runtime: resolve staged local-dir path to avoid symlink rejection on macOS (#857)

strix/runtime/local_dir_staging.py

@@ -110,7 +110,7 @@ def stage_symlink_safe_dir(src_root: Path) -> tuple[Path, Path | None]:
     if not tree_has_symlink(root):
         return root, None
 
-    staged = Path(tempfile.mkdtemp(prefix=_STAGING_PREFIX))
+    staged = Path(tempfile.mkdtemp(prefix=_STAGING_PREFIX)).resolve()
     try:
         _stage_dir(root, staged, root, frozenset({root}))
     except OSError:

tests/test_local_dir_staging.py

@@ -106,3 +106,38 @@ def test_nested_symlinks_inside_linked_dir(tmp_path: Path) -> None:
     assert (staged / "pkg" / "shared_link" / "conf.json").read_text() == "{}\n"
     assert not (staged / "pkg" / "shared_link" / "escape").exists()
     assert not (staged / "shared" / "escape").exists()
+
+
+def test_staged_path_has_no_symlink_ancestor(tmp_path: Path, monkeypatch) -> None:  # noqa: ANN001
+    """The staging directory itself must never sit behind a symlink.
+
+    ``tempfile.mkdtemp()`` honors ``$TMPDIR``, and on macOS the default
+    ``$TMPDIR`` resolves through ``/var``, which is itself a symlink to
+    ``/private/var``. ``LocalDir`` rejects any symlink component in its
+    source path, so returning the raw ``mkdtemp()`` result breaks every
+    local-dir upload on macOS whenever the source tree contains a symlink.
+    This reproduces that shape without depending on the host OS layout.
+    """
+    repo = _make_repo(tmp_path)
+    (repo / "link.py").symlink_to(repo / "pkg" / "mod.py")
+
+    real_tmp_root = tmp_path / "real_tmp"
+    real_tmp_root.mkdir()
+    symlinked_tmp_root = tmp_path / "tmp_symlink"
+    symlinked_tmp_root.symlink_to(real_tmp_root)
+
+    def fake_mkdtemp(prefix: str = "") -> str:
+        real_dir = real_tmp_root / f"{prefix}fake"
+        real_dir.mkdir()
+        return str(symlinked_tmp_root / real_dir.name)
+
+    monkeypatch.setattr(
+        "strix.runtime.local_dir_staging.tempfile.mkdtemp", fake_mkdtemp
+    )
+
+    upload_path, staged = stage_symlink_safe_dir(repo)
+
+    assert staged is not None
+    assert upload_path == staged
+    for path in (staged, *staged.parents):
+        assert not path.is_symlink(), f"staged path has a symlink ancestor: {path}"