Replaces the single-radius Tick with a two-tier model that consumes
StreamingRegion's TwoTierDiff (5-list) and routes to the appropriate
JobKind:
- ToLoadFar -> _enqueueLoad(id, LoadFar)
- ToLoadNear -> _enqueueLoad(id, LoadNear)
- ToPromote -> _enqueueLoad(id, PromoteToNear)
- ToDemote -> _state.RemoveEntitiesFromLandblock(id) on render thread
- ToUnload -> _enqueueUnload(id)
Drain switch handles Loaded (terrain + entity layer), Promoted (entity
layer only -- terrain already loaded), Unloaded, Failed, WorkerCrashed.
Constructor signature: nearRadius/farRadius separate ints. Old single-
radius ctor removed; existing single-radius tests updated to pass
nearRadius=farRadius for backward-compat coverage.
GameWindow's enqueueLoad lambda updated from (id =>...) to (id, kind) =>
to match new Action<uint, LandblockStreamJobKind> signature; radius: arg
renamed to nearRadius:/farRadius: (both set to _streamingRadius until T16
wires the full two-tier env-var parsing).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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