diff --git a/bdai_ros2_wrappers/bdai_ros2_wrappers/feeds.py b/bdai_ros2_wrappers/bdai_ros2_wrappers/feeds.py
index b431869..3a4c865 100644
--- a/bdai_ros2_wrappers/bdai_ros2_wrappers/feeds.py
+++ b/bdai_ros2_wrappers/bdai_ros2_wrappers/feeds.py
@@ -1,12 +1,14 @@
 # Copyright (c) 2024 Boston Dynamics AI Institute Inc.  All rights reserved.
 
-from typing import Any, Callable, Iterator, List, Optional
+from typing import Any, Callable, Iterable, Iterator, List, Optional
 
-from message_filters import SimpleFilter
+import tf2_ros
+from message_filters import ApproximateTimeSynchronizer, SimpleFilter
 from rclpy.node import Node
 from rclpy.task import Future
 
 import bdai_ros2_wrappers.scope as scope
+from bdai_ros2_wrappers.filters import TransformFilter
 from bdai_ros2_wrappers.utilities import Tape
 
 
@@ -34,7 +36,7 @@ def __init__(
             history_length = 1
         self._link = link
         self._tape = Tape(history_length)
-        self._link.registerCallback(self._tape.write)
+        self._link.registerCallback(lambda *msgs: self._tape.write(msgs if len(msgs) > 1 else msgs[0]))
         node.context.on_shutdown(self._tape.close)
 
     @property
@@ -50,7 +52,7 @@ def history(self) -> List[Any]:
     @property
     def latest(self) -> Optional[Any]:
         """Gets the latest message received, if any."""
-        return next(self._tape.content(), None)
+        return self._tape.head
 
     @property
     def update(self) -> Future:
@@ -99,3 +101,105 @@ def stream(
     def close(self) -> None:
         """Closes the message feed."""
         self._tape.close()
+
+
+class FramedMessageFeed(MessageFeed):
+    """A message feed decorator, incorporating transforms using a `TransformFilter` instance."""
+
+    def __init__(
+        self,
+        feed: MessageFeed,
+        target_frame_id: str,
+        *,
+        tolerance_sec: float = 1.0,
+        tf_buffer: Optional[tf2_ros.Buffer] = None,
+        history_length: Optional[int] = None,
+        node: Optional[Node] = None,
+    ) -> None:
+        """Initializes the message feed.
+
+        Args:
+            feed: the upstream message feed.
+            target_frame_id: the target frame ID for transforms.
+            tf_buffer: optional buffer of transforms to look up. If none is provided
+            a transforms' buffer and a listener will be instantiated.
+            tolerance_sec: optional tolerance, in seconds, to wait for late transforms.
+            history_length: optional historic data size, defaults to 1.
+            node: optional node for the underlying native subscription, defaults to
+            the current process node.
+        """
+        if node is None:
+            node = scope.ensure_node()
+        if tf_buffer is None:
+            tf_buffer = tf2_ros.Buffer()
+            self._tf_listener = tf2_ros.TransformListener(tf_buffer, node)
+        super().__init__(
+            TransformFilter(
+                feed.link,
+                target_frame_id,
+                tf_buffer,
+                tolerance_sec,
+                node.get_logger(),
+            ),
+            history_length=history_length,
+            node=node,
+        )
+        self._feed = feed
+
+    @property
+    def feed(self) -> MessageFeed:
+        """Gets the upstream message feed."""
+        return self._feed
+
+    def close(self) -> None:
+        """Closes this message feed and the upstream one as well."""
+        self._feed.close()
+        super().close()
+
+
+class SynchronizedMessageFeed(MessageFeed):
+    """A message feeds' aggregator using a `message_filters.ApproximateTimeSynchronizer` instance."""
+
+    def __init__(
+        self,
+        *feeds: MessageFeed,
+        queue_size: int = 10,
+        delay: float = 0.2,
+        allow_headerless: bool = False,
+        history_length: Optional[int] = None,
+        node: Optional[Node] = None,
+    ) -> None:
+        """Initializes the message feed.
+
+        Args:
+            feeds: upstream message feeds to be synchronized.
+            queue_size: the message queue size for synchronization.
+            delay: the maximum delay, in seconds, between messages for synchronization to succeed.
+            allow_headerless: whether it's OK for there to be no header in the messages (in which
+            case, the ROS time of arrival will be used).
+            history_length: optional historic data size, defaults to 1.
+            node: optional node for the underlying native subscription, defaults to
+            the current process node.
+        """
+        super().__init__(
+            ApproximateTimeSynchronizer(
+                [f.link for f in feeds],
+                queue_size,
+                delay,
+                allow_headerless=allow_headerless,
+            ),
+            history_length=history_length,
+            node=node,
+        )
+        self._feeds = feeds
+
+    @property
+    def feeds(self) -> Iterable[MessageFeed]:
+        """Gets all aggregated message feeds."""
+        return self._feeds
+
+    def close(self) -> None:
+        """Closes this message feed and all upstream ones as well."""
+        for feed in self._feeds:
+            feed.close()
+        super().close()
diff --git a/bdai_ros2_wrappers/bdai_ros2_wrappers/filters.py b/bdai_ros2_wrappers/bdai_ros2_wrappers/filters.py
index 1b438dc..dd4fb80 100644
--- a/bdai_ros2_wrappers/bdai_ros2_wrappers/filters.py
+++ b/bdai_ros2_wrappers/bdai_ros2_wrappers/filters.py
@@ -43,7 +43,7 @@ def __init__(
         """
         super().__init__()
         self._logger = logger
-        self._lock = threading.Lock()
+        self._lock = threading.RLock()
         self._waitqueue: collections.deque = collections.deque()
         self._ongoing_wait: Optional[Future] = None
         self._ongoing_wait_time: Optional[Time] = None
diff --git a/bdai_ros2_wrappers/bdai_ros2_wrappers/utilities.py b/bdai_ros2_wrappers/bdai_ros2_wrappers/utilities.py
index b646cdf..8ce9723 100644
--- a/bdai_ros2_wrappers/bdai_ros2_wrappers/utilities.py
+++ b/bdai_ros2_wrappers/bdai_ros2_wrappers/utilities.py
@@ -200,6 +200,16 @@ def write(self, data: Any) -> bool:
                     self._future_matching_writes.remove(item)
             return True
 
+    @property
+    def head(self) -> Optional[Any]:
+        """Returns the data tape head, if any."""
+        with self._lock:
+            if self._content is None:
+                return None
+            if len(self._content) == 0:
+                return None
+            return self._content[0]
+
     def content(
         self,
         *,
@@ -450,3 +460,20 @@ def take_kwargs(func: Callable, kwargs: Mapping) -> Tuple[Mapping, Mapping]:
         else:
             dropped[name] = value
     return taken, dropped
+
+
+def ensure(value: Optional[Any]) -> Any:
+    """Ensures `value` is not None or fails trying."""
+    if value is None:
+        frame = inspect.currentframe()
+        assert frame is not None
+        frame = frame.f_back
+        assert frame is not None
+        traceback = inspect.getframeinfo(frame)
+        message = f"{traceback.filename}:{traceback.lineno}: "
+        if traceback.code_context is not None:
+            message += "".join(traceback.code_context).strip("\n ") + " failed"
+        else:
+            message += "ensure() failed"
+        raise ValueError(message)
+    return value
diff --git a/bdai_ros2_wrappers/test/test_feeds.py b/bdai_ros2_wrappers/test/test_feeds.py
new file mode 100644
index 0000000..eb6f285
--- /dev/null
+++ b/bdai_ros2_wrappers/test/test_feeds.py
@@ -0,0 +1,75 @@
+# Copyright (c) 2024 Boston Dynamics AI Institute Inc.  All rights reserved.
+
+
+import tf2_ros
+from geometry_msgs.msg import (
+    PoseStamped,
+    TransformStamped,
+    TwistStamped,
+)
+from message_filters import SimpleFilter
+
+from bdai_ros2_wrappers.feeds import (
+    FramedMessageFeed,
+    MessageFeed,
+    SynchronizedMessageFeed,
+)
+from bdai_ros2_wrappers.scope import ROSAwareScope
+from bdai_ros2_wrappers.utilities import ensure
+
+
+def test_framed_message_feed(ros: ROSAwareScope) -> None:
+    tf_buffer = tf2_ros.Buffer()
+    pose_message_feed = MessageFeed(SimpleFilter())
+    framed_message_feed = FramedMessageFeed(
+        pose_message_feed,
+        target_frame_id="map",
+        tf_buffer=tf_buffer,
+        node=ros.node,
+    )
+
+    expected_transform_message = TransformStamped()
+    expected_transform_message.header.frame_id = "map"
+    expected_transform_message.child_frame_id = "odom"
+    expected_transform_message.transform.translation.y = 1.0
+    expected_transform_message.transform.rotation.w = 1.0
+    tf_buffer.set_transform_static(expected_transform_message, "pytest")
+
+    expected_pose_message = PoseStamped()
+    expected_pose_message.header.frame_id = "odom"
+    expected_pose_message.header.stamp.sec = 1
+    expected_pose_message.pose.position.x = 1.0
+    expected_pose_message.pose.orientation.w = 1.0
+    pose_message_feed.link.signalMessage(expected_pose_message)
+
+    pose_message, transform_message = ensure(framed_message_feed.latest)
+    assert pose_message.pose.position.x == expected_pose_message.pose.position.x
+    assert transform_message.transform.translation.y == expected_transform_message.transform.translation.y
+
+
+def test_synchronized_message_feed(ros: ROSAwareScope) -> None:
+    pose_message_feed = MessageFeed(SimpleFilter())
+    twist_message_feed = MessageFeed(SimpleFilter())
+    synchronized_message_feed = SynchronizedMessageFeed(
+        pose_message_feed,
+        twist_message_feed,
+        node=ros.node,
+    )
+
+    expected_pose_message = PoseStamped()
+    expected_pose_message.header.frame_id = "odom"
+    expected_pose_message.header.stamp.sec = 1
+    expected_pose_message.pose.position.x = 1.0
+    expected_pose_message.pose.orientation.w = 1.0
+    pose_message_feed.link.signalMessage(expected_pose_message)
+
+    expected_twist_message = TwistStamped()
+    expected_twist_message.header.frame_id = "base_link"
+    expected_twist_message.header.stamp.sec = 1
+    expected_twist_message.twist.linear.x = 1.0
+    expected_twist_message.twist.angular.z = 1.0
+    twist_message_feed.link.signalMessage(expected_twist_message)
+
+    pose_message, twist_message = ensure(synchronized_message_feed.latest)
+    assert pose_message.pose.position.x == expected_pose_message.pose.position.x
+    assert twist_message.twist.linear.x == expected_twist_message.twist.linear.x
diff --git a/bdai_ros2_wrappers/test/test_subscription.py b/bdai_ros2_wrappers/test/test_subscription.py
index 3f9fac0..1ad820c 100644
--- a/bdai_ros2_wrappers/test/test_subscription.py
+++ b/bdai_ros2_wrappers/test/test_subscription.py
@@ -1,7 +1,7 @@
 # Copyright (c) 2024 Boston Dynamics AI Institute Inc.  All rights reserved.
 import itertools
 import time
-from typing import Any, Iterator, cast
+from typing import Any, Iterator
 
 from rclpy.qos import DurabilityPolicy, HistoryPolicy, QoSProfile
 from std_msgs.msg import Int8, String
@@ -10,6 +10,7 @@
 from bdai_ros2_wrappers.node import Node
 from bdai_ros2_wrappers.scope import ROSAwareScope
 from bdai_ros2_wrappers.subscription import Subscription, wait_for_message, wait_for_messages
+from bdai_ros2_wrappers.utilities import ensure
 
 DEFAULT_QOS_PROFILE = QoSProfile(
     durability=DurabilityPolicy.TRANSIENT_LOCAL,
@@ -44,7 +45,7 @@ def test_subscription_future_wait(ros: ROSAwareScope) -> None:
     pub.publish(Int8(data=1))
 
     assert wait_for_future(sequence.update, timeout_sec=5.0)
-    assert cast(Int8, sequence.latest).data == 1
+    assert ensure(sequence.latest).data == 1
 
 
 def test_subscription_matching_future_wait(ros: ROSAwareScope) -> None:
@@ -132,7 +133,7 @@ def deferred_cancellation() -> None:
     assert len(historic_numbers) == 1
     assert historic_numbers[0] == 1
 
-    assert cast(Int8, sequence.latest).data == 1
+    assert ensure(sequence.latest).data == 1
 
 
 def test_wait_for_messages(ros: ROSAwareScope) -> None:
diff --git a/bdai_ros2_wrappers/test/test_utilities.py b/bdai_ros2_wrappers/test/test_utilities.py
index 366fafb..a286002 100644
--- a/bdai_ros2_wrappers/test/test_utilities.py
+++ b/bdai_ros2_wrappers/test/test_utilities.py
@@ -2,7 +2,9 @@
 
 import argparse
 
-from bdai_ros2_wrappers.utilities import either_or, namespace_with
+import pytest
+
+from bdai_ros2_wrappers.utilities import either_or, ensure, namespace_with
 
 
 def test_either_or() -> None:
@@ -18,3 +20,10 @@ def test_namespace_with() -> None:
     assert namespace_with("", "foo") == "foo"
     assert namespace_with("/", "foo") == "/foo"
     assert namespace_with("foo", "bar") == "foo/bar"
+
+
+def test_ensure() -> None:
+    data = None
+    with pytest.raises(ValueError) as excinfo:
+        ensure(data)
+    assert "ensure(data) failed" in str(excinfo.value)