Fifth and final Phase A.1 hotfix. Replaces the previous "drop on
miss" semantics in GpuWorldState.AppendLiveEntity with a per-landblock
pending bucket that survives the race where a CreateObject arrives
before its landblock has been streamed in.
Root cause:
The post-login spawn flood (40+ NPCs/items) drains in a single
WorldSession.Tick() call. The synchronous streamer enqueues all 25
visible-window landblocks in one shot but StreamingController.Tick
was capped at MaxCompletionsPerFrame=4, so only 4 landblocks landed
in GpuWorldState on the first frame. The center landblock 0xA9B4FFFF
may or may not have been in those first 4 (HashSet iteration order
is undefined). Spawns whose target landblock wasn't yet loaded were
silently dropped by AppendLiveEntity. Re-ordering the OnUpdate
(streaming first, live second) didn't fix it because the cap still
limited to 4 per frame; spawns for landblocks #5+ kept dropping
until the queue drained, by which point the spawn flood was over.
The reordering was correct but insufficient. The cap was a relic of
the original async streamer design (limit GPU upload spikes per
frame). With the synchronous streamer there's no backlog to spread,
so the cap was pure latency for no benefit. Setting it to int.MaxValue
restores "drain everything you just enqueued" semantics.
The pending-spawn list is the *correct* architecture fix that makes
the system robust against any future ordering bug, not just the cap:
- AppendLiveEntity for an unloaded landblock parks the entity in a
per-landblock pending bucket instead of dropping it.
- AddLandblock drains pending entries for its landblock and merges
them into the loaded record before storing.
- RemoveLandblock drops pending entries for the same landblock —
if the player moved away, the spawns are no longer relevant; the
server resends them via CreateObject when the player returns.
Diagnostic counter PendingLiveEntityCount exposes the bucket size
so future regressions are visible without spelunking.
7 new GpuWorldStateTests pin the contract:
- AppendLiveEntity_LandblockAlreadyLoaded_AppendsImmediately
- AppendLiveEntity_LandblockNotLoaded_ParksInPending
- AddLandblock_DrainsPendingEntriesForThatLandblock
- AddLandblock_DoesNotDrainPendingForADifferentLandblock
- RemoveLandblock_DropsPendingForThatLandblock
- RemoveLandblock_LoadedThenRemoved_DropsItsEntities
- IsLoaded_ReturnsTrueForLoaded_FalseForPendingOnly
Also removes the diagnostic Console.WriteLine I added in the previous
debugging round and the old LiveAppendsResolved/Dropped counters that
were never read by anyone.
219 tests green (212 + 7 new).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Called once per frame from OnUpdate. Owns a StreamingRegion and uses
delegates into LandblockStreamer + a terrain-apply callback so unit
tests can inject fakes. Handles first-tick bootstrap (whole window
loads), boundary recenter (diff against previous center), and
drain completions (up to N per frame to cap GPU upload spikes).
4 new tests, all green.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
