Convex Cron Jobs

What it does

When your agent uses it

• Something needs to run on a timer
• In the background
• A cron is not firing

Example prompts

• “Use the convex-cron-jobs skill to schedule work in Convex: cron jobs in convex/crons.ts, one off scheduled functions with runAfter and runAt…”
• “/convex-cron-jobs”

Requirements

• Node.js

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

1. 1The file is exactly convex/crons.ts and ends with export default crons.
2. 2npx convex dev is running and the last push succeeded. Cron changes only apply on push.
3. 3The target is internal.* and the args match its validator. A mismatch fails at push time.
4. 4The expression is UTC. Convert your local hour before comparing.
5. 5Check Logs for a thrown error. A job that throws every run looks like a job that never runs.

What it can do on your machine

Read from SKILL.md and the folder at commit 82d1ce2. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • npx

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • docs.convex.dev

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Convex Cron Jobs loads about 2k tokens when it runs, and up to ~6.4k if it reads all its reference files. Until then it costs about 72 tokens; SKILL.md has 821 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~72

When it runs · the whole SKILL.md, loaded when a task matches

~2k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~6.4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from waynesutton/builder-skills at commit 82d1ce2, republished under its Apache-2.0 licence (© waynesutton). 821 words, ~1,959 tokens.

name

convex-cron-jobs

description

Schedules work in Convex: cron jobs in convex/crons.ts, one off scheduled functions with runAfter and runAt, batching large jobs, and cancelling or inspecting the queue. Use when something needs to run on a timer, later, or in the background, or when a cron is not firing.

// convex/crons.ts
import { cronJobs } from "convex/server";
import { internal } from "./_generated/api";

const crons = cronJobs();

// Every hour
crons.interval(
  "expire sessions",
  { hours: 1 },
  internal.sessions.expireBatch,
  {},
);

// Every day at 09:00 UTC. Cron expressions are always UTC.
crons.cron("daily digest", "0 9 * * *", internal.digest.send, {});

export default crons;

// convex/sessions.ts
import { internalMutation } from "./_generated/server";
import { internal } from "./_generated/api";
import { v } from "convex/values";

const BATCH = 100;

export const expireBatch = internalMutation({
  args: {},
  returns: v.null(),
  handler: async (ctx) => {
    // Date.now() is fine in a mutation. Never call it in a query.
    const now = Date.now();
    const expired = await ctx.db
      .query("sessions")
      .withIndex("by_expiresAt", (q) => q.lt("expiresAt", now))
      .take(BATCH);

    await Promise.all(expired.map((s) => ctx.db.delete(s._id)));

    // A full batch means more may remain. Chain the next one.
    if (expired.length === BATCH) {
      await ctx.scheduler.runAfter(0, internal.sessions.expireBatch, {});
    }
    return null;
  },
});

// Relative: 5 minutes from now
const jobId = await ctx.scheduler.runAfter(
  5 * 60 * 1000,
  internal.reminders.send,
  { taskId: args.taskId },
);

// Absolute: a timestamp you already store (ms since epoch or a Date)
await ctx.scheduler.runAt(trial.endsAt, internal.billing.endTrial, {
  userId: trial.userId,
});

© waynesutton, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 5 other files (references, assets) in skills/convex-cron-jobs of waynesutton/builder-skills.

• SKILL.md
• agents/openai.yaml
• assets/large-logo.png
• assets/small-logo.svg
• references/cron-recipes.md
• references/scheduling-patterns.md

Open the folder on GitHubat commit 82d1ce2