T2.3-T2.6: BWE guard, relay conformance Tier A/B/C, Prometheus metrics

crates/wzp-relay/src/room.rs

@@ -17,6 +17,7 @@ use wzp_proto::packet::TrunkFrame;
 use wzp_proto::quality::{AdaptiveQualityController, Tier};
 use wzp_proto::traits::QualityController;
 
+use crate::conformance::ConformanceMeter;
 use crate::metrics::RelayMetrics;
 use crate::trunk::TrunkBatcher;
 
@@ -780,6 +781,7 @@ async fn run_participant_plain(
     let mut max_forward_ms = 0u64;
     let mut send_errors = 0u64;
     let mut last_log_instant = std::time::Instant::now();
+    let mut conformance = ConformanceMeter::new();
 
     let mut tap_stats = if debug_tap.as_ref().map_or(false, |t| t.matches(&room_name)) {
         Some(TapStats::new())
@@ -829,6 +831,22 @@ async fn run_participant_plain(
             );
         }
 
+        // Conformance check (Tier A/B/C — observe-only)
+        let violation = conformance
+            .observe(&pkt.header, pkt.payload.len(), std::time::Instant::now())
+            .err();
+        metrics.record_conformance(&pkt.header, pkt.payload.len(), recv_gap_ms, violation);
+        if let Some(v) = violation {
+            warn!(
+                room = %room_name,
+                participant = participant_id,
+                codec = ?pkt.header.codec_id,
+                seq = pkt.header.seq,
+                violation = ?v,
+                "conformance violation"
+            );
+        }
+
         // Update per-session quality metrics if a quality report is present
         if let Some(ref report) = pkt.quality_report {
             metrics.update_session_quality(session_id, report);
@@ -998,6 +1016,7 @@ async fn run_participant_trunked(
     let mut max_forward_ms = 0u64;
     let mut send_errors = 0u64;
     let mut last_log_instant = std::time::Instant::now();
+    let mut conformance = ConformanceMeter::new();
 
     info!(
         room = %room_name,
@@ -1051,6 +1070,22 @@ async fn run_participant_trunked(
                     );
                 }
 
+                // Conformance check (Tier A/B/C — observe-only)
+                let violation = conformance
+                    .observe(&pkt.header, pkt.payload.len(), std::time::Instant::now())
+                    .err();
+                metrics.record_conformance(&pkt.header, pkt.payload.len(), recv_gap_ms, violation);
+                if let Some(v) = violation {
+                    warn!(
+                        room = %room_name,
+                        participant = participant_id,
+                        codec = ?pkt.header.codec_id,
+                        seq = pkt.header.seq,
+                        violation = ?v,
+                        "conformance violation (trunked)"
+                    );
+                }
+
                 if let Some(ref report) = pkt.quality_report {
                     metrics.update_session_quality(session_id, report);
                 }