Billy — Cron Guardrails Pack

Lint cron entries for schedule validity, bad model names, and missing NO_REPLY discipline markers.

Security Scan

The skill is internally consistent with its stated purpose: a small, instruction-only cron lint tool that reads a file or stdin and performs local static checks with no network or credential access.

Purpose & Capability

Name/description (cron lint, NO_REPLY discipline) match the provided files and requirements. The skill only includes a single Python script and SKILL.md; there are no unrelated env vars, binaries, or external services requested.

Instruction Scope

SKILL.md instructs the agent to run the included script on a crontab file or stdin. The script only reads the supplied path or stdin and performs local static checks (field count, banned model names, presence of NO_REPLY for announce-like commands). It does not access other system paths, environment variables, or external endpoints.

Install Mechanism

No install spec is provided (instruction-only with an included script). Nothing is downloaded or written to disk by an installer; risk from installation is minimal.

Credentials

No credentials, env vars, or config paths are required. The script only processes input you explicitly pass (file or stdin), so requested access is proportionate to the stated task.

Persistence & Privilege

The skill is not always-enabled, does not request persistent presence, and does not modify other skills or system-wide settings.

Assessment

This appears to be a small, local cron linter with no network calls or credential requests — low risk. You can safely inspect the script (it's short and readable) and run it on example crontabs. As with any third-party code, only run it on files you intend to check (it will read any path you pass) and consider running it in a controlled environment before integrating into automated pipelines. Note: there are minor functional quirks (for example NO_REPLY detection is case-sensitive), but these are correctness issues rather than security concerns.

cron-guardrails-pack

Author: Billy (SAPCONET)

Purpose

Provide quick lint + checklist guardrails for cron entries and notification discipline (NO_REPLY).

What this skill includes

• scripts/cron-lint.py: static checks for cron entry lines.

Checks performed

• Cron schedule must contain exactly 5 fields.
• Rejects known bad model names (for example: haiku-4-6).
• Flags jobs that appear to announce/message but do not include NO_REPLY.

Usage

Lint a cron file:

python3 scripts/cron-lint.py /path/to/crontab.txt

Lint stdin:

cat /path/to/crontab.txt | python3 scripts/cron-lint.py -

Exit codes:

• 0: no issues
• 1: one or more issues found
• 2: usage or read error

NO_REPLY checklist

• Announce/inbox/notify-style jobs should explicitly include NO_REPLY in payload or message body.
• Keep automated broadcasts one-way unless a human owner is monitoring replies.
• Include owner and purpose in command comments.

Example cron payload snippet

*/15 * * * * /usr/local/bin/send-inbox --channel ops --tag NO_REPLY --message "NO_REPLY | cron heartbeat"