fix(monitor): throttle stats, show slow mixer edges, and improve moq_peer counters

crates/core/src/state.rs

@@ -160,7 +160,11 @@ pub enum NodeState {
     /// - Partial functionality (some features unavailable)
     ///
     /// The node continues processing but users should be aware of reduced quality.
-    Degraded { reason: String },
+    Degraded {
+        reason: String,
+        #[ts(type = "JsonValue")]
+        details: Option<serde_json::Value>,
+    },
 
     /// Node has encountered a fatal error and stopped processing.
     /// Manual intervention is required to restart the node.
@@ -306,7 +310,8 @@ pub mod state_helpers {
         state_tx: &mpsc::Sender<NodeStateUpdate>,
         node_name: &str,
         reason: impl Into<String>,
+        details: Option<serde_json::Value>,
     ) {
-        emit_state(state_tx, node_name, NodeState::Degraded { reason: reason.into() });
+        emit_state(state_tx, node_name, NodeState::Degraded { reason: reason.into(), details });
     }
 }

crates/core/src/stats.rs

@@ -6,7 +6,7 @@
 //!
 //! This module provides types and utilities for collecting runtime statistics
 //! from nodes during pipeline execution. Statistics are throttled to prevent
-//! overload (typically every 10 seconds or 1000 packets).
+//! overload (typically every 2 seconds or 1000 packets).
 
 use serde::{Deserialize, Serialize};
 use std::time::SystemTime;
@@ -35,7 +35,7 @@ impl Default for NodeStats {
 }
 
 /// A statistics update message sent by a node to report its current metrics.
-/// These updates are throttled to prevent overload (typically every 10s or 1000 packets).
+/// These updates are throttled to prevent overload (typically every 2s or 1000 packets).
 #[derive(Debug, Clone)]
 pub struct NodeStatsUpdate {
     /// The unique identifier of the node reporting the stats
@@ -47,18 +47,19 @@ pub struct NodeStatsUpdate {
 }
 
 /// Helper for tracking and throttling node statistics updates.
-/// Automatically sends updates every 10 seconds or 1000 packets.
+/// Automatically sends updates every 2 seconds or 1000 packets.
 pub struct NodeStatsTracker {
     stats: NodeStats,
     start_time: std::time::Instant,
     last_send: std::time::Instant,
+    has_sent_once: bool,
     node_id: String,
     stats_tx: Option<tokio::sync::mpsc::Sender<NodeStatsUpdate>>,
 }
 
 impl NodeStatsTracker {
     /// Throttling configuration
-    const SEND_INTERVAL: std::time::Duration = std::time::Duration::from_secs(10);
+    const SEND_INTERVAL: std::time::Duration = std::time::Duration::from_secs(2);
     const SEND_PACKET_THRESHOLD: u64 = 1000;
 
     /// Create a new stats tracker for a node
@@ -67,7 +68,14 @@ impl NodeStatsTracker {
         stats_tx: Option<tokio::sync::mpsc::Sender<NodeStatsUpdate>>,
     ) -> Self {
         let now = std::time::Instant::now();
-        Self { stats: NodeStats::default(), start_time: now, last_send: now, node_id, stats_tx }
+        Self {
+            stats: NodeStats::default(),
+            start_time: now,
+            last_send: now,
+            has_sent_once: false,
+            node_id,
+            stats_tx,
+        }
     }
 
     /// Record a received packet
@@ -88,23 +96,49 @@ impl NodeStatsTracker {
         self.stats.sent += 1;
     }
 
+    /// Record multiple sent packets (for batched stats reporting)
+    #[inline]
+    pub const fn sent_n(&mut self, count: u64) {
+        self.stats.sent += count;
+    }
+
     /// Record a discarded packet
     #[inline]
     pub const fn discarded(&mut self) {
         self.stats.discarded += 1;
     }
 
+    /// Record multiple discarded packets (for batched stats reporting)
+    #[inline]
+    pub const fn discarded_n(&mut self, count: u64) {
+        self.stats.discarded += count;
+    }
+
     /// Record an error
     #[inline]
     pub const fn errored(&mut self) {
         self.stats.errored += 1;
     }
 
-    /// Automatically send stats if threshold is met (every 10s or 1000 packets).
+    /// Record multiple errors (for batched stats reporting)
+    #[inline]
+    pub const fn errored_n(&mut self, count: u64) {
+        self.stats.errored += count;
+    }
+
+    /// Automatically send stats if threshold is met (every 2s or 1000 packets).
     /// Call this after processing a batch of packets.
     pub fn maybe_send(&mut self) {
-        let should_send = self.last_send.elapsed() >= Self::SEND_INTERVAL
-            || self.stats.received.is_multiple_of(Self::SEND_PACKET_THRESHOLD);
+        // Many nodes only increment one side of the counters (e.g. pure sources only `sent`,
+        // pure sinks only `received`). Use the max to keep the threshold behavior consistent
+        // across node shapes and avoid the `0.is_multiple_of(..)` pitfall.
+        let packet_count = self.stats.received.max(self.stats.sent).max(self.stats.discarded);
+
+        // Always emit the first non-empty snapshot promptly so monitoring can "lock on"
+        // even if the node later blocks under backpressure.
+        let should_send = (!self.has_sent_once && packet_count > 0)
+            || self.last_send.elapsed() >= Self::SEND_INTERVAL
+            || (packet_count > 0 && packet_count.is_multiple_of(Self::SEND_PACKET_THRESHOLD));
 
         if should_send {
             self.force_send();
@@ -123,6 +157,44 @@ impl NodeStatsTracker {
                 timestamp: SystemTime::now(),
             });
             self.last_send = std::time::Instant::now();
+            self.has_sent_once = true;
         }
     }
 }
+
+#[cfg(test)]
+#[allow(clippy::unwrap_used)]
+mod tests {
+    use super::*;
+    use tokio::sync::mpsc;
+
+    #[tokio::test]
+    async fn maybe_send_does_not_fire_when_empty() {
+        let (tx, mut rx) = mpsc::channel::<NodeStatsUpdate>(10);
+        let mut tracker = NodeStatsTracker::new("node".to_string(), Some(tx));
+
+        tracker.maybe_send();
+
+        assert!(rx.try_recv().is_err());
+    }
+
+    #[tokio::test]
+    async fn maybe_send_emits_on_first_activity_and_on_threshold() {
+        let (tx, mut rx) = mpsc::channel::<NodeStatsUpdate>(10);
+        let mut tracker = NodeStatsTracker::new("node".to_string(), Some(tx));
+
+        tracker.sent();
+        tracker.maybe_send();
+        let first = rx.try_recv().unwrap();
+        assert_eq!(first.stats.sent, 1);
+
+        for _ in 1..NodeStatsTracker::SEND_PACKET_THRESHOLD {
+            tracker.sent();
+            tracker.maybe_send();
+        }
+
+        let threshold = rx.try_recv().unwrap();
+        assert_eq!(threshold.node_id, "node");
+        assert_eq!(threshold.stats.sent, NodeStatsTracker::SEND_PACKET_THRESHOLD);
+    }
+}

crates/nodes/Cargo.toml

@@ -97,7 +97,7 @@ default = [
 # Individual features for each node.
 passthrough = ["dep:schemars"]
 audio_gain = ["dep:schemars"]
-audio_mixer = ["dep:schemars"]
+audio_mixer = ["dep:schemars", "dep:serde_json"]
 audio_resampler = ["dep:schemars", "dep:rubato"]
 audio_pacer = ["dep:schemars"]
 file_io = ["dep:schemars"]