fix: deliver validated AI insight responses

internal/insight/builder_transaction_test.go

@@ -0,0 +1,45 @@
+package insight
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestDeterministicTransactionCopyDistinguishesPaymentStatesWithoutCausalClaims(t *testing.T) {
+	copy := deterministicTransactionCopy(
+		PeriodScope{JalaliLabelFA: "مرداد ۱۴۰۵"},
+		aggregate{Sessions: 10, Paid: 7, Verified: 5, Unverified: 2, Failed: 2, Reversed: 1},
+		aggregate{Sessions: 8, Paid: 6},
+		true,
+		TimeContext{},
+		ConfidenceHigh,
+	)
+
+	body := copy.LatestObserved.Body
+	for _, expected := range []string{"پرداخت‌شده و در انتظار تأیید", "تأیید نهایی", "ناموفق"} {
+		if !strings.Contains(body, expected) {
+			t.Fatalf("expected transaction copy to contain %q: %s", expected, body)
+		}
+	}
+	if !strings.Contains(copy.Past.Body, "علت آن را مشخص نمی‌کند") {
+		t.Fatalf("expected non-causal comparison language: %s", copy.Past.Body)
+	}
+}
+
+func TestDeterministicTransactionCopyHandlesEmptyPeriod(t *testing.T) {
+	copy := deterministicTransactionCopy(
+		PeriodScope{JalaliLabelFA: "امروز"},
+		aggregate{},
+		aggregate{},
+		false,
+		TimeContext{},
+		ConfidenceInsufficientData,
+	)
+
+	if strings.Contains(copy.LatestObserved.Body, "<nil>") {
+		t.Fatalf("empty-period copy exposed an implementation value: %s", copy.LatestObserved.Body)
+	}
+	if !strings.Contains(copy.LatestObserved.Body, "ناموجود") {
+		t.Fatalf("expected unavailable rates in empty-period copy: %s", copy.LatestObserved.Body)
+	}
+}