The Bot Mode relay drains every registered connection every 30s. The local
route is exempt from relay socket retention (#93594), so each tick dials a
fresh requestGatewayForAgent('local', ...) secondary and disposes it after
the RPC. From the second tick, openSecondary saw the scope in
openedSecondaryScopes, treated the dial as a backend reopen, and called
resetTileRuntimeBindings (added in 613822afff), which drops the runtime of
every tile without an owner route plus the delegate's stored->runtime cache.
Those tiles ride the ambient gateway, so every split pane re-resumed and
remounted its composer every ~30s: caret reset, layout shift, and a reverted
composer model pick on an idle Desktop.
A reopened secondary that is not the window's active scope now resets only
tiles whose ownerRoute names that route (resetRouteOwnedTileRuntimeBindings
plus a drop-only dropRuntimeBindings delegate hook). The active-scope reopen
keeps the window-wide reset, so the stale-runtime guard from 613822afff still
covers the tiles that actually live on that socket.
Refs #108088, #118856
ee94a6727f