diff --git a/src/runtime2/component/component_context.rs b/src/runtime2/component/component_context.rs
index b2c3435d5606f217b687597005aec6e3b4e3a262..1d00c2c83fa9b0ae269fe690f659ef94cf4c9e1d 100644
--- a/src/runtime2/component/component_context.rs
+++ b/src/runtime2/component/component_context.rs
@@ -14,6 +14,15 @@ pub enum PortInstruction {
     SourceLocation(ExpressionId),
 }
 
+impl PortInstruction {
+    pub fn is_none(&self) -> bool {
+        match self {
+            PortInstruction::None => return true,
+            _ => return false,
+        }
+    }
+}
+
 /// Directionality of a port
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
 pub enum PortKind {
@@ -29,6 +38,8 @@ pub enum PortStateFlag {
     Closed = 0x01, // If not closed, then the port is open
     BlockedDueToPeerChange = 0x02, // busy changing peers, hence use of port is temporarily blocked
     BlockedDueToFullBuffers = 0x04,
+    Transmitted = 0x08, // Transmitted, so cannot be used anymore
+    Received = 0x10, // Received, so cannot be used yet, only after the sync round
 }
 
 #[derive(Copy, Clone)]
@@ -48,6 +59,14 @@ impl PortState {
         return !self.is_closed();
     }
 
+    #[inline]
+    pub fn can_send(&self) -> bool {
+        return
+            !self.is_set(PortStateFlag::Closed) &&
+            !self.is_set(PortStateFlag::Transmitted) &&
+            !self.is_set(PortStateFlag::Received);
+    }
+
     #[inline]
     pub fn is_closed(&self) -> bool {
         return self.is_set(PortStateFlag::Closed);
@@ -60,6 +79,11 @@ impl PortState {
             self.is_set(PortStateFlag::BlockedDueToFullBuffers);
     }
 
+    #[inline]
+    pub fn is_blocked_due_to_port_change(&self) -> bool {
+        return self.is_set(PortStateFlag::BlockedDueToPeerChange);
+    }
+
     // lower-level utils
     #[inline]
     pub fn set(&mut self, flag: PortStateFlag) {
@@ -85,7 +109,8 @@ impl Debug for PortState {
         for (flag_name, flag_value) in &[
             ("closed", Closed),
             ("blocked_peer_change", BlockedDueToPeerChange),
-            ("blocked_full_buffers", BlockedDueToFullBuffers)
+            ("blocked_full_buffers", BlockedDueToFullBuffers),
+            ("transmitted", Transmitted),
         ] {
             s.field(flag_name, &self.is_set(*flag_value));
         }
@@ -176,7 +201,7 @@ impl CompCtx {
         return Channel{ putter_id, getter_id };
     }
 
-    /// Adds a new port. Make sure to call `add_peer` afterwards.
+    /// Adds a new port. Make sure to call `change_peer` afterwards.
     pub(crate) fn add_port(&mut self, peer_comp_id: CompId, peer_port_id: PortId, kind: PortKind, state: PortState) -> LocalPortHandle {
         let self_id = PortId(self.take_port_id());
         self.ports.push(Port{
@@ -189,7 +214,28 @@ impl CompCtx {
         return LocalPortHandle(self_id);
     }
 
-    /// Removes a port. Make sure you called `remove_peer` first.
+    /// Adds a self-reference. Called by the runtime/scheduler
+    pub(crate) fn add_self_reference(&mut self, self_handle: CompHandle) {
+        debug_assert_eq!(self.id, self_handle.id());
+        debug_assert!(self.get_peer_index_by_id(self.id).is_none());
+        self.peers.push(Peer{
+            id: self.id,
+            num_associated_ports: 0,
+            handle: self_handle
+        });
+    }
+
+    /// Removes a self-reference. Called by the runtime/scheduler
+    pub(crate) fn remove_self_reference(&mut self) -> Option<CompKey> {
+        let self_index = self.get_peer_index_by_id(self.id).unwrap();
+        let peer = &mut self.peers[self_index];
+        let maybe_comp_key = peer.handle.decrement_users();
+        self.peers.remove(self_index);
+
+        return maybe_comp_key;
+    }
+
+    /// Removes a port. Make sure you called `change_peer` first.
     pub(crate) fn remove_port(&mut self, port_handle: LocalPortHandle) -> Port {
         let port_index = self.must_get_port_index(port_handle);
         let port = self.ports.remove(port_index);
@@ -307,11 +353,6 @@ impl CompCtx {
     // Local utilities
     // -------------------------------------------------------------------------
 
-    #[inline]
-    fn requires_peer_reference(port: &Port, self_id: CompId, required_if_closed: bool) -> bool {
-        return (!port.state.is_closed() || required_if_closed) && port.peer_comp_id != self_id;
-    }
-
     fn must_get_port_index(&self, handle: LocalPortHandle) -> usize {
         for (index, port) in self.ports.iter().enumerate() {
             if port.self_id == handle.0 {