SSE stream stability
Validate six SSE events continuously or across one planned interruption and explicit Last-Event-ID resume.
Checking network test availability…
Check event continuity and controlled recovery
This runs against our fixed endpoint. It uses a fetch-based SSE reader with signed session headers, not the browser’s native EventSource client. No measurement starts on page load.
The server sends events 1–3 and a checkpoint, then deliberately ends the stream. This client waits 500 ms and resumes once with Last-Event-ID: 3, expecting events 4–6.
- Data events
- 6, in sequence
- Nominal cadence
- 250 ms
- Response deadline
- 6 seconds
- Run deadline
- 20 seconds, plus cleanup
At most two streams, each with a 32 KiB read cap. Admission reserves an 8 MiB allowance without sending it; each stream debits 256 KiB conservatively. Stop also requests server-side stream termination.
Interpret the result within its scope
Sequence validation checks this diagnostic’s data contract, not an arbitrary application. A continuous run does not test reconnection. A resumed run tests one deliberate checkpoint and one client-managed request, not retry storms or every disconnect condition.
Browser scheduling, server handling and intermediate buffering can change arrival gaps. Neither gaps nor failed streams are IP packet-loss measurements. No Wi-Fi, router or ISP cause is inferred.