The weather: evening sun, rain and leaves over any court, coming and going (v390)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

PROJECT.md

@@ -636,6 +636,28 @@ Each phase ships to staging and gets a phone verdict, and tests ride along with
 5. **LATER.** The metal bed (when Oliver has a track: start at the transformation, gore only) and Members'
    Night (option C).
 
+## Session log: the weather (2026-10-16, v390)
+
+Shown first as a mock-up over real v389 frames (artifact "Splatter Tennis Wetter", five kinds, one per
+act court). Oliver kept **evening sun, rain, leaves** (heat/gusts and fog/floodlight dropped), asked for
+rain and leaves less extreme, for weather that is sometimes simply absent and comes back ("irgendeine
+softe Range"), and for it to be court-independent — except no evening sun on the night court.
+
+`src/weather.js`, render-owned and purely visual (render's own Math.random, nothing gameplay reads):
+- **The sky** (`tickSky`): one kind or none, intensity `k` eased linearly over `TUNE.skyFade` 10 s toward a
+  target redrawn every `skyHold` 25-60 s — 0 with `skyLull` 0.35, else in `skyRange` 0.35-1. The KIND only
+  changes from a clear sky (k < 0.02; `skyClear` 0.3 keeps it clear), so nothing snaps from one to another.
+  Sun is never picked on `gloom`, and fades out if you walk onto it. It runs on across runs and modes.
+- **Drawing** (`drawWeather`), in render right after the un-shake: over the world, UNDER the gore grade (so
+  the gore sky is red too) and under the HUD. Logical-pixel particles; rain splashes and lying leaves are
+  world points through `proj`, so they sit on the court in perspective. Lying leaves have per-spot
+  thresholds, so the court fills as k rises and clears as it falls. Full-intensity counts in TUNE
+  (`rainDrops` 70, `rainSplash` 30/s, `leafFall` 22, `leafLie` 36) — about half the preview's density, with
+  the colour casts at roughly 0.55x.
+- `TUNE.weather` 'auto' | 'off' | 'sun' | 'rain' | 'leaves'; the URL door `?weather=rain` sets it.
+Test: two simulated hours — never a snap, kind changes only under a clear sky, all three come round, clear
+25-80% of the time, no sun on the night court, the forced door works.
+
 ## Session log: the burning ball and the gore grade (2026-10-16, v389)
 
 Oliver picked two of the polish ideas (1 and 5; weather only after he has seen a preview):