fix(net): skip old groups without reporting them as lost

rs/moq-net/src/lite/subscriber.rs

@@ -766,7 +766,11 @@ impl<S: crate::transport::poll::Session> GroupRecv<S> {
 						}
 					};
 
-					let GroupRecvState::Serve { group, .. } = std::mem::replace(&mut self.state, GroupRecvState::Done)
+					// Held until the group settles below, so a frame the track or group cut
+					// short drops into an already-aborted group instead of reporting a loss.
+					let GroupRecvState::Serve {
+						group, ingest: _ingest, ..
+					} = std::mem::replace(&mut self.state, GroupRecvState::Done)
 					else {
 						unreachable!()
 					};

rs/moq-net/src/model/frame.rs

@@ -359,11 +359,16 @@ impl<G: std::borrow::BorrowMut<group::Producer>> Drop for Raw<G> {
 		if !self.done {
 			// An unfinished frame leaves the group stream broken; fail the group so
 			// consumers surface an error instead of hanging on the partial forever.
-			tracing::warn!(
-				group = self.group.borrow_mut().info().sequence,
-				"frame::Producer dropped before writing all bytes"
-			);
-			self.group.borrow_mut().frame_abort(Error::Dropped);
+			// A group already aborted (superseded, evicted, cancelled) carries its own
+			// reason, so cutting its in-flight frame short is expected.
+			let group = self.group.borrow_mut();
+			if !group.is_aborted() {
+				tracing::warn!(
+					group = group.info().sequence,
+					"frame::Producer dropped before writing all bytes"
+				);
+			}
+			group.frame_abort(Error::Dropped);
 		}
 	}
 }

rs/moq-net/src/model/resume.rs

@@ -1214,12 +1214,16 @@ impl Group {
 			Some((_, err)) => {
 				// The only place a spliced group's loss becomes visible, so say which
 				// frames went missing rather than leaving a stuck group to explain itself.
-				tracing::warn!(
-					group = self.sequence,
-					frame = self.index,
-					%err,
-					"no route can serve the rest of this group"
-				);
+				// An old group was skipped on purpose (something newer superseded it), so
+				// it is not a loss worth reporting.
+				if !matches!(crate::StreamError::from(err), crate::StreamError::Old) {
+					tracing::warn!(
+						group = self.sequence,
+						frame = self.index,
+						%err,
+						"no route can serve the rest of this group"
+					);
+				}
 				Err(err.clone())
 			}
 			None => Ok(false),