diff --git a/src/macros.rs b/src/macros.rs
index a377585f4426a71b9c85d6181a502652a69e7891..efe5ce62c31163a0cef6c8340f05e14de173f927 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -9,16 +9,16 @@ macro_rules! log {
         // }
     }};
     (@MARK, $logger:expr, $($arg:tt)*) => {{
-        if let Some(w) = $logger.line_writer() {
-            let _ = writeln!(w, $($arg)*);
-        }
+        // if let Some(w) = $logger.line_writer() {
+        //     let _ = writeln!(w, $($arg)*);
+        // }
     }};
     (@ENDPT, $logger:expr, $($arg:tt)*) => {{
         // ignore
     }};
     ($logger:expr, $($arg:tt)*) => {{
-        if let Some(w) = $logger.line_writer() {
-            let _ = writeln!(w, $($arg)*);
-        }
+        // if let Some(w) = $logger.line_writer() {
+        //     let _ = writeln!(w, $($arg)*);
+        // }
     }};
 }
diff --git a/src/runtime/communication.rs b/src/runtime/communication.rs
index 30f7f4b74ab9feca14968d12ab5749e9583859b1..953151bdc93532b35e4ca164763cd350ecd96ba7 100644
--- a/src/runtime/communication.rs
+++ b/src/runtime/communication.rs
@@ -396,6 +396,7 @@ impl Connector {
         let ret = match decision {
             Decision::Failure => {
                 // dropping {branching_proto_components, branching_native}
+                log!(cu.inner.logger, "Failure with {:#?}", &rctx.solution_storage);
                 Err(Se::RoundFailure)
             }
             Decision::Success(predicate) => {
@@ -903,8 +904,8 @@ impl BranchingProtoComponent {
                     } else {
                         // keep in "unblocked"
                         branch.inner.did_put_or_get.insert(putter);
-                        log!(cu.logger(), "Proto component {:?} putting payload {:?} on port {:?} (using var {:?})",
-                            proto_component_id, &payload, putter, var);
+                        log!(cu.logger(), "Proto component {:?} with pred {:?} putting payload {:?} on port {:?} (using var {:?})",
+                            proto_component_id, &predicate, &payload, putter, var);
                         let msg = SendPayloadMsg { predicate: predicate.clone(), payload };
                         rctx.putter_push(cu, putter, msg);
                         drainer.add_input(predicate, branch);
@@ -1033,6 +1034,7 @@ impl BranchingProtoComponent {
                 for (k, v) in branch.inner.inbox.drain() {
                     old.inner.inbox.insert(k, v);
                 }
+                old.ended |= branch.ended;
             }
         }
     }
@@ -1109,6 +1111,7 @@ impl SolutionStorage {
         let Self { subtree_solutions, new_local, old_local, .. } = self;
         let was_new = subtree_solutions[index].insert(predicate.clone());
         if was_new {
+            // iterator over SETS of solutions, one for every component except `subtree_id` (me)
             let set_visitor = left.chain(right).map(|index| &subtree_solutions[index]);
             Self::elaborate_into_new_local_rec(cu, predicate, set_visitor, old_local, new_local);
         }
@@ -1168,13 +1171,6 @@ impl NonsyncProtoContext<'_> {
     pub fn new_component(&mut self, moved_ports: HashSet<PortId>, state: ComponentState) {
         // called by a PROTO COMPONENT. moves its own ports.
         // 1. sanity check: this component owns these ports
-        log!(
-            self.logger,
-            "Component {:?} added new component with state {:?}, moving ports {:?}",
-            self.proto_component_id,
-            &state,
-            &moved_ports
-        );
         // sanity check
         for port in moved_ports.iter() {
             assert_eq!(
@@ -1184,6 +1180,14 @@ impl NonsyncProtoContext<'_> {
         }
         // 2. create new component
         let new_cid = self.current_state.id_manager.new_component_id();
+        log!(
+            self.logger,
+            "Component {:?} added new component {:?} with state {:?}, moving ports {:?}",
+            self.proto_component_id,
+            new_cid,
+            &state,
+            &moved_ports
+        );
         self.unrun_components.push((new_cid, state));
         // 3. update ownership of moved ports
         for port in moved_ports.iter() {
@@ -1225,8 +1229,18 @@ impl NonsyncProtoContext<'_> {
 }
 impl ProtoComponentBranch {
     fn feed_msg(&mut self, getter: PortId, payload: Payload) {
-        let was = self.inner.inbox.insert(getter, payload);
-        assert!(was.is_none())
+        let e = self.inner.inbox.entry(getter);
+        use std::collections::hash_map::Entry;
+        match e {
+            Entry::Vacant(ev) => {
+                // new message
+                ev.insert(payload);
+            }
+            Entry::Occupied(eo) => {
+                // redundant recv. can happen as a result of a component A having two branches X and Y related by
+                assert_eq!(eo.get(), &payload);
+            }
+        }
     }
 }
 impl<'a, K: Eq + Hash + 'static, V: 'static> CyclicDrainer<'a, K, V> {
diff --git a/src/runtime/tests.rs b/src/runtime/tests.rs
index e758c82a34f270a78d78d1574f131a6c9a574246..622f006ee0daf87fc2f3ff6c0c8a11843dd3abbe 100644
--- a/src/runtime/tests.rs
+++ b/src/runtime/tests.rs
@@ -1019,7 +1019,7 @@ fn pdl_msg_consensus() {
 fn sequencer3_prim() {
     let test_log_path = Path::new("./logs/sequencer3_prim");
     let pdl = b"
-    primitive seq3primitive(out a, out b, out c) {
+    primitive sequencer3(out a, out b, out c) {
         int i = 0;
         while(true) synchronous {
             out to = a;
@@ -1035,14 +1035,14 @@ fn sequencer3_prim() {
     let pd = reowolf::ProtocolDescription::parse(pdl).unwrap();
     let mut c = file_logged_configured_connector(0, test_log_path, Arc::new(pd));
 
-    // setup a session between (a) native, and (b) primitive sequencer3, connected by 3 ports.
+    // setup a session between (a) native, and (b) sequencer3, connected by 3 ports.
     let [p0, g0] = c.new_port_pair();
     let [p1, g1] = c.new_port_pair();
     let [p2, g2] = c.new_port_pair();
-    c.add_component(b"seq3primitive", &[p0, p1, p2]).unwrap();
+    c.add_component(b"sequencer3", &[p0, p1, p2]).unwrap();
     c.connect(None).unwrap();
 
-    let mut which_of_three = move || {
+    let which_of_three = move |c: &mut Connector| {
         // setup three sync batches. sync. return which succeeded
         c.get(g0).unwrap();
         c.next_batch().unwrap();
@@ -1055,7 +1055,10 @@ fn sequencer3_prim() {
     const TEST_ROUNDS: usize = 50;
     // check that the batch index for rounds 0..TEST_ROUNDS are [0, 1, 2, 0, 1, 2, ...]
     for expected_batch_idx in (0..=2).cycle().take(TEST_ROUNDS) {
-        assert_eq!(expected_batch_idx, which_of_three());
+        // silent round
+        assert_eq!(0, c.sync(None).unwrap());
+        // non silent round
+        assert_eq!(expected_batch_idx, which_of_three(&mut c));
     }
 }
 
@@ -1079,7 +1082,7 @@ fn sequencer3_comp() {
     composite fifo1(in a, out b) {
         new fifo1_init(null, a, b);
     }
-    composite seq3composite(out a, out b, out c) {
+    composite sequencer3(out a, out b, out c) {
         channel d -> e;
         channel f -> g;
         channel h -> i;
@@ -1098,26 +1101,153 @@ fn sequencer3_comp() {
     let pd = reowolf::ProtocolDescription::parse(pdl).unwrap();
     let mut c = file_logged_configured_connector(0, test_log_path, Arc::new(pd));
 
-    // setup a session between (a) native, and (b) composite sequencer3, connected by 3 ports.
+    // setup a session between (a) native, and (b) sequencer3, connected by 3 ports.
     let [p0, g0] = c.new_port_pair();
     let [p1, g1] = c.new_port_pair();
     let [p2, g2] = c.new_port_pair();
-    c.add_component(b"seq3composite", &[p0, p1, p2]).unwrap();
+    c.add_component(b"sequencer3", &[p0, p1, p2]).unwrap();
     c.connect(None).unwrap();
 
-    let mut which_of_three = move || {
+    let which_of_three = move |c: &mut Connector| {
         // setup three sync batches. sync. return which succeeded
         c.get(g0).unwrap();
         c.next_batch().unwrap();
         c.get(g1).unwrap();
         c.next_batch().unwrap();
         c.get(g2).unwrap();
-        c.sync(None).unwrap()
+        c.sync(SEC1).unwrap()
     };
 
     const TEST_ROUNDS: usize = 50;
     // check that the batch index for rounds 0..TEST_ROUNDS are [0, 1, 2, 0, 1, 2, ...]
     for expected_batch_idx in (0..=2).cycle().take(TEST_ROUNDS) {
-        assert_eq!(expected_batch_idx, which_of_three());
+        // silent round
+        assert_eq!(0, c.sync(SEC1).unwrap());
+        // non silent round
+        assert_eq!(expected_batch_idx, which_of_three(&mut c));
+    }
+}
+
+enum XRouter2Item {
+    Silent,
+    GetA,
+    GetB,
+}
+// Hardcoded pseudo-random sequence of round behaviors for the native component
+const XROUTER2_ITEMS: &[XRouter2Item] = {
+    use XRouter2Item::{GetA as A, GetB as B, Silent as S};
+    &[
+        B, A, S, B, A, A, B, S, B, S, A, A, S, B, B, S, B, S, B, B, S, B, B, A, B, B, A, B, A, B,
+        S, B, S, B, S, A, S, B, A, S, B, A, B, S, B, S, B, S, S, B, B, A, A, A, S, S, S, B, A, A,
+        A, S, S, B, B, B, A, B, S, S, A, A, B, A, B, B, A, A, A, B, A, B, S, A, B, S, A, A, B, S,
+    ]
+};
+
+#[test]
+fn xrouter2_prim() {
+    let test_log_path = Path::new("./logs/xrouter2_prim");
+    let pdl = b"
+    primitive xrouter2(in a, out b, out c) {
+        while(true) synchronous {
+            if(fires(a)) {
+                if(fires(b)) put(b, get(a));
+                else         put(c, get(a));
+            }
+        }
+    }
+    ";
+    let pd = reowolf::ProtocolDescription::parse(pdl).unwrap();
+    let mut c = file_logged_configured_connector(0, test_log_path, Arc::new(pd));
+
+    // setup a session between (a) native, and (b) xrouter2, connected by 3 ports.
+    let [p0, g0] = c.new_port_pair();
+    let [p1, g1] = c.new_port_pair();
+    let [p2, g2] = c.new_port_pair();
+    c.add_component(b"xrouter2", &[g0, p1, p2]).unwrap();
+    c.connect(None).unwrap();
+
+    let now = std::time::Instant::now();
+    for item in XROUTER2_ITEMS.iter() {
+        match item {
+            XRouter2Item::Silent => {}
+            XRouter2Item::GetA => {
+                c.put(p0, TEST_MSG.clone()).unwrap();
+                c.get(g1).unwrap();
+            }
+            XRouter2Item::GetB => {
+                c.put(p0, TEST_MSG.clone()).unwrap();
+                c.get(g2).unwrap();
+            }
+        }
+        assert_eq!(0, c.sync(SEC1).unwrap());
+    }
+    println!("PRIM {:?}", now.elapsed());
+}
+#[test]
+fn xrouter2_comp() {
+    let test_log_path = Path::new("./logs/xrouter2_comp");
+    let pdl = b"
+    primitive lossy(in a, out b) {
+        while(true) synchronous {
+            if(fires(a)) {
+                msg m = get(a);
+                if(fires(b)) put(b, get(a));
+            }
+        }
+    }
+    primitive sync_drain2(in a, in b) {
+        while(true) synchronous {
+            if(fires(a)) {
+                get(a);
+                get(b);
+            }
+        }
+    }
+    composite xrouter2(in a, out b, out c) {
+        channel d -> e;
+        channel f -> g;
+        channel h -> i;
+        channel j -> k;
+        channel l -> m;
+        channel n -> o;
+        channel p -> q;
+        channel r -> s;
+        channel t -> u;
+
+        new replicator2(a, d, f); // ok
+        new replicator2(g, t, h); // ok
+        new lossy(e, l); // ok
+        new lossy(i, j); // ok
+        new replicator2(m, b, p); // ok
+        new replicator2(k, n, c); // ok
+        new merger2(q, o, r);
+        new sync_drain2(u, s);
+    }
+    ";
+    let pd = reowolf::ProtocolDescription::parse(pdl).unwrap();
+    let mut c = file_logged_configured_connector(0, test_log_path, Arc::new(pd));
+
+    // setup a session between (a) native, and (b) xrouter2, connected by 3 ports.
+    let [p0, g0] = c.new_port_pair();
+    let [p1, g1] = c.new_port_pair();
+    let [p2, g2] = c.new_port_pair();
+    c.add_component(b"xrouter2", &[g0, p1, p2]).unwrap();
+    c.connect(None).unwrap();
+
+    let now = std::time::Instant::now();
+    for item in XROUTER2_ITEMS.iter() {
+        match item {
+            XRouter2Item::Silent => {}
+            XRouter2Item::GetA => {
+                c.put(p0, TEST_MSG.clone()).unwrap();
+                c.get(g1).unwrap();
+            }
+            XRouter2Item::GetB => {
+                c.put(p0, TEST_MSG.clone()).unwrap();
+                c.get(g2).unwrap();
+            }
+        }
+        assert_eq!(0, c.sync(SEC1).unwrap());
     }
+    println!("COMP {:?}", now.elapsed());
 }