feat(evolution, web): add live match counter per plan §16.18

- Add matches_today and active_bots fields to LiveData Totals (evolver)
- Query matches table for COUNT(*) WHERE completed_at >= today
- Query bots table for COUNT(*) WHERE status = 'active'
- Add fields to index builder EvolutionMeta struct
- Update homepage to render "X matches today · Y bots active · Gen #Z evolving"
- Add CSS styling for .home-live-stats section

Closes: bf-4m8mo

cmd/acb-evolver/internal/live/exporter.go

@@ -133,6 +133,8 @@ type Totals struct {
 	HighestEvolvedRating int     `json:"highest_evolved_rating"`
 	EvolvedInTop10       int     `json:"evolved_in_top_10"`
 	MutationsPerHour     float64 `json:"mutations_per_hour"`
+	MatchesToday         int     `json:"matches_today"`         // plan §16.18: matches completed today
+	ActiveBots           int     `json:"active_bots"`           // plan §16.18: active bot count
 }
 
 // LiveData is the full evolution dashboard payload written to live.json (plan §14 format).
@@ -312,6 +314,24 @@ func fillTotals(ctx context.Context, db *sql.DB, data *LiveData) error {
 		mutationsLastHour = 0
 	}
 
+	// Matches today (plan §16.18: completed matches since midnight UTC)
+	var matchesToday int
+	err = db.QueryRowContext(ctx, `
+		SELECT COUNT(*) FROM matches
+		WHERE completed_at >= $1::date`, today).Scan(&matchesToday)
+	if err != nil {
+		matchesToday = 0
+	}
+
+	// Active bots (plan §16.18: bots with status = 'active')
+	var activeBots int
+	err = db.QueryRowContext(ctx, `
+		SELECT COUNT(*) FROM bots
+		WHERE status = 'active'`).Scan(&activeBots)
+	if err != nil {
+		activeBots = 0
+	}
+
 	data.Totals = Totals{
 		GenerationsTotal:     maxGen,
 		CandidatesToday:      candidatesToday,
@@ -320,6 +340,8 @@ func fillTotals(ctx context.Context, db *sql.DB, data *LiveData) error {
 		HighestEvolvedRating: highestRating,
 		EvolvedInTop10:       top10Count,
 		MutationsPerHour:     round3(float64(mutationsLastHour)),
+		MatchesToday:         matchesToday,
+		ActiveBots:           activeBots,
 	}
 
 	return nil

cmd/acb-index-builder/db.go

@@ -1035,6 +1035,8 @@ type EvolutionMeta struct {
 	TotalPromoted     int                `json:"total_promoted"`     // all-time promoted count
 	PromotionRate     float64            `json:"promotion_rate"`     // promoted/total
 	UpdatedAt         string             `json:"updated_at"`
+	MatchesToday      int                `json:"matches_today"`      // plan §16.18: matches completed today
+	ActiveBots        int                `json:"active_bots"`        // plan §16.18: active bot count
 }
 
 // EvolvedBotRating represents an evolved bot's rating info
@@ -1091,6 +1093,8 @@ func fetchEvolutionMeta(ctx context.Context, db *sql.DB) (*EvolutionMeta, error)
 			TotalPromoted:     0,
 			PromotionRate:     0,
 			UpdatedAt:         updatedAt,
+			MatchesToday:      0,
+			ActiveBots:        0,
 		}, nil
 	}
 
@@ -1140,6 +1144,28 @@ func fetchEvolutionMeta(ctx context.Context, db *sql.DB) (*EvolutionMeta, error)
 	// Count evolved bots in top 10
 	meta.Top10Count = len(meta.BestRatings)
 
+	// Fetch matches today (plan §16.18: completed matches since midnight UTC)
+	var matchesToday int
+	matchErr := db.QueryRowContext(ctx, `
+		SELECT COUNT(*) FROM matches
+		WHERE completed_at >= CURRENT_DATE
+	`).Scan(&matchesToday)
+	if matchErr != nil {
+		matchesToday = 0
+	}
+	meta.MatchesToday = matchesToday
+
+	// Fetch active bots count (plan §16.18: bots with status = 'active')
+	var activeBots int
+	botErr := db.QueryRowContext(ctx, `
+		SELECT COUNT(*) FROM bots
+		WHERE status = 'active'
+	`).Scan(&activeBots)
+	if botErr != nil {
+		activeBots = 0
+	}
+	meta.ActiveBots = activeBots
+
 	meta.UpdatedAt = updatedAt
 	return &meta, nil
 }

web/src/api-types.ts

@@ -449,13 +449,16 @@ export interface EvolutionMeta {
   promoted_today: number;
   top_10_count: number;
   updated_at: string;
+  matches_today?: number;   // plan §16.18: matches completed today
+  active_bots?: number;     // plan §16.18: active bot count
 }
 
 export async function fetchEvolutionMeta(): Promise<EvolutionMeta> {
   return swr('evolution-meta', async () => {
     const response = await fetch('/data/evolution/meta.json');
     if (!response.ok) {
-      return { generation: 0, promoted_today: 0, top_10_count: 0, updated_at: '' };
+      const fallback: EvolutionMeta = { generation: 0, promoted_today: 0, top_10_count: 0, updated_at: '', matches_today: 0, active_bots: 0 };
+      return fallback;
     }
     return response.json();
   });

web/src/pages/home.ts

@@ -146,6 +146,8 @@ export async function renderHomePage(): Promise<void> {
       promoted_today: 0,
       top_10_count: 0,
       updated_at: '',
+      matches_today: 0,
+      active_bots: 0,
     })),
     fetchSeasonIndex().catch(() => ({
       updated_at: '',
@@ -200,7 +202,8 @@ export async function renderHomePage(): Promise<void> {
 
   const evoHtml = lazySection(
     'home-evo',
-    `<section class="home-evo"><div class="home-evo-info"><span class="home-evo-icon">&#129516;</span><span class="home-evo-text"><strong>Evolution Observatory</strong> &mdash; Gen #${evolutionMeta.generation}${evolutionMeta.promoted_today > 0 ? ` &middot; ${evolutionMeta.promoted_today} promoted today` : ''}${evolutionMeta.top_10_count > 0 ? ` &middot; ${evolutionMeta.top_10_count} in top 10` : ''}</span></div><a href="#/evolution" class="btn small secondary">Watch evolution live &rarr;</a></section>`,
+    `<section class="home-evo"><div class="home-evo-info"><span class="home-evo-icon">&#129516;</span><span class="home-evo-text"><strong>Evolution Observatory</strong> &mdash; Gen #${evolutionMeta.generation}${evolutionMeta.promoted_today > 0 ? ` &middot; ${evolutionMeta.promoted_today} promoted today` : ''}${evolutionMeta.top_10_count > 0 ? ` &middot; ${evolutionMeta.top_10_count} in top 10` : ''}</span></div><a href="#/evolution" class="btn small secondary">Watch evolution live &rarr;</a></section>
+<div class="home-live-stats"><span class="home-live-icon">&#9876;</span><span class="home-live-text">${(evolutionMeta.matches_today ?? 0).toLocaleString()} matches today &middot; ${(evolutionMeta.active_bots ?? 0).toLocaleString()} bots active &middot; Gen #${evolutionMeta.generation} evolving</span></div>`,
     { placeholder: '<div class="lazy-placeholder" style="min-height:60px"></div>' }
   );
 
@@ -535,6 +538,22 @@ export async function renderHomePage(): Promise<void> {
 }
 .home-evo-text strong { color: var(--text-primary); }
 
+/* Live stats bar (plan §16.18) */
+.home-live-stats {
+  background: var(--bg-tertiary);
+  border-radius: 8px;
+  padding: 8px 12px;
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  margin-top: 8px;
+}
+.home-live-icon { font-size: 1rem; }
+.home-live-text {
+  color: var(--text-muted);
+  font-size: 0.75rem;
+}
+
 .home-empty {
   color: var(--text-muted);
   text-align: center;