fix(auth): improve robustness of user signup and email flow

- 【auth】make welcome email sending non-blocking to prevent signup failures
- 【email】enhance error handling for email API to manage non-json responses

feat(email): add detailed logging for traceability
- log email payloads, raw API responses, and success/error states
- improves debugging capabilities for email delivery issues

refactor(db): remove unused clientId field from UserSession
- clean up the prisma schema by removing the obsolete `clientId` column

prisma/schema.prisma

@@ -110,7 +110,6 @@ model UserSession {
   ipAddress    String?
   userAgent    String?        @db.Text
   geoIpCountry String?
-  clientId     String?
   status       SESSION_STATUS @default(CURRENT)
   loginAt      DateTime?      @db.Timestamp(3)
   logoutAt     DateTime?      @db.Timestamp(3)

src/modules/user/auth/auth.service.ts

@@ -341,12 +341,17 @@ export class UserAuthService {
       },
     });
 
-    // Send welcome email
-    await this.emailService.sendWelcomeEmail(
-      email,
-      user.firstName || 'User',
-      user.lastName || '',
-    );
+    // Send welcome email (don't block profile completion if email fails)
+    try {
+      await this.emailService.sendWelcomeEmail(
+        email,
+        user.firstName || 'User',
+        user.lastName || '',
+      );
+    } catch (emailError) {
+      // Log error but don't fail the request
+      console.error('Failed to send welcome email:', emailError);
+    }
 
     return {
       user: updatedUser,

src/shared/modules/email/email.service.ts

@@ -7,7 +7,7 @@ export class EmailService {
   private readonly logger = new Logger(EmailService.name);
   private readonly config: EmailConfig;
 
-  constructor(private configService: ConfigService) {
+  constructor(configService: ConfigService) {
     this.config = new EmailConfig(configService);
   }
 
@@ -17,37 +17,55 @@ export class EmailService {
     firstName?: string,
   ): Promise<void> {
     try {
+      this.logger.log(`📧 Attempting to send OTP email to: ${email}`);
       const greeting = firstName ? `Hi ${firstName}` : 'Hello';
 
+      const payload = {
+        sender: {
+          email: this.config.otpEmail,
+          name: 'StreamFlix',
+        },
+        to: [{ email, name: firstName || email }],
+        templateId: this.config.otpTemplateId,
+        params: {
+          GREETING: greeting,
+          OTP: otp,
+        },
+      };
+
+      this.logger.log('📧 OTP Email payload:', {
+        sender: payload.sender,
+        to: payload.to,
+        templateId: payload.templateId,
+        params: payload.params,
+      });
+
       const response = await fetch('https://api.brevo.com/v3/smtp/email', {
         method: 'POST',
         headers: {
           'api-key': this.config.apiKey,
           'Content-Type': 'application/json',
         },
-        body: JSON.stringify({
-          sender: {
-            email: this.config.otpEmail,
-            name: 'StreamFlix',
-          },
-          to: [{ email, name: firstName || email }],
-          templateId: this.config.otpTemplateId,
-          params: {
-            GREETING: greeting,
-            OTP: otp,
-          },
-        }),
+        body: JSON.stringify(payload),
       });
 
+      const responseText = await response.text();
+      this.logger.log(`📧 Raw Response: ${responseText}`);
+
       if (!response.ok) {
-        const error = await response.json();
-        this.logger.error('Failed to send OTP email', error);
+        let error;
+        try {
+          error = JSON.parse(responseText);
+        } catch {
+          error = responseText;
+        }
+        this.logger.error('📧 Failed to send OTP email:', error);
         throw new Error('Failed to send OTP email');
       }
 
-      this.logger.log(`OTP email sent to ${email}`);
+      this.logger.log(`📧 ✅ OTP email sent successfully to ${email}`);
     } catch (error) {
-      this.logger.error('Error sending OTP email', error);
+      this.logger.error('📧 ❌ Error sending OTP email:', error);
       throw error;
     }
   }
@@ -58,7 +76,27 @@ export class EmailService {
     lastName: string,
   ): Promise<void> {
     try {
-      const fullName = `${firstName} ${lastName}`;
+      this.logger.log(`📧 Attempting to send welcome email to: ${email}`);
+      const fullName = `${firstName} ${lastName}`.trim();
+
+      const payload = {
+        sender: {
+          email: this.config.welcomeEmail,
+          name: 'StreamFlix',
+        },
+        to: [{ email, name: fullName || email }],
+        templateId: this.config.welcomeTemplateId,
+        params: {
+          FIRSTNAME: fullName || firstName || 'User',
+        },
+      };
+
+      this.logger.log('📧 Welcome Email payload:', {
+        sender: payload.sender,
+        to: payload.to,
+        templateId: payload.templateId,
+        params: payload.params,
+      });
 
       const response = await fetch('https://api.brevo.com/v3/smtp/email', {
         method: 'POST',
@@ -66,28 +104,26 @@ export class EmailService {
           'api-key': this.config.apiKey,
           'Content-Type': 'application/json',
         },
-        body: JSON.stringify({
-          sender: {
-            email: this.config.welcomeEmail,
-            name: 'StreamFlix',
-          },
-          to: [{ email, name: fullName }],
-          templateId: this.config.welcomeTemplateId,
-          params: {
-            FIRSTNAME: fullName,
-          },
-        }),
+        body: JSON.stringify(payload),
       });
 
+      const responseText = await response.text();
+      this.logger.log(`📧 Raw Response: ${responseText}`);
+
       if (!response.ok) {
-        const error = await response.json();
-        this.logger.error('Failed to send welcome email', error);
+        let error;
+        try {
+          error = JSON.parse(responseText);
+        } catch {
+          error = responseText;
+        }
+        this.logger.error('📧 Failed to send welcome email:', error);
         throw new Error('Failed to send welcome email');
       }
 
-      this.logger.log(`Welcome email sent to ${email}`);
+      this.logger.log(`📧 ✅ Welcome email sent successfully to ${email}`);
     } catch (error) {
-      this.logger.error('Error sending welcome email', error);
+      this.logger.error('📧 ❌ Error sending welcome email:', error);
       throw error;
     }
   }