diff --git a/masque/builder/renderpather.py b/masque/builder/renderpather.py
index 29a8173..4bc3b5f 100644
--- a/masque/builder/renderpather.py
+++ b/masque/builder/renderpather.py
@@ -430,6 +430,7 @@ class RenderPather(PatherMixin):
         self.paths[portspec].append(step)
 
         self.pattern.ports[portspec] = out_port.copy()
+        self._log_port_update(portspec)
 
         if plug_into is not None:
             self.plugged({portspec: plug_into})
@@ -506,6 +507,7 @@ class RenderPather(PatherMixin):
         step = RenderStep('S', tool, port.copy(), out_port.copy(), data)
         self.paths[portspec].append(step)
         self.pattern.ports[portspec] = out_port.copy()
+        self._log_port_update(portspec)
 
         if plug_into is not None:
             self.plugged({portspec: plug_into})
diff --git a/masque/pattern.py b/masque/pattern.py
index 94555cc..05a8962 100644
--- a/masque/pattern.py
+++ b/masque/pattern.py
@@ -638,6 +638,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         """
         for entry in chain(chain_elements(self.shapes, self.labels, self.refs), self.ports.values()):
             cast('Positionable', entry).translate(offset)
+        self._log_bulk_update(f"translate({offset})")
         return self
 
     def scale_elements(self, c: float) -> Self:
@@ -705,6 +706,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         self.rotate_elements(rotation)
         self.rotate_element_centers(rotation)
         self.translate_elements(+pivot)
+        self._log_bulk_update(f"rotate_around({pivot}, {rotation})")
         return self
 
     def rotate_element_centers(self, rotation: float) -> Self:
@@ -761,6 +763,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         """
         for entry in chain(chain_elements(self.shapes, self.refs, self.labels), self.ports.values()):
             cast('Flippable', entry).flip_across(axis=axis)
+        self._log_bulk_update(f"mirror({axis})")
         return self
 
     def copy(self) -> Self:
@@ -1160,6 +1163,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
             pp.rotate_around(pivot, rotation)
             pp.translate(offset)
             self.ports[name] = pp
+            self._log_port_update(name)
 
         if append:
             if isinstance(other, Abstract):
@@ -1315,6 +1319,7 @@ class Pattern(PortList, AnnotatableImpl, Mirrorable):
         # get rid of plugged ports
         for ki, vi in map_in.items():
             del self.ports[ki]
+            self._log_port_removal(ki)
             map_out[vi] = None
 
         if isinstance(other, Pattern):
diff --git a/masque/ports.py b/masque/ports.py
index 45aedb5..5260b19 100644
--- a/masque/ports.py
+++ b/masque/ports.py
@@ -17,6 +17,7 @@ from .error import PortError, format_stacktrace
 
 
 logger = logging.getLogger(__name__)
+port_logger = logging.getLogger('masque.ports')
 
 
 @functools.total_ordering
@@ -207,6 +208,19 @@ class PortList(metaclass=ABCMeta):
     def ports(self, value: dict[str, Port]) -> None:
         pass
 
+    def _log_port_update(self, name: str) -> None:
+        """ Log the current state of the named port """
+        port_logger.info("Port %s: %s", name, self.ports[name])
+
+    def _log_port_removal(self, name: str) -> None:
+        """ Log that the named port has been removed """
+        port_logger.info("Port %s: removed", name)
+
+    def _log_bulk_update(self, label: str) -> None:
+        """ Log all current ports at DEBUG level """
+        for name, port in self.ports.items():
+            port_logger.debug("%s: Port %s: %s", label, name, port)
+
     @overload
     def __getitem__(self, key: str) -> Port:
         pass
@@ -260,6 +274,7 @@ class PortList(metaclass=ABCMeta):
             raise PortError(f'Port {name} already exists.')
         assert name not in self.ports
         self.ports[name] = value
+        self._log_port_update(name)
         return self
 
     def rename_ports(
@@ -286,11 +301,22 @@ class PortList(metaclass=ABCMeta):
             if duplicates:
                 raise PortError(f'Unrenamed ports would be overwritten: {duplicates}')
 
+        for kk, vv in mapping.items():
+            if vv is None:
+                self._log_port_removal(kk)
+            elif vv != kk:
+                self._log_port_removal(kk)
+
         renamed = {vv: self.ports.pop(kk) for kk, vv in mapping.items()}
         if None in renamed:
             del renamed[None]
 
         self.ports.update(renamed)      # type: ignore
+
+        for vv in mapping.values():
+            if vv is not None:
+                self._log_port_update(vv)
+
         return self
 
     def add_port_pair(
@@ -319,6 +345,8 @@ class PortList(metaclass=ABCMeta):
             }
         self.check_ports(names)
         self.ports.update(new_ports)
+        self._log_port_update(names[0])
+        self._log_port_update(names[1])
         return self
 
     def plugged(
@@ -388,6 +416,7 @@ class PortList(metaclass=ABCMeta):
 
         for pp in chain(a_names, b_names):
             del self.ports[pp]
+            self._log_port_removal(pp)
         return self
 
     def check_ports(