diff --git a/tractor/ipc/__init__.py b/tractor/ipc/__init__.py
index 0c8e09ca..dd4d9e5a 100644
--- a/tractor/ipc/__init__.py
+++ b/tractor/ipc/__init__.py
@@ -16,6 +16,7 @@
 import platform
 
 from ._transport import (
+    MsgTransportKey as MsgTransportKey,
     AddressType as AddressType,
     MsgType as MsgType,
     MsgTransport as MsgTransport,
@@ -26,6 +27,7 @@ from ._tcp import MsgpackTCPStream as MsgpackTCPStream
 from ._uds import MsgpackUDSStream as MsgpackUDSStream
 
 from ._types import (
+    default_lo_addrs as default_lo_addrs,
     transport_from_destaddr as transport_from_destaddr,
     transport_from_stream as transport_from_stream,
     AddressTypes as AddressTypes
diff --git a/tractor/ipc/_tcp.py b/tractor/ipc/_tcp.py
index 71265f38..4a69ebbd 100644
--- a/tractor/ipc/_tcp.py
+++ b/tractor/ipc/_tcp.py
@@ -90,3 +90,11 @@ class MsgpackTCPStream(MsgpackTransport):
             tuple(lsockname[:2]),
             tuple(rsockname[:2]),
         )
+
+    @classmethod
+    def get_random_addr(self) -> tuple[str, int]:
+        return (None, 0)
+
+    @classmethod
+    def get_root_addr(self) -> tuple[str, int]:
+        return ('127.0.0.1', 1616)
diff --git a/tractor/ipc/_transport.py b/tractor/ipc/_transport.py
index 70ba2088..55a218f7 100644
--- a/tractor/ipc/_transport.py
+++ b/tractor/ipc/_transport.py
@@ -31,10 +31,6 @@ from collections.abc import (
     AsyncIterator,
 )
 import struct
-from typing import (
-    Any,
-    Callable,
-)
 
 import trio
 import msgspec
@@ -58,6 +54,10 @@ from tractor.msg import (
 log = get_logger(__name__)
 
 
+# (codec, transport)
+MsgTransportKey = tuple[str, str]
+
+
 # from tractor.msg.types import MsgType
 # ?TODO? this should be our `Union[*msgtypes.__spec__]` alias now right..?
 # => BLEH, except can't bc prots must inherit typevar or param-spec
@@ -77,6 +77,9 @@ class MsgTransport(Protocol[AddressType, MsgType]):
     drained: list[MsgType]
     address_type: ClassVar[Type[AddressType]]
 
+    codec_key: ClassVar[str]
+    name_key: ClassVar[str]
+
     # XXX: should this instead be called `.sendall()`?
     async def send(self, msg: MsgType) -> None:
         ...
@@ -95,6 +98,10 @@ class MsgTransport(Protocol[AddressType, MsgType]):
     def drain(self) -> AsyncIterator[dict]:
         ...
 
+    @classmethod
+    def key(cls) -> MsgTransportKey:
+        return cls.codec_key, cls.name_key
+
     @property
     def laddr(self) -> AddressType:
         ...
@@ -126,6 +133,14 @@ class MsgTransport(Protocol[AddressType, MsgType]):
         '''
         ...
 
+    @classmethod
+    def get_random_addr(self) -> AddressType:
+        ...
+
+    @classmethod
+    def get_root_addr(self) -> AddressType:
+        ...
+
 
 class MsgpackTransport(MsgTransport):
 
@@ -411,7 +426,7 @@ class MsgpackTransport(MsgTransport):
         #         __tracebackhide__: bool = False
         #     raise
 
-    async def recv(self) -> Any:
+    async def recv(self) -> msgtypes.MsgType:
         return await self._aiter_pkts.asend(None)
 
     async def drain(self) -> AsyncIterator[dict]:
diff --git a/tractor/ipc/_types.py b/tractor/ipc/_types.py
index 93c5e3c9..92d3af91 100644
--- a/tractor/ipc/_types.py
+++ b/tractor/ipc/_types.py
@@ -18,15 +18,24 @@ from typing import Type, Union
 import trio
 import socket
 
-from ._transport import MsgTransport
+from ._transport import (
+    MsgTransportKey,
+    MsgTransport
+)
 from ._tcp import MsgpackTCPStream
 from ._uds import MsgpackUDSStream
 
 
+_msg_transports = [
+    MsgpackTCPStream,
+    MsgpackUDSStream
+]
+
+
 # manually updated list of all supported codec+transport types
-_msg_transports = {
-    ('msgpack', 'tcp'): MsgpackTCPStream,
-    ('msgpack', 'uds'): MsgpackUDSStream
+key_to_transport: dict[MsgTransportKey, Type[MsgTransport]] = {
+    cls.key(): cls
+    for cls in _msg_transports
 }
 
 
@@ -34,11 +43,17 @@ _msg_transports = {
 AddressTypes = Union[
     tuple([
         cls.address_type
-        for key, cls in _msg_transports.items()
+        for cls in _msg_transports
     ])
 ]
 
 
+default_lo_addrs: dict[MsgTransportKey, AddressTypes] = {
+    cls.key(): cls.get_root_addr()
+    for cls in _msg_transports
+}
+
+
 def transport_from_destaddr(
     destaddr: AddressTypes,
     codec_key: str = 'msgpack',
diff --git a/tractor/ipc/_uds.py b/tractor/ipc/_uds.py
index 3b848898..eb2e7f32 100644
--- a/tractor/ipc/_uds.py
+++ b/tractor/ipc/_uds.py
@@ -18,6 +18,8 @@ Unix Domain Socket implementation of tractor.ipc._transport.MsgTransport protoco
 
 '''
 from __future__ import annotations
+import tempfile
+from uuid import uuid4
 
 import trio
 
@@ -82,3 +84,11 @@ class MsgpackUDSStream(MsgpackTransport):
             stream.socket.getsockname(),
             stream.socket.getpeername(),
         )
+
+    @classmethod
+    def get_random_addr(self) -> str:
+        return f'{tempfile.gettempdir()}/{uuid4()}.sock'
+
+    @classmethod
+    def get_root_addr(self) -> str:
+        return 'tractor.sock'
diff --git a/tractor/msg/types.py b/tractor/msg/types.py
index 1cc8b78e..76d0bad6 100644
--- a/tractor/msg/types.py
+++ b/tractor/msg/types.py
@@ -46,6 +46,7 @@ from msgspec import (
 from tractor.msg import (
     pretty_struct,
 )
+from tractor.ipc import AddressTypes
 from tractor.log import get_logger
 
 
@@ -167,8 +168,8 @@ class SpawnSpec(
 
     # TODO: not just sockaddr pairs?
     # -[ ] abstract into a `TransportAddr` type?
-    reg_addrs: list[tuple[str, int]]
-    bind_addrs: list[tuple[str, int]]
+    reg_addrs: list[AddressTypes]
+    bind_addrs: list[AddressTypes]
 
 
 # TODO: caps based RPC support in the payload?