fix: 接线 Prometheus 指标到连接与投递事件

internal/app/message/ack.go

@@ -17,6 +17,8 @@ func (a *App) Ack(ctx context.Context, endpointID string, req *protocol.Ack) (Ac
 	nowMs := a.now().UnixMilli()
 	var out AckResult
 	var seq int64
+	var ackLatencySec float64
+	var observeAck bool
 	err := a.db.Queue.Do(ctx, func(tx *sql.Tx) error {
 		err := tx.QueryRow(`SELECT seq FROM messages WHERE sender_id = ? AND id = ?`, req.From, req.ID).Scan(&seq)
 		if err == sql.ErrNoRows {
@@ -25,6 +27,10 @@ func (a *App) Ack(ctx context.Context, endpointID string, req *protocol.Ack) (Ac
 		if err != nil {
 			return err
 		}
+		var pushedAt sql.NullInt64
+		_ = tx.QueryRow(`
+SELECT pushed_at FROM deliveries
+WHERE seq = ? AND endpoint_id = ? AND state = 'pending'`, seq, endpointID).Scan(&pushedAt)
 		res, err := tx.Exec(`
 UPDATE deliveries SET state = ?, reason = '', pushed_conn = NULL, updated_at = ?
 WHERE seq = ? AND endpoint_id = ? AND state = 'pending'`,
@@ -35,6 +41,10 @@ WHERE seq = ? AND endpoint_id = ? AND state = 'pending'`,
 		aff, _ := res.RowsAffected()
 		if aff > 0 {
 			out.Result = DeliveryAccepted
+			if pushedAt.Valid && pushedAt.Int64 > 0 && nowMs >= pushedAt.Int64 {
+				ackLatencySec = float64(nowMs-pushedAt.Int64) / 1000.0
+				observeAck = true
+			}
 			if e := insertReceiptTx(tx, req.From, seq, endpointID, DeliveryAccepted, "", nowMs); e != nil {
 				return e
 			}
@@ -55,6 +65,9 @@ SELECT state FROM deliveries WHERE seq = ? AND endpoint_id = ?`, seq, endpointID
 	if err != nil {
 		return out, err
 	}
+	if observeAck && a.met != nil {
+		a.met.AckSeconds.Observe(ackLatencySec)
+	}
 	if out.Result == DeliveryAccepted {
 		a.releaseLarge(seq, endpointID)
 	}

internal/app/message/app.go

@@ -7,6 +7,7 @@ import (
 	"git.asio.asia/nixevol/NixMsg/internal/app/port"
 	"git.asio.asia/nixevol/NixMsg/internal/auth"
 	"git.asio.asia/nixevol/NixMsg/internal/config"
+	"git.asio.asia/nixevol/NixMsg/internal/metrics"
 	"git.asio.asia/nixevol/NixMsg/internal/protocol"
 	"git.asio.asia/nixevol/NixMsg/internal/store"
 )
@@ -86,6 +87,7 @@ type App struct {
 
 	down  port.Downlink
 	conns ConnRegistry
+	met   *metrics.Registry
 
 	mu            sync.Mutex
 	largeSem      chan struct{}
@@ -117,6 +119,11 @@ func WithConnRegistry(c ConnRegistry) Option {
 	return func(a *App) { a.conns = c }
 }
 
+// WithMetrics 注入 Prometheus 注册表（投递耗时直方图）。
+func WithMetrics(m *metrics.Registry) Option {
+	return func(a *App) { a.met = m }
+}
+
 // New 创建消息服务实现。
 func New(db *store.DB, lim Limits, hash auth.HashPool, opts ...Option) *App {
 	if lim.RequestBurst <= 0 {

internal/app/message/push.go

@@ -229,11 +229,20 @@ WHERE seq = ? AND endpoint_id = ? AND state = 'pending' AND pushed_conn IS NULL`
 				a.releaseLarge(it.seq, endpointID)
 			}
 			a.scheduleRepush(endpointID, time.Second)
+		} else {
+			a.observeDispatchToPush(it.sendAt, nowMs)
 		}
 	}
 	return a.pushReceipts(ctx, endpointID, connID, nowMs)
 }
 
+func (a *App) observeDispatchToPush(sendAtMs, pushedAtMs int64) {
+	if a.met == nil || pushedAtMs < sendAtMs {
+		return
+	}
+	a.met.DispatchToPushSeconds.Observe(float64(pushedAtMs-sendAtMs) / 1000.0)
+}
+
 func (a *App) rejectTooLarge(ctx context.Context, seq int64, endpointID, senderID string, nowMs int64) error {
 	return a.db.Queue.Do(ctx, func(tx *sql.Tx) error {
 		res, err := tx.Exec(`