From Val Town
Use when building a val that runs on a schedule — periodic jobs, recurring tasks, polling, cron jobs, monitoring, alerting. Covers the interval handler signature, cron expressions, the UTC timezone constraint, and the `lastRunAt` pattern for detecting new items since the previous run.
How this skill is triggered — by the user, by Claude, or both
Slash command
/vals:cron-and-intervalsThe summary Claude sees in its skill listing — used to decide when to auto-load this skill
Interval vals (`fileType: "interval"`) run on a recurring schedule defined by a cron expression. Use them for polling external APIs, sending reminders, running cleanups, generating reports, or any work that should happen on a clock rather than in response to a request.
Interval vals (fileType: "interval") run on a recurring schedule defined by a cron expression. Use them for polling external APIs, sending reminders, running cleanups, generating reports, or any work that should happen on a clock rather than in response to a request.
// Learn more: https://docs.val.town/vals/cron/
export default async function (interval: Interval) {
// interval.lastRunAt: Date | undefined
console.log(interval);
}
The file must have an export — export default for the handler.
Cron expressions run in UTC. Convert any human-readable schedule (e.g. "9am Eastern") to UTC before writing the cron expression. Daylight savings is not handled — pick a UTC time that's close enough year-round.
lastRunAt patterninterval.lastRunAt is the timestamp of the previous successful run (or undefined on the first run). Use it to fetch only items created since the last run, instead of re-scanning everything:
export default async function (interval: Interval) {
const since = interval.lastRunAt ?? new Date(Date.now() - 24 * 60 * 60 * 1000);
const newItems = await fetchItemsSince(since);
for (const item of newItems) {
await handle(item);
}
}
This makes the val idempotent against missed runs and avoids reprocessing.
read_interval_settings — fetch the current cron expression and active state of an interval file.write_interval_settings — change the cron expression or pause/resume an interval.For simple scheduled jobs, create a new val with a single interval-type file directly — no template needed. Templates are for more complex shapes (dashboards, AI agents, webhook + UI combos).
After editing an interval val, use run_file to invoke the handler manually instead of waiting for the next scheduled run.
npx claudepluginhub val-town/plugins --plugin valtownBlocks Edit/Write/Bash actions until Claude investigates importers, data schemas, and user instructions. Improves output quality by forcing concrete facts before edits.