fix(guard): skip NUL-binary text in recursion and bound remote script reads

cron/lifecycle_guard.py

@@ -332,6 +332,15 @@ def _contains_unsafe_gateway_action(
         if script_text is None and read_remote_script is not None:
             # Local path missing; try the remote backend if one is available.
             script_text = read_remote_script(str(script_path))
+        if script_text and "\x00" in script_text:
+            # Any read_remote_script callback (terminal_tool's env-based
+            # fallback, SSH/Modal/Daytona backends) may return binary
+            # content. A NUL byte in the text marks machine code, not a
+            # shell script: feeding it to the recursion re-tokenizes it
+            # into NUL-bearing paths that crash os.open with
+            # `ValueError: embedded null byte` (#77703, #77780). Treat it
+            # as "nothing to scan", mirroring _read_referenced_script.
+            continue
         if not script_text:
             continue
         # Relative references inside a script resolve against that script's

tools/terminal_tool.py

@@ -2565,6 +2565,11 @@ def _read_script_in_env(script_path: str) -> Optional[str]:
                             # Binary content from a remote `cat`: skip for the
                             # same reason as the local branch above (#77703).
                             return None
+                        if len(output) > 1024 * 1024:
+                            # Same size bound as the local branch: never feed
+                            # oversized content (e.g. a large remote binary)
+                            # into the scanner recursion (#77780).
+                            return None
                         return output
                 except Exception:
                     pass