Additive WebSocket wire contract for a client-driven heartbeat.
The gateway.ready payload now advertises "heartbeat": True so clients can
discover the capability, and the WS read loop answers a gateway.ping request
with a {"ok": True} pong short-circuited BEFORE method dispatch (no method is
invoked). The WSTransport gains closed / last_inbound_at properties and a
mark_inbound() hook, updated on every inbound frame, for later liveness checks.
Backward-compatible in both directions: old clients never send gateway.ping,
and old servers simply never advertise the heartbeat flag. This is the first
slice of a WebSocket-recovery series; the follow-on slices consume this
contract (server-side transport rebind, TUI/desktop clients).
Receipts:
bash scripts/run_tests.sh tests/test_tui_gateway_ws.py -q
=> 1 file, 7 tests passed, 0 failed (100%) in 0.8s; exit 0
Eva
9a71cb95cb