feat(quic): replace probe UDP data plane with QUIC datagrams

backend/src/MoShiro.Backend.Analysis/Metrics/LinkMetrics.cs

@@ -26,10 +26,18 @@ public static class LinkMetrics
         "jitter.down", s_udpMsg, Ops.OwdVar(Dir.Down), "Jitter (down)", "One-way delay variation, offset and drift removed.", Unit.Ms, [Stat.P95], good: 3, poor: 20);
 
     public static readonly MetricDef LossRun = Metric.RunLength(
-        "loss.run", s_udpMsg, Ops.LossRuns, "Loss runs", "Lengths of consecutive lost packets.",
+        "loss.run", s_udpMsg, Ops.LossRuns(Dir.Down), "Loss runs (legacy downstream alias)", "Legacy downstream-only consecutive loss metric.",
         new MetricExport("loss.run_max", Stat.Max, Unit.Packets, 2, 10),
         new MetricExport("loss.run_mean", Stat.Mean, Unit.Packets));
 
+    public static readonly MetricDef LossRunUp = Metric.Max(
+        "loss.run.up", s_udpMsg, Ops.LossRunMax(Dir.Up), "Upstream longest loss run", "Longest consecutive Probe-to-Agent Datagram loss run in each chunk; zero means no loss.",
+        Unit.Packets, "loss.run.up_max", good: 0, poor: 10);
+
+    public static readonly MetricDef LossRunDown = Metric.Max(
+        "loss.run.down", s_udpMsg, Ops.LossRunMax(Dir.Down), "Downstream longest loss run", "Longest consecutive Agent-to-Probe Datagram loss run in each chunk, conditioned on the request reaching the Agent; zero means no loss.",
+        Unit.Packets, "loss.run.down_max", good: 0, poor: 10);
+
     public static readonly MetricDef Reorder = Metric.Counter(
         "reorder", s_udpMsg, Ops.Reorder, "Reordered", "Replies that arrived after a higher sequence number.", new MetricExport("reorder", Stat.Count, Unit.Count));
 

backend/src/MoShiro.Backend.Analysis/Metrics/MetricRegistry.cs

@@ -11,7 +11,7 @@ public static class MetricRegistry
     public static readonly IReadOnlyList<MetricDef> All =
     [
         LinkMetrics.Rtt, LinkMetrics.LossUp, LinkMetrics.LossDown, LinkMetrics.LossTotal,
-        LinkMetrics.JitterUp, LinkMetrics.JitterDown, LinkMetrics.LossRun, LinkMetrics.Reorder, LinkMetrics.Dup, LinkMetrics.SamplesUdp,
+        LinkMetrics.JitterUp, LinkMetrics.JitterDown, LinkMetrics.LossRun, LinkMetrics.LossRunUp, LinkMetrics.LossRunDown, LinkMetrics.Reorder, LinkMetrics.Dup, LinkMetrics.SamplesUdp,
         TcpMetrics.Rtt, TcpMetrics.Slow, TcpMetrics.Stall, TcpMetrics.StallMax, TcpMetrics.Retrans, TcpMetrics.Srtt, TcpMetrics.BulkRate, TcpMetrics.BulkPeak, TcpMetrics.SamplesTcp,
         SessionMetrics.ConnectSuccess, SessionMetrics.ConnectTcp, SessionMetrics.ConnectTls,
         SessionMetrics.FailTimeout, SessionMetrics.FailReset, SessionMetrics.FailTls,
@@ -22,7 +22,8 @@ public static class MetricRegistry
     /// <summary>指标分组：前端按分组展示，新增指标只需要把它加进分组。</summary>
     public static readonly IReadOnlyList<PresetDef> Presets =
     [
-        new("udp", "UDP", ["loss.up", "loss.down", "loss.total", "rtt.p50", "rtt.p95", "rtt.p99", "jitter.up.p95", "jitter.down.p95", "loss.run_max", "reorder", "dup"]),
+        new("quic", "QUIC Datagram", ["loss.up", "loss.down", "loss.total", "rtt.p50", "rtt.p95", "rtt.p99", "jitter.up.p95", "jitter.down.p95", "loss.run.up_max", "loss.run.down_max", "reorder", "dup"]),
+        new("udp", "QUIC Datagram (legacy alias)", ["loss.up", "loss.down", "loss.total", "rtt.p50", "rtt.p95", "rtt.p99", "jitter.up.p95", "jitter.down.p95", "loss.run_max", "reorder", "dup"]),
         new("tcp", "TCP", ["tcp.rtt.p50", "tcp.rtt.p95", "tcp.rtt.p99", "tcp.rtt.p999", "tcp.rtt.max", "tcp.rtt.tail", "tcp.slow", "tcp.stall.per_min", "tcp.stall_max", "tcp.retrans", "tcp.srtt.p95"]),
         new("connect", "Connect", ["connect.success", "connect.tcp_ms.p95", "connect.tls_ms.p95", "connect.fail.timeout", "connect.fail.rst", "connect.fail.tls"]),
         new("session", "Session", ["hold.resets.per_h", "hold.lifetime_max"]),

backend/src/MoShiro.Backend.Analysis/Metrics/SessionMetrics.cs

@@ -1,6 +1,6 @@
 namespace MoShiro.Backend.Analysis;
 
-/// <summary>连接建立、长连接、UDP 压测（udp_train）的指标。</summary>
+/// <summary>TCP 建连、长连接、QUIC Datagram 压测（legacy kind udp_train）的指标。</summary>
 public static class SessionMetrics
 {
     private static readonly string[] s_conn = ["connect.conn"];
@@ -33,13 +33,13 @@ public static class SessionMetrics
         "hold.lifetime", s_hold, Ops.HoldLifetime, "Longest connection lifetime", "Longest observed lifetime of the held connection (ms).", Unit.Ms, "hold.lifetime_max", Better.Higher);
 
     public static readonly MetricDef TrainLoss = Metric.Ratio(
-        "train.loss", s_train, Ops.TrainLoss, "Train loss", "Loss of a fixed-rate UDP stream.", good: 1, poor: 10);
+        "train.loss", s_train, Ops.TrainLoss, "Datagram train loss", "Loss of a fixed-rate QUIC Datagram stream.", good: 1, poor: 10);
 
     public static readonly MetricDef TrainJitter = Metric.Histogram(
-        "train.jitter", s_train, Ops.TrainJitter, "Train jitter", "One-way delay variation of a fixed-rate UDP stream.", Unit.Ms, [Stat.P95], good: 3, poor: 20);
+        "train.jitter", s_train, Ops.TrainJitter, "Datagram train delay variation", "One-way delay variation of a fixed-rate QUIC Datagram stream.", Unit.Ms, [Stat.P95], good: 3, poor: 20);
 
     public static readonly MetricDef TrainRate = Metric.Histogram(
-        "train.rate", s_train, Ops.TrainRate, "Train rate", "Delivered rate of a fixed-rate UDP stream per second.", Unit.Mbps, [Stat.P50, Stat.Mean], Better.Higher);
+        "train.rate", s_train, Ops.TrainRate, "Datagram train rate", "Delivered rate of a fixed-rate QUIC Datagram stream per second.", Unit.Mbps, [Stat.P50, Stat.Mean], Better.Higher);
 
     public static readonly MetricDef SamplesConnect = Metric.Counter(
         "n.connect", s_conn, Ops.RowCount, "connect samples", "Number of connection attempts.", new MetricExport("n.connect", Stat.Count, Unit.Count), Better.None);

backend/src/MoShiro.Backend.Analysis/Models/Models.cs

@@ -12,9 +12,9 @@ public sealed class BaseModel : ServiceModelBase
 
     public override string Title => "Line quality";
 
-    public override int Version => 1;
+    public override int Version => 2;
 
-    public override IReadOnlyList<string> Needs { get; } = ["rtt.p95", "loss.total", "jitter.down.p95", "jitter.up.p95", "loss.run_max"];
+    public override IReadOnlyList<string> Needs { get; } = ["rtt.p95", "loss.total", "jitter.down.p95", "jitter.up.p95", "loss.run.up_max", "loss.run.down_max"];
 
     public override ModelScore Score(MetricView view) =>
         Combine(
@@ -24,7 +24,8 @@ public sealed class BaseModel : ServiceModelBase
                 Dim(view, "loss.total", "Packet loss", 4, s_loss),
                 Dim(view, "jitter.down.p95", "Jitter (down)", 1.5, s_jitter),
                 Dim(view, "jitter.up.p95", "Jitter (up)", 1.5, s_jitter),
-                Dim(view, "loss.run_max", "Longest loss run", 1, s_run),
+                Dim(view, "loss.run.up_max", "Longest upstream loss run", 0.5, s_run),
+                Dim(view, "loss.run.down_max", "Longest downstream loss run", 0.5, s_run),
             ],
             estimated: false);
 }

backend/src/MoShiro.Backend.Analysis/Ops/EchoOps.cs

@@ -273,7 +273,14 @@ internal static class JitterEmitter
 /// <summary>连续丢失段的长度（按发送顺序）。</summary>
 internal sealed class LossRunsOp : MetricOp
 {
-    public override string Signature => "loss_runs/1";
+    private readonly Dir _direction;
+
+    public LossRunsOp(Dir direction)
+    {
+        _direction = direction;
+    }
+
+    public override string Signature => $"loss_runs/{_direction}/2";
 
     public override void Evaluate(ChunkView view, RawStream stream, IObservationSink sink)
     {
@@ -292,7 +299,13 @@ internal sealed class LossRunsOp : MetricOp
                 continue;
             }
 
-            if (c.IsReplyLost(i))
+            bool lost = _direction switch
+            {
+                Dir.Up => c.IsUpLost(i),
+                Dir.Down => !c.IsUpLost(i) && c.IsReplyLost(i),
+                _ => c.IsReplyLost(i),
+            };
+            if (lost)
             {
                 if (run == 0)
                 {
@@ -315,6 +328,59 @@ internal sealed class LossRunsOp : MetricOp
     }
 }
 
+/// <summary>每个块一个最长连续丢包值；无丢包的有效块明确输出 0。</summary>
+internal sealed class LossRunMaxOp(Dir direction) : MetricOp
+{
+    public override string Signature => $"loss_run_max/{direction}/1";
+
+    public override void Evaluate(ChunkView view, RawStream stream, IObservationSink sink)
+    {
+        var c = new EchoColumns(stream);
+        if (!c.HasBasics || (direction != Dir.Total && c.T2 is null))
+        {
+            return;
+        }
+
+        int run = 0;
+        int maximum = 0;
+        bool hasSample = false;
+        long sampleAt = 0;
+        for (int i = 0; i < c.Count; i++)
+        {
+            if (!c.T1!.IsValid(i))
+            {
+                continue;
+            }
+
+            bool lost = direction switch
+            {
+                Dir.Up => c.IsUpLost(i),
+                Dir.Down => !c.IsUpLost(i) && c.IsReplyLost(i),
+                _ => c.IsReplyLost(i),
+            };
+            if (direction == Dir.Down && c.IsUpLost(i))
+            {
+                // A request lost before reaching the Agent is not a downstream sample.
+                run = 0;
+                continue;
+            }
+
+            if (!hasSample)
+            {
+                sampleAt = c.SentUtcMs(view, i);
+                hasSample = true;
+            }
+            run = lost ? run + 1 : 0;
+            maximum = Math.Max(maximum, run);
+        }
+
+        if (hasSample)
+        {
+            sink.Emit(sampleAt, maximum);
+        }
+    }
+}
+
 /// <summary>乱序：按到达顺序，序号比之前见过的最大序号还小。重复的序号不算乱序。</summary>
 internal sealed class ReorderOp : MetricOp
 {

backend/src/MoShiro.Backend.Analysis/Ops/Ops.cs

@@ -11,7 +11,9 @@ public static class Ops
 
     public static MetricOp OwdVar(Dir dir) => new OwdVarOp(dir);
 
-    public static MetricOp LossRuns { get; } = new LossRunsOp();
+    public static MetricOp LossRuns(Dir direction) => new LossRunsOp(direction);
+
+    public static MetricOp LossRunMax(Dir direction) => new LossRunMaxOp(direction);
 
     public static MetricOp Reorder { get; } = new ReorderOp();