Start this window's scroll group service: subscribe to the host's announcements, hand over any
state stored before the host existed, then seed from the host.
Subscribing first so a change made while the rest is in flight is not lost, and handing over
before seeding so the first seed after an upgrade carries the reference the user left off at.
Nothing here is allowed to fail this window's startup. The cache is already usable — it was
filled from what came with the window before React rendered, and the subscription above keeps it
current — so a host that is slow or missing costs freshness, not correctness, and must not take
down the unrelated services that start alongside this one. Until the seed succeeds every write is
sent to the host regardless of what the cache predicts (see setScrRefSync), which is what
keeps a never-seeded window honest.
Start this window's scroll group service: subscribe to the host's announcements, hand over any state stored before the host existed, then seed from the host.
Subscribing first so a change made while the rest is in flight is not lost, and handing over before seeding so the first seed after an upgrade carries the reference the user left off at.
Nothing here is allowed to fail this window's startup. The cache is already usable — it was filled from what came with the window before React rendered, and the subscription above keeps it current — so a host that is slow or missing costs freshness, not correctness, and must not take down the unrelated services that start alongside this one. Until the seed succeeds every write is sent to the host regardless of what the cache predicts (see setScrRefSync), which is what keeps a never-seeded window honest.
Call once at renderer startup.