diff --git a/src/data/repositories/auth_repository.ts b/src/data/repositories/auth_repository.ts
index d63c0c76..f6ccb5ef 100644
--- a/src/data/repositories/auth_repository.ts
+++ b/src/data/repositories/auth_repository.ts
@@ -123,16 +123,31 @@ export class AuthRepository implements IAuthRepository {
    * 成功后写 guest token + deviceId + userId。
    */
   async guestLogin(deviceId: string): Promise<Result<GuestLoginResponse>> {
+    console.log("[AuthRepository.guestLogin] API call START", {
+      deviceIdLength: deviceId.length,
+      deviceIdPrefix: deviceId.slice(0, 8),
+    });
     return Result.wrap(async () => {
       const response = await this.api.guestLogin(
         GuestLoginRequest.from({ deviceId }),
       );
+      console.log("[AuthRepository.guestLogin] API call SUCCESS (Zod parsed)", {
+        hasToken: !!response.token,
+        hasUser: !!response.user,
+        userLastMessageAt: response.user?.lastMessageAt,
+      });
       await this.storage.setGuestToken(response.token);
       await this.storage.setDeviceId(deviceId);
       if (response.userId) {
         await this.userStorage.setUserId(response.userId);
       }
       return response;
+    }).catch((e) => {
+      console.error("[AuthRepository.guestLogin] API call FAILED", {
+        errorName: e?.name,
+        errorMessage: e?.message,
+      });
+      return Result.err(e);
     });
   }
 
diff --git a/src/data/services/api/auth_api.ts b/src/data/services/api/auth_api.ts
index 7ceb3fb6..84562d57 100644
--- a/src/data/services/api/auth_api.ts
+++ b/src/data/services/api/auth_api.ts
@@ -4,6 +4,8 @@
  * 认证相关接口
  * 原始 Dart: lib/data/services/api/auth_api_client.dart
  */
+import { z } from "zod";
+
 import { httpClient } from "./http_client";
 import { ApiPath } from "./api_path";
 import { ApiEnvelope, unwrap } from "./response_helper";
@@ -117,7 +119,29 @@ export class AuthApi {
       method: "POST",
       body: body.toJson(),
     });
-    return GuestLoginResponse.fromJson(unwrap(env) as Record<string, unknown>);
+    console.log("[AuthApi.guestLogin] raw envelope from backend", env);
+    const unwrapped = unwrap(env) as Record<string, unknown>;
+    const userObj = unwrapped.user as { lastMessageAt?: unknown } | undefined;
+    console.log("[AuthApi.guestLogin] unwrapped data (pre-parse)", {
+      hasUser: "user" in unwrapped,
+      userKeys: userObj && typeof userObj === "object" ? Object.keys(userObj) : null,
+      lastMessageAt: userObj?.lastMessageAt,
+      lastMessageAtType: typeof userObj?.lastMessageAt,
+    });
+    try {
+      return GuestLoginResponse.fromJson(unwrapped);
+    } catch (e) {
+      if (e instanceof z.ZodError) {
+        console.error("[AuthApi.guestLogin] ZodError parsing response", {
+          issueCount: e.issues.length,
+          firstIssue: e.issues[0],
+          allPaths: e.issues.map((i) => i.path),
+        });
+      } else {
+        console.error("[AuthApi.guestLogin] unexpected error", e);
+      }
+      throw e;
+    }
   }
 
   /**
diff --git a/src/stores/auth/auth-machine.ts b/src/stores/auth/auth-machine.ts
index 1d4c2021..1e3f62bf 100644
--- a/src/stores/auth/auth-machine.ts
+++ b/src/stores/auth/auth-machine.ts
@@ -120,16 +120,35 @@ const syncFacebookBackendActor = fromPromise<
 // 受保护 API 401 会由 HTTP 层清掉 token 回到 splash，无需在此处主动校验。
 
 const guestLoginActor = fromPromise<LoginStatus, void>(async () => {
+  console.log("[auth-machine] guestLoginActor ENTRY");
+
   // 1. 先查本地 guestToken —— 已有就直接进 idle（带 pendingRedirect）
   const hasTokenR = await AuthStorage.getInstance().hasGuestToken();
+  console.log("[auth-machine] guestLoginActor hasGuestToken", {
+    success: hasTokenR.success,
+    hasData: hasTokenR.success ? !!hasTokenR.data : null,
+  });
   if (hasTokenR.success && hasTokenR.data) {
+    console.log("[auth-machine] guestLoginActor SHORT-CIRCUIT (has local guestToken) → return guest");
     return "guest" as LoginStatus;
   }
   // Result.err(_) 时**不**抛 —— 落到 API 路径让真正的错误信号出现
 
   // 2. 没有（或读不出）才走完整流程：拿 deviceId → 调后端
   const deviceId = await deviceIdentifier.getDeviceId();
+  console.log("[auth-machine] guestLoginActor deviceId", {
+    length: deviceId.length,
+    prefix: deviceId.slice(0, 8),
+  });
+
+  console.log("[auth-machine] guestLoginActor calling authRepository.guestLogin");
   const result = await authRepository.guestLogin(deviceId);
+  console.log("[auth-machine] guestLoginActor authRepository.guestLogin DONE", {
+    success: result.success,
+    hasData: result.success ? !!result.data : null,
+    errorName: result.success ? null : result.error?.name,
+    errorMessage: result.success ? null : result.error?.message,
+  });
   if (Result.isErr(result)) throw result.error;
   return "guest" as LoginStatus;
 });