`_root`: drop unused `typing` import

Allows forcing the opened actor to either obtain the passed registry
addrs or raise a runtime error.

tests/test_debugger.py

@@ -10,6 +10,7 @@ TODO:
     - wonder if any of it'll work on OS X?
 
 """
+from functools import partial
 import itertools
 from typing import Optional
 import platform
@@ -26,6 +27,10 @@ from pexpect.exceptions import (
 from tractor._testing import (
     examples_dir,
 )
+from tractor.devx._debug import (
+    _pause_msg,
+    _crash_msg,
+)
 from conftest import (
     _ci_env,
 )
@@ -123,20 +128,52 @@ def expect(
         raise
 
 
+def in_prompt_msg(
+    prompt: str,
+    parts: list[str],
+
+    pause_on_false: bool = False,
+    print_prompt_on_false: bool = True,
+
+) -> bool:
+    '''
+    Predicate check if (the prompt's) std-streams output has all
+    `str`-parts in it.
+
+    Can be used in test asserts for bulk matching expected
+    log/REPL output for a given `pdb` interact point.
+
+    '''
+    for part in parts:
+        if part not in prompt:
+
+            if pause_on_false:
+                import pdbp
+                pdbp.set_trace()
+
+            if print_prompt_on_false:
+                print(prompt)
+
+            return False
+
+    return True
+
 def assert_before(
     child,
     patts: list[str],
 
+    **kwargs,
+
 ) -> None:
 
-    before = str(child.before.decode())
+    # as in before the prompt end
+    before: str = str(child.before.decode())
+    assert in_prompt_msg(
+        prompt=before,
+        parts=patts,
 
-    for patt in patts:
-        try:
-            assert patt in before
-        except AssertionError:
-            print(before)
-            raise
+        **kwargs
+    )
 
 
 @pytest.fixture(
@@ -195,7 +232,10 @@ def test_root_actor_error(spawn, user_in_out):
     before = str(child.before.decode())
 
     # make sure expected logging and error arrives
-    assert "Attaching to pdb in crashed actor: ('root'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('root'"]
+    )
     assert 'AssertionError' in before
 
     # send user command
@@ -332,7 +372,10 @@ def test_subactor_error(
     child.expect(PROMPT)
 
     before = str(child.before.decode())
-    assert "Attaching to pdb in crashed actor: ('name_error'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('name_error'"]
+    )
 
     if do_next:
         child.sendline('n')
@@ -353,9 +396,15 @@ def test_subactor_error(
     before = str(child.before.decode())
 
     # root actor gets debugger engaged
-    assert "Attaching to pdb in crashed actor: ('root'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('root'"]
+    )
     # error is a remote error propagated from the subactor
-    assert "RemoteActorError: ('name_error'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('name_error'"]
+    )
 
     # another round
     if ctlc:
@@ -380,7 +429,10 @@ def test_subactor_breakpoint(
     child.expect(PROMPT)
 
     before = str(child.before.decode())
-    assert "Attaching pdb to actor: ('breakpoint_forever'" in before
+    assert in_prompt_msg(
+        before,
+        [_pause_msg, "('breakpoint_forever'"]
+    )
 
     # do some "next" commands to demonstrate recurrent breakpoint
     # entries
@@ -396,7 +448,10 @@ def test_subactor_breakpoint(
         child.sendline('continue')
         child.expect(PROMPT)
         before = str(child.before.decode())
-        assert "Attaching pdb to actor: ('breakpoint_forever'" in before
+        assert in_prompt_msg(
+            before,
+            [_pause_msg, "('breakpoint_forever'"]
+        )
 
         if ctlc:
             do_ctlc(child)
@@ -441,7 +496,10 @@ def test_multi_subactors(
     child.expect(PROMPT)
 
     before = str(child.before.decode())
-    assert "Attaching pdb to actor: ('breakpoint_forever'" in before
+    assert in_prompt_msg(
+        before,
+        [_pause_msg, "('breakpoint_forever'"]
+    )
 
     if ctlc:
         do_ctlc(child)
@@ -461,7 +519,10 @@ def test_multi_subactors(
     # first name_error failure
     child.expect(PROMPT)
     before = str(child.before.decode())
-    assert "Attaching to pdb in crashed actor: ('name_error'" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('name_error'"]
+    )
     assert "NameError" in before
 
     if ctlc:
@@ -487,7 +548,10 @@ def test_multi_subactors(
     child.sendline('c')
     child.expect(PROMPT)
     before = str(child.before.decode())
-    assert "Attaching pdb to actor: ('breakpoint_forever'" in before
+    assert in_prompt_msg(
+        before,
+        [_pause_msg, "('breakpoint_forever'"]
+    )
 
     if ctlc:
         do_ctlc(child)
@@ -527,9 +591,12 @@ def test_multi_subactors(
     child.expect(PROMPT)
     before = str(child.before.decode())
 
-    assert_before(child, [
+    assert_before(
+        child, [
             # debugger attaches to root
-        "Attaching to pdb in crashed actor: ('root'",
+            # "Attaching to pdb in crashed actor: ('root'",
+            _crash_msg,
+            "('root'",
 
             # expect a multierror with exceptions for each sub-actor
             "RemoteActorError: ('breakpoint_forever'",
@@ -537,7 +604,8 @@ def test_multi_subactors(
             "RemoteActorError: ('spawn_error'",
             "RemoteActorError: ('name_error_1'",
             'bdb.BdbQuit',
-    ])
+        ]
+    )
 
     if ctlc:
         do_ctlc(child)
@@ -574,15 +642,22 @@ def test_multi_daemon_subactors(
     # the root's tty lock first so anticipate either crash
     # message on the first entry.
 
-    bp_forever_msg = "Attaching pdb to actor: ('bp_forever'"
+    bp_forev_parts = [_pause_msg, "('bp_forever'"]
+    bp_forev_in_msg = partial(
+        in_prompt_msg,
+        parts=bp_forev_parts,
+    )
+
     name_error_msg = "NameError: name 'doggypants' is not defined"
+    name_error_parts = [name_error_msg]
 
     before = str(child.before.decode())
-    if bp_forever_msg in before:
-        next_msg = name_error_msg
+
+    if bp_forev_in_msg(prompt=before):
+        next_parts = name_error_parts
 
     elif name_error_msg in before:
-        next_msg = bp_forever_msg
+        next_parts = bp_forev_parts
 
     else:
         raise ValueError("Neither log msg was found !?")
@@ -599,7 +674,10 @@ def test_multi_daemon_subactors(
 
     child.sendline('c')
     child.expect(PROMPT)
-    assert_before(child, [next_msg])
+    assert_before(
+        child,
+        next_parts,
+    )
 
     # XXX: hooray the root clobbering the child here was fixed!
     # IMO, this demonstrates the true power of SC system design.
@@ -623,9 +701,15 @@ def test_multi_daemon_subactors(
     child.expect(PROMPT)
 
     try:
-        assert_before(child, [bp_forever_msg])
+        assert_before(
+            child,
+            bp_forev_parts,
+        )
     except AssertionError:
-        assert_before(child, [name_error_msg])
+        assert_before(
+            child,
+            name_error_parts,
+        )
 
     else:
         if ctlc:
@@ -637,7 +721,10 @@ def test_multi_daemon_subactors(
 
         child.sendline('c')
         child.expect(PROMPT)
-        assert_before(child, [name_error_msg])
+        assert_before(
+            child,
+            name_error_parts,
+        )
 
     # wait for final error in root
     # where it crashs with boxed error
@@ -647,7 +734,7 @@ def test_multi_daemon_subactors(
             child.expect(PROMPT)
             assert_before(
                 child,
-                [bp_forever_msg]
+                bp_forev_parts
             )
         except AssertionError:
             break
@@ -656,7 +743,9 @@ def test_multi_daemon_subactors(
         child,
         [
             # boxed error raised in root task
-            "Attaching to pdb in crashed actor: ('root'",
+            # "Attaching to pdb in crashed actor: ('root'",
+            _crash_msg,
+            "('root'",
             "_exceptions.RemoteActorError: ('name_error'",
         ]
     )
@@ -770,7 +859,7 @@ def test_multi_nested_subactors_error_through_nurseries(
 
     child = spawn('multi_nested_subactors_error_up_through_nurseries')
 
-    timed_out_early: bool = False
+    # timed_out_early: bool = False
 
     for send_char in itertools.cycle(['c', 'q']):
         try:
@@ -871,11 +960,14 @@ def test_root_nursery_cancels_before_child_releases_tty_lock(
 
     if not timed_out_early:
         before = str(child.before.decode())
-        assert_before(child, [
+        assert_before(
+            child,
+            [
                 "tractor._exceptions.RemoteActorError: ('spawner0'",
                 "tractor._exceptions.RemoteActorError: ('name_error'",
                 "NameError: name 'doggypants' is not defined",
-        ])
+            ],
+        )
 
 
 def test_root_cancels_child_context_during_startup(
@@ -909,8 +1001,10 @@ def test_different_debug_mode_per_actor(
 
     # only one actor should enter the debugger
     before = str(child.before.decode())
-    assert "Attaching to pdb in crashed actor: ('debugged_boi'" in before
-    assert "RuntimeError" in before
+    assert in_prompt_msg(
+        before,
+        [_crash_msg, "('debugged_boi'", "RuntimeError"],
+    )
 
     if ctlc:
         do_ctlc(child)

tractor/_context.py

@@ -868,6 +868,9 @@ class Context:
 
         # TODO: maybe we should also call `._res_scope.cancel()` if it
         # exists to support cancelling any drain loop hangs?
+        # NOTE: this usage actually works here B)
+        # from .devx._debug import breakpoint
+        # await breakpoint()
 
     # TODO: add to `Channel`?
     @property

tractor/_root.py

@@ -37,7 +37,7 @@ from ._runtime import (
     # Arbiter as Registry,
     async_main,
 )
-from . import _debug
+from .devx import _debug
 from . import _spawn
 from . import _state
 from . import log
@@ -99,7 +99,7 @@ async def open_root_actor(
     # https://github.com/python-trio/trio/issues/1155#issuecomment-742964018
     builtin_bp_handler = sys.breakpointhook
     orig_bp_path: str | None = os.environ.get('PYTHONBREAKPOINT', None)
-    os.environ['PYTHONBREAKPOINT'] = 'tractor._debug.pause_from_sync'
+    os.environ['PYTHONBREAKPOINT'] = 'tractor.devx._debug.pause_from_sync'
 
     # attempt to retreive ``trio``'s sigint handler and stash it
     # on our debugger lock state.
@@ -146,7 +146,7 @@ async def open_root_actor(
 
         # expose internal debug module to every actor allowing
         # for use of ``await tractor.breakpoint()``
-        enable_modules.append('tractor._debug')
+        enable_modules.append('tractor.devx._debug')
 
         # if debug mode get's enabled *at least* use that level of
         # logging for some informative console prompts.

tractor/_runtime.py

@@ -78,7 +78,7 @@ from ._exceptions import (
     ContextCancelled,
     TransportClosed,
 )
-from . import _debug
+from .devx import _debug
 from ._discovery import get_registry
 from ._portal import Portal
 from . import _state
@@ -197,7 +197,7 @@ class Actor:
         self._parent_main_data = _mp_fixup_main._mp_figure_out_main()
 
         # always include debugging tools module
-        enable_modules.append('tractor._debug')
+        enable_modules.append('tractor.devx._debug')
 
         self.enable_modules: dict[str, str] = {}
         for name in enable_modules:

tractor/_spawn.py

@@ -34,7 +34,7 @@ from typing import (
 import trio
 from trio import TaskStatus
 
-from ._debug import (
+from .devx._debug import (
     maybe_wait_for_debugger,
     acquire_debug_lock,
 )
@@ -554,13 +554,14 @@ async def trio_proc(
                         with trio.move_on_after(0.5):
                             await proc.wait()
 
-                log.pdb(
-                    'Delaying subproc reaper while debugger locked..'
-                )
                 await maybe_wait_for_debugger(
                     child_in_debug=_runtime_vars.get(
                         '_debug_mode', False
                     ),
+                    header_msg=(
+                        'Delaying subproc reaper while debugger locked..\n'
+                    ),
+
                     # TODO: need a diff value then default?
                     # poll_steps=9999999,
                 )

tractor/_supervise.py

@@ -28,7 +28,7 @@ import warnings
 
 import trio
 
-from ._debug import maybe_wait_for_debugger
+from .devx._debug import maybe_wait_for_debugger
 from ._state import current_actor, is_main_process
 from .log import get_logger, get_loglevel
 from ._runtime import Actor

tractor/devx/__init__.py

@@ -0,0 +1,37 @@
+# tractor: structured concurrent "actors".
+# Copyright 2018-eternity Tyler Goodlet.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""
+Runtime "developer experience" utils and addons to aid our
+(advanced) users and core devs in building distributed applications
+and working with/on the actor runtime.
+
+"""
+from ._debug import (
+    maybe_wait_for_debugger as maybe_wait_for_debugger,
+    acquire_debug_lock as acquire_debug_lock,
+    breakpoint as breakpoint,
+    pause as pause,
+    pause_from_sync as pause_from_sync,
+    shield_sigint_handler as shield_sigint_handler,
+    MultiActorPdb as MultiActorPdb,
+    open_crash_handler as open_crash_handler,
+    maybe_open_crash_handler as maybe_open_crash_handler,
+    post_mortem as post_mortem,
+)
+from ._stackscope import (
+    enable_stack_on_sig as enable_stack_on_sig,
+)

tractor/devx/_debug.py

@@ -1,18 +1,19 @@
 # tractor: structured concurrent "actors".
 # Copyright 2018-eternity Tyler Goodlet.
 
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Affero General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
+# This program is free software: you can redistribute it and/or
+# modify it under the terms of the GNU Affero General Public License
+# as published by the Free Software Foundation, either version 3 of
+# the License, or (at your option) any later version.
 
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Affero General Public License for more details.
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Affero General Public License for more details.
 
-# You should have received a copy of the GNU Affero General Public License
-# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+# You should have received a copy of the GNU Affero General Public
+# License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
 
 """
 Multi-core debugging for da peeps!
@@ -20,14 +21,19 @@ Multi-core debugging for da peeps!
 """
 from __future__ import annotations
 import bdb
-import os
-import sys
-import signal
+from contextlib import (
+    asynccontextmanager as acm,
+    contextmanager as cm,
+    nullcontext,
+)
 from functools import (
     partial,
     cached_property,
 )
-from contextlib import asynccontextmanager as acm
+import os
+import signal
+import sys
+import traceback
 from typing import (
     Any,
     Callable,
@@ -39,27 +45,31 @@ from types import FrameType
 import pdbp
 import tractor
 import trio
+from trio.lowlevel import current_task
 from trio_typing import (
     TaskStatus,
     # Task,
 )
 
-from .log import get_logger
-from ._discovery import get_root
-from ._state import (
+from ..log import get_logger
+from .._state import (
+    current_actor,
     is_root_process,
     debug_mode,
 )
-from ._exceptions import (
+from .._exceptions import (
     is_multi_cancelled,
     ContextCancelled,
 )
-from ._ipc import Channel
+from .._ipc import Channel
 
 log = get_logger(__name__)
 
 
-__all__ = ['breakpoint', 'post_mortem']
+__all__ = [
+    'breakpoint',
+    'post_mortem',
+]
 
 
 class Lock:
@@ -85,12 +95,12 @@ class Lock:
     # and must be cancelled if this actor is cancelled via IPC
     # request-message otherwise deadlocks with the parent actor may
     # ensure
-    _debugger_request_cs: trio.CancelScope | None = None
+    _debugger_request_cs: trio.CancelScope|None = None
 
     # NOTE: set only in the root actor for the **local** root spawned task
     # which has acquired the lock (i.e. this is on the callee side of
     # the `lock_tty_for_child()` context entry).
-    _root_local_task_cs_in_debug: trio.CancelScope | None = None
+    _root_local_task_cs_in_debug: trio.CancelScope|None = None
 
     # actor tree-wide actor uid that supposedly has the tty lock
     global_actor_in_debug: tuple[str, str] = None
@@ -232,7 +242,7 @@ async def _acquire_debug_lock_from_root_task(
     to the ``pdb`` repl.
 
     '''
-    task_name: str = trio.lowlevel.current_task().name
+    task_name: str = current_task().name
     we_acquired: bool = False
 
     log.runtime(
@@ -317,14 +327,13 @@ async def lock_tty_for_child(
     highly reliable at releasing the mutex complete!
 
     '''
-    task_name = trio.lowlevel.current_task().name
-
+    task_name: str = current_task().name
     if tuple(subactor_uid) in Lock._blocked:
         log.warning(
             f'Actor {subactor_uid} is blocked from acquiring debug lock\n'
             f"remote task: {task_name}:{subactor_uid}"
         )
-        ctx._enter_debugger_on_cancel = False
+        ctx._enter_debugger_on_cancel: bool = False
         await ctx.cancel(f'Debug lock blocked for {subactor_uid}')
         return 'pdb_lock_blocked'
 
@@ -375,12 +384,14 @@ async def wait_for_parent_stdin_hijack(
 
     This function is used by any sub-actor to acquire mutex access to
     the ``pdb`` REPL and thus the root's TTY for interactive debugging
-    (see below inside ``_pause()``). It can be used to ensure that
+    (see below inside ``pause()``). It can be used to ensure that
     an intermediate nursery-owning actor does not clobber its children
     if they are in debug (see below inside
     ``maybe_wait_for_debugger()``).
 
     '''
+    from .._discovery import get_root
+
     with trio.CancelScope(shield=True) as cs:
         Lock._debugger_request_cs = cs
 
@@ -390,7 +401,7 @@ async def wait_for_parent_stdin_hijack(
                 # this syncs to child's ``Context.started()`` call.
                 async with portal.open_context(
 
-                    tractor._debug.lock_tty_for_child,
+                    lock_tty_for_child,
                     subactor_uid=actor_uid,
 
                 ) as (ctx, val):
@@ -399,11 +410,13 @@ async def wait_for_parent_stdin_hijack(
                     assert val == 'Locked'
 
                     async with ctx.open_stream() as stream:
-                        # unblock local caller
-
                         try:
+                            # unblock local caller
                             assert Lock.local_pdb_complete
                             task_status.started(cs)
+
+                            # wait for local task to exit and
+                            # release the REPL
                             await Lock.local_pdb_complete.wait()
 
                         finally:
@@ -441,171 +454,6 @@ def mk_mpdb() -> tuple[MultiActorPdb, Callable]:
     return pdb, Lock.unshield_sigint
 
 
-async def _pause(
-
-    debug_func: Callable | None = None,
-    release_lock_signal: trio.Event | None = None,
-
-    # TODO:
-    # shield: bool = False
-    task_status: TaskStatus[trio.Event] = trio.TASK_STATUS_IGNORED
-
-) -> None:
-    '''
-    A pause point (more commonly known as a "breakpoint") interrupt
-    instruction for engaging a blocking debugger instance to
-    conduct manual console-based-REPL-interaction from within
-    `tractor`'s async runtime, normally from some single-threaded
-    and currently executing actor-hosted-`trio`-task in some
-    (remote) process.
-
-    NOTE: we use the semantics "pause" since it better encompasses
-    the entirety of the necessary global-runtime-state-mutation any
-    actor-task must access and lock in order to get full isolated
-    control over the process tree's root TTY:
-    https://en.wikipedia.org/wiki/Breakpoint
-
-    '''
-    __tracebackhide__ = True
-    actor = tractor.current_actor()
-    pdb, undo_sigint = mk_mpdb()
-    task_name = trio.lowlevel.current_task().name
-
-    # TODO: is it possible to debug a trio.Cancelled except block?
-    # right now it seems like we can kinda do with by shielding
-    # around ``tractor.breakpoint()`` but not if we move the shielded
-    # scope here???
-    # with trio.CancelScope(shield=shield):
-    #     await trio.lowlevel.checkpoint()
-
-    if (
-        not Lock.local_pdb_complete
-        or Lock.local_pdb_complete.is_set()
-    ):
-        Lock.local_pdb_complete = trio.Event()
-
-    # TODO: need a more robust check for the "root" actor
-    if (
-        not is_root_process()
-        and actor._parent_chan  # a connected child
-    ):
-
-        if Lock.local_task_in_debug:
-
-            # Recurrence entry case: this task already has the lock and
-            # is likely recurrently entering a breakpoint
-            if Lock.local_task_in_debug == task_name:
-                # noop on recurrent entry case but we want to trigger
-                # a checkpoint to allow other actors error-propagate and
-                # potetially avoid infinite re-entries in some subactor.
-                await trio.lowlevel.checkpoint()
-                return
-
-            # if **this** actor is already in debug mode block here
-            # waiting for the control to be released - this allows
-            # support for recursive entries to `tractor.breakpoint()`
-            log.warning(f"{actor.uid} already has a debug lock, waiting...")
-
-            await Lock.local_pdb_complete.wait()
-            await trio.sleep(0.1)
-
-        # mark local actor as "in debug mode" to avoid recurrent
-        # entries/requests to the root process
-        Lock.local_task_in_debug = task_name
-
-        # this **must** be awaited by the caller and is done using the
-        # root nursery so that the debugger can continue to run without
-        # being restricted by the scope of a new task nursery.
-
-        # TODO: if we want to debug a trio.Cancelled triggered exception
-        # we have to figure out how to avoid having the service nursery
-        # cancel on this task start? I *think* this works below:
-        # ```python
-        #   actor._service_n.cancel_scope.shield = shield
-        # ```
-        # but not entirely sure if that's a sane way to implement it?
-        try:
-            with trio.CancelScope(shield=True):
-                await actor._service_n.start(
-                    wait_for_parent_stdin_hijack,
-                    actor.uid,
-                )
-                Lock.repl = pdb
-        except RuntimeError:
-            Lock.release()
-
-            if actor._cancel_called:
-                # service nursery won't be usable and we
-                # don't want to lock up the root either way since
-                # we're in (the midst of) cancellation.
-                return
-
-            raise
-
-    elif is_root_process():
-
-        # we also wait in the root-parent for any child that
-        # may have the tty locked prior
-        # TODO: wait, what about multiple root tasks acquiring it though?
-        if Lock.global_actor_in_debug == actor.uid:
-            # re-entrant root process already has it: noop.
-            return
-
-        # XXX: since we need to enter pdb synchronously below,
-        # we have to release the lock manually from pdb completion
-        # callbacks. Can't think of a nicer way then this atm.
-        if Lock._debug_lock.locked():
-            log.warning(
-                'Root actor attempting to shield-acquire active tty lock'
-                f' owned by {Lock.global_actor_in_debug}')
-
-            # must shield here to avoid hitting a ``Cancelled`` and
-            # a child getting stuck bc we clobbered the tty
-            with trio.CancelScope(shield=True):
-                await Lock._debug_lock.acquire()
-        else:
-            # may be cancelled
-            await Lock._debug_lock.acquire()
-
-        Lock.global_actor_in_debug = actor.uid
-        Lock.local_task_in_debug = task_name
-        Lock.repl = pdb
-
-    try:
-        # breakpoint()
-        if debug_func is None:
-            # assert release_lock_signal, (
-            #     'Must pass `release_lock_signal: trio.Event` if no '
-            #     'trace func provided!'
-            # )
-            print(f"{actor.uid} ENTERING WAIT")
-            task_status.started()
-
-            # with trio.CancelScope(shield=True):
-            #     await release_lock_signal.wait()
-
-        else:
-            # block here one (at the appropriate frame *up*) where
-            # ``breakpoint()`` was awaited and begin handling stdio.
-            log.debug("Entering the synchronous world of pdb")
-            debug_func(actor, pdb)
-
-    except bdb.BdbQuit:
-        Lock.release()
-        raise
-
-    # XXX: apparently we can't do this without showing this frame
-    # in the backtrace on first entry to the REPL? Seems like an odd
-    # behaviour that should have been fixed by now. This is also why
-    # we scrapped all the @cm approaches that were tried previously.
-    # finally:
-    #     __tracebackhide__ = True
-    #     # frame = sys._getframe()
-    #     # last_f = frame.f_back
-    #     # last_f.f_globals['__tracebackhide__'] = True
-    #     # signal.signal = pdbp.hideframe(signal.signal)
-
-
 def shield_sigint_handler(
     signum: int,
     frame: 'frame',  # type: ignore # noqa
@@ -625,7 +473,7 @@ def shield_sigint_handler(
 
     uid_in_debug: tuple[str, str] | None = Lock.global_actor_in_debug
 
-    actor = tractor.current_actor()
+    actor = current_actor()
     # print(f'{actor.uid} in HANDLER with ')
 
     def do_cancel():
@@ -764,27 +612,62 @@ def shield_sigint_handler(
         # https://github.com/prompt-toolkit/python-prompt-toolkit/blob/c2c6af8a0308f9e5d7c0e28cb8a02963fe0ce07a/prompt_toolkit/patch_stdout.py
 
 
+_pause_msg: str = 'Attaching to pdb REPL in actor'
+
+
 def _set_trace(
     actor: tractor.Actor | None = None,
     pdb: MultiActorPdb | None = None,
-):
-    __tracebackhide__ = True
-    actor: tractor.Actor = actor or tractor.current_actor()
+    shield: bool = False,
 
-    # start 2 levels up in user code
-    frame: FrameType | None = sys._getframe()
-    if frame:
+    extra_frames_up_when_async: int = 1,
+):
+    __tracebackhide__: bool = True
+    actor: tractor.Actor = actor or current_actor()
+
+    # always start 1 level up from THIS in user code.
+    frame: FrameType|None
+    if frame := sys._getframe():
         frame: FrameType = frame.f_back  # type: ignore
 
     if (
         frame
-        and pdb
+        and (
+            pdb
             and actor is not None
+        )
+        # or shield
     ):
-        log.pdb(f"\nAttaching pdb to actor: {actor.uid}\n")
+        msg: str = _pause_msg
+        if shield:
+            # log.warning(
+            msg = (
+                '\n\n'
+                '            ------ - ------\n'
+                'Debugger invoked with `shield=True` so an extra\n'
+                '`trio.CancelScope.__exit__()` frame is shown..\n'
+                '\n'
+                'Try going up one frame to see your pause point!\n'
+                '\n'
+                '          SORRY we need to fix this!\n'
+                '            ------ - ------\n\n'
+            ) + msg
+
+        # pdbp.set_trace()
+        # TODO: maybe print the actor supervion tree up to the
+        # root here? Bo
+        log.pdb(
+            f'{msg}\n'
+            '|\n'
+            f'|_ {actor.uid}\n'
+        )
         # no f!#$&* idea, but when we're in async land
         # we need 2x frames up?
-        frame = frame.f_back
+        for i in range(extra_frames_up_when_async):
+            frame: FrameType = frame.f_back
+            log.debug(
+                f'Going up frame {i} -> {frame}\n'
+            )
 
     else:
         pdb, undo_sigint = mk_mpdb()
@@ -794,18 +677,278 @@ def _set_trace(
         Lock.local_task_in_debug = 'sync'
 
     pdb.set_trace(frame=frame)
-    # undo_
 
 
-# TODO: allow pausing from sync code, normally by remapping
-# python's builtin breakpoint() hook to this runtime aware version.
+async def _pause(
+
+    debug_func: Callable = _set_trace,
+    release_lock_signal: trio.Event | None = None,
+
+    # TODO: allow caller to pause despite task cancellation,
+    # exactly the same as wrapping with:
+    # with CancelScope(shield=True):
+    #     await pause()
+    # => the REMAINING ISSUE is that the scope's .__exit__() frame
+    # is always show in the debugger on entry.. and there seems to
+    # be no way to override it?..
+    # shield: bool = False,
+
+    shield: bool = False,
+    task_status: TaskStatus[trio.Event] = trio.TASK_STATUS_IGNORED
+
+) -> None:
+    '''
+    Inner impl for `pause()` to avoid the `trio.CancelScope.__exit__()`
+    stack frame when not shielded (since apparently i can't figure out
+    how to hide it using the normal mechanisms..)
+
+    Hopefully we won't need this in the long run.
+
+    '''
+    __tracebackhide__: bool = True
+    actor = current_actor()
+    pdb, undo_sigint = mk_mpdb()
+    task_name: str = trio.lowlevel.current_task().name
+
+    if (
+        not Lock.local_pdb_complete
+        or Lock.local_pdb_complete.is_set()
+    ):
+        Lock.local_pdb_complete = trio.Event()
+
+    debug_func = partial(
+        debug_func,
+    )
+
+    # TODO: need a more robust check for the "root" actor
+    if (
+        not is_root_process()
+        and actor._parent_chan  # a connected child
+    ):
+
+        if Lock.local_task_in_debug:
+
+            # Recurrence entry case: this task already has the lock and
+            # is likely recurrently entering a breakpoint
+            if Lock.local_task_in_debug == task_name:
+                # noop on recurrent entry case but we want to trigger
+                # a checkpoint to allow other actors error-propagate and
+                # potetially avoid infinite re-entries in some subactor.
+                await trio.lowlevel.checkpoint()
+                return
+
+            # if **this** actor is already in debug mode block here
+            # waiting for the control to be released - this allows
+            # support for recursive entries to `tractor.breakpoint()`
+            log.warning(f"{actor.uid} already has a debug lock, waiting...")
+
+            await Lock.local_pdb_complete.wait()
+            await trio.sleep(0.1)
+
+        # mark local actor as "in debug mode" to avoid recurrent
+        # entries/requests to the root process
+        Lock.local_task_in_debug = task_name
+
+        # this **must** be awaited by the caller and is done using the
+        # root nursery so that the debugger can continue to run without
+        # being restricted by the scope of a new task nursery.
+
+        # TODO: if we want to debug a trio.Cancelled triggered exception
+        # we have to figure out how to avoid having the service nursery
+        # cancel on this task start? I *think* this works below:
+        # ```python
+        #   actor._service_n.cancel_scope.shield = shield
+        # ```
+        # but not entirely sure if that's a sane way to implement it?
+        try:
+            with trio.CancelScope(shield=True):
+                await actor._service_n.start(
+                    wait_for_parent_stdin_hijack,
+                    actor.uid,
+                )
+                Lock.repl = pdb
+        except RuntimeError:
+            Lock.release()
+
+            if actor._cancel_called:
+                # service nursery won't be usable and we
+                # don't want to lock up the root either way since
+                # we're in (the midst of) cancellation.
+                return
+
+            raise
+
+    elif is_root_process():
+
+        # we also wait in the root-parent for any child that
+        # may have the tty locked prior
+        # TODO: wait, what about multiple root tasks acquiring it though?
+        if Lock.global_actor_in_debug == actor.uid:
+            # re-entrant root process already has it: noop.
+            return
+
+        # XXX: since we need to enter pdb synchronously below,
+        # we have to release the lock manually from pdb completion
+        # callbacks. Can't think of a nicer way then this atm.
+        if Lock._debug_lock.locked():
+            log.warning(
+                'Root actor attempting to shield-acquire active tty lock'
+                f' owned by {Lock.global_actor_in_debug}')
+
+            # must shield here to avoid hitting a ``Cancelled`` and
+            # a child getting stuck bc we clobbered the tty
+            with trio.CancelScope(shield=True):
+                await Lock._debug_lock.acquire()
+        else:
+            # may be cancelled
+            await Lock._debug_lock.acquire()
+
+        Lock.global_actor_in_debug = actor.uid
+        Lock.local_task_in_debug = task_name
+        Lock.repl = pdb
+
+    try:
+        # TODO: do we want to support using this **just** for the
+        # locking / common code (prolly to help address #320)?
+        #
+        # if debug_func is None:
+            # assert release_lock_signal, (
+            #     'Must pass `release_lock_signal: trio.Event` if no '
+            #     'trace func provided!'
+            # )
+            # print(f"{actor.uid} ENTERING WAIT")
+            # with trio.CancelScope(shield=True):
+            #     await release_lock_signal.wait()
+
+        # else:
+            # block here one (at the appropriate frame *up*) where
+            # ``breakpoint()`` was awaited and begin handling stdio.
+        log.debug('Entering sync world of the `pdb` REPL..')
+        try:
+            debug_func(
+                actor,
+                pdb,
+                extra_frames_up_when_async=2,
+                shield=shield,
+            )
+        except BaseException:
+            log.exception(
+                'Failed to invoke internal `debug_func = '
+                f'{debug_func.func.__name__}`\n'
+            )
+            raise
+
+    except bdb.BdbQuit:
+        Lock.release()
+        raise
+
+    except BaseException:
+        log.exception(
+            'Failed to engage debugger via `_pause()` ??\n'
+        )
+        raise
+
+# XXX: apparently we can't do this without showing this frame
+# in the backtrace on first entry to the REPL? Seems like an odd
+# behaviour that should have been fixed by now. This is also why
+# we scrapped all the @cm approaches that were tried previously.
+# finally:
+#     __tracebackhide__ = True
+#     # frame = sys._getframe()
+#     # last_f = frame.f_back
+#     # last_f.f_globals['__tracebackhide__'] = True
+#     # signal.signal = pdbp.hideframe(signal.signal)
+
+
+async def pause(
+
+    debug_func: Callable = _set_trace,
+    release_lock_signal: trio.Event | None = None,
+
+    # TODO: allow caller to pause despite task cancellation,
+    # exactly the same as wrapping with:
+    # with CancelScope(shield=True):
+    #     await pause()
+    # => the REMAINING ISSUE is that the scope's .__exit__() frame
+    # is always show in the debugger on entry.. and there seems to
+    # be no way to override it?..
+    # shield: bool = False,
+
+    shield: bool = False,
+    task_status: TaskStatus[trio.Event] = trio.TASK_STATUS_IGNORED
+
+) -> None:
+    '''
+    A pause point (more commonly known as a "breakpoint") interrupt
+    instruction for engaging a blocking debugger instance to
+    conduct manual console-based-REPL-interaction from within
+    `tractor`'s async runtime, normally from some single-threaded
+    and currently executing actor-hosted-`trio`-task in some
+    (remote) process.
+
+    NOTE: we use the semantics "pause" since it better encompasses
+    the entirety of the necessary global-runtime-state-mutation any
+    actor-task must access and lock in order to get full isolated
+    control over the process tree's root TTY:
+    https://en.wikipedia.org/wiki/Breakpoint
+
+    '''
+    __tracebackhide__: bool = True
+
+    if shield:
+        # NOTE XXX: even hard coding this inside the `class CancelScope:`
+        # doesn't seem to work for me!?
+        # ^ XXX ^
+
+        # def _exit(self, *args, **kwargs):
+        #     __tracebackhide__: bool = True
+        #     super().__exit__(*args, **kwargs)
+
+        trio.CancelScope.__enter__.__tracebackhide__ = True
+        trio.CancelScope.__exit__.__tracebackhide__ = True
+
+        # import types
+        # with trio.CancelScope(shield=shield) as cs:
+            # cs.__exit__ = types.MethodType(_exit, cs)
+            # cs.__exit__.__tracebackhide__ = True
+
+        with trio.CancelScope(shield=shield) as cs:
+            # setattr(cs.__exit__.__func__, '__tracebackhide__', True)
+            # setattr(cs.__enter__.__func__, '__tracebackhide__', True)
+
+            # NOTE: so the caller can always cancel even if shielded
+            task_status.started(cs)
+            return await _pause(
+                debug_func=debug_func,
+                release_lock_signal=release_lock_signal,
+                shield=True,
+                task_status=task_status,
+            )
+    else:
+        return await _pause(
+            debug_func=debug_func,
+            release_lock_signal=release_lock_signal,
+            shield=False,
+            task_status=task_status,
+        )
+
+
+
+
+# TODO: allow pausing from sync code.
+# normally by remapping python's builtin breakpoint() hook to this
+# runtime aware version which takes care of all .
 def pause_from_sync() -> None:
     print("ENTER SYNC PAUSE")
+    actor: tractor.Actor = current_actor(
+        err_on_no_runtime=False,
+    )
+    if actor:
         try:
             import greenback
-        __tracebackhide__ = True
+            # __tracebackhide__ = True
+
 
-        actor: tractor.Actor = tractor.current_actor()
             # task_can_release_tty_lock = trio.Event()
 
             # spawn bg task which will lock out the TTY, we poll
@@ -818,8 +961,11 @@ def pause_from_sync() -> None:
                     # release_lock_signal=task_can_release_tty_lock,
                 ))
             )
+
         except ModuleNotFoundError:
             log.warning('NO GREENBACK FOUND')
+    else:
+        log.warning('Not inside actor-runtime')
 
     db, undo_sigint = mk_mpdb()
     Lock.local_task_in_debug = 'sync'
@@ -854,11 +1000,7 @@ def pause_from_sync() -> None:
 # using the "pause" semantics instead since
 # that better covers actually somewhat "pausing the runtime"
 # for this particular paralell task to do debugging B)
-pause = partial(
-    _pause,
-    _set_trace,
-)
-pp = pause  # short-hand for "pause point"
+# pp = pause  # short-hand for "pause point"
 
 
 async def breakpoint(**kwargs):
@@ -869,9 +1011,18 @@ async def breakpoint(**kwargs):
     await pause(**kwargs)
 
 
+_crash_msg: str = (
+    'Attaching to pdb REPL in crashed actor'
+)
+
+
 def _post_mortem(
     actor: tractor.Actor,
     pdb: MultiActorPdb,
+    shield: bool = False,
+
+    # only for compat with `._set_trace()`..
+    extra_frames_up_when_async=0,
 
 ) -> None:
     '''
@@ -879,20 +1030,28 @@ def _post_mortem(
     debugger instance.
 
     '''
-    log.pdb(f"\nAttaching to pdb in crashed actor: {actor.uid}\n")
+    # TODO: print the actor supervion tree up to the root
+    # here! Bo
+    log.pdb(
+        f'{_crash_msg}\n'
+        '|\n'
+        f'|_ {actor.uid}\n'
+    )
 
-    # TODO: you need ``pdbpp`` master (at least this commit
-    # https://github.com/pdbpp/pdbpp/commit/b757794857f98d53e3ebbe70879663d7d843a6c2)
-    # to fix this and avoid the hang it causes. See issue:
-    # https://github.com/pdbpp/pdbpp/issues/480
-    # TODO: help with a 3.10+ major release if/when it arrives.
-
-    pdbp.xpm(Pdb=lambda: pdb)
+    # TODO: only replacing this to add the
+    # `end=''` to the print XD
+    # pdbp.xpm(Pdb=lambda: pdb)
+    info = sys.exc_info()
+    print(traceback.format_exc(), end='')
+    pdbp.post_mortem(
+        t=info[2],
+        Pdb=lambda: pdb,
+    )
 
 
 post_mortem = partial(
-    _pause,
-    _post_mortem,
+    pause,
+    debug_func=_post_mortem,
 )
 
 
@@ -933,9 +1092,10 @@ async def acquire_debug_lock(
     '''
     Grab root's debug lock on entry, release on exit.
 
-    This helper is for actor's who don't actually need
-    to acquired the debugger but want to wait until the
-    lock is free in the process-tree root.
+    This helper is for actor's who don't actually need to acquired
+    the debugger but want to wait until the lock is free in the
+    process-tree root such that they don't clobber an ongoing pdb
+    REPL session in some peer or child!
 
     '''
     if not debug_mode():
@@ -956,14 +1116,18 @@ async def maybe_wait_for_debugger(
     poll_delay: float = 0.1,
     child_in_debug: bool = False,
 
-) -> None:
+    header_msg: str = '',
+
+) -> bool:  # was locked and we polled?
 
     if (
         not debug_mode()
         and not child_in_debug
     ):
-        return
+        return False
 
+
+    msg: str = header_msg
     if (
         is_root_process()
     ):
@@ -973,41 +1137,147 @@ async def maybe_wait_for_debugger(
         # will make the pdb repl unusable.
         # Instead try to wait for pdb to be released before
         # tearing down.
-        sub_in_debug: tuple[str, str] | None = None
+        in_debug: tuple[str, str]|None = Lock.global_actor_in_debug
+        debug_complete: trio.Event|None = Lock.no_remote_has_tty
 
-        for _ in range(poll_steps):
-
-            if Lock.global_actor_in_debug:
-                sub_in_debug = tuple(Lock.global_actor_in_debug)
-
-            log.debug('Root polling for debug')
-
-            with trio.CancelScope(shield=True):
-                await trio.sleep(poll_delay)
-
-                # TODO: could this make things more deterministic?  wait
-                # to see if a sub-actor task will be scheduled and grab
-                # the tty lock on the next tick?
-                # XXX: doesn't seem to work
-                # await trio.testing.wait_all_tasks_blocked(cushion=0)
-
-                debug_complete = Lock.no_remote_has_tty
-                if (
-                    debug_complete
-                    and sub_in_debug is not None
-                    and not debug_complete.is_set()
-                ):
-                    log.pdb(
-                        'Root has errored but pdb is in use by '
-                        f'child {sub_in_debug}\n'
-                        'Waiting on tty lock to release..'
+        if in_debug == current_actor().uid:
+            log.debug(
+                msg
+                +
+                'Root already owns the TTY LOCK'
             )
+            return True
 
-                    await debug_complete.wait()
-
-                await trio.sleep(poll_delay)
-                continue
+        elif in_debug:
+            msg += (
+                f'Debug `Lock` in use by subactor: {in_debug}\n'
+            )
+            # TODO: could this make things more deterministic?
+            # wait to see if a sub-actor task will be
+            # scheduled and grab the tty lock on the next
+            # tick?
+            # XXX => but it doesn't seem to work..
+            # await trio.testing.wait_all_tasks_blocked(cushion=0)
         else:
             log.debug(
-                    'Root acquired TTY LOCK'
+                msg
+                +
+                'Root immediately acquired debug TTY LOCK'
             )
+            return False
+
+        for istep in range(poll_steps):
+            if (
+                debug_complete
+                and not debug_complete.is_set()
+                and in_debug is not None
+            ):
+                log.pdb(
+                    msg
+                    +
+                    'Root is waiting on tty lock to release..\n'
+                )
+                with trio.CancelScope(shield=True):
+                    await debug_complete.wait()
+                log.pdb(
+                    f'Child subactor released debug lock\n'
+                    f'|_{in_debug}\n'
+                )
+
+            # is no subactor locking debugger currently?
+            if (
+                in_debug is None
+                and (
+                    debug_complete is None
+                    or debug_complete.is_set()
+                )
+            ):
+                log.pdb(
+                    msg
+                    +
+                    'Root acquired tty lock!'
+                )
+                break
+
+            else:
+                # TODO: don't need this right?
+                # await trio.lowlevel.checkpoint()
+
+                log.debug(
+                    'Root polling for debug:\n'
+                    f'poll step: {istep}\n'
+                    f'poll delya: {poll_delay}'
+                )
+                with trio.CancelScope(shield=True):
+                    await trio.sleep(poll_delay)
+                    continue
+
+        # fallthrough on failure to acquire..
+        # else:
+        #     raise RuntimeError(
+        #         msg
+        #         +
+        #         'Root actor failed to acquire debug lock?'
+        #     )
+        return True
+
+    # else:
+    #     # TODO: non-root call for #320?
+    #     this_uid: tuple[str, str] = current_actor().uid
+    #     async with acquire_debug_lock(
+    #         subactor_uid=this_uid,
+    #     ):
+    #         pass
+    return False
+
+# TODO: better naming and what additionals?
+# - [ ] optional runtime plugging?
+# - [ ] detection for sync vs. async code?
+# - [ ] specialized REPL entry when in distributed mode?
+# - [x] allow ignoring kbi Bo
+@cm
+def open_crash_handler(
+    catch: set[BaseException] = {
+        Exception,
+        BaseException,
+    },
+    ignore: set[BaseException] = {
+        KeyboardInterrupt,
+    },
+):
+    '''
+    Generic "post mortem" crash handler using `pdbp` REPL debugger.
+
+    We expose this as a CLI framework addon to both `click` and
+    `typer` users so they can quickly wrap cmd endpoints which get
+    automatically wrapped to use the runtime's `debug_mode: bool`
+    AND `pdbp.pm()` around any code that is PRE-runtime entry
+    - any sync code which runs BEFORE the main call to
+      `trio.run()`.
+
+    '''
+    try:
+        yield
+    except tuple(catch) as err:
+
+        if type(err) not in ignore:
+            pdbp.xpm()
+
+        raise
+
+
+@cm
+def maybe_open_crash_handler(pdb: bool = False):
+    '''
+    Same as `open_crash_handler()` but with bool input flag
+    to allow conditional handling.
+
+    Normally this is used with CLI endpoints such that if the --pdb
+    flag is passed the pdb REPL is engaed on any crashes B)
+    '''
+    rtctx = nullcontext
+    if pdb:
+        rtctx = open_crash_handler
+
+    with rtctx():
+        yield

tractor/devx/_stackscope.py

@@ -0,0 +1,84 @@
+# tractor: structured concurrent "actors".
+# Copyright eternity Tyler Goodlet.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+'''
+The fundamental cross process SC abstraction: an inter-actor,
+cancel-scope linked task "context".
+
+A ``Context`` is very similar to the ``trio.Nursery.cancel_scope`` built
+into each ``trio.Nursery`` except it links the lifetimes of memory space
+disjoint, parallel executing tasks in separate actors.
+
+'''
+from signal import (
+    signal,
+    SIGUSR1,
+)
+
+import trio
+
+@trio.lowlevel.disable_ki_protection
+def dump_task_tree() -> None:
+    import stackscope
+    from tractor.log import get_console_log
+
+    tree_str: str = str(
+        stackscope.extract(
+            trio.lowlevel.current_root_task(),
+            recurse_child_tasks=True
+        )
+    )
+    log = get_console_log('cancel')
+    log.pdb(
+        f'Dumping `stackscope` tree:\n\n'
+        f'{tree_str}\n'
+    )
+    # import logging
+    # try:
+    #     with open("/dev/tty", "w") as tty:
+    #         tty.write(tree_str)
+    # except BaseException:
+    #     logging.getLogger(
+    #         "task_tree"
+    #     ).exception("Error printing task tree")
+
+
+def signal_handler(sig: int, frame: object) -> None:
+    import traceback
+    try:
+        trio.lowlevel.current_trio_token(
+        ).run_sync_soon(dump_task_tree)
+    except RuntimeError:
+        # not in async context -- print a normal traceback
+        traceback.print_stack()
+
+
+
+def enable_stack_on_sig(
+    sig: int = SIGUSR1
+) -> None:
+    '''
+    Enable `stackscope` tracing on reception of a signal; by
+    default this is SIGUSR1.
+
+    '''
+    signal(
+        sig,
+        signal_handler,
+    )
+    # NOTE: not the above can be triggered from
+    # a (xonsh) shell using:
+    # kill -SIGUSR1 @$(pgrep -f '<cmd>')

tractor/devx/cli.py

@@ -0,0 +1,129 @@
+# tractor: structured concurrent "actors".
+# Copyright 2018-eternity Tyler Goodlet.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+"""
+CLI framework extensions for hacking on the actor runtime.
+
+Currently popular frameworks supported are:
+
+  - `typer` via the `@callback` API
+
+"""
+from __future__ import annotations
+from typing import (
+    Any,
+    Callable,
+)
+from typing_extensions import Annotated
+
+import typer
+
+
+_runtime_vars: dict[str, Any] = {}
+
+
+def load_runtime_vars(
+    ctx: typer.Context,
+    callback: Callable,
+    pdb: bool = False,  # --pdb
+    ll: Annotated[
+        str,
+        typer.Option(
+            '--loglevel',
+            '-l',
+            help='BigD logging level',
+        ),
+    ] = 'cancel',  # -l info
+):
+    '''
+    Maybe engage crash handling with `pdbp` when code inside
+    a `typer` CLI endpoint cmd raises.
+
+    To use this callback simply take your `app = typer.Typer()` instance
+    and decorate this function with it like so:
+
+    .. code:: python
+
+        from tractor.devx import cli
+
+        app = typer.Typer()
+
+        # manual decoration to hook into `click`'s context system!
+        cli.load_runtime_vars = app.callback(
+            invoke_without_command=True,
+        )
+
+    And then you can use the now augmented `click` CLI context as so,
+
+    .. code:: python
+
+        @app.command(
+            context_settings={
+                "allow_extra_args": True,
+                "ignore_unknown_options": True,
+            }
+        )
+        def my_cli_cmd(
+            ctx: typer.Context,
+        ):
+            rtvars: dict = ctx.runtime_vars
+            pdb: bool = rtvars['pdb']
+
+            with tractor.devx.cli.maybe_open_crash_handler(pdb=pdb):
+                trio.run(
+                    partial(
+                        my_tractor_main_task_func,
+                        debug_mode=pdb,
+                        loglevel=rtvars['ll'],
+                    )
+                )
+
+    which will enable log level and debug mode globally for the entire
+    `tractor` + `trio` runtime thereafter!
+
+    Bo
+
+    '''
+    global _runtime_vars
+    _runtime_vars |= {
+        'pdb': pdb,
+        'll': ll,
+    }
+
+    ctx.runtime_vars: dict[str, Any] = _runtime_vars
+    print(
+        f'`typer` sub-cmd: {ctx.invoked_subcommand}\n'
+        f'`tractor` runtime vars: {_runtime_vars}'
+    )
+
+    # XXX NOTE XXX: hackzone.. if no sub-cmd is specified (the
+    # default if the user just invokes `bigd`) then we simply
+    # invoke the sole `_bigd()` cmd passing in the "parent"
+    # typer.Context directly to that call since we're treating it
+    # as a "non sub-command" or wtv..
+    # TODO: ideally typer would have some kinda built-in way to get
+    # this behaviour without having to construct and manually
+    # invoke our own cmd..
+    if (
+        ctx.invoked_subcommand is None
+        or ctx.invoked_subcommand == callback.__name__
+    ):
+        cmd: typer.core.TyperCommand = typer.core.TyperCommand(
+            name='bigd',
+            callback=callback,
+        )
+        ctx.params = {'ctx': ctx}
+        cmd.invoke(ctx)