1.0 defaults to close: honoring 'Connection: Keep-Alive' without echoing
it back left spec-following clients waiting for an EOF that never came
(ab -k deadlocked to its poll timeout on response 1).
As agreed:
- serialise_response echoes 'connection: keep-alive' when keep_alive
is on AND version is 1.0. 1.1 keep-alive stays implicit.
- Error statuses (>=400) on 1.0 force keep_alive off in the conn actor
(joins the existing 1.0-stream force-close): we don't advertise reuse
on a 4xx/5xx to a protocol generation where reuse is opt-in.
- HEAD needs nothing: the echo is framing-neutral.
- Parse-error responses already carried 'connection: close'.
Tests: unit pair (1.0 echo / 1.1 implicit) + integration pair (socket
actually reused on 1.0; 404 forces close + EOF). Validated against the
original repro: ab -k -n 5000 -c 50 GET /users -> 5000/5000 keep-alive,
0 failed, ~63k rps (~18.9k without keep-alive).
Claude
64137cccf0