User-observed regression 2026-04-23: acdream spawned rain particles
when retail showed no rain at the same server tick. Root cause: my
Phase 3e shortcut mapped DayGroup.Name = "Rainy" → WeatherKind.Rain →
rain particle emitter. That's not what retail does.
Parallel decompile research confirms:
- Agent A (2026-04-23-physicsscript.md): PhysicsScript runtime lives
at FUN_0051bed0 → FUN_0051bfb0, runs per PhysicsObj; sky calls it
from NOWHERE.
- Agent B (2026-04-23-sky-pes-wiring.md): FUN_00508010 (sky render
loop) never reads SkyObject.DefaultPesObjectId — the field is dead
at render time. Rain/snow particles in retail come from a separate
camera-attached weather subsystem that has NOT yet been located.
So the correct behavior is: DayGroup name should only drive
fog/ambient tone (via keyframes, already in the Snapshot path),
never spawn particle emitters. Any retail-faithful particle rain
belongs to a future phase once we find the camera-attached weather
subsystem driver.
Change: MapDayGroupNameToKind now maps all weathery substrings
(storm/snow/rain/cloud/overcast/dark/fog) → Overcast — fog-only
visuals, no particle spawn. Clear names stay Clear. The Rain, Snow,
Storm enum values remain and are still accessible via ForceWeather()
for debug overrides.
Tests updated (WeatherSystemTests): the name→kind theory now expects
Overcast for Rainy/Snowy/Stormy variants.
Also commits the four research docs from this session's parallel
hunt: PhysicsScript dat+runtime, sky↔PES wiring (negative finding),
lightning timer (negative finding — agent #3), fog on sky
(positive: retail applies fog to sky geometry).
NOTE on lightning: agent #3's research only ruled out the CLIENT-SIDE
RANDOM TIMER hypothesis for lightning. User confirms retail does have
visible lightning + thunder. A follow-up agent (#5, in flight as of
this commit) is hunting the real mechanism — PlayScript opcode,
SetLight PhysicsScript hooks, AdminEnvirons side effects, or the
weather-volume draw. This commit does NOT attempt to port lightning.
Build + 733 tests green.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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