modelcontextprotocol/inspector
Watch
1
0
Fork
You've already forked inspector
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions 2
inspector/pr-screenshots/README.md
Cliff Hall 320daf2f67
 Resources: subscriptions/listen model on modern servers (era fork) (#1630) (#1730) 
Fork resource subscriptions by protocol era: legacy keeps resources/subscribe; modern (2026-07-28) models subscriptions as a filter over one long-lived subscriptions/listen stream with reconnect-by-re-listen (capped backoff), an optimistic Connecting→Listening header badge, and a fix so the browser proxy no longer blocks listen() ~60s. Closes #1630.
2026-07-20 19:33:40 -04:00

3.4 KiB
Raw Blame History

Resource subscriptions era fork (#1630) — proof screenshots

End-to-end verification of the era fork against two real test servers (test-servers/configs/subscriptions-modern-http.json on port 3220 and subscriptions-legacy-http.json on 3221), driven in a real browser.

Modern era (2026-07-28)

Modern header badge

subscriptions-modern-header-badge.png — on the modern era the Subscriptions section shows a single stream-status badge in its accordion header (next to the count, so it stays visible while the section is collapsed): ● Listening when the subscriptions/listen stream is acknowledged, ● Reconnecting… while it re-lists after a drop, ● Stream ended on graceful close — each explained in a tooltip. Legacy connections show no badge.

Modern listen + acknowledged

subscriptions-modern-listen-acknowledged.png — subscribing on a Modern-negotiated connection sends subscriptions/listen (long-lived → PENDING) and the server answers with notifications/subscriptions/acknowledged. No resources/subscribe is sent — the defining era-fork behavior. Two other details: the connection era is shown once in the panel header (Messages · MODERN), not per entry; and the sub ⧉ listen:0 subscription-id tag rides the notification's top line (beside the direction) so the method badge below gets the full column width instead of truncating against the pin control.

Legacy era (contrast)

Legacy resources/subscribe

subscriptions-legacy-resources-subscribe.png — the same subscribe on a Legacy connection sends resources/subscribe (Protocol view, LEGACY) and the Subscriptions section shows no stream badge and no header dot (there is no persistent stream on the legacy era). Legacy behavior is unchanged.

Legacy live update

subscriptions-legacy-live-update.png — calling the update_resource tool emits notifications/resources/updated (server → client, Protocol view), and the subscribed resource_1 tile stamps its last-updated time (2:53:17 PM) — the full subscribe → update → notify round-trip on the legacy era.

Notes

  • Modern subscribe in the browser is now prompt (Connecting… → Listening) and stable: the web backend's /api/mcp/send and the browser remote transport used to hold the subscriptions/listen request waiting for a JSON-RPC response that a long-lived stream never sends, blocking listen() ~60s and then spuriously driving the reconnect loop. Both sides now exempt subscriptions/listen from the response-wait (its ack + notifications ride the SSE event channel), so the badge no longer oscillates. (Some of the older screenshots here were captured before that fix and show the transient Reconnecting…/RECONNECTING… state.)
  • A tool-triggered resources/updated does not reach the modern subscriptions/listen stream on the SDK's stateless modern leg (a tool call and the listen stream are separate connections; server.notification() rides the tool call's connection). This is an SDK server-side gap — the same class as the logging showcase's stateless-notification caveat — independent of this PR's client-side work. Hence the live-update proof is shown on the legacy era, where the round-trip completes.