Every customer's upload folder is a stream, and the stream belongs to them

You sell a document-intake product. Every customer asks for the same feature: tell my system when a file lands. On a shared platform that is a webhook queue, retries, a per-tenant filter, and a status page for the day the queue backs up.

Each customer runs in their own container, and each container has its own watch service. At onboarding your script registers one watcher on their uploads directory (recursive, include */.pdf, coalesce_ms 200) and hands the customer the watcher's SSE URL behind their own proxy token.

Their integration reads events as they happen: created, path, size, timestamp. If it disconnects, it reconnects with since_timestamp and catches up from the watcher's history. There is nothing to filter by tenant, because the service can only see one tenant's disk.

Eighty customers, eighty watchers, one flat-rate box; the idle ones add nothing to the bill.

The events feature is a URL per customer, and the queue was never built.