test(node): the backslash-path test modelled the wrong platform

It asserted `Path(win_dir).as_posix() == "C:/Users/alice/Media"`, which is only
true where `Path` is a `WindowsPath`. On every other machine a backslash is an
ordinary filename character, `as_posix()` converts nothing, and the test failed
against correct code — so it has never passed on this suite's usual host, and
never guarded anything there. `PureWindowsPath` names the flavour and makes it
the same assertion on all three platforms.

The round trip also only ever proved that `as_posix()` produces a parseable
string, never that the config writer calls it — which is the defect, and one no
Linux machine can reproduce: the file is written, parsed and served correctly
here and fails on the operator's Windows box. A second test reads ops.py for
every f-string landing on the right of a TOML `path =` and requires
`as_posix()` in it. Weak evidence, and the only kind available for a platform
the suite does not run on; checked to fail with the call removed.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011pvMdvLBG92jyhvD5pD6us

1 files changed, 40 insertions, 6 deletions

diff --git a/packages/meshbay-node/tests/test_ops.py b/packages/meshbay-node/tests/test_ops.py
index b3f0378..c118b5a 100644
--- a/packages/meshbay-node/tests/test_ops.py
+++ b/packages/meshbay-node/tests/test_ops.py
@@ -11,7 +11,7 @@ call them.
 
 import asyncio
 import inspect
-from pathlib import Path
+from pathlib import Path, PureWindowsPath
 from types import SimpleNamespace
 
 import pytest
@@ -359,13 +359,47 @@ def test_update_node_toml_forces_lf_and_keeps_standalone_comments(tmp_path):
 
 
 def test_a_backslash_path_written_into_node_toml_stays_parseable():
-    # attach_group / add_root / init embed a directory into a TOML basic string.
-    # A raw Windows path there (drive + backslash + "Users" + ...) is a parse
-    # error since backslash sequences are escapes; the code writes as_posix().
+    """
+    attach_group and add_root embed a directory into a TOML basic string. A raw
+    Windows path there is a parse error, because backslash sequences are escapes
+    (`\\U`, `\\a`, ...); the code writes `as_posix()` and pathlib reads `/` back
+    on Windows.
+
+    `PureWindowsPath`, not `Path`: on this suite's usual machine `Path` is a
+    `PosixPath`, where a backslash is an ordinary filename character and
+    `as_posix()` converts nothing — so the test modelled the wrong platform and
+    failed everywhere except the one it was written for. Naming the flavour
+    explicitly is what makes it the same assertion on all three.
+    """
     import tomllib
     bs = chr(92)
     win_dir = f"C:{bs}Users{bs}alice{bs}Media"
-    assert tomllib.loads(f'path = "{Path(win_dir).as_posix()}"\n')["path"] == \
-        "C:/Users/alice/Media"
+
+    assert tomllib.loads(
+        f'path = "{PureWindowsPath(win_dir).as_posix()}"\n'
+    )["path"] == "C:/Users/alice/Media"
+
     with pytest.raises(tomllib.TOMLDecodeError):
         tomllib.loads(f'path = "{win_dir}"\n')   # the bug this guards against
+
+
+def test_every_path_written_into_node_toml_goes_through_as_posix():
+    """
+    The half the round trip above cannot see.
+
+    Proving `as_posix()` produces a parseable string says nothing about whether
+    the code calls it, and this is a defect no Linux machine can reproduce: the
+    config is written, parsed and served correctly here, and fails on the
+    operator's Windows box. So the source is read for the shape instead —
+    weak evidence, and the only kind available for a platform the suite does
+    not run on.
+    """
+    import re
+    source = inspect.getsource(ops)
+    # Every f-string interpolation that lands on the right of a TOML `path =`.
+    writes = re.findall(r'path\s*=\s*\\?"\{([^}]+)\}', source)
+    assert writes, "no TOML path writer found — did the config writer move?"
+    for expr in writes:
+        assert "as_posix()" in expr, (
+            f'node.toml path written as `{expr}` — a Windows path needs '
+            f'as_posix(), or the file it lands in will not parse')