Sanitize Chapa checkout customization text for initialize API.

Strip disallowed characters from customization title and description so subscription payments pass Chapa validation.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/services/chapa/customization_test.go

@@ -0,0 +1,28 @@
+package chapa
+
+import "testing"
+
+func TestSanitizeChapaCustomization(t *testing.T) {
+	tests := []struct {
+		in   string
+		want string
+	}{
+		{"Subscription: Premium", "Subscription Premium"},
+		{"New Test Monthly Premium", "New Test Monthly Premium"},
+		{"IELTS (Prep) / Monthly", "IELTS Prep Monthly"},
+		{"", "Yimaru subscription"},
+	}
+	for _, tc := range tests {
+		if got := sanitizeChapaCustomization(tc.in); got != tc.want {
+			t.Fatalf("sanitizeChapaCustomization(%q) = %q, want %q", tc.in, got, tc.want)
+		}
+	}
+}
+
+func TestChapaSubscriptionDescription(t *testing.T) {
+	got := chapaSubscriptionDescription("New Test Monthly Premium")
+	want := "Subscription New Test Monthly Premium"
+	if got != want {
+		t.Fatalf("chapaSubscriptionDescription() = %q, want %q", got, want)
+	}
+}

internal/services/chapa/service.go

@@ -141,8 +141,8 @@ func (s *Service) InitiateSubscriptionPayment(ctx context.Context, userID int64,
 		CallbackURL: s.cfg.CHAPA_CALLBACK_URL,
 		ReturnURL:   s.cfg.CHAPA_RETURN_URL,
 	}
-	initReq.Customization.Title = "Yimaru LMS"
+	initReq.Customization.Title = sanitizeChapaCustomization("Yimaru LMS")
-	initReq.Customization.Description = fmt.Sprintf("Subscription: %s", plan.Name)
+	initReq.Customization.Description = chapaSubscriptionDescription(plan.Name)
 
 	checkoutURL, err := s.initializeTransaction(ctx, initReq)
 	if err != nil {
@@ -453,6 +453,31 @@ func formatAmount(amount float64) string {
 	return strconv.FormatFloat(math.Round(amount*100)/100, 'f', 2, 64)
 }
 
+// sanitizeChapaCustomization keeps only characters allowed by Chapa customization fields.
+func sanitizeChapaCustomization(value string) string {
+	var b strings.Builder
+	b.Grow(len(value))
+	for _, r := range value {
+		switch {
+		case r >= 'a' && r <= 'z', r >= 'A' && r <= 'Z', r >= '0' && r <= '9':
+			b.WriteRune(r)
+		case r == '-', r == '_', r == ' ', r == '.':
+			b.WriteRune(r)
+		default:
+			b.WriteRune(' ')
+		}
+	}
+	cleaned := strings.Join(strings.Fields(b.String()), " ")
+	if cleaned == "" {
+		return "Yimaru subscription"
+	}
+	return cleaned
+}
+
+func chapaSubscriptionDescription(planName string) string {
+	return sanitizeChapaCustomization("Subscription " + strings.TrimSpace(planName))
+}
+
 func normalizeCurrency(currency string) string {
 	c := strings.TrimSpace(strings.ToUpper(currency))
 	if c == "" {