feat(admin): wave metrics split by model version (M6)

The library page compares listen-through, early-skip and like rates per
impression model version, so v1 and the trained ranker can be compared online.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

services/api/internal/library/store.go

@@ -624,10 +624,36 @@ func (st *Store) AnalysisCounts(ctx context.Context) (AnalysisCounts, error) {
 
 // WaveMetrics — метрики волны за 7 дней (docs/recommendations.md#1-цели-и-как-измеряем-успех).
 type WaveMetrics struct {
-	Served, Sessions                   int
+	Served, Sessions int
+	WaveRates
+	ByModel []WaveModelMetrics
+}
+
+// WaveRates — доли по показам с известным исходом (nil — исходов ещё нет).
+type WaveRates struct {
 	ListenThrough, EarlySkip, LikeRate *float32
 }
 
+// WaveModelMetrics — метрики показов одной версии модели.
+type WaveModelMetrics struct {
+	ModelVer string
+	Served   int
+	WaveRates
+}
+
+func rates(judged, through, early, liked int) WaveRates {
+	if judged == 0 {
+		return WaveRates{}
+	}
+	lt, es, lr := float32(through)/float32(judged), float32(early)/float32(judged), float32(liked)*100/float32(judged)
+	return WaveRates{ListenThrough: &lt, EarlySkip: &es, LikeRate: &lr}
+}
+
+const waveOutcomes = `count(outcome),
+			count(*) FILTER (WHERE outcome IN ('complete', 'like')),
+			count(*) FILTER (WHERE outcome IN ('skip_early', 'dislike')),
+			count(*) FILTER (WHERE outcome = 'like')`
+
 // WaveMetrics считает метрики по показам с известным исходом.
 func (st *Store) WaveMetrics(ctx context.Context) (WaveMetrics, error) {
 	var (
@@ -635,20 +661,32 @@ func (st *Store) WaveMetrics(ctx context.Context) (WaveMetrics, error) {
 		judged, through, early, liked int
 	)
 	err := st.pool.QueryRow(ctx, `
-		SELECT count(*), count(DISTINCT wave_session_id), count(outcome),
-			count(*) FILTER (WHERE outcome IN ('complete', 'like')),
-			count(*) FILTER (WHERE outcome IN ('skip_early', 'dislike')),
-			count(*) FILTER (WHERE outcome = 'like')
+		SELECT count(*), count(DISTINCT wave_session_id), `+waveOutcomes+`
 		FROM wave_impressions WHERE served_at > now() - interval '7 days'`).
 		Scan(&m.Served, &m.Sessions, &judged, &through, &early, &liked)
 	if err != nil {
 		return WaveMetrics{}, fmt.Errorf("library: wave metrics: %w", err)
 	}
-	if judged > 0 {
-		lt, es, lr := float32(through)/float32(judged), float32(early)/float32(judged), float32(liked)*100/float32(judged)
-		m.ListenThrough, m.EarlySkip, m.LikeRate = &lt, &es, &lr
+	m.WaveRates = rates(judged, through, early, liked)
+
+	rows, err := st.pool.Query(ctx, `
+		SELECT coalesce(model_ver, ''), count(*), `+waveOutcomes+`
+		FROM wave_impressions WHERE served_at > now() - interval '7 days'
+		GROUP BY 1 ORDER BY 2 DESC`)
+	if err != nil {
+		return WaveMetrics{}, fmt.Errorf("library: wave metrics by model: %w", err)
 	}
-	return m, nil
+	defer rows.Close()
+	m.ByModel = []WaveModelMetrics{}
+	for rows.Next() {
+		var mm WaveModelMetrics
+		if err := rows.Scan(&mm.ModelVer, &mm.Served, &judged, &through, &early, &liked); err != nil {
+			return WaveMetrics{}, fmt.Errorf("library: wave metrics by model: %w", err)
+		}
+		mm.WaveRates = rates(judged, through, early, liked)
+		m.ByModel = append(m.ByModel, mm)
+	}
+	return m, rows.Err()
 }
 
 // FingerprintTodo — файл, которому нужны отпечатки.