Decides the WS-13 legitimate-silence question as option (b): 60s of no
chunk progress is an intentional eviction line even for silent
subscriptions; no WS ping/pong keepalive is added because a keepalive
can only rescue app-silence by re-arming the deadline, which reopens
the dribble hole the knob exists to seal. Documented in the byte_adapter
module doc, on DEFAULT_WS_IDLE_TIMEOUT, on the unchanged
HttpAdapter::with_ws_idle_timeout knob, and in websocket.md (new
'Idle-read timeout' section, including the FWD-15 SSE-keepalive
layering note). Deployment posture for long-lived silent sessions:
with_ws_idle_timeout(None) + WsSessions abort + write-side caps.
glm-5.3-flash
3f1d5913e7