fix(terminal): correct off-by-one in _hermes_repo_root path resolution

_hermes_repo_root used parents[1] which resolves to tools/ instead of
the repository root. The file lives at tools/environments/local.py so it
needs parents[2] to reach the actual repo root that Electron injects
into PYTHONPATH.

The test test_repo_root_stripped reused the module constant under test
as its input. This made it pass regardless of what the constant pointed
at. The test now computes the real repo root independently from the
source file location. It fails with the old parents[1] code and passes
with the fix.

Reported by spfcraze in PR #78917 review.

tests/tools/test_local_env_blocklist.py

@@ -10,6 +10,7 @@ See: https://github.com/NousResearch/hermes-agent/issues/1264
 
 import os
 import threading
+from pathlib import Path
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -532,16 +533,31 @@ class TestPythonpathSelectiveStrip:
         assert "/home/user/my-lib" in entries
 
     def test_repo_root_stripped(self):
-        """The Hermes repo root entry is stripped from PYTHONPATH."""
-        from tools.environments.local import _strip_mismatched_site_packages, _hermes_repo_root
-        repo_root = str(_hermes_repo_root)
+        """The Hermes repo root entry is stripped from PYTHONPATH.
+
+        Electron prepends the *actual* repository root (the directory
+        containing ``tools/``, ``hermes_cli/``, etc.) to PYTHONPATH so the
+        backend can ``import tools``.  This test independently computes that
+        real repo root from the source-file location - three levels up from
+        ``tools/environments/local.py`` - rather than reusing the module
+        constant under test.  That way an off-by-one in ``_hermes_repo_root``
+        (e.g. ``parents[1]`` resolving to ``tools/``) would cause this test
+        to fail instead of silently passing.
+        """
+        from tools.environments.local import _strip_mismatched_site_packages
+
+        # Independently compute the real repo root: local.py lives at
+        # tools/environments/local.py, so the repo root is parents[2].
+        local_file = Path(__import__("tools.environments.local", fromlist=["__file__"]).__file__).resolve()
+        real_repo_root = str(local_file.parents[2])
+
         env = {
-            "PYTHONPATH": os.pathsep.join([repo_root, "/home/user/my-lib"]),
+            "PYTHONPATH": os.pathsep.join([real_repo_root, "/home/user/my-lib"]),
         }
         _strip_mismatched_site_packages(env)
         pp = env.get("PYTHONPATH", "")
         entries = pp.split(os.pathsep) if pp else []
-        assert repo_root not in entries
+        assert real_repo_root not in entries
         assert "/home/user/my-lib" in entries
 
 

tools/environments/local.py

@@ -1364,12 +1364,13 @@ def _is_path_under(child: Path, parent: Path) -> bool:
 #: the interpreter is actually inside a venv (``sys.prefix != sys.base_prefix``).
 _hermes_venv_root: Path = Path(sys.prefix)
 
-#: The Hermes repository root - two levels up from this file
-#: (``tools/environments/local.py`` -> ``tools/`` -> repo root).  This is the
-#: directory the Electron app prepends to PYTHONPATH so the backend can do
-#: ``import tools``, ``import hermes_cli``, etc.  Subprocesses that are NOT
-#: the Hermes backend don't need it and it can shadow local packages.
-_hermes_repo_root: Path = Path(__file__).resolve().parents[1]
+#: The Hermes repository root - three levels up from this file
+#: (``tools/environments/local.py`` -> ``tools/environments`` -> ``tools``
+#: -> repo root).  This is the directory the Electron app prepends to
+#: PYTHONPATH so the backend can do ``import tools``, ``import hermes_cli``,
+#: etc.  Subprocesses that are NOT the Hermes backend don't need it and it
+#: can shadow local packages.
+_hermes_repo_root: Path = Path(__file__).resolve().parents[2]
 
 #: Whether the current interpreter is running inside a venv.  On Python 3.3+
 #: ``sys.base_prefix != sys.prefix`` indicates a venv (or virtualenv).