webhook handler processed retries out of order and agent sent the drip sequence backwards

TL;DR

Webhook retries have no ordering guarantee. Store a per-recipient sequence number or timestamp, ignore stale events, and drive the drip from your own state machine instead of raw webhook order.

webhook handler processed retries out of order and agent sent the drip sequence backwards

Use this when

• A drip campaign fired steps out of order after webhook retries.
• Logs show an older event processed after a newer one.
• Retries from the provider arrive minutes late and trigger stale actions.

Not for this skill when

• Duplicate webhook deliveries, which need idempotency keys only.
• Missing webhooks, which need a reconciliation job.
• Provider-side ordering guarantees, which webhooks do not offer.

Steps

1. Confirm the ordering failure in logs: match event timestamps against processing order. Verify: you have examples of older events processed later.
2. Add a sequence guard: store the last processed event time per recipient and skip older events. Verify: a replayed old event is ignored in a test.
3. Make every send idempotent with a key derived from recipient plus step. Verify: processing the same event twice sends once.
4. Move the drip logic into your own state machine driven by the latest known state, not by event arrival order. Verify: the state machine produces the right next step regardless of order.
5. Respond 200 fast and process asynchronously so retries do not stack up. Verify: handler latency stays under a second under retry load.

Variant phrasings

webhook retries out of order

Common phrasing of the problem.

webhook idempotency ordering drip campaign

The drip-angle search.

handle out of order webhooks

The pattern-angle search.

Compatibility: Any webhook provider (Stripe, HubSpot, and similar); at-least-once delivery without ordering is universal.

Why it happens

Providers retry failed webhooks on their own schedule, so a retry of step 1 can arrive after step 2 already processed. A handler that acts on arrival order instead of event arrival time will happily run the sequence backwards.

Edge cases / pitfalls

• Clock skew between systems makes timestamp guards fuzzy; prefer sequence numbers when the provider offers them.
• Ignoring stale events needs care during legitimate replays; distinguish replays from retries.
• Async processing needs its own ordering; a queue without ordering just moves the bug.
• Dead-letter the events you skip so an audit can explain the gap.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_Pf9-p1odNwcRMeH9FwO0og