fix(skills): shorten Testbox SSH socket paths

.agents/skills/autoreview/SKILL.md

@@ -235,6 +235,12 @@ happen before the test shell starts:
 OPENCLAW_TESTBOX=1 "$AUTOREVIEW" --parallel-tests "pnpm check:changed"
 ```
 
+On POSIX, the helper puts this isolated Testbox home under the short, sticky
+system `/tmp`; Blacksmith creates an SSH control socket below that home, and a
+long macOS `TMPDIR` can exceed the Unix-socket path limit. With an older helper,
+prefix the outer autoreview process with `TMPDIR=/tmp`. Setting `TMPDIR` inside
+the quoted test command is too late because the isolated home already exists.
+
 This is the narrow trusted-maintainer-code exception: it stages only the Blacksmith
 credential file into the temporary home so the command can delegate remotely. Never
 use this credential-hydrated path for untrusted contributor or fork code. Run other

.agents/skills/autoreview/scripts/autoreview

@@ -968,6 +968,29 @@ def safe_temp_root(repo: Path) -> Path:
     return root
 
 
+def parallel_test_temp_root(repo: Path) -> Path:
+    root = safe_temp_root(repo)
+    if os.name == "nt" or not env_truthy("OPENCLAW_TESTBOX"):
+        return root
+
+    # Blacksmith stores its SSH control socket below HOME. macOS temp roots can
+    # already consume the Unix-socket path budget before the socket name.
+    try:
+        short_root = Path("/tmp").resolve(strict=True)
+        short_root_stat = short_root.stat()
+    except OSError as exc:
+        raise SystemExit(f"unable to resolve short Testbox temp root: {exc}") from exc
+    if not stat.S_ISDIR(short_root_stat.st_mode):
+        raise SystemExit("short Testbox temp root must be a directory")
+    if is_within(short_root, repo.resolve()):
+        raise SystemExit("short Testbox temp root must be outside the reviewed repository")
+    if short_root_stat.st_mode & stat.S_IWOTH and not (
+        short_root_stat.st_mode & stat.S_ISVTX
+    ):
+        raise SystemExit("world-writable Testbox temp root must have the sticky bit set")
+    return short_root
+
+
 def safe_proxy_url(value: str) -> bool:
     try:
         candidate = value if "://" in value else f"http://{value}"
@@ -8971,7 +8994,10 @@ def start_parallel_tests(
 ) -> tuple[subprocess.Popen, float]:
     print(f"tests: {command}")
     test_home = Path(
-        tempfile.mkdtemp(prefix="autoreview-test-home-", dir=safe_temp_root(repo))
+        tempfile.mkdtemp(
+            prefix="autoreview-test-home-",
+            dir=parallel_test_temp_root(repo),
+        )
     )
     try:
         env = safe_test_env(repo, test_home)

.agents/skills/autoreview/tests/test_autoreview_hardening.py

@@ -4149,6 +4149,53 @@ class AutoreviewHardeningTests(unittest.TestCase):
             ):
                 self.helper["safe_temp_root"](repo)
 
+    @unittest.skipIf(os.name == "nt", "POSIX Testbox temp-root behavior")
+    def test_testbox_parallel_test_temp_root_stays_within_socket_limit(self) -> None:
+        with tempfile.TemporaryDirectory() as tempdir:
+            root = Path(tempdir)
+            repo = init_repo(root)
+            long_temp = root / ("macos-temp-root-" + "x" * 96)
+            long_temp.mkdir()
+
+            with mock.patch.object(
+                tempfile,
+                "gettempdir",
+                return_value=str(long_temp),
+            ), mock.patch.dict(
+                os.environ,
+                {"OPENCLAW_TESTBOX": "1"},
+            ):
+                selected = self.helper["parallel_test_temp_root"](repo)
+
+            self.assertEqual(selected, Path("/tmp").resolve())
+            socket_path = (
+                selected
+                / ("autoreview-test-home-" + "x" * 8)
+                / ".blacksmith"
+                / "c"
+                / "6d146d2f25180c1d.sock"
+            )
+            self.assertLess(len(os.fsencode(socket_path)), 104)
+
+    def test_parallel_test_temp_root_keeps_configured_root_without_testbox(self) -> None:
+        with tempfile.TemporaryDirectory() as tempdir:
+            root = Path(tempdir)
+            repo = init_repo(root)
+            configured_temp = root / "configured-temp"
+            configured_temp.mkdir()
+
+            with mock.patch.object(
+                tempfile,
+                "gettempdir",
+                return_value=str(configured_temp),
+            ), mock.patch.dict(
+                os.environ,
+                {"OPENCLAW_TESTBOX": "0"},
+            ):
+                selected = self.helper["parallel_test_temp_root"](repo)
+
+            self.assertEqual(selected, configured_temp.resolve())
+
     def test_claude_fable_alias_requires_fable_safe_mode_version(self) -> None:
         args = argparse.Namespace(
             claude_bin="claude",