Generate headless Claude Code cron jobs with safety.
Generate headless Claude Code cron jobs from a task description and schedule. Creates a wrapper script with safety mechanisms (lockfile, budget cap, dry-run default, logging) and installs crontab entries. All crontab mutations go through scripts/crontab-manager.py, which writes to temp files and creates timestamped backups in ~/.claude/crontab-backups/ before every change -- never pipe directly to crontab - because a mid-stream pipe failure wipes the entire crontab.
Extract job parameters from the user's request.
Required parameters:
reddit-automod, feed-health-check)Optional parameters (with defaults):
cd before running (default: current repo root)2.00; user may override)Bash Read; user may override){workdir}/cron-logs/{name})Human-readable schedule conversion -- use off-minutes (7, 23, 47) instead of :00/:30 because every cron job on the system fires at round minutes, creating load spikes:
| Human Input | Cron Expression |
|---|---|
| every 12 hours | 7 */12 * * * |
| twice daily | 7 8,20 * * * |
| hourly | 23 * * * * |
| daily at 6am | 7 6 * * * |
| weekly on sunday | 7 9 * * 0 |
| every 30 minutes | */30 * * * * |
Gate: All required parameters extracted. Proceed to Phase 2.
Create the wrapper script using crontab-manager.py generate-wrapper. Embed the prompt via bash heredoc to avoid escaping issues.
python3 ~/.claude/scripts/crontab-manager.py generate-wrapper \
--name "{name}" \
--prompt "{prompt}" \
--schedule "{schedule}" \
--workdir "{workdir}" \
--budget "{budget}" \
--allowed-tools "{allowed_tools}"
Review the generated script. Verify it contains:
set -euo pipefailflock lockfile -- prevents concurrent runs of the same job--permission-mode auto -- never use --dangerously-skip-permissions (auto is sufficient) or --bare (breaks OAuth/keychain auth)--max-budget-usd -- caps spend per run (default $2.00)--no-session-persistence--allowedToolstee to per-run timestamped log file--executePIPESTATUS[0]Do not use the CronCreate tool -- it is session-scoped (dies when the session ends, auto-expires after 7 days). Use system crontab via crontab-manager.py instead.
Gate: Script generated and reviewed. Proceed to Phase 3.
Verify the generated script meets cron best practices.
Run the script in dry-run mode:
bash -n scripts/{name}-cron.sh # syntax check
Run cron-job-auditor checks:
set -e)flock)tee, LOG_DIR)cd)claude -- cron has minimal PATH, so all commands must use absolute paths)Gate: All checks pass. Proceed to Phase 4.
Install the crontab entry. Every entry gets a # claude-cron: <tag> marker so crontab-manager.py can identify and manage only its own entries without touching non-Claude crontab lines. All paths in the crontab entry must be absolute because cron has minimal PATH.
Show the proposed entry:
python3 ~/.claude/scripts/crontab-manager.py add \
--tag "{name}" \
--schedule "{schedule}" \
--command "{absolute_script_path} --execute >> {logdir}/cron.log 2>&1" \
--dry-run
Ask the user for confirmation before installing. Never install without explicit approval.
If confirmed:
python3 ~/.claude/scripts/crontab-manager.py add \
--tag "{name}" \
--schedule "{schedule}" \
--command "{absolute_script_path} --execute >> {logdir}/cron.log 2>&1"
Verify:
python3 ~/.claude/scripts/crontab-manager.py verify --tag "{name}"
Gate: Entry installed and verified. Proceed to Phase 5.
Summarize the created cron job and print the exact commands to test and manage it.
Output:
python3 ~/.claude/scripts/crontab-manager.py list # see all claude cron jobs
python3 ~/.claude/scripts/crontab-manager.py verify --tag {name} # health check
python3 ~/.claude/scripts/crontab-manager.py remove --tag {name} # uninstall
To modify an existing wrapper script, regenerate it with --force rather than editing in place.
Cause: A cron entry with this tag is already installed.
Solution: Either remove --tag {name} first, or choose a different name.
Cause: Cron has minimal PATH; claude isn't in it.
Solution: generate-wrapper resolves the absolute path to claude at generation time.
If the path changes, regenerate the wrapper with --force.
Cause: System crontab service issue.
Solution: Check crontab -l manually. Restore from ~/.claude/crontab-backups/.
scripts/crontab-manager.py -- all crontab mutations (add, remove, list, verify, generate-wrapper)skills/cron-job-auditor/SKILL.md -- validation checks for generated scripts