Anchor a Loose File on Its Own Parent, Not on Where the Caller Stands

The no-repository fallback anchored a file argument on `.`, which is the
caller's directory. Scanning a loose file from inside an operational
repository therefore exempted it, which is this PR's own defect in
miniature, reintroduced by the fix for the previous round's regression.
A file now anchors on its own parent. A bare filename still anchors on `.`
and that stays correct, since `.` is the directory holding it.
The test meant to guard this passed a directory, so it never reached the
branch that broke. It passes the file now, with `operational_checkout`
mocked to treat `.` as operational, which is the arrangement that fails on
the old behaviour. A second case keeps the directory path covered.
Verified live as well: a loose file scanned from an operational checkout
reports the planted violation, and the multi-file invocation outside a
repository still exits 0.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: ptr727

scripts/prose_lint.py

@@ -1122,12 +1122,14 @@ def main(argv: list[str] | None = None) -> int:
 file=sys.stderr)
 return2
 # With one repository in play, the model is that repository's own.
-# With none, anchor the way discovery does, so the rule set is decided over the tree that will actually be read.
+# With none, a file anchors on its own parent rather than on `.`, which is where the caller stands.
+# Anchoring a loose file on `.` reintroduces this defect in miniature, exempting a file the caller's repository does not contain.
+# A bare filename still anchors on `.`, correctly, since that is the directory holding it.
 ifgit_roots:
 scan_root=Path(next(iter(git_roots)))
 else:
 first=Path(scan_paths[0])
-scan_root=firstiffirst.is_dir() elsePath('.')
+scan_root=firstiffirst.is_dir() elsefirst.parent
 
 # An operational repository's runbook carries the literal path an operator types.
 # That is the repository's own content, not an agent quoting an environment it observed.

scripts/test_prose_lint.py

@@ -1881,19 +1881,35 @@ def test_one_repository_plus_a_loose_path_is_not_a_conflict(self) -> None:
  [str(self.release), str(loose), '--check', 'home-path']))
 self.assertNotIn('more than one repository', self.err.getvalue())
 
-deftest_a_path_under_no_repository_falls_back_to_itself_rather_than_the_caller(self) ->None:
+deftest_a_loose_file_anchors_on_its_own_parent_rather_than_on_the_caller(self) ->None:
 """The fallback must not reintroduce the dependency the fix removes.
 
- `repo_root` returns '' for a path git cannot place, and resolving that to `.` would put the
- caller's directory back in charge of the verdict.
+ A *file* argument is the case that matters. Anchoring it on `.` puts the caller's directory
+ back in charge, so scanning a loose file from inside an operational repository exempts it.
+ Passing a directory here would not exercise that branch at all, which is how the earlier
+ version of this test let the regression through.
  """
 loose=self.tmp/'loose'
 loose.mkdir()
 bait=loose/'notes.md'
 bait.write_text(f'Deploy into {NIX_HOME}/stack here.\n', encoding='utf-8')
+# The caller stands somewhere operational; the scanned file's own directory does not.
 withmock.patch.object(prose_lint, 'repo_root', return_value=''), \
+mock.patch.object(prose_lint, 'operational_checkout',
+side_effect=lambdaroot: Path(root) ==Path('.')), \
+mock.patch.object(prose_lint, 'discover', return_value=[bait]):
+self.assertEqual(1, prose_lint.main([str(bait), '--check', 'home-path']))
+self.assertNotIn('operational repository', self.err.getvalue())
+
+deftest_a_loose_directory_anchors_on_itself(self) ->None:
+loose=self.tmp/'loose'
+loose.mkdir()
+bait=loose/'notes.md'
+bait.write_text(f'Deploy into {NIX_HOME}/stack here.\n', encoding='utf-8')
+withmock.patch.object(prose_lint, 'repo_root', return_value=''), \
+mock.patch.object(prose_lint, 'operational_checkout',
+side_effect=lambdaroot: Path(root) ==Path('.')), \
 mock.patch.object(prose_lint, 'discover', return_value=[bait]):
-# Not a repository, so it carries no operational payload and the rule stays on.
 self.assertEqual(1, prose_lint.main([str(loose), '--check', 'home-path']))
 self.assertNotIn('operational repository', self.err.getvalue())