preview.read / preview.act / terminal.read / window.read / tour are answered
only by the Desktop window that shows the requesting session (#114981). When
no attached window showed it, every window stayed silent and the agent waited
out the full 30-45s bridge deadline, then got the generic "No preview tab is
open, or the read timed out."
A window not hosting the session now declines with JSON-RPC error 4404
instead of staying silent. The gateway counts a decline as that client's vote,
not as the answer: the request stays open for the owner window and settles
only once every attached answering client declined, with a distinct refusal
("No Hermes Desktop window is showing this chat ... Ask the user to open this
chat in the Desktop app, then retry."). A bystander window therefore still
cannot beat the owner (#113348).
The backend advertises the counting via client.capabilities
(declines_not_shown); the shared channel only sends a decline to a backend
that did, so a new app against an older backend keeps today's silence.
Fixes#119333
e33f1a0faf