diff --git a/docs/progress/ai-robot-mca-progress.md b/docs/progress/ai-robot-mca-progress.md
index 08298bc..fd79434 100644
--- a/docs/progress/ai-robot-mca-progress.md
+++ b/docs/progress/ai-robot-mca-progress.md
@@ -140,6 +140,23 @@ public interface MessageRouterService {
 
 ## 🧾 Session History
 
+### Session #5 (2026-02-24)
+- completed:
+  - L2 契约升级: openapi.provider.yaml L0 → L2 ✅
+  - L2 契约对齐: DTO 添加 validation 注解 ✅
+  - L2 契约对齐: Controller 添加 @Valid 校验 ✅
+  - L2 契约对齐: 创建全局异常处理器 ✅
+- changes:
+  - 更新 spec/ai-robot/openapi.provider.yaml (L0 → L2)
+  - 更新 src/main/java/com/wecom/robot/dto/ApiResponse.java (code=200 → 0, 添加注解)
+  - 更新 src/main/java/com/wecom/robot/dto/SessionInfo.java (添加 @NotBlank, @Size, channelType 字段)
+  - 更新 src/main/java/com/wecom/robot/dto/MessageInfo.java (添加 @NotBlank, @Size)
+  - 更新 src/main/java/com/wecom/robot/dto/AcceptSessionRequest.java (添加 @NotBlank, @Size)
+  - 更新 src/main/java/com/wecom/robot/dto/SendMessageRequest.java (添加 @NotBlank, @Size)
+  - 更新 src/main/java/com/wecom/robot/controller/SessionController.java (添加 @Valid, channelType 参数)
+  - 新增 src/main/java/com/wecom/robot/config/GlobalExceptionHandler.java
+- commits: f09f22f, 0786e6a
+
 ### Session #4 (2026-02-24)
 - completed:
   - TASK-001: 定义统一消息模型 DTO ✅