fix(cron): prevent lifecycle guard crash on binary remote-read paths

[o269]

Summary

• Fixes ValueError: embedded null byte crash in cron/lifecycle_guard.py when the gateway terminal tool scans shell scripts that reference system binaries (e.g. /usr/bin/flock in godmode-bus/bin/disk-watchdog.sh)
• Root cause: _read_referenced_script correctly skips local binary reads, but the read_remote_script callback (used by terminal_tool.py in _HERMES_GATEWAY sessions) decodes ELF contents with NUL bytes intact; tokenizing that machine code produced paths with embedded NULs, crashing os.open
• Workaround before fix: copy script to /tmp first (bypasses the recursive binary scan path)

Fix (3 defensive layers, same class as #76762)

Site	Change
_iter_command_segments()	Strip \x00 before tokenization
_read_referenced_script()	except (OSError, ValueError) at os.open
_contains_unsafe_gateway_action()	Skip remote-read content containing NUL bytes
_resolve_script_path()	NUL-strip before Path() construction

Test plan

• tests/hermes_cli/test_gateway_restart_loop.py — 84 passed
• New regression: test_remote_read_of_binary_does_not_crash_the_guard (ELF via remote callback)
• New regression: test_shell_script_referencing_system_binary_does_not_crash_guard (flock-shaped godmode-bus script)
• Manual repro: bash ~/godmode-bus/bin/disk-watchdog.sh with read_remote_script callback → no crash

Made with Cursor

[alt-glitch]

This was generated by AI during triage.

Related: #79038 repairs the same lifecycle-guard crash by preventing remote binary fallback; this PR uses NUL sanitization plus a defensive catch. These are competing mechanisms for #77780 and need maintainer selection.

[kshitijk4poor]

Closing as superseded by #80258, which fixes this whole bug class architecturally rather than per-callsite: path candidates are sanitized once at the ingestion boundary (NUL/empty/unexpandable tokens rejected before any OS call), text from any read_remote_script callback is sanitized at the recursion boundary (NUL = binary = nothing to scan; >1 MiB = fail closed), the remote fallback read is bounded at the source (head -c, so oversized binaries never cross the wire), and the public guard is total by construction — an unexpected walk failure logs and falls back to the direct-scan verdict instead of breaking every terminal command.

Your report and fix targeted a real member of this class — thank you. The per-callsite patches kept leaving sibling frames exposed (#76762 → #77703 → #77780 → #78256 each crashed one frame away from the previous fix), which is why we went with the boundary fix instead of merging the fragments individually. #80258 carries regression tests for the NUL-path, binary-callback, oversized-read, unset-HOME, and walk-crash cases plus an adversarial never-raises sweep.