Whether the server SHOULD emit an SSE retry: field before closing a
connection that it is *not* terminating (so the client knows how long to
wait before reconnecting). This is a 2025-11-25-only SHOULD
(basic/transports §Sending Messages item 6 / §Listening for Messages item 4):
"If the server does close the connection prior to terminating the SSE stream,
it SHOULD send an SSE event with a standard retry field before closing the
connection." It builds on the 2025-11-25 connection/stream split (reconnect
via Last-Event-ID), which does not exist in 2025-03-26 / 2025-06-18, and the
draft dropped Last-Event-ID resumability — so this MUST NOT alter those
versions' wire output. Gated here as a single pure predicate so the version
boundary is directly testable.
Whether the server SHOULD emit an SSE retry: field before closing a connection that it is *not* terminating (so the client knows how long to wait before reconnecting). This is a 2025-11-25-only SHOULD (basic/transports §Sending Messages item 6 / §Listening for Messages item 4): "If the server does close the connection prior to terminating the SSE stream, it SHOULD send an SSE event with a standard retry field before closing the connection." It builds on the 2025-11-25 connection/stream split (reconnect via Last-Event-ID), which does not exist in 2025-03-26 / 2025-06-18, and the draft dropped Last-Event-ID resumability — so this MUST NOT alter those versions' wire output. Gated here as a single pure predicate so the version boundary is directly testable.