A small raft of changes to address comments raised.

borgmatic/borg/diff.py

@@ -28,6 +28,8 @@ def diff(
     arguments, optional local and remote Borg paths, executes the diff command with the given
     arguments.
     '''
+    borgmatic.logger.add_custom_log_levels()
+
     lock_wait = config.get('lock_wait', None)
     exclude_flags = flags.make_exclude_flags(config)
     extra_borg_options = config.get('extra_borg_options', {}).get('diff', '')
@@ -38,6 +40,11 @@ def diff(
         borgmatic.config.paths.get_working_directory(config),
     )
 
+    if borgmatic.borg.feature.available(borgmatic.borg.feature.Feature.NUMERIC_IDS, local_borg_version):
+        numeric_ids_flags = ('--numeric-ids',) if config.get('numeric_ids') else ()
+    else:
+        numeric_ids_flags = ('--numeric-owner',) if config.get('numeric_ids') else ()
+
     diff_command = (
         (local_path, 'diff')
         + (('--remote-path', remote_path) if remote_path else ())
@@ -47,6 +54,7 @@ def diff(
         + (('--debug', '--show-rc') if logger.isEnabledFor(logging.DEBUG) else ())
         + (('--patterns-from', patterns_file.name) if patterns_file else ())
         + exclude_flags
+        + numeric_ids_flags
         + (tuple(shlex.split(extra_borg_options)) if extra_borg_options else ())
         + (
             (
@@ -61,21 +69,18 @@ def diff(
                 borgmatic.borg.feature.Feature.SEPARATE_REPOSITORY_ARCHIVE,
                 local_borg_version,
             )
-            else (
-                flags.make_repository_archive_flags(repository, archive, local_borg_version)
-                if archive
-                else flags.make_repository_flags(repository, local_borg_version)
-            )
+            else flags.make_repository_archive_flags(repository, archive, local_borg_version)
         )
         + (('--same-chunker-params',) if diff_arguments.same_chunker_params else ())
         + (('--sort-by', diff_arguments.sort_by) if diff_arguments.sort_by else ())
+        + (tuple(diff_arguments.sort_keys) if diff_arguments.sort_keys else ())
         + (('--content-only',) if diff_arguments.content_only else ())
         + (diff_arguments.second_archive, )
     )
 
     borgmatic.execute.execute_command(
         full_command=diff_command,
-        output_log_level=logging.INFO,
+        output_log_level=logging.ANSWER,
         environment=borgmatic.borg.environment.make_environment(config),
         working_directory=borgmatic.config.paths.get_working_directory(config),
         borg_local_path=local_path,

borgmatic/commands/arguments.py

@@ -1984,16 +1984,13 @@ def make_parsers(schema, unparsed_arguments):  # noqa: PLR0915
     )
     diff_group.add_argument(
         '--archive',
-        help='Archive name, hash, or series to diff, defaults to all archives in the repository (if specified)',
+        help='Archive name, hash, or series to diff',
+        required=True,
     )
     diff_group.add_argument(
         '--second-archive',
         help='Second archive name, hash, or series to diff',
-    )
-    diff_group.add_argument(
-        '--numeric-ids',
-        action='store_true',
-        help='Only consider numeric user and group identifiers',
+        required=True,
     )
     diff_group.add_argument(
         '--same-chunker-params',
@@ -2002,8 +1999,10 @@ def make_parsers(schema, unparsed_arguments):  # noqa: PLR0915
     )
     diff_group.add_argument(
         '--sort-by',
-        metavar='KEYS',
-        help='Advanced sorting: specify field(s) to sort by. Accepts a comma-separated list. Prefix with > for descending or < for ascending (default).'
+        metavar='KEY',
+        dest='sort_keys',
+        action='append',
+        help='Advanced sorting: specify field(s) to sort by. Prefix with > for descending or < for ascending (default).'
     )
     diff_group.add_argument(
         '--content-only',