diff --git a/cron/lifecycle_guard.py b/cron/lifecycle_guard.py
index 6c70c1af8ae8..65306a02fa1d 100644
--- a/cron/lifecycle_guard.py
+++ b/cron/lifecycle_guard.py
@@ -100,12 +100,20 @@ def _read_script_for_scanning(script_path: str) -> str:
     ``UnicodeDecodeError`` on such files, and swallowing that error would let
     an attacker hide the command in binary noise.  Returns an empty string
     only when the file cannot be read at all.
+
+    ``_resolve_script_path``'s ``Path.expanduser()`` raises ``RuntimeError``
+    (not ``OSError``) for a ``~user``-shaped path with no matching system
+    user — e.g. an LLM-authored ``script`` value that happens to start with
+    ``~someuser/...``.  Catch it alongside ``OSError`` so a malformed script
+    path degrades to "can't scan it" instead of crashing job creation with an
+    unhandled exception (same bug class as agent/subdirectory_hints.py's
+    tilde-expansion crash).
     """
     try:
         return _resolve_script_path(script_path).read_bytes().decode(
             "utf-8", errors="replace"
         )
-    except OSError:
+    except (OSError, RuntimeError):
         return ""
 
 
diff --git a/tests/hermes_cli/test_gateway_restart_loop.py b/tests/hermes_cli/test_gateway_restart_loop.py
index 03ef426ec896..dc0dc72285e8 100644
--- a/tests/hermes_cli/test_gateway_restart_loop.py
+++ b/tests/hermes_cli/test_gateway_restart_loop.py
@@ -428,6 +428,23 @@ def test_missing_script_does_not_raise(self, tmp_path):
         from cron.lifecycle_guard import check_gateway_lifecycle
         check_gateway_lifecycle("clean prompt", str(tmp_path / "nonexistent.sh"))
 
+    def test_tilde_unknown_user_script_does_not_crash(self):
+        """A ``~user``-shaped script path with no matching system user must
+        degrade to "can't scan it" instead of raising RuntimeError.
+
+        ``Path.expanduser()`` raises ``RuntimeError`` (not ``OSError``) for
+        an unresolvable ``~user`` prefix — same bug class as
+        agent/subdirectory_hints.py's tilde-expansion crash (an LLM-authored
+        script value like ``~nonexistent_user_xyzzy_12345/restart.sh`` must
+        not crash cron job creation).
+        """
+        from cron.lifecycle_guard import check_gateway_lifecycle
+        # Must not raise RuntimeError — the guard treats an unscannable
+        # script as absent and only judges the (clean) prompt.
+        check_gateway_lifecycle(
+            "clean prompt", "~nonexistent_user_xyzzy_12345/restart.sh",
+        )
+
     def test_relative_script_resolved_under_scripts_dir(self, tmp_path, monkeypatch):
         """A bare/relative script name resolves under HERMES_HOME/scripts (the
         same place the scheduler runs it from) — otherwise the guard would read