Explanation

Why ingestion fails as a whole

Backpressure is ordinary. A full stop of every producer is not a necessary consequence of it. This page is why Northwind currently treats them as the same event — and why RFC 014 is a routing change, not a capacity change.

One path, many callers

Checkout, Catalog, and Inventory all share /events and one queue. That sharing is the feature: producers do not run their own brokers. It is also the failure domain. When the queue cannot accept, the gateway has nowhere to put work, so it stops accepting. 41% of platform footprint is downstream of that decision.

It is not (only) size

A larger queue delays the halt. It does not create a second place for work to go. Detection at 120s of lag delays the page. It does not create a degrade path. Those are real improvements; they answer a different why.

Degrade means a defined leftover

"Degrade throughput" only means something if a producer can still land some events. Two queues, or a shed that returns 202, are ways to leave a leftover. Blocking until 503 leaves none.

How to split, how to replay, how to page: other documents. This one is the picture that makes those procedures make sense.