diff --git a/hermes_cli/auth.py b/hermes_cli/auth.py
index 98ac4edb31..28c5bd9a61 100644
--- a/hermes_cli/auth.py
+++ b/hermes_cli/auth.py
@@ -619,7 +619,25 @@ def _oauth_trace(event: str, *, sequence_id: Optional[str] = None, **fields: Any
 # =============================================================================
 
 def _auth_file_path() -> Path:
-    return get_hermes_home() / "auth.json"
+    path = get_hermes_home() / "auth.json"
+    # Seat belt: if pytest is running and HERMES_HOME resolves to the real
+    # user's auth store, refuse rather than silently corrupt it. This catches
+    # tests that forgot to monkeypatch HERMES_HOME, tests invoked without the
+    # hermetic conftest, or sandbox escapes via threads/subprocesses. In
+    # production (no PYTEST_CURRENT_TEST) this is a single dict lookup.
+    if os.environ.get("PYTEST_CURRENT_TEST"):
+        real_home_auth = (Path.home() / ".hermes" / "auth.json").resolve(strict=False)
+        try:
+            resolved = path.resolve(strict=False)
+        except Exception:
+            resolved = path
+        if resolved == real_home_auth:
+            raise RuntimeError(
+                f"Refusing to touch real user auth store during test run: {path}. "
+                "Set HERMES_HOME to a tmp_path in your test fixture, or run "
+                "via scripts/run_tests.sh for hermetic CI-parity env."
+            )
+    return path
 
 
 def _auth_lock_path() -> Path:
diff --git a/tests/agent/test_credential_pool.py b/tests/agent/test_credential_pool.py
index 7ec0385b60..76e1412bf4 100644
--- a/tests/agent/test_credential_pool.py
+++ b/tests/agent/test_credential_pool.py
@@ -333,66 +333,6 @@ def test_mark_exhausted_and_rotate_persists_status(tmp_path, monkeypatch):
     assert persisted["last_error_code"] == 402
 
 
-def test_try_refresh_current_updates_only_current_entry(tmp_path, monkeypatch):
-    monkeypatch.setenv("HERMES_HOME", str(tmp_path / "hermes"))
-    _write_auth_store(
-        tmp_path,
-        {
-            "version": 1,
-            "credential_pool": {
-                "openai-codex": [
-                    {
-                        "id": "cred-1",
-                        "label": "primary",
-                        "auth_type": "oauth",
-                        "priority": 0,
-                        "source": "device_code",
-                        "access_token": "access-old",
-                        "refresh_token": "refresh-old",
-                        "base_url": "https://chatgpt.com/backend-api/codex",
-                    },
-                    {
-                        "id": "cred-2",
-                        "label": "secondary",
-                        "auth_type": "oauth",
-                        "priority": 1,
-                        "source": "device_code",
-                        "access_token": "access-other",
-                        "refresh_token": "refresh-other",
-                        "base_url": "https://chatgpt.com/backend-api/codex",
-                    },
-                ]
-            },
-        },
-    )
-
-    from agent.credential_pool import load_pool
-
-    monkeypatch.setattr(
-        "hermes_cli.auth.refresh_codex_oauth_pure",
-        lambda access_token, refresh_token, timeout_seconds=20.0: {
-            "access_token": "access-new",
-            "refresh_token": "refresh-new",
-        },
-    )
-
-    pool = load_pool("openai-codex")
-    current = pool.select()
-    assert current.id == "cred-1"
-
-    refreshed = pool.try_refresh_current()
-
-    assert refreshed is not None
-    assert refreshed.access_token == "access-new"
-
-    auth_payload = json.loads((tmp_path / "hermes" / "auth.json").read_text())
-    primary, secondary = auth_payload["credential_pool"]["openai-codex"]
-    assert primary["access_token"] == "access-new"
-    assert primary["refresh_token"] == "refresh-new"
-    assert secondary["access_token"] == "access-other"
-    assert secondary["refresh_token"] == "refresh-other"
-
-
 def test_load_pool_seeds_env_api_key(tmp_path, monkeypatch):
     monkeypatch.setenv("HERMES_HOME", str(tmp_path / "hermes"))
     monkeypatch.setenv("OPENROUTER_API_KEY", "sk-or-seeded")