-design/icons-vue'
 import ContextPill from './ContextPill.vue'
 import MentionDropdown from './MentionDropdown.vue'
 import BoardMeetingModal from './BoardMeetingModal.vue'
@@ -155,16 +164,19 @@ interface ModelInfo {
 
 interface IProps {
   disabled?: boolean
+  isGenerating?: boolean
   placeholder?: string
 }
 
 const props = withDefaults(defineProps<IProps>(), {
   disabled: false,
+  isGenerating: false,
   placeholder: '输入消息，按 Enter 发送...',
 })
 
 const emit = defineEmits<{
   send: [message: string, model?: string]
+  stop: []
 }>()
 
 const inputText = ref('')
@@ -290,6 +302,10 @@ function handleSend(): void {
   setTimeout(() => { inputText.value = '' }, 0)
 }
 
+function handleStop(): void {
+  emit('stop')
+}
+
 function handleBoardSubmit(command: string): void {
   // The BoardMeetingModal constructs an @board:expert1,expert2 topic command.
   // Send it through the normal chat pipeline — the backend intercepts @board prefix.
@@ -480,6 +496,21 @@ function removePill(idx: number): void {
   border-color: var(--text-primary) !important;
 }
 
+.chat-input__stop {
+  flex-shrink: 0;
+  width: 28px;
+  height: 28px;
+  border-radius: var(--radius-md) !important;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  padding: 0 !important;
+}
+
+.chat-input__stop:hover {
+  opacity: 0.85;
+}
+
 .chat-input__footer {
   display: flex;
   align-items: center;
diff --git a/src/agentkit/server/frontend/src/stores/chat.ts b/src/agentkit/server/frontend/src/stores/chat.ts
index 1a06582..15db83e 100644
--- a/src/agentkit/server/frontend/src/stores/chat.ts
+++ b/src/agentkit/server/frontend/src/stores/chat.ts
@@ -343,6 +343,31 @@ export const useChatStore = defineStore('chat', () => {
     }
   }
 
+  /** Stop the in-flight generation by sending a `cancel` WS message.
+   *
+   * The backend (`/api/v1/portal/ws`) handles `{"type":"cancel"}` by
+   * cancelling the active asyncio task and replying with a `result`
+   * event whose `data.status === "cancelled"`. That `result` event
+   * clears `isLoading` via the normal handler — so this function only
+   * needs to send the cancel message and guard against send failures.
+   */
+  function stopGeneration(): void {
+    if (!ws.value || ws.value.readyState !== WebSocket.OPEN) {
+      // No open socket — just reset the loading flag locally.
+      isLoading.value = false
+      streamingSteps.value = []
+      return
+    }
+    try {
+      const cancelMsg: WsClientMessage = { type: 'cancel' }
+      ws.value.send(JSON.stringify(cancelMsg))
+    } catch (error) {
+      console.error('Failed to send cancel message:', error)
+      isLoading.value = false
+      streamingSteps.value = []
+    }
+  }
+
   /** After WebSocket reconnects, check for running tasks and resume them */
   async function _recoverTaskAfterReconnect(): Promise<void> {
     if (!currentConversationId.value) return
@@ -918,6 +943,7 @@ export const useChatStore = defineStore('chat', () => {
     sendMessage,
     sendWsMessage,
     resendLastUserMessage,
+    stopGeneration,
     connectWebSocket,
     disconnectWebSocket,
   }
diff --git a/src/agentkit/server/frontend/src/views/ChatView.vue b/src/agentkit/server/frontend/src/views/ChatView.vue
index db35e35..de2d205 100644
--- a/src/agentkit/server/frontend/src/views/ChatView.vue
+++ b/src/agentkit/server/frontend/src/views/ChatView.vue
@@ -57,7 +57,9 @@
           <div class="chat-view__input-inner">
             <ChatInput
               :disabled="chatStore.isLoading"
+              :is-generating="chatStore.isLoading"
               @send="handleSend"
+              @stop="chatStore.stopGeneration"
             />
           </div>
         </div>
diff --git a/src/agentkit/server/routes/auth.py b/src/agentkit/server/routes/auth.py
index 8b49e46..d569478 100644
--- a/src/agentkit/server/routes/auth.py
+++ b/src/agentkit/server/routes/auth.py
@@ -36,6 +36,7 @@ from agentkit.server.auth.jwt_utils import (
     ACCESS_TOKEN_TTL,
     REFRESH_TOKEN_TTL,
     REFRESH_TOKEN_TTL_REMEMBER_ME,
+    create_access_token,
     create_token_pair,
     get_or_create_jwt_secret,
     verify_token,
@@ -574,8 +575,8 @@ async def whoami(request: Request) -> WhoamiResponse:
         db.row_factory = aiosqlite.Row
         cursor = await db.execute("SELECT * FROM users WHERE id = ?", (user_id,))
         row = await cursor.fetchone()
-    if row is None:
-        raise HTTPException(status_code=404, detail="User not found")
+    if row is None or not bool(row["is_active"]):
+        raise HTTPException(status_code=401, detail="User not found or disabled")
     user_response = _user_row_to_response(row)
 
     # V2 token with sid: validate the session is still active.
@@ -591,16 +592,18 @@ async def whoami(request: Request) -> WhoamiResponse:
         )
 
     # Cold-start: refresh token presented → issue a fresh access token.
+    # Use ``create_access_token`` (not ``create_token_pair``) to avoid
+    # minting a new refresh token that would silently be discarded —
+    # the client already holds a valid refresh token.
     new_access_token: str | None = None
     if token_type == "refresh":
-        new_pair = create_token_pair(
+        new_access_token = create_access_token(
             user_id=str(row["id"]),
             username=str(row["username"]),
             role=str(row["role"]),
             secret=secret,
             session_id=sid,
         )
-        new_access_token = new_pair.access_token
 
     return WhoamiResponse(
         user=user_response,
diff --git a/tests/integration/auth/test_admin_routes.py b/tests/integration/auth/test_admin_routes.py
index c6d6dfd..381f6cb 100644
--- a/tests/integration/auth/test_admin_routes.py
+++ b/tests/integration/auth/test_admin_routes.py
@@ -171,6 +171,25 @@ class TestAdminListUserSessions:
         )
         assert resp.status_code in (403, 401)
 
+    def test_admin_list_unknown_user_returns_404(
+        self,
+        auth_client: TestClient,
+        users: dict[str, dict[str, Any]],
+    ):
+        """Admin lists sessions for a non-existent user → 404 (not 500)."""
+        admin_body = _login(
+            auth_client,
+            users["admin"]["username"],
+            users["admin"]["password"],
+        )
+        fake_id = str(uuid.uuid4())
+        resp = auth_client.get(
+            f"/api/v1/admin/users/{fake_id}/sessions",
+            headers={"Authorization": f"Bearer {admin_body['access_token']}"},
+        )
+        # The route 404s on unknown user — no 500 leak.
+        assert resp.status_code == 404
+
 
 # ---------------------------------------------------------------------------
 # Admin: revoke user session
@@ -273,3 +292,24 @@ class TestAdminListAllSessions:
         sessions = resp.json()
         # At least 2 sessions (member + admin).
         assert len(sessions) >= 2
+        # Sessions span both users (stronger than just count).
+        user_ids = {s["user_id"] for s in sessions}
+        assert users["member"]["id"] in user_ids
+        assert users["admin"]["id"] in user_ids
+
+    def test_non_admin_cannot_list_all_sessions(
+        self,
+        auth_client: TestClient,
+        users: dict[str, dict[str, Any]],
+    ):
+        """A member must NOT be able to call GET /admin/sessions (403/401)."""
+        member_body = _login(
+            auth_client,
+            users["member"]["username"],
+            users["member"]["password"],
+        )
+        resp = auth_client.get(
+            "/api/v1/admin/sessions",
+            headers={"Authorization": f"Bearer {member_body['access_token']}"},
+        )
+        assert resp.status_code in (403, 401)
diff --git a/tests/integration/auth/test_auth_routes.py b/tests/integration/auth/test_auth_routes.py
index 78b7764..fdea777 100644
--- a/tests/integration/auth/test_auth_routes.py
+++ b/tests/integration/auth/test_auth_routes.py
@@ -190,6 +190,58 @@ class TestWhoamiColdStart:
         )
         assert resp.status_code == 401
 
+    async def test_whoami_disabled_user_returns_401(
+        self,
+        auth_client: TestClient,
+        auth_db_with_user: dict[str, Any],
+        tmp_auth_db: Path,
+    ):
+        """A disabled user (is_active=0) must not pass whoami (U1 fix)."""
+        body = _login(
+            auth_client,
+            auth_db_with_user["username"],
+            auth_db_with_user["password"],
+        )
+        # Disable the user directly in the DB.
+        async with aiosqlite.connect(str(tmp_auth_db)) as db:
+            await db.execute(
+                "UPDATE users SET is_active = 0 WHERE id = ?",
+                (auth_db_with_user["id"],),
+            )
+            await db.commit()
+        # whoami with the still-valid access token must now 401.
+        resp = auth_client.get(
+            "/api/v1/auth/whoami",
+            headers={"Authorization": f"Bearer {body['access_token']}"},
+        )
+        assert resp.status_code == 401
+        assert "disabled" in resp.json()["detail"].lower()
+
+    async def test_whoami_refresh_token_does_not_leak_new_refresh_token(
+        self,
+        auth_client: TestClient,
+        auth_db_with_user: dict[str, Any],
+    ):
+        """Cold-start must NOT issue a new refresh token (U1 token-amplification fix).
+
+        The response only carries ``access_token``; the client keeps using
+        its existing refresh token.
+        """
+        body = _login(
+            auth_client,
+            auth_db_with_user["username"],
+            auth_db_with_user["password"],
+        )
+        resp = auth_client.get(
+            "/api/v1/auth/whoami",
+            headers={"Authorization": f"Bearer {body['refresh_token']}"},
+        )
+        assert resp.status_code == 200, resp.text
+        data = resp.json()
+        assert data["access_token"] is not None
+        # WhoamiResponse has no refresh_token field — verify it's absent.
+        assert "refresh_token" not in data
+
 
 class TestSessionsManagement:
     """GET /auth/sessions, DELETE /auth/sessions/{id}."""
@@ -230,7 +282,7 @@ class TestSessionsManagement:
         assert resp.status_code == 200, resp.text
         assert resp.json()["revoked"] is True
 
-    def test_revoke_other_user_session_returns_404(
+    async def test_revoke_other_user_session_returns_404(
         self,
         auth_client: TestClient,
         auth_db_with_user: dict[str, Any],
@@ -238,7 +290,7 @@ class TestSessionsManagement:
     ):
         """A user cannot revoke another user's session (404, not 403, to avoid leaking)."""
         # Create a second user and log in as them.
-        other = _login_sync_create_user(auth_client, tmp_auth_db, username="bob")
+        other = await _login_async_create_user(auth_client, tmp_auth_db, username="bob")
         # Alice tries to revoke Bob's session.
         body = _login(auth_client, auth_db_with_user["username"], auth_db_with_user["password"])
         resp = auth_client.delete(
@@ -248,7 +300,7 @@ class TestSessionsManagement:
         assert resp.status_code == 404
 
 
-def _login_sync_create_user(
+async def _login_async_create_user(
     client: TestClient,
     db_path: Path,
     *,
@@ -257,12 +309,13 @@ def _login_sync_create_user(
     """Insert a user directly into the DB and log in via the API.
 
     Returns the login response + the session_id extracted from the JWT.
+    Async so it can be ``await``-ed inside pytest-asyncio tests without
+    triggering the ``asyncio.run() cannot be called from a running event
+    loop`` error.
     """
-    import asyncio
-
     from agentkit.server.auth.jwt_utils import verify_token
 
-    user = asyncio.run(_insert_user(db_path, username=username))
+    user = await _insert_user(db_path, username=username)
     body = _login(client, username, user["password"])
     payload = verify_token(body["access_token"], client.app.state.jwt_secret)
     return {**body, "session_id": payload.get("sid"), "user_id": user["id"]}
diff --git a/tests/unit/auth/test_session_service.py b/tests/unit/auth/test_session_service.py
index de679c7..35a9116 100644
--- a/tests/unit/auth/test_session_service.py
+++ b/tests/unit/auth/test_session_service.py
@@ -254,3 +254,82 @@ async def test_is_session_valid_rejects_expired(svc: SessionService, user_id: st
 
 async def test_is_session_valid_returns_false_for_unknown(svc: SessionService):
     assert await svc.is_session_valid("nonexistent-id") is False
+
+
+# ---------------------------------------------------------------------------
+# list_active_by_provider (U2 fix: expired sessions must be filtered)
+# ---------------------------------------------------------------------------
+
+
+async def test_list_active_by_provider_excludes_expired(svc: SessionService, user_id: str):
+    """Expired sessions must NOT appear in list_active_by_provider (U2 fix).
+
+    The docstring promises "non-revoked, non-expired" — before the U2 fix
+    the SQL only checked ``revoked = 0`` and ignored ``expires_at``.
+    """
+    # An expired session (TTL=0 → expires immediately).
+    expired_create = SessionCreate(
+        user_id=user_id,
+        refresh_token="rt-expired",
+        device_fingerprint="fp",
+        device_label="expired-device",
+        ip="",
+        user_agent="",
+        auth_provider="local",
+        ttl_seconds=0,
+    )
+    expired_info = await svc.create(expired_create)
+
+    # A live session.
+    live_info = await svc.create(_make_create(user_id, "rt-live"))
+
+    # list_active_by_provider must return ONLY the live one.
+    active = await svc.list_active_by_provider("local")
+    active_ids = {s.id for s in active}
+    assert live_info.id in active_ids
+    assert expired_info.id not in active_ids
+
+
+async def test_list_active_by_provider_excludes_revoked(svc: SessionService, user_id: str):
+    """Revoked sessions must also be excluded (regression guard)."""
+    a = await svc.create(_make_create(user_id, "rt-a"))
+    b = await svc.create(_make_create(user_id, "rt-b"))
+    await svc.revoke(a.id)
+    active = await svc.list_active_by_provider("local")
+    active_ids = {s.id for s in active}
+    assert b.id in active_ids
+    assert a.id not in active_ids
+
+
+async def test_list_active_by_provider_filters_by_provider(
+    svc: SessionService, user_id: str
+):
+    """Only sessions matching the requested auth_provider are returned."""
+    # SessionCreate is a frozen dataclass — build each with its provider.
+    local_create = SessionCreate(
+        user_id=user_id,
+        refresh_token="rt-local",
+        device_fingerprint="fp",
+        device_label="d",
+        ip="",
+        user_agent="",
+        auth_provider="local",
+        ttl_seconds=3600,
+    )
+    await svc.create(local_create)
+
+    oidc_create = SessionCreate(
+        user_id=user_id,
+        refresh_token="rt-oidc",
+        device_fingerprint="fp",
+        device_label="d",
+        ip="",
+        user_agent="",
+        auth_provider="oidc",
+        ttl_seconds=3600,
+    )
+    await svc.create(oidc_create)
+
+    local_only = await svc.list_active_by_provider("local")
+    assert all(s.auth_provider == "local" for s in local_only)
+    assert len(local_only) == 1