Cron Mastery Zc

Master OpenClaw's timing systems. Use for scheduling reliable reminders, setting up periodic maintenance (janitor jobs), and understanding when to use Cron v...

Security Scan

The skill's instructions mostly match a cron/scheduling purpose, but the runtime guidance asks agents to touch system state, delete gateway files, and run janitor jobs from the 'main' session — actions that are broader than a simple scheduler helper and could be misused.

Purpose & Capability

The name/description and the instructions consistently describe cron scheduling, one-shot reminders, janitor cleanup, and timezone handling. There are no unrelated requested env vars or binaries, and the included templates match the stated purpose.

Instruction Scope

SKILL.md explicitly instructs agents to: edit MEMORY.md to store user timezone; delete a gateway state file (~/.openclaw/state/cron/jobs.json); run janitor jobs with sessionTarget: "main" (which can list and delete other cron jobs); and create AgentTurn payloads that announce to Telegram channels/IDs. These are functional for a scheduler but they reach into persistent state, system paths, and global job lists—operations that expand the skill's runtime privileges and could be abused or cause collateral impact if misapplied.

Install Mechanism

Instruction-only skill with no install spec and no code files. This minimizes installation risk because nothing is written to disk by the skill bundle itself.

Credentials

The skill declares no required environment variables or credentials, which is proportionate. However, the examples use delivery channels (telegram) and concrete recipient IDs; while examples are fine, in practice sending proactive messages will depend on platform-level credentials and permissions outside the skill. The SKILL.md does not request or explain these credentials, which is reasonable but means operators must ensure proper credential scoping.

Persistence & Privilege

The skill does not request 'always: true', but it instructs using the 'main' session for janitor tasks and recommends manual deletion of gateway state files. Those instructions imply and rely on a session with broad tool access and the ability to modify global scheduler state and filesystem paths—privileges that are beyond a simple helper and warrant caution.

What to consider before installing

This skill appears to be a detailed guide for scheduling and cleanup, but it tells agents to edit memory files, delete gateway state (~/.openclaw/state/cron/jobs.json), and run janitor jobs from the 'main' session which can list/delete other cron jobs. Before installing or using: (1) Confirm you want agents that can modify global scheduler state and filesystem paths; back up jobs.json before following deletion steps. (2) Prefer least-privilege: avoid running janitor tasks from a session with unnecessary rights unless you trust the job definitions. (3) Review any templates that send messages to external channels (e.g., Telegram) and replace example recipient IDs with verified targets. (4) If possible, test on a non-production instance first. If you want, I can point out specific lines to change to make the guidance safer (e.g., add a backup step, require explicit confirmation before deletions, avoid hardcoded recipient IDs).

Cron Mastery

Rule #1: Heartbeats drift. Cron is precise.

This skill provides the definitive guide for managing time in OpenClaw 2026.2.15+. It solves the "I missed my reminder" problem by enforcing a strict separation between casual checks (heartbeat) and hard schedules (cron).

The Core Principle

System	Behavior	Best For	Risk
Heartbeat	"I'll check in when I can" (e.g., every 30-60m)	Email checks, casual news summaries, low-priority polling.	Drift: A "remind me in 10m" task will fail if the heartbeat is 30m.
Cron	"I will run at exactly X time"	Reminders ("in 5 mins"), daily reports, system maintenance.	Clutter: Creates one-off jobs that need cleanup.

1. Setting Reliable Reminders (2026.2.15+ Standard)

Rule: Never use act:wait or internal loops for long delays (>1 min). Use cron:add with a one-shot at schedule.

Precision & The "Scheduler Tick"

While Cron is precise, execution depends on the Gateway Heartbeat (typically every 10-60s). A job set for :00 seconds will fire on the first "tick" after that time. Expect up to ~30s of variance depending on your gateway config.

Modern One-Shot Reminder Pattern

Use this payload structure for "remind me in X minutes" tasks.

Key Features (v2026.2.15+):

• Payload Choice: Use AgentTurn with Strict Instructions for push notifications (reminders that ping your phone). Use systemEvent only for silent logs or background state updates.
• Reliability: nextRunAtMs corruption and "Add-then-Update" deadlocks are resolved.
• Auto-Cleanup: One-shot jobs auto-delete after success (deleteAfterRun: true).

CRITICAL: Push Notifications vs. Silent Logs

• systemEvent (Silent): Injects text into the chat history. Great for background logs, but WILL NOT ping the user's phone on Telegram/WhatsApp.
• AgentTurn (Proactive): Wakes an agent to deliver the message. REQUIRED for push notifications. Use the "Strict" prompt to avoid AI chatter.

For push-notification reminders (Reliable):

{
  "name": "Remind: Water",
  "schedule": { "kind": "at", "at": "2026-02-06T01:30:00Z" },
  "payload": {
    "kind": "agentTurn",
    "message": "DELIVER THIS EXACT MESSAGE TO THE USER WITHOUT MODIFICATION OR COMMENTARY:\n\n💧 Drink water, Momo!"
  },
  "sessionTarget": "isolated",
  "delivery": { "mode": "announce", "channel": "telegram", "to": "1027899060" }
}

For background logs (Silent):

{
  "name": "Log: System Pulse",
  "schedule": { "kind": "every", "everyMs": 3600000 },
  "payload": {
    "kind": "systemEvent",
    "text": "[PULSE] System healthy."
  },
  "sessionTarget": "main"
}

Cron Concurrency Rule (Stabilized)

Pre-2026.2.15, the "Add-then-Update" pattern caused deadlocks. While this is now stabilized, it is still best practice to pass all parameters (including wakeMode: "now") directly in the initial cron.add call for maximum efficiency.

2. The Janitor (Auto-Cleanup) - LEGACY

Note: As of v2026.2.14, OpenClaw includes maintenance recompute semantics. The gateway now automatically cleans up stuck jobs and repairs corrupted schedules.

Manual cleanup is only needed for:

• One-shot jobs created with deleteAfterRun: false.
• Stale recurring jobs you no longer want.

Why use sessionTarget: "main"? (CRITICAL)

Sub-agents (isolated) often have restricted tool policies and cannot call gateway or delete other cron jobs. For system maintenance like the Janitor, always target the main session via systemEvent so the primary agent (with full tool access) performs the cleanup.

3. Reference: Timezone Lock

For cron to work, the agent must know its time.

• Action: Add the user's timezone to MEMORY.md.
• Example: Timezone: Cairo (GMT+2)
• Validation: If a user says "remind me at 9 PM," confirm: "9 PM Cairo time?" before scheduling.

4. The Self-Wake Rule (Behavioral)

Problem: If you say "I'll wait 30 seconds" and end your turn, you go to sleep. You cannot wake up without an event. Solution: If you need to "wait" across turns, you MUST schedule a Cron job.

• Wait < 1 minute (interactive): Only allowed if you keep the tool loop open (using act:wait).
• Wait > 1 minute (async): Use Cron with wakeMode: "now".

5. Legacy Migration Guide

If you have old cron jobs using these patterns, update them:

Legacy (Pre-2026.2.3)	Modern (2026.2.15+)
"schedule": {"kind": "at", "atMs": 1234567890}	"schedule": {"kind": "at", "at": "2026-02-06T01:30:00Z"}
"deliver": true in payload	Not needed - announce mode handles delivery
"sessionTarget": "main"	"sessionTarget": "isolated" (default behavior)
Manual ghost cleanup required	One-shots auto-delete (deleteAfterRun: true)
cron.update after cron.add	Single-step cron.add with all properties

Troubleshooting

• "My reminder didn't fire": Check cron:list. Verify the at timestamp is in the future (ISO 8601 format). Ensure wakeMode: "now" is set.
• "Gateway Timeout (10000ms)": This happens if the cron tool takes too long (huge job list or file lock).
  • Fix 1: Manually delete ~/.openclaw/state/cron/jobs.json and restart the gateway if it's corrupted.
  • Fix 2: Run a manual sweep to reduce the job count.
• "Job ran but I didn't get the message": Ensure you are using the Strict Instruction Pattern with agentTurn + announce mode for proactive pings.
• "The reminder message has extra commentary": The subagent is being conversational. Use the strict prompt pattern: "DELIVER THIS EXACT MESSAGE TO THE USER WITHOUT MODIFICATION OR COMMENTARY:\n\n💧 Your message here"