diff --git a/tines-core/tests/pair.rs b/tines-core/tests/pair.rs
index 31a4cc1..b69a833 100644
--- a/tines-core/tests/pair.rs
+++ b/tines-core/tests/pair.rs
@@ -3,7 +3,7 @@ use common::PairTransport;
 
 use std::collections::BTreeSet;
 use tines_core::observation::Payload;
-use tines_core::transport::{Event, FrameBuf, Transport};
+use tines_core::transport::{Event, FrameBuf, SendError, Transport};
 use tines_core::{consts, LatestWins, MemStore, Node, ObserveError, Store};
 
 #[test]
@@ -206,3 +206,17 @@ fn third_party_observation_propagates_within_contact() {
     );
     assert_eq!(nb.store().len(), 1);
 }
+
+#[test]
+fn pair_transport_disconnect_enqueues_lost() {
+    let (mut a, _b) = PairTransport::pair(1500);
+    a.disconnect();
+    assert_eq!(a.poll(), Some(Event::Lost(1)));
+}
+
+#[test]
+fn pair_transport_send_rejects_unreachable() {
+    let (mut a, _b) = PairTransport::pair(1500);
+    // a's only peer is 1; sending to 2 is unreachable.
+    assert_eq!(a.send(&2, b"hi"), Err(SendError::Unreachable));
+}
diff --git a/tines-sim/src/transport.rs b/tines-sim/src/transport.rs
index fbde1ee..adf8e1f 100644
--- a/tines-sim/src/transport.rs
+++ b/tines-sim/src/transport.rs
@@ -57,10 +57,11 @@ impl Transport for SimTransport {
             return Ok(());
         }
         let buf = FrameBuf::from_slice(frame).map_err(|_| SendError::TooLarge)?;
+        let dup = w.rng.gen::<f64>() < w.cfg.dup;
         w.inboxes[*to].push_back(Event::Frame(self.me, buf.clone()));
         w.frames_sent += 1;
-        if w.rng.gen::<f64>() < w.cfg.dup {
-            w.inboxes[*to].push_back(Event::Frame(self.me, buf.clone()));
+        if dup {
+            w.inboxes[*to].push_back(Event::Frame(self.me, buf));
             w.frames_sent += 1;
         }
         Ok(())
diff --git a/tines-sim/tests/props.rs b/tines-sim/tests/props.rs
index 84b0af6..8848324 100644
--- a/tines-sim/tests/props.rs
+++ b/tines-sim/tests/props.rs
@@ -72,12 +72,19 @@ type Scenario = (usize, ContactTrace, Vec<(usize, Vec<u8>, Vec<u8>)>);
 fn scenario() -> impl Strategy<Value = Scenario> {
     (2..=6usize).prop_flat_map(|nodes| {
         let trace = proptest::collection::vec(contact(nodes), 1..=12usize);
-        let obs = proptest::collection::vec(observation(), nodes..=nodes);
-        (trace, obs).prop_map(move |(contacts, per_node)| {
+        // Each node publishes 0..=10 observations, flattened to (node, topic,
+        // payload) triples so per-node counts vary across scenarios.
+        let per_node = proptest::collection::vec(
+            proptest::collection::vec(observation(), 0..=10usize),
+            nodes..=nodes,
+        );
+        (trace, per_node).prop_map(move |(contacts, per_node)| {
             let trace = ContactTrace { contacts };
             let mut list = Vec::new();
-            for (node, (topic, payload)) in per_node.into_iter().enumerate() {
-                list.push((node, topic, payload));
+            for (node, node_obs) in per_node.into_iter().enumerate() {
+                for (topic, payload) in node_obs {
+                    list.push((node, topic, payload));
+                }
             }
             (nodes, trace, list)
         })