Whether a POST-initiated SSE stream must lead with the priming event (an
event id + empty data field) for the given negotiated version. This is a
2025-11-25-only SHOULD (basic/transports §Sending Messages item 6): it did
not exist in 2025-03-26 / 2025-06-18, and the draft removed Last-Event-ID
resumability altogether, so the priming event must NOT alter those versions'
wire output. Gated here as a single pure predicate so the version boundary is
directly testable.
Whether a POST-initiated SSE stream must lead with the priming event (an event id + empty data field) for the given negotiated version. This is a 2025-11-25-only SHOULD (basic/transports §Sending Messages item 6): it did not exist in 2025-03-26 / 2025-06-18, and the draft removed Last-Event-ID resumability altogether, so the priming event must NOT alter those versions' wire output. Gated here as a single pure predicate so the version boundary is directly testable.