Reopened multiple inheritance phases: own-class isinstance and CLI failure roster become capabilities

src/agent_comms/cli_protocol.py

@@ -27,14 +27,13 @@
 from pydantic_core import CoreSchema
 from typing_extensions import TypeForm
 
-from .coordination_errors import CoordinationError, CoordinationReadUnavailable
+from .coordination_errors import CommandFailure, CoordinationReadUnavailable
 from .declared_family import DeclaredFamily, UnknownFamilyMember
 from .external_transcript import RequestedEarlierPage
 from .field_codec import FieldCodec, TimestampText
 from .maintenance_barrier import MaintenanceHeldError
 from .messages import Message
 from .recorded_time import UnrecordedTimeError
-from .repo import GitCommandError
 from .turn_item import NativeTurnId, TurnItem
 from .wire_models import DeclaredWireFamily, WireModel
 
@@ -43,7 +42,7 @@
     from .cli_bridges.shared import BindingThread, CliBridge, DeliveryRow
 
 
-CLI_FAILURES = (ValueError, OSError, CoordinationError, GitCommandError)
+CLI_FAILURES = (ValueError, OSError, CommandFailure)
 
 
 async def raise_child_exit(child: AttachedChild, reason: str) -> NoReturn:

src/agent_comms/coordination_errors.py

@@ -11,11 +11,15 @@ class DrainDeferred(Exception):  # noqa: N818 - capability, not an outcome
     """A failure an inbox drain records and retries later instead of stopping on."""
 
 
+class CommandFailure(Exception):  # noqa: N818 - capability, not an outcome
+    """A failure a command reports to its caller as a failed result instead of crashing."""
+
+
 class DrainUnavailable(DrainDeferred):
     """A failure meaning the drain's store or coordinator is unavailable right now."""
 
 
-class CoordinationError(RuntimeError, DrainUnavailable):
+class CoordinationError(RuntimeError, DrainUnavailable, CommandFailure):
     """Base class for fail-loud coordinator errors."""
 
     def __reduce__(self):

src/agent_comms/registry_document.py

@@ -295,9 +295,10 @@ def bind(self, binding: Callable[[Thread], Thread]) -> None:
 
     def __eq__(self, other: object) -> bool:
         """Rows still stored on both sides compare as their JSON; only rows that differ there,
-        or that either side wrote, are decoded, so a one-row edit never decodes the registry."""
+        or that either side wrote, are decoded, so a one-row edit never decodes the registry.
+        Rows equal only rows: a plain mapping is a different value."""
         if not isinstance(other, ThreadRows):
-            return super().__eq__(other)
+            return NotImplemented
         return self.keys() == other.keys() and all(
             (name in self._raw and name in other._raw and self._raw[name] == other._raw[name])
             or self[name] == other[name]

src/agent_comms/repo.py

@@ -12,6 +12,7 @@
 
 from pydantic import BaseModel, ConfigDict, InstanceOf, PlainSerializer, PlainValidator
 
+from .coordination_errors import CommandFailure
 from .declared_family import DeclaredFamily
 from .errors import MissingSourceLine
 from .field_codec import FieldCodec, WireValue
@@ -34,7 +35,7 @@ def founding(self, commander: str) -> tuple[Repo, ...]: ...
     def without_commander(self) -> None: ...
 
 
-class GitCommandError(RuntimeError):
+class GitCommandError(RuntimeError, CommandFailure):
     """A Git operation failure, not malformed order data to aggregate and continue past."""
 
     def __init__(self, repository: str, run: subprocess.CompletedProcess[bytes]):

tests/test_registration_components.py

@@ -38,7 +38,7 @@ def test_edit_owns_turn_and_document_owns_later_changes(tmp_path, *, thread_regi
     document.unregister("renamed")
     document.begin_delete("renamed")
     assert document.remove("renamed") == ()
-    assert document.threads == {}
+    assert not document.threads
     assert not list(tmp_path.iterdir())