Workers

Cron and scheduler

The cron backbone is two workers. ultron-cron is the master firer for fixed-schedule platform jobs (reconciler, janitor, lifecycle emails). ultron-cron-scheduler reads dynamic schedule definitions from the app database and dispatches per-workspace recurring tasks at their configured times.

Updated today

Overview

At a glance

Master firer: ultron-cron
Dispatcher: ultron-cron-scheduler
Trigger style: Both use the edge runtime's native cron triggers
Webhook secret: Shared with the app for signed POSTs
Dispatched endpoint: POST /api/cron/<handler> on the app

Two workers

Static schedules vs dynamic schedules.

Concern	ultron-cron	ultron-cron-scheduler
Driven by	Fixed cron expressions in wrangler.toml	Rows in the schedules table
Tick frequency	Per-handler (5 min, hourly, daily, ...)	Every minute
What it fires	Platform jobs (reconciler, janitor, lifecycle emails)	User-defined recurring tasks (scheduled agents, scheduled posts, scheduled crawls)
Modifiable at runtime	No (wrangler deploy required)	Yes (write to schedules table)
Multi-tenant	No	Yes

Worker shape

ultron-cron/wrangler.tomltoml

1name = "ultron-cron"

2main = "src/index.ts"

4# Each cron line maps to a handler key. The scheduled() handler dispatches.

5[triggers]

6crons = [

7 "*/5 * * * *", # reconciler (every 5 min)

8 "0 * * * *", # janitor (hourly)

9 "0 9 * * *", # lifecycle-emails (daily 09:00 UTC)

10]

12[vars]

13APP_BASE = "https://app.51ultron.com"

14WEBHOOK_SECRET_KV_KEY = "ultron-cron:webhook-secret"

ultron-cron-scheduler/wrangler.tomltoml

1name = "ultron-cron-scheduler"

2main = "src/index.ts"

4[triggers]

5crons = ["* * * * *"] # every minute

7[vars]

8APP_BASE = "https://app.51ultron.com"

9SCHEDULES_TABLE = "scheduled_tasks"

Schedule catalogue

What ultron-cron fires by default.

Cron	Handler	What it does
/5 * * *	reconciler	Walks workspaces with stalled jobs, retries up to 3 attempts
0 * * * *	janitor	Drops expired sandbox sessions, cleans /work R2 snapshots older than 7 days
0 9 * * *	lifecycle-emails	Sends day-1, day-7, day-14, day-30 lifecycle emails based on user activity
15 * * * *	metrics-rollup	Aggregates analytics_dataset rows into per-workspace daily counts
0 0 * * 0	weekly-digest	Sends the weekly digest email to opted-in workspaces

Note

ultron-cron does not do work itself. Each handler is a thin HTTP POST to the app with a signed body so the actual logic lives where the rest of the platform lives.

Dispatch contract

The body each handler dispatch carries.

dispatch payloadjson

1{

2 "handler": "reconciler",

3 "firedAt": "2026-05-19T12:05:00Z",

4 "nonce": "<sha256-derived>",

5 "secret": "<HMAC of body + nonce signed with WEBHOOK_SECRET>"

6}

The app verifies the HMAC, idempotency-checks the nonce against a short-lived KV cache, and runs the handler. On failure it returns 5xx; the cron worker retries up to twice with exponential backoff before logging a warning to the analytics dataset.

File map

cf-workers/ultron-cron

wrangler.toml

src

index.tsscheduled() dispatcher + fetch() webhook receiver

dispatch.tssigned POST helper

cf-workers/ultron-cron-scheduler

wrangler.toml

src

index.tsscheduled() reads schedules + dispatches