fix: enhance monitoring metrics with latest sample aggregation and derived metrics calculations

server/internal/tenant/app/monitoring_service_date_test.go

@@ -1,6 +1,7 @@
 package app
 
 import (
+	"database/sql"
 	"testing"
 	"time"
 
@@ -234,3 +235,73 @@ func TestApplyDerivedRatesToOverviewSnapshotUsesAllSamplesForMentionRate(t *test
 	assert.InDelta(t, 0.25, snapshot.FirstRecommendRate.Float64, 0.0001)
 	assert.InDelta(t, 0.25, snapshot.PositiveMentionRate.Float64, 0.0001)
 }
+
+func TestBuildMonitoringDerivedMetricsUsesLatestSamplePerQuestionPlatform(t *testing.T) {
+	day := time.Date(2026, 6, 29, 0, 0, 0, 0, monitoringBusinessLocation())
+	questionID := int64(177)
+	samples := map[monitoringDerivedSampleKey]monitoringDerivedParseSample{}
+
+	upsertLatestMonitoringDerivedParseSample(samples, monitoringDerivedParseSample{
+		BusinessDate: day,
+		PlatformID:   "doubao",
+		QuestionID:   questionID,
+		EventAt:      sql.NullTime{Time: day.Add(10 * time.Hour), Valid: true},
+		RunID:        2507,
+		Summary: monitoringAnswerParseSummary{
+			BrandMentioned:       true,
+			BrandMentionPosition: "mentioned",
+		},
+	})
+	upsertLatestMonitoringDerivedParseSample(samples, monitoringDerivedParseSample{
+		BusinessDate: day,
+		PlatformID:   "doubao",
+		QuestionID:   questionID,
+		EventAt:      sql.NullTime{Time: day.Add(11 * time.Hour), Valid: true},
+		RunID:        2628,
+		Summary: monitoringAnswerParseSummary{
+			BrandMentioned:       false,
+			BrandMentionPosition: "not_mentioned",
+		},
+	})
+	upsertLatestMonitoringDerivedParseSample(samples, monitoringDerivedParseSample{
+		BusinessDate: day,
+		PlatformID:   "qwen",
+		QuestionID:   questionID,
+		EventAt:      sql.NullTime{Time: day.Add(10*time.Hour + 30*time.Minute), Valid: true},
+		RunID:        2510,
+		Summary: monitoringAnswerParseSummary{
+			BrandMentioned:       true,
+			BrandMentionPosition: "mentioned",
+		},
+	})
+
+	metrics := buildMonitoringDerivedMetricsFromLatestSamples(samples)
+	stats := metrics.ByDateQuestion["2026-06-29"][questionID]
+
+	require.True(t, stats.hasSamples())
+	assert.Equal(t, int64(2), stats.Total)
+	assert.Equal(t, int64(1), stats.MentionedCount)
+	require.NotNil(t, stats.mentionRate())
+	assert.InDelta(t, 0.5, *stats.mentionRate(), 0.0001)
+}
+
+func TestMonitoringDerivedPositiveMentionRequiresBrandMention(t *testing.T) {
+	var stats monitoringDerivedRateStats
+
+	stats.add(monitoringAnswerParseSummary{
+		BrandMentioned:       false,
+		BrandMentionPosition: "not_mentioned",
+		SentimentLabel:       "positive",
+	})
+	stats.add(monitoringAnswerParseSummary{
+		BrandMentioned:       true,
+		BrandMentionPosition: "mentioned",
+		SentimentLabel:       "positive",
+	})
+
+	assert.Equal(t, int64(2), stats.Total)
+	assert.Equal(t, int64(1), stats.MentionedCount)
+	assert.Equal(t, int64(1), stats.PositiveMentions)
+	require.NotNil(t, stats.positiveMentionRate())
+	assert.InDelta(t, 0.5, *stats.positiveMentionRate(), 0.0001)
+}