diff --git a/tractor/_runtime.py b/tractor/_runtime.py
index 9316837..08ddabc 100644
--- a/tractor/_runtime.py
+++ b/tractor/_runtime.py
@@ -30,7 +30,6 @@ import sys
 from typing import (
     Any,
     Callable,
-    Optional,
     Union,
     TYPE_CHECKING,
 )
@@ -101,7 +100,7 @@ async def _invoke(
 
     cancel_scope = trio.CancelScope()
     # activated cancel scope ref
-    cs: Optional[trio.CancelScope] = None
+    cs: trio.CancelScope | None = None
 
     ctx = actor.get_context(
         chan,
@@ -468,16 +467,20 @@ class Actor:
     msg_buffer_size: int = 2**6
 
     # nursery placeholders filled in by `async_main()` after fork
-    _root_n: Optional[trio.Nursery] = None
-    _service_n: Optional[trio.Nursery] = None
-    _server_n: Optional[trio.Nursery] = None
+    _root_n: trio.Nursery | None = None
+    _service_n: trio.Nursery | None = None
+    _server_n: trio.Nursery | None = None
 
     # Information about `__main__` from parent
     _parent_main_data: dict[str, str]
-    _parent_chan_cs: Optional[trio.CancelScope] = None
+    _parent_chan_cs: trio.CancelScope | None = None
 
     # syncs for setup/teardown sequences
-    _server_down: Optional[trio.Event] = None
+    _server_down: trio.Event | None = None
+
+    # user toggled crash handling (including monkey-patched in
+    # `trio.open_nursery()` via `.trionics._supervisor` B)
+    _debug_mode: bool = False
 
     # if started on ``asycio`` running ``trio`` in guest mode
     _infected_aio: bool = False
@@ -493,8 +496,8 @@ class Actor:
         enable_modules: list[str] = [],
         uid: str | None = None,
         loglevel: str | None = None,
-        arbiter_addr: Optional[tuple[str, int]] = None,
-        spawn_method: Optional[str] = None
+        arbiter_addr: tuple[str, int] | None = None,
+        spawn_method: str | None = None
     ) -> None:
         '''
         This constructor is called in the parent actor **before** the spawning
@@ -554,9 +557,8 @@ class Actor:
         ] = {}
 
         self._listeners: list[trio.abc.Listener] = []
-        self._parent_chan: Optional[Channel] = None
-        self._forkserver_info: Optional[
-            tuple[Any, Any, Any, Any, Any]] = None
+        self._parent_chan: Channel | None = None
+        self._forkserver_info: tuple | None = None
         self._actoruid2nursery: dict[
             tuple[str, str],
             ActorNursery | None,
@@ -647,7 +649,7 @@ class Actor:
         self._no_more_peers = trio.Event()  # unset
 
         chan = Channel.from_stream(stream)
-        uid: Optional[tuple[str, str]] = chan.uid
+        uid: tuple[str, str] | None = chan.uid
         log.runtime(f"New connection to us {chan}")
 
         # send/receive initial handshake response
@@ -695,7 +697,7 @@ class Actor:
         # append new channel
         self._peers[uid].append(chan)
 
-        local_nursery: Optional[ActorNursery] = None  # noqa
+        local_nursery: ActorNursery | None = None  # noqa
         disconnected: bool = False
 
         # Begin channel management - respond to remote requests and
@@ -947,8 +949,8 @@ class Actor:
 
     async def _from_parent(
         self,
-        parent_addr: Optional[tuple[str, int]],
-    ) -> tuple[Channel, Optional[tuple[str, int]]]:
+        parent_addr: tuple[str, int] | None,
+    ) -> tuple[Channel, tuple[str, int] | None]:
         try:
             # Connect back to the parent actor and conduct initial
             # handshake. From this point on if we error, we
@@ -961,7 +963,7 @@ class Actor:
             # Initial handshake: swap names.
             await self._do_handshake(chan)
 
-            accept_addr: Optional[tuple[str, int]] = None
+            accept_addr: tuple[str, int] | None = None
 
             if self._spawn_method == "trio":
                 # Receive runtime state from our parent
@@ -1020,7 +1022,7 @@ class Actor:
         self._server_down = trio.Event()
         try:
             async with trio.open_nursery() as server_n:
-                l: list[trio.abc.Listener] = await server_n.start(
+                listeners: list[trio.abc.Listener] = await server_n.start(
                     partial(
                         trio.serve_tcp,
                         self._stream_handler,
@@ -1031,10 +1033,13 @@ class Actor:
                         host=accept_host,
                     )
                 )
+                sockets: list[trio.socket] = [
+                    getattr(listener, 'socket', 'unknown socket')
+                    for listener in listeners
+                ]
                 log.runtime(
-                    "Started tcp server(s) on"
-                    f" {[getattr(l, 'socket', 'unknown socket') for l in l]}")
-                self._listeners.extend(l)
+                    f'Started tcp server(s) on {sockets}')
+                self._listeners.extend(listeners)
                 task_status.started(server_n)
         finally:
             # signal the server is down since nursery above terminated
@@ -1215,7 +1220,7 @@ class Actor:
             self._server_n.cancel_scope.cancel()
 
     @property
-    def accept_addr(self) -> Optional[tuple[str, int]]:
+    def accept_addr(self) -> tuple[str, int] | None:
         '''
         Primary address to which the channel server is bound.
 
@@ -1267,7 +1272,7 @@ class Actor:
 
 async def async_main(
     actor: Actor,
-    accept_addr: Optional[tuple[str, int]] = None,
+    accept_addr: tuple[str, int] | None = None,
 
     # XXX: currently ``parent_addr`` is only needed for the
     # ``multiprocessing`` backend (which pickles state sent to
@@ -1276,7 +1281,7 @@ async def async_main(
     # change this to a simple ``is_subactor: bool`` which will
     # be False when running as root actor and True when as
     # a subactor.
-    parent_addr: Optional[tuple[str, int]] = None,
+    parent_addr: tuple[str, int] | None = None,
     task_status: TaskStatus[None] = trio.TASK_STATUS_IGNORED,
 
 ) -> None: