The protocol version in effect for THIS request (negotiated version on the
stateful 2025-era protocols; the per-request _meta.protocolVersion on the
stateless draft). Request-scoped so a concurrent request that yields mid-
handle cannot have its effective version flipped by another in-flight
request: the dispatcher reads it from here, not from a mutable field on the
shared server instance.
The protocol version in effect for THIS request (negotiated version on the stateful 2025-era protocols; the per-request _meta.protocolVersion on the stateless draft). Request-scoped so a concurrent request that yields mid- handle cannot have its effective version flipped by another in-flight request: the dispatcher reads it from here, not from a mutable field on the shared server instance.