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

server/internal/tenant/app/monitoring_callback_service_test.go

@@ -1,6 +1,7 @@
 package app
 
 import (
+	"context"
 	"database/sql"
 	"encoding/json"
 	"errors"
@@ -9,6 +10,8 @@ import (
 	"time"
 
 	"github.com/google/uuid"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestDecideHeartbeatPrimaryLease(t *testing.T) {
@@ -111,6 +114,42 @@ func TestMonitoringHeartbeatPrimaryLeaseMetrics(t *testing.T) {
 	}
 }
 
+func TestLoadMonitoringBrandDailyAggregateUsesLatestQuestionPlatformSamples(t *testing.T) {
+	tx := &captureDailyMonitorTaskTx{}
+
+	_, err := (&MonitoringCallbackService{}).loadMonitoringBrandDailyAggregate(
+		context.Background(),
+		tx,
+		3,
+		3,
+		time.Date(2026, 6, 29, 0, 0, 0, 0, monitoringBusinessLocation()),
+	)
+
+	require.NoError(t, err)
+	require.Len(t, tx.queryRowSQLs, 5)
+	combined := normalizeSQLWhitespace(strings.Join(tx.queryRowSQLs, " "))
+	assert.Contains(t, combined, "SELECT DISTINCT ON (business_date, question_id, ai_platform_id)")
+	assert.Contains(t, combined, "p.brand_mentioned IS TRUE AND p.sentiment_label = 'positive'")
+}
+
+func TestLoadMonitoringPlatformDailyAggregatesUsesLatestQuestionPlatformSamples(t *testing.T) {
+	tx := &captureDailyMonitorTaskTx{}
+
+	_, err := (&MonitoringCallbackService{}).loadMonitoringPlatformDailyAggregates(
+		context.Background(),
+		tx,
+		3,
+		3,
+		time.Date(2026, 6, 29, 0, 0, 0, 0, monitoringBusinessLocation()),
+		[]monitoringPlatformMetadata{{ID: "doubao", Name: "豆包"}},
+	)
+
+	require.NoError(t, err)
+	require.GreaterOrEqual(t, len(tx.querySQLs), 2)
+	combined := normalizeSQLWhitespace(strings.Join(tx.querySQLs, " "))
+	assert.Contains(t, combined, "SELECT DISTINCT ON (business_date, question_id, ai_platform_id)")
+}
+
 func TestDecideMonitoringHeartbeatSnapshot(t *testing.T) {
 	now := time.Date(2026, 4, 24, 3, 0, 0, 0, time.UTC)
 	base := monitoringPlatformAccessSnapshotState{