feat: mail service

authsession/internal/ports/mail_sender.go

@@ -24,8 +24,16 @@ type SendLoginCodeInput struct {
 	// Email identifies the normalized target e-mail address.
 	Email common.Email
 
+	// IdempotencyKey stores the raw challenge_id value sent to Mail Service as
+	// the required Idempotency-Key header.
+	IdempotencyKey string
+
 	// Code stores the cleartext login code that should be delivered to Email.
 	Code string
+
+	// Locale stores the canonical BCP 47 language tag that selects the auth
+	// mail template locale.
+	Locale string
 }
 
 // Validate reports whether SendLoginCodeInput contains a complete delivery
@@ -35,10 +43,18 @@ func (i SendLoginCodeInput) Validate() error {
 		return fmt.Errorf("send login code input email: %w", err)
 	}
 	switch {
+	case strings.TrimSpace(i.IdempotencyKey) == "":
+		return errors.New("send login code input idempotency key must not be empty")
+	case strings.TrimSpace(i.IdempotencyKey) != i.IdempotencyKey:
+		return errors.New("send login code input idempotency key must not contain surrounding whitespace")
 	case strings.TrimSpace(i.Code) == "":
 		return errors.New("send login code input code must not be empty")
 	case strings.TrimSpace(i.Code) != i.Code:
 		return errors.New("send login code input code must not contain surrounding whitespace")
+	case strings.TrimSpace(i.Locale) == "":
+		return errors.New("send login code input locale must not be empty")
+	case strings.TrimSpace(i.Locale) != i.Locale:
+		return errors.New("send login code input locale must not contain surrounding whitespace")
 	default:
 		return nil
 	}