subscriptions/listen

[maxisbey]

The opt-in long-lived notification stream: server accepts a filter, acks first, routes only opted-in types, tags with subscriptionId; client demux helper for #2894 to wire in.

What's in it

• Server: accept subscriptions/listen with a filter, send the ack first, route only opted-in notification types, tag each with subscriptionId.
• A way for the existing notification publishers (list_changed, resources/updated) to feed the listen stream.
• Client demux helper (open/maintain stream, demux by id, re-subscribe after a stdio reconnect) — wired in by New Client (all-versions, low-level + high-level) #2894.

Conformance

• The sep-2575-server-* subscription checks inside server-stateless run (not skip) and pass
• Together with Backwards compatibility & version negotiation, New HTTP serving path (modern + dual-era), Capabilities API + server/discover handler, Context object (layered, per-request): server-stateless

Dependencies

• Depends on: New HTTP serving path (modern + dual-era) #2893

References

• Subscriptions
• SEP-2575

[maxisbey]

Shipped across #3035 (server runtime: filtered listen, ack-first, opted-in routing, subscriptionId tagging, pluggable subscription bus), #3046 (client plumbing: request-id options, transport-correct cancellation), and #3047 (client driver: client.listen() async context manager with typed events). The sep-2575 subscription checks inside server-stateless run and pass.

Two notes: re-subscribe-after-reconnect is deliberately an explicit user loop (no auto-re-listen); listen over stdio is not yet served and is tracked as follow-up work before the stable release.

_{AI Disclaimer}