Route all diagnostic logging through the plain "kanta" logger.

Module loggers used __name__, splitting diagnostics across eight
module-named loggers and colliding kanta.transaction with the
transaction event channel.  Diagnostics (integrity errors, flush
failures, rotation notes) are few; they now all go through the
"kanta" logger, following the application's root logging
configuration like any ordinary library output.

kanta/__main__.py

@@ -17,7 +17,7 @@ from typing import Any
 import msgspec
 
 from kanta import Kanta
-from kanta.callbacks import InjectionContext
+from kanta.callbacks import InjectionContext, callback_error_reporter
 from kanta.exceptions import DatabaseError, DataIntegrityError, ReplayError
 from kanta.grep import GrepPattern, evaluate
 from kanta.logging import (
@@ -50,8 +50,6 @@ EXIT_PARSE_ERROR = 10
 EXIT_MIGRATION_ERROR = 20
 EXIT_VALIDATION_ERROR = 21
 
-_logger = logging.getLogger(__name__)
-
 
 def _print(*args: Any) -> None:
     """Print to stderr, stripping ANSI codes when the stream has no color support.
@@ -408,13 +406,11 @@ async def _log_migration(
     """
     registry = kanta._impl.callback_registry
     if registry.has("logmigr"):
-        try:
         await registry.invoke(
             "logmigr",
             InjectionContext(kanta=kanta, report=result),
+            on_error=callback_error_reporter("logmigr"),
         )
-        except Exception:
-            _logger.exception("logmigr callback failed")
         return
     if quiet:
         return

kanta/callbacks.py

@@ -54,7 +54,37 @@ def _state_tag(ann: Any) -> str | None:
     return None
 
 
-_logger = logging.getLogger(__name__)
+_logger = logging.getLogger("kanta")
+
+
+def describe_callback(callback: Callable[..., Any]) -> str:
+    """Return ``name (docstring first line)`` identifying *callback*.
+
+    Used in failure messages so a bare log line names the function that
+    failed, e.g. ``myformatter (Concise log formatter)``.
+    """
+    name = getattr(callback, "__name__", None) or type(callback).__name__
+    doc = inspect.getdoc(callback)
+    if doc:
+        return f"{name} ({doc.splitlines()[0]})"
+    return name
+
+
+def callback_error_reporter(
+    kind: str,
+) -> Callable[[Exception, Callable[..., Any]], None]:
+    """Return an ``on_error`` reporter for :meth:`CallbackRegistry.invoke`.
+
+    The returned callable logs ``Kanta.<kind> <name (docstring)> failed:
+    <error>`` for each failing callback; invoke continues with the rest.
+    """
+
+    def _report(callback_error: Exception, callback: Callable[..., Any]) -> None:
+        _logger.exception(
+            "Kanta.%s %s failed: %s", kind, describe_callback(callback), callback_error
+        )
+
+    return _report
 
 
 class LogFmt:
@@ -281,7 +311,7 @@ class CallbackRegistry:
                 except Exception:
                     # Formatting must never break functionality; a failing
                     # callback is reported and treated as a fall-through.
-                    _logger.exception("logfmt callback %r failed", fn)
+                    _logger.exception("Kanta.logfmt %s failed", describe_callback(fn))
                     continue
                 if resolved is not None:
                     return resolved

kanta/filelock.py

@@ -16,7 +16,7 @@ from pathlib import Path
 
 from kanta.exceptions import FileLockError
 
-_logger = logging.getLogger(__name__)
+_logger = logging.getLogger("kanta")
 
 
 def _fatal(msg: str, *, db_path: Path | None = None) -> None:

kanta/kantaimpl.py

@@ -10,7 +10,7 @@ from datetime import UTC, datetime, timedelta
 from types import SimpleNamespace
 from typing import Any, Generic, TypeVar
 
-from kanta.callbacks import CallbackRegistry, InjectionContext
+from kanta.callbacks import CallbackRegistry, InjectionContext, callback_error_reporter
 from kanta.exceptions import DatabaseError, DataIntegrityError, ReplayError
 from kanta.logging import (
     _USER_PATH,
@@ -25,16 +25,11 @@ from kanta.rotation import execute_rotation, plan_rotation
 from kanta.serialization import restore_data_in_place, struct_to_dict
 from kanta.serialization.base import replay
 
-_logger = logging.getLogger(__name__)
+_logger = logging.getLogger("kanta")
 
 T = TypeVar("T")
 
 
-def _log_callback_error(callback_error, callback):
-    """Report a failing logging callback and continue with the next one."""
-    _logger.exception("Log callback %r failed: %s", callback, callback_error)
-
-
 class KantaImpl(PersistenceMixin, Generic[T]):
     """Internal state and logic for Kanta."""
 
@@ -119,7 +114,7 @@ class KantaImpl(PersistenceMixin, Generic[T]):
                     kanta=self._kanta,
                     report=report,
                 ),
-                on_error=_log_callback_error,
+                on_error=callback_error_reporter("logmigr"),
             )
             return
 

kanta/persistence.py

@@ -12,7 +12,7 @@ from datetime import UTC, datetime
 from pathlib import Path
 from typing import Any
 
-from kanta.callbacks import CallbackRegistry, InjectionContext
+from kanta.callbacks import CallbackRegistry, InjectionContext, callback_error_reporter
 from kanta.diff import diff
 from kanta.exceptions import DatabaseError, DataIntegrityError
 from kanta.filelock import LockedFile
@@ -21,7 +21,7 @@ from kanta.serialization import JsonSerializer, Serializer
 from kanta.serialization.framing import Framer
 from kanta.snapshot import SnapshotState
 
-_logger = logging.getLogger(__name__)
+_logger = logging.getLogger("kanta")
 
 
 class PersistenceMixin:
@@ -110,18 +110,10 @@ class PersistenceMixin:
                 break
             except DatabaseError as e:
                 self.background_error = e
-
-                def _log_callback_error(callback_error, callback):
-                    _logger.exception(
-                        "Background error callback %r failed: %s",
-                        callback,
-                        callback_error,
-                    )
-
                 await self.callback_registry.invoke(
                     "fatal_error",
                     InjectionContext(error=e, kanta=self._kanta),
-                    on_error=_log_callback_error,
+                    on_error=callback_error_reporter("fatal_error"),
                 )
                 _logger.error("Background flush loop stopped: %s", e)
                 break

kanta/rotation.py

@@ -20,7 +20,7 @@ from kanta.structs import ChangeRecord, Snapshot
 from kanta.serialization.base import Serializer, apply_diff
 from kanta.serialization.framing import Framer
 
-_logger = logging.getLogger(__name__)
+_logger = logging.getLogger("kanta")
 
 
 @dataclass

kanta/snapshot.py

@@ -10,7 +10,7 @@ from kanta.structs import Snapshot
 from kanta.serialization import JsonSerializer, Serializer
 from kanta.serialization.framing import Framer, LineFramer
 
-_logger = logging.getLogger(__name__)
+_logger = logging.getLogger("kanta")
 
 MINDIFFS = 100
 
@@ -69,7 +69,7 @@ class SnapshotState:
             self._write(file, version, state, ts, m=m)
             self._force_pending = False
         except Exception as exc:
-            _logger.error("snapshot: failed to write snapshot: %r", exc)
+            _logger.error("Kanta snapshot failed: %r", exc)
 
     def _write(
         self, file, version: int, state: dict, now: datetime, m: datetime | None = None

kanta/transaction.py

@@ -13,7 +13,7 @@ from kanta.callbacks import InjectionContext
 from kanta.logging import _USER_PATH, LogEvent, emit_event, transaction_logger
 from kanta.serialization import restore_data_in_place, struct_to_dict
 
-_logger = logging.getLogger(__name__)
+_logger = logging.getLogger("kanta")
 
 
 def _build_logfmt(impl, previous: dict, current: dict):