feat(render): weather-driven foliage wind for procedural scenery, shadows follow (Campaign VM VM6b)

Procedural-scenery foliage (trees/bushes — entity ids in the
ProceduralSceneryIdAllocator's 0x8XXYYIII namespace) sways with weather in
mesh_atmospheric.vert and all four directional_shadow_world_* caster vertex
shaders, both calling the identical new foliage_wind.glsl include so the
shadow moves with the leaf by construction.

Classification (FoliageWindClassification, AcDream.App.Rendering.Wb): two
new BatchData.flags bits, computed once per (entity, subset) from four
inputs — entity id (bit 31 for procedural scenery), the pack's declared
FoliageExclusions membership, the subset's TranslucencyKind, and
ObjectRenderData.HasCutoutSubset (computed once per mesh at build time, not
per frame). Bit 1 marks an alpha-cutout leaf subset; bit 2 marks an opaque
trunk subset (only when its own mesh also owns a cutout subset, so rocks
stay still). WbDrawDispatcher.ClassifyBatches (world receiver) and
AddDirectionalShadowBatches (caster) call this with the same four inputs, so
casters and receivers classify identically without needing to share state.
Retail's mesh_modern/terrain_modern/mesh_detail pipelines never read these
bits, so pack-off output is unaffected.

Motion model (foliage_wind.glsl, mirrored bit-for-bit in the new
FoliageWindModel for hermetic CPU tests): height-squared-scaled slow lean
for every foliage subset, plus branch swing and per-vertex-hash-decorrelated
flutter for cutout subsets only. AtmosphericPostProcessGraph.ResolveFoliageWind
resolves the wind block once per frame.Serial — advanced by whichever of
RenderDirectionalShadows (which runs first) or RenderPostProcess is called
first that frame, with the second reading the already-advanced state, which
is what keeps the caster and receiver reading byte-identical clock/strength
values. The per-day-group mean/gust target (AtmospherePolicyDeclaration.
FoliageWindByDayGroup, keyed by the same day-group index convention
ActiveDayGroupMultipliers already established: Clear/Cloudy/Overcast/Rainy)
eases toward its target over WeatherSystem.TransitionSeconds (10s) so a
weather change never snaps; wind-enabled off or indoor instead gates the
OUTPUT to an exact zero (not an asymptotic approach) so a settings toggle or
cell transition is immediate. The wind clock is a Stopwatch started at graph
construction (monotonic, session-relative magnitude for GPU sin() accuracy),
overridable by the same ACDREAM_SKY_PHASE_SECONDS pin SkyRenderer already
uses, for deterministic offline gates.

New settings: wind-enabled, wind-strength, wind-direction-degrees (225°
default — no authored retail wind direction exists to read),
wind-lean-metres, wind-branch-metres, wind-flutter-metres (0 on Low),
wind-canopy-height-metres.

Register row IA-25 files this as an intentional, strictly opt-in divergence:
retail applies no per-vertex wind displacement to any geometry. Known,
accepted limitation: classification is per mesh-subset (one BatchData.flags
word per indirect-draw batch), not per entity instance, so the rare case of
one mesh subset being reachable from both a procedural-scenery and a
non-scenery placement would classify all of that subset's instances alike.

Tests: FoliageWindClassificationTests (the full classification matrix),
FoliageWindModelTests (identity on non-foliage/calm-wind/base-vertex,
canopy-top displacement bound, z-never-increases, trunk has no flutter
term), RenderPackAtmospherePolicyEvaluationTests (exact day-group lookup,
no interpolation across day-group ids, easing convergence without overshoot
or discontinuity), AtmosphericShaderAbiTests (each of the five shaders calls
acdreamFoliageDisplace exactly once; mesh_modern/terrain/mesh_detail call it
never), and four AtmosphericPostProcessGraphTests additions (indoor/disabled
exact-zero gating, settings-to-UBO wiring, same-frame-Serial idempotency —
the last proxies the caster/receiver agreement invariant without needing
this hermetic harness's WbDrawDispatcher/TerrainModernRenderer dependency
chain to exercise RenderDirectionalShadows directly).

App hermetic filter: 6015/6017 (the same 2 pre-existing failures as VM6a,
confirmed unrelated). Core.Tests hermetic: 4697/4697. RenderPackValidator.Tests:
30/30. Full solution Debug and Release builds green. Shader recompile
touched exactly the 5 edited files' .spv (plus manifest); the retail oracle
set and every other pack shader are byte-identical.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

docs/architecture/retail-divergence-register.md

@@ -37,7 +37,7 @@ accepted-divergence entries (#96, #49, #50).
 
 ---
 
-## 1. Intentional architecture (IA) — 21 active rows (IA-24 filed 2026-08-22 for Campaign AR's opt-in real-time sun/moon directional shadows; IA-23 filed 2026-08-17 at the night-round review fix round (F8) — the House tab's not-yet-expired purchase-restriction line renders .NET's culture-default `DateTime.ToString()` where retail renders the C runtime's `strftime("%c", localtime(...))`, a different formatting engine producing a different-shaped (but equivalent-intent) date string; IA-22 filed 2026-08-13 — the #391 user-directed modern-only curated resolution list + desktop-mode default, replacing retail's full adapter enumeration + authored 800x600 default)
+## 1. Intentional architecture (IA) — 22 active rows (IA-25 filed 2026-08-22 for Campaign VM VM6's opt-in weather-driven foliage wind — a render-only vertex displacement with no authored retail wind direction to read; IA-24 filed 2026-08-22 for Campaign AR's opt-in real-time sun/moon directional shadows; IA-23 filed 2026-08-17 at the night-round review fix round (F8) — the House tab's not-yet-expired purchase-restriction line renders .NET's culture-default `DateTime.ToString()` where retail renders the C runtime's `strftime("%c", localtime(...))`, a different formatting engine producing a different-shaped (but equivalent-intent) date string; IA-22 filed 2026-08-13 — the #391 user-directed modern-only curated resolution list + desktop-mode default, replacing retail's full adapter enumeration + authored 800x600 default)
 
 | # | Divergence | Where (file:line) | Why it is safe / justified | Risk if assumption breaks | Retail oracle |
 |---|---|---|---|---|---|
@@ -62,6 +62,7 @@ accepted-divergence entries (#96, #49, #50).
 | IA-22 | **Filed 2026-08-13 (#391, user-directed: "we should only support modern resolutions. Not any old format").** The Config Resolution dropdown offers a CURATED list — the monitor's real mode enumeration filtered to modern widescreen families (16:9/16:10/21:9/32:9, ≥1280 wide, fitting the desktop; `DisplayModeCatalog.Curate`) — and its Defaults value is the desktop's own mode. Retail offered the adapter's complete enumeration including 4:3 legacy modes and authored `800x600` as the row default (`gmConfigUI::InitOptions SetDefaultValue(0x03200258)`; `gmClient::Init @0x004047af` `Device::ForceDisplayResolution(1, 0x320, 0x258)`). | `src/AcDream.App/Rendering/DisplayModeCatalog.cs`; `src/AcDream.App/UI/Layout/ConfigOptionsPageController.cs` (Resolution row); fixture fallback `src/AcDream.UI.Abstractions/Panels/Settings/DisplaySettings.cs` (`AvailableResolutions`, 800x600 removed) | Explicit product direction. **Amended 2026-08-16 (#407, Campaign CC gate round 1):** the dropdown now offers `DisplayModeCatalog.WindowedResolutions` — the curated hardware modes UNIONed with the static modern-ladder sizes that fit the desktop — because a WINDOWED pick is a plain Size write needing no video mode, and remote/RDP virtual displays advertise almost no modes (the live RDP display exposed only 1920x1080 + the 2056x1290 desktop, starving the dropdown). The original "an offered mode is supported by construction" invariant now holds for the FULLSCREEN half only: the fullscreen apply still validates against the hardware `Resolutions` list plus `GlfwDisplayModeSwitcher`'s monitor-mode-list hard guard, so a fullscreen pick of a windowed-only entry refuses safely (log-and-stay, #388; the #392 apply-result seam is that family's open follow-up) — "Graphics mode not supported" crashes remain unreachable from the dropdown. | A user wanting a genuine legacy 4:3 mode cannot pick it; retail-parity comparisons of the Config tab's list/default will show the deviation. | decomp sites in the Divergence column; ISSUES #391 |
 | IA-23 | **Filed 2026-08-17 at the night-round review fix round (F8).** `gmHouseUI::DisplayPurchaseTimeText @0x004a3110`'s not-yet-expired branch renders `"You may buy another landscape house at " + strftime("%c", localtime(timestamp + 0x278d00)) + ". This restriction does not apply to apartments."` — byte-decoded from raw pushed literals at `@0x004a3265`/`@0x004a321d`/`@0x004a3235` (all three text pieces confirmed; a prior filing had wrongly called this "unrecoverable"). This port renders the SAME three pieces, in the same order, with the same expiry-timestamp math, but formats the middle date/time piece with .NET's culture-default `DateTime.ToString()` (no explicit format string) rather than the C runtime's `strftime("%c", ...)` — the two engines do not share a format table, so the RENDERED SHAPE of the date/time differs (e.g. .NET's short numeric date+time vs the CRT's `Ddd Mon DD HH:MM:SS YYYY`-style locale string) even though both express "the process's own locale's full date+time" and use the SAME underlying instant (local time, matching retail's `localtime()`). | `src/AcDream.Runtime/Gameplay/RuntimeHouseState.cs` (`Recompute`'s not-expired branch) | Both are "whatever the process locale says" full date+time strings; no game-logic reads or parses this text back, it is pure chat-scroll presentation, so a differently-shaped (but equally legible) date string carries no functional risk | A retail-side-by-side visual comparison will show a differently formatted date/time (not a byte-identical `strftime("%c")` reproduction) — cosmetic only | `gmHouseUI::DisplayPurchaseTimeText @0x004a3110`; `strftime`/`localtime` CRT calls at `@0x004a322c`/`@0x004a3216` |
 | IA-24 | **Filed 2026-08-22, Campaign AR.** An explicitly selected atmospheric render pack adds cascaded real-time directional shadows from terrain, trees, buildings, players, monsters, and other retained outdoor casters. The one shadow direction follows the visible authored sun, then the dominant haloed moon (`0x01001F6A`), then the secondary moon (`0x01001F67`); a moon supplies direction only while colour/energy remains retail's single interpolated `SkyTimeOfDay.DirColor × DirBright` channel. Retail renders none of these real-time object-shadow maps and does not expose a second moon light. | `src/AcDream.App/Rendering/Packs/AuthoredCelestialShadowSource.cs`; `src/AcDream.App/Rendering/DirectionalSunShadowRenderer.cs`; pack-only receiver shaders; evidence `docs/research/2026-08-22-dereth-celestial-shadow-sources.md` | This is the user-requested headline graphics enhancement and is strictly opt-in. The retail path remains the default and authoritative fallback; pack-off does not build/select shadow work or change `SceneLighting`. One selected source reuses one cascade array, so moon support does not multiply shadow resources. | Pack-on output intentionally differs from retail. A wrong celestial identity/transform or stale source transition would visibly misalign shadows from the sky; pack-off output changing would violate the campaign's primary safety contract. | `SkyDesc::GetLighting @0x00500A80`; `GameSky::UseTime @0x005075B0`; installed Region `0x13000000`; cited research note |
+| IA-25 | **Filed 2026-08-22, Campaign VM VM6.** An explicitly selected atmospheric render pack sways procedural-scenery foliage (trees/bushes — entity ids in the `0x8XXYYIII` `ProceduralSceneryIdAllocator` namespace) in `mesh_atmospheric.vert` and the four `directional_shadow_world_*` caster vertex shaders, driven by a weather-table lean/branch/flutter vertex displacement (`foliage_wind.glsl`, `FoliageWindModel` CPU mirror) whose mean/gust strength is looked up per active day group and eases toward its target over `WeatherSystem.TransitionSeconds` (10 s) so a weather change never snaps. Retail's fixed-function renderer applies no per-vertex wind displacement to any scenery mesh — Dereth's trees are static geometry. Wind direction (`wind-direction-degrees`, default 225°) is a plain pack default: there is no authored retail wind direction to read (no wind data exists in retail at all). Render-only: `WorldPicker` picks the undisplaced mesh, so a swaying leaf can be up to `lean + branch` metres from its pick volume at the moment of a click; foliage subsets are cosmetic scenery, not interactable in retail either. | `src/AcDream.App/Rendering/Shaders/foliage_wind.glsl`; `src/AcDream.App/Rendering/Wb/FoliageWindClassification.cs`; `src/AcDream.App/Rendering/Packs/FoliageWindModel.cs`; `src/AcDream.App/Rendering/Packs/AtmosphericPostProcessGraph.cs` (`ResolveFoliageWind`); `src/AcDream.App/Rendering/Packs/BuiltInAtmosphericRenderPack.cs` (wind settings + `FoliageWindByDayGroup`) | Explicitly opt-in graphics enhancement — the retail path (`mesh_modern`, `terrain_modern`, `mesh_detail`) never reads `BatchData.flags` bits 1/2 and is pixel-identical with the pack off. The classification never touches Runtime/Core physics — the collision BSP is the trunk, and picking against the undisplaced mesh has no gameplay consequence since foliage is not interactable. | Pack-on output intentionally differs from retail (moving foliage where retail has none). A wrong classification bit would sway a non-foliage object or leave a real tree still; a caster/receiver clock or amplitude mismatch would visibly misalign a leaf's shadow from the leaf itself. Pack-off output changing would violate the campaign's primary safety contract. | None — retail applies no vertex wind displacement to any geometry; `ProceduralSceneryIdAllocator` (bit 31 entity-id namespace, existing acdream mechanism, not retail) |
 
 ---