From 26837b56e0349de7f387aea5e9562855c58ec8fa Mon Sep 17 00:00:00 2001
From: AJ Banerjee <anuragb2010@gmail.com>
Date: Sun, 3 May 2026 21:52:41 -0700
Subject: [PATCH] fix(gateway): detect stale sys.modules via expected exports
 (Issue #17648)

- Add _loaded_modules_missing_expected_exports() for cfg_get / utils helpers
- Run export check before mtime comparison so live-update mismatches restart
- Log when mtime baseline is zero but boot time was captured
- Extend stale-code self-check tests
---
 gateway/run.py                              | 23 ++++++++++++++
 tests/gateway/test_stale_code_self_check.py | 33 +++++++++++++++++++--
 2 files changed, 53 insertions(+), 3 deletions(-)

diff --git a/gateway/run.py b/gateway/run.py
index 7871686256873..1565dadb1a8f7 100644
--- a/gateway/run.py
+++ b/gateway/run.py
@@ -133,6 +133,20 @@ def _compute_repo_mtime(repo_root: Path) -> float:
     return newest
 
 
+def _loaded_modules_missing_expected_exports() -> bool:
+    """Return True if loaded ``hermes_cli.config`` or ``utils`` lack expected attributes."""
+    cfg_mod = sys.modules.get("hermes_cli.config")
+    if cfg_mod is not None and not hasattr(cfg_mod, "cfg_get"):
+        return True
+    utils_mod = sys.modules.get("utils")
+    if utils_mod is not None:
+        if not hasattr(utils_mod, "atomic_replace"):
+            return True
+        if not hasattr(utils_mod, "base_url_host_matches"):
+            return True
+    return False
+
+
 def _coerce_gateway_timestamp(value: Any) -> Optional[float]:
     """Best-effort conversion of stored gateway timestamps to epoch seconds.
 
@@ -1019,6 +1033,13 @@ def __init__(self, config: Optional[GatewayConfig] = None):
             self._boot_repo_mtime: float = _compute_repo_mtime(
                 self._repo_root_for_staleness,
             )
+            if self._boot_repo_mtime <= 0.0 and self._boot_wall_time:
+                logger.warning(
+                    "Stale-code mtime baseline unavailable (no readable sentinel "
+                    "files under %s). Export-based detection still applies. "
+                    "See Issue #17648.",
+                    self._repo_root_for_staleness,
+                )
         except Exception:
             self._boot_wall_time = 0.0
             self._repo_root_for_staleness = Path(".")
@@ -2637,6 +2658,8 @@ def _detect_stale_code(self) -> bool:
         sentinel file is readable, to avoid false-positive restart loops
         in unusual checkouts (sparse clones, read-only filesystems).
         """
+        if _loaded_modules_missing_expected_exports():
+            return True
         if not self._boot_wall_time or not self._boot_repo_mtime:
             return False
         try:
diff --git a/tests/gateway/test_stale_code_self_check.py b/tests/gateway/test_stale_code_self_check.py
index 5289f575d40f8..a20fca4e6cc17 100644
--- a/tests/gateway/test_stale_code_self_check.py
+++ b/tests/gateway/test_stale_code_self_check.py
@@ -9,15 +9,15 @@
 """
 
 import os
+import sys
 import time
+import types
 from pathlib import Path
-from unittest.mock import MagicMock, patch
-
-import pytest
 
 from gateway.run import (
     GatewayRunner,
     _compute_repo_mtime,
+    _loaded_modules_missing_expected_exports,
     _STALE_CODE_SENTINELS,
 )
 
@@ -96,6 +96,33 @@ def test_detect_stale_code_false_when_files_unchanged(tmp_path):
     assert runner._detect_stale_code() is False
 
 
+def test_loaded_modules_missing_expected_exports_detects_stale_config(monkeypatch):
+    stale_cfg = types.ModuleType("hermes_cli.config")
+    monkeypatch.setitem(sys.modules, "hermes_cli.config", stale_cfg)
+    assert _loaded_modules_missing_expected_exports() is True
+
+
+def test_loaded_modules_missing_expected_exports_detects_stale_utils(monkeypatch):
+    stale_utils = types.ModuleType("utils")
+    monkeypatch.setitem(sys.modules, "utils", stale_utils)
+    assert _loaded_modules_missing_expected_exports() is True
+
+
+def test_detect_stale_code_true_when_sys_modules_config_lacks_cfg_get(
+    tmp_path, monkeypatch
+):
+    stale_cfg = types.ModuleType("hermes_cli.config")
+    monkeypatch.setitem(sys.modules, "hermes_cli.config", stale_cfg)
+
+    repo = _make_tmp_repo(tmp_path)
+    baseline = time.time() - 100
+    for rel in _STALE_CODE_SENTINELS:
+        os.utime(repo / rel, (baseline, baseline))
+
+    runner = _make_runner(repo, boot_mtime=baseline, boot_wall=baseline)
+    assert runner._detect_stale_code() is True
+
+
 def test_detect_stale_code_true_after_update(tmp_path):
     """Sentinel files newer than boot snapshot → stale."""
     repo = _make_tmp_repo(tmp_path)