fawx-skill-scheduler

A Fawx WASM skill for scheduling, cron jobs, and reminders. Jobs persist across invocations via the host KV store.

Features

• Cron-based scheduling — standard 5-field cron expressions (minute hour day month weekday)
• Timezone support — per-job UTC offset
• Double-fire prevention — jobs won't fire twice in the same minute
• Persistent storage — jobs survive across invocations via host KV store

Cron Expression Support

Pattern	Meaning	Example
*	Every value	* * * * * (every minute)
N	Exact value	30 9 * * * (9:30)
*/N	Every N	*/15 * * * * (every 15 min)
N,M	List	0,30 * * * * (on :00 and :30)
N-M	Range	0 9-17 * * * (9 AM to 5 PM)

Fields: minute(0-59) hour(0-23) day(1-31) month(1-12) weekday(0-6, 0=Sun)

Actions

Add a job

{
  "action": "add",
  "name": "daily-standup",
  "schedule": "0 9 * * 1-5",
  "message": "Time for standup!",
  "tz_offset_hours": -7
}

Response:

{"status": "added", "name": "daily-standup", "schedule": "0 9 * * 1-5"}

Remove a job

{"action": "remove", "name": "daily-standup"}

Response:

{"status": "removed", "name": "daily-standup"}

List all jobs

{"action": "list"}

Response:

{
  "jobs": [
    {"name": "daily-standup", "schedule": "0 9 * * 1-5", "message": "Time for standup!"}
  ]
}

Check for due jobs

Called periodically by the engine to trigger due jobs:

{"action": "check", "now_unix": 1709888400}

Response:

{"due": [{"name": "daily-standup", "message": "Time for standup!"}]}

Building

# Native tests
cargo test

# WASM target
cargo build --target wasm32-unknown-unknown --release

Technical Details

• Storage key: scheduler:jobs (JSON array in host KV store)
• Entry point: run() (extern "C", no_mangle)
• API version: host_api_v1
• Capabilities: storage
• Zero external cron dependencies — pure Rust cron parser