feat: ground competitive insights in peer metrics

internal/insight/avalai_test.go

@@ -1,8 +1,11 @@
 package insight
 
 import (
+	"encoding/json"
 	"strings"
 	"testing"
+
+	"git.amiirkhl.ir/starcoach-hackathon/zarinpal-analytics-backend/internal/peercomparison"
 )
 
 func TestGeneratedInsightTextMustBeOnePlainParagraph(t *testing.T) {
@@ -55,3 +58,32 @@ func TestGeneratedInsightMustNameSelectedAndPrecedingPeriods(t *testing.T) {
 		t.Fatal("generic period wording was accepted")
 	}
 }
+
+func TestPeerInsightAllowsOnlyGroundedAggregateNumbers(t *testing.T) {
+	evidence, err := json.Marshal(map[string]any{
+		"peerComparison": peercomparison.Result{
+			State:                peercomparison.StateReady,
+			EligiblePeerCount:    10,
+			CombinedPeerSessions: 1000,
+			Metrics: []peercomparison.Metric{{
+				MetricID:                      "payment_success_rate",
+				CohortMedian:                  "72.50",
+				MerchantPerformancePercentile: "85.00",
+				Direction:                     "HIGHER_IS_BETTER",
+			}},
+		},
+	})
+	if err != nil {
+		t.Fatalf("marshal evidence: %v", err)
+	}
+	labels := []string{"مرداد ۱۴۰۵"}
+	if containsUnexpectedPeerNumber("در مرداد ۱۴۰۵، جایگاه شما صدک ۸۵٫۰۰ است.", labels, evidence) {
+		t.Fatal("grounded Persian percentile was rejected")
+	}
+	if containsUnexpectedPeerNumber("این مقایسه بر پایه ۱٬۰۰۰ نشست است.", labels, evidence) {
+		t.Fatal("grounded Persian session count was rejected")
+	}
+	if !containsUnexpectedPeerNumber("جایگاه شما صدک ۹۱ است.", labels, evidence) {
+		t.Fatal("invented percentile was accepted")
+	}
+}