fix(lighting): #142 — per-instance sun gate for windowed-building interiors

Standing inside (or looking into) a windowed building like the Agent of
Arcanum, interior objects (furniture, NPCs, the player) were lit by the
directional sun because acdream's sun gate was per-FRAME (keyed on the
player being in a sealed cell), not per-DRAW as retail does it.

Retail's PView::DrawCells (0x005a4840) runs two stages per frame:
  outdoor stage   → useSunlightSet(1) (0x005a485a): sun ON
  interior stage  → useSunlightSet(0) (0x005a49f3): sun OFF
DrawMeshInternal (0x0059f398) then calls minimize_object_lighting only
when useSunlight==0, so indoor objects ALWAYS skip the sun regardless of
whether the player's cell is windowed or sealed.

Fix: add a per-instance uint SSBO (binding=6 instanceIndoor[]) whose value
is IndoorObjectReceivesTorches(ParentCellId) — the same predicate AP-43
already uses for the torch gate. In mesh_modern.vert, nest the sun loop
inside an additional `if (instanceIndoor[instanceIndex] == 0u)` check
inside the existing `if (uLightingMode == 0)` block. Indoor objects get
torches (unchanged) but now skip the sun; outdoor objects keep the sun and
still get no torches. The ambient regime (UpdateSunFromSky: 0.2 sealed /
sky otherwise) is untouched — it was already correct.

Mechanically: _currentEntityIndoor set once per entity in
ComputeEntityLightSet; appended to InstanceGroup.IndoorFlags in
AppendCurrentLightSet; grown/packed/uploaded in the same cursor loop as
_clipSlotData and _lightSetData; deleted in Dispose. Mode-1 draws
(EnvCellRenderer) never read binding=6 — the sun loop is inside the
uLightingMode==0 uniform-control-flow branch.

AP-43 divergence register updated: the sun half is now per-draw (no
longer a residual). Residual narrowed to the unaudited ebp_2 test in
CellManager::ChangePosition (no observed impact).

Tests: WbDrawDispatcherIndoorFlagTests pins IndoorObjectReceivesTorches
for the spec §5 representative ids: 0xA9B40172 (Agent of Arcanum EnvCell)
→ 1; 0xA9B40031 (land sub-cell) → 0; 0xA9B4FFFF (landblock) → 0; null
(outdoor shell) → 0; plus the boundary cases 0x0100/0x00FF.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/architecture/retail-divergence-register.md

@@ -136,7 +136,7 @@ accepted-divergence entries (#96, #49, #50).
 | AP-33 | Interior-root look-in cells (**#124** sub-pass) draw their statics + DYNAMICS + emitters WHOLE — no per-part/per-object viewcone check; retail viewconeCheck's each vs the installed view (the **#131** portal closure: a server object in a look-in cell drew nowhere — dynamics-last culls cells absent from the main cone, and post-seal it z-fails anyway) | `src/AcDream.App/Rendering/RetailPViewRenderer.cs` (`DrawBuildingLookIns`) | The main viewcone has no entries for look-in cells; over-include is the safe direction (z-correct, repainted outside apertures by the root's shells); look-in cell counts are small (~1-3 cells) | A few wasted draws on content outside the doorway region (repainted); no under-draw direction remains | `viewconeCheck` 0x0054c250; nested `DrawCells` objects pc:432878 |
 | AP-34 | Landscape-stage alpha deferral is a TWO-PHASE slice split (statics-early / dynamics+particles+weather-late around the **#124** look-ins) + outdoor-root attached scene emitters moved to the post-frame pass, not retail's single deferred alpha flush. Residual: building exteriors' / outside-stage dynamics' own translucent MESH batches still draw within their stage draw call (before later stage content) | `src/AcDream.App/Rendering/RetailPViewRenderer.cs` (`DrawLandscapeThroughOutsideView` late loop) + `GameWindow` post-frame Scene pass | The MDI dispatcher draws translucency inside each Draw call; a faithful FlushAlphaList port needs a global deferred alpha list across all landscape draws — the split covers the user-visible cases (#131 portal swirl, #132 candle flame indoors + outdoors) | Translucent landscape content drawn early and screen-overlapped by content drawn later in the stage gets overpainted (no depth self-protection) — the portal-swirl/candle-flame class re-appears in the residual configurations | `D3DPolyRender::FlushAlphaList` (DrawCells pc:432722) |
 | AP-36 | Dungeon streaming gate triggers on the player's CURRENT cell being a sealed EnvCell (`CurrCell.IsEnv && !SeenOutside`), an approximation of ACE's full landblock `IsDungeon` (all-heights-zero + NumCells>0 + Buildings.Count==0). The retail BEHAVIOR (a dungeon loads no adjacent landblocks) is faithful — only the runtime TRIGGER is the cheap cell predicate instead of classifying the center landblock. **#135 pre-collapse:** at login/teleport the same collapse is triggered EARLY (the instant the streaming center is recentered onto the spawn/dest cell) via `IsSealedDungeonCell` reading the EnvCell **dat** `SeenOutside` flag — because the physics `CurrCell` is null until placement, which waits for hydration; without the early trigger the full 25×25 ocean-grid window loads then unloads (the ~30 s login FPS ramp) | `src/AcDream.App/Rendering/GameWindow.cs:6895` (per-frame predicate) + `:IsSealedDungeonCell` + `:OnLiveEntitySpawnedLocked`/`:OnLivePositionUpdated` (login/teleport pre-collapse hooks) + `src/AcDream.App/Streaming/StreamingController.cs` (collapse/expand/`PreCollapseToDungeon`) | The predicate is already computed for sun/sky gating (playerInsideCell) and exactly matches for sealed dungeons vs windowed building interiors (SeenOutside=true → not gated); no landblock re-classification needed. The dat-flag read is the same `EnvCellFlags.SeenOutside` the hydrated `ObjCell.SeenOutside` is built from (`EnvCell.cs:72`/`PhysicsDataCache.cs:224`), so the pre-collapse decision matches the eventual per-frame gate exactly | A dungeon cell that reports SeenOutside (an entrance cell open to the surface) briefly un-collapses and re-streams the window; a hypothetical windowless building back-room (IsEnv && !SeenOutside but HasBuildings) would wrongly collapse its outdoor neighbors; a sealed-dungeon entrance cell that is itself SeenOutside is simply MISSED by the early trigger and falls back to the existing late collapse (no worse than before #135) | ACE `LandblockManager.GetAdjacentIDs` (dungeons→empty) Landblock.cs:577-582; `IsDungeon` Landblock.cs:1264-1277 |
-| AP-43 | Per-object torch (point/spot) lighting is gated on the OBJECT's own cell: an object selects the static wall-torches ONLY when its `ParentCellId` is an EnvCell (`(id & 0xFFFF) >= 0x0100`); outdoor objects (building exterior shells with null ParentCellId, outdoor scenery, outdoor creatures) get the SUN + ambient and NO torches. This is the faithful port of retail's `useSunlight` gate — `DrawMeshInternal` (0x0059f398) calls `minimize_object_lighting` only `if (Render::useSunlight == 0)`, and the outdoor landscape stage runs `useSunlightSet(1)` (`PView::DrawCells` 0x005a485a, before `LScape::draw`) so outdoor objects are never torch-lit (closes the Holtburg meeting-hall facade torch-flood — A7 Fix D round 2, the dat's intensity-100 `falloff 6` orange torches were washing the exterior shell). **Residual approximation:** the sun/no-sun half is a per-FRAME global keyed on the PLAYER being inside a cell (`UpdateSunFromSky` zeroes the sun when `playerInsideCell`), NOT retail's per-draw-STAGE `useSunlight` toggle. So a mixed-stage frame (standing in a doorway / look-in) lights through-aperture objects with the player's regime, not the object's stage regime | `src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs` (`IndoorObjectReceivesTorches` + `ComputeEntityLightSet`); sun half `src/AcDream.App/Rendering/GameWindow.cs:10421` (`UpdateSunFromSky`) | The visible case — player OUTSIDE, looking at an outdoor building/scenery — is now exactly faithful (sun+ambient, no torches); player INSIDE a cell gets torches with the sun globally killed = faithful indoor regime. Cross-aperture mismatch only affects objects seen THROUGH a doorway from the other lighting context | A through-aperture interior object viewed from outside gets the sun (player outside) instead of retail's indoor torches-no-sun; an outdoor object viewed from inside gets no sun (player inside) instead of retail's sunlit outside stage — doorway/look-in frames only, not the standalone outdoor or indoor case | `useSunlight` gate `DrawMeshInternal` 0x0059f398; `useSunlightSet` 0x0054d450; outside stage `PView::DrawCells` 0x005a485a (`useSunlightSet(1)`); `minimize_object_lighting` 0x0054d480; `config_hardware_light` Range=falloff×`rangeAdjust`(1.5) 0x0059ad30 |
+| AP-43 | Per-object torch (point/spot) lighting AND sun are both gated on the OBJECT's own cell via the same `IndoorObjectReceivesTorches(ParentCellId)` predicate (`(id & 0xFFFF) >= 0x0100`): indoor objects (EnvCell-parented) get torches + NO sun; outdoor objects get the SUN + ambient + NO torches. This is the faithful per-draw port of retail's `useSunlight` gate — `DrawMeshInternal` (0x0059f398) calls `minimize_object_lighting` only `if (Render::useSunlight == 0)`, and `PView::DrawCells` (0x005a4840) calls `useSunlightSet(1)` (0x005a485a) for the outdoor stage and `useSunlightSet(0)` (0x005a49f3) for the interior-cell stage. **#142 (2026-06-20):** the sun gate is now PER-INSTANCE in the shader (binding=6 `instanceIndoor[]` flag in `mesh_modern.vert`, filled by `AppendCurrentLightSet`) — it was previously a per-FRAME global keyed on the PLAYER cell (`UpdateSunFromSky`). The per-frame global is retained for sealed dungeons (correctly kills the sun frame-wide when no sky is visible). **Residual:** the `ebp_2` second seen-outside test in `CellManager::ChangePosition` (0x004559B0) is unaudited — unclear whether it changes the ambient/sun regime for a subset of cells. No observed behavioral impact in tested cells. | `src/AcDream.App/Rendering/Wb/WbDrawDispatcher.cs` (`IndoorObjectReceivesTorches`, `ComputeEntityLightSet`, `AppendCurrentLightSet`, `_instIndoorSsbo`/`_indoorData`/`InstanceGroup.IndoorFlags`); `src/AcDream.App/Rendering/Shaders/mesh_modern.vert` (binding=6 `instanceIndoor[]` gate on sun loop); per-frame sun `src/AcDream.App/Rendering/GameWindow.cs:10421` (`UpdateSunFromSky`, unchanged) | Torches: outdoor objects never torch-lit (exact retail). Sun: indoor objects (furniture, NPCs, player in a windowed building) never sun-lit (exact retail per-stage). Ambient: per-player-cell regime unchanged (exact retail `ChangePosition`). | The `ebp_2` unaudited test in `ChangePosition` could affect a narrow class of cells (entrance cells? sub-cells with special flags?) — no symptom observed; audit it if a lighting edge case arises in an unusual cell type | `useSunlight` gate `DrawMeshInternal` 0x0059f398; `useSunlightSet` 0x0054d450; per-stage `PView::DrawCells` 0x005a4840 (`useSunlightSet(1)` 0x005a485a / `useSunlightSet(0)` 0x005a49f3); `minimize_object_lighting` 0x0054d480; `CellManager::ChangePosition` 0x004559B0 (ambient + seen_outside) |
 | AP-35 | Point/spot lights are now PER-VERTEX Gouraud (`pointContribution` ~line 153 of `mesh_modern.vert`) matching retail's `SetStaticLightingVertexColors` bake path. Half-Lambert wrap (`(1/1.5)·(N·D + 0.5·d)`) AND norm distance attenuation (`distsq>1 ? distsq·d : d`) ARE ported (A7 Fix A, `aa94ced`). Point-light sum clamped to [0,1] on its own accumulator before adding ambient+sun (A7 Fix D D-1, mirrors retail's per-vertex bake clamp). CPU oracle: `src/AcDream.Core/Lighting/LightBake.cs`, locked by `tests/AcDream.Core.Tests/Lighting/LightBakeConformanceTests.cs`. **Residual (two parts):** (a) acdream lights in-shader each frame (per-frame GPU evaluate); retail bakes into the vertex buffer ONCE — an architecture/performance difference; the wrap + norm + clamp formula is the same, but bake-once is cheaper for static geometry; (b) acdream's `SelectForObject` keeps only the 8 NEAREST reaching point/spot lights per object/cell (`MaxLightsPerObject=8`, see AP-16), whereas retail's bake sums ALL reaching static lights per vertex — a surface reached by >8 point lights is dimmer in acdream than retail's bake result (rare in practice; a room has a handful of torches) | `src/AcDream.App/Rendering/Shaders/mesh_modern.vert` (`pointContribution` ~line 153; wrap ~line 163; norm ~line 167; point-sum clamp line 210) | Per-vertex Gouraud + wrap + norm + clamp all match retail. The two residuals are: (a) per-frame GPU vs bake-once — architecture/perf only; (b) 8-light cap dimming when >8 lights reach one surface — rare. `LightInfoLoader.cs:81` folds static_light_factor 1.3 into Range | (a) A new frame-time consumer bypassing `accumulateLights` would need to replicate the wrap + norm formula; per-frame GPU re-evaluate has higher per-frame cost than bake for static geometry. (b) A densely lit scene (>8 torches reaching one wall) renders dimmer than retail — see AP-16 for the 8-cap ownership | `calc_point_light` 0x0059c8b0 (line 0x0059c9a2 ramp; 0x0059c925 wrap); `SetStaticLightingVertexColors` 0x0059cfe0; static_light_factor 0x00820e24 |
 | AP-37 | LayoutDesc importer collapses the dat's nested meter structure (Type-7 meter → two Type-3 container children → three Type-3 image-slice grandchildren each) into `UiMeter`'s programmatic 3-slice fields (`BackLeft..FrontRight`) + reuses `UiMeter.DrawHBar`'s scissor-fill, instead of building those child nodes generically and porting `UIElement_Meter::DrawChildren`. Vitals number elements are meter children (not recursed); `VitalsController` attaches a centered `UiText` child for the cur/max number (Task 8 landed — retail `gmVitalsUI` uses `UIElement_Text`), so `UiMeter.Label` is no longer used for vitals (`UiText.Centered` reuses the meter's former centering formula → pixel-identical, user-confirmed). The inheritance `Merge` treats Width/Height==0 as "inherit from base", diverging from format-doc §12 rule 2 (documented inline in `ElementReader.cs`) | `src/AcDream.App/UI/Layout/DatWidgetFactory.cs` (`BuildMeter`/`SliceIds`) + `src/AcDream.App/UI/Layout/LayoutImporter.cs` (`BuildWidget` meter-child skip) | Reuses the tested `UiMeter` render that already visually matches retail's stacked vitals bars; the full nested-element + `DrawChildren` scissor port is deferred to Plan 2. Locked by the conformance fixture (`tests/AcDream.App.Tests/UI/Layout/fixtures/vitals_2100006C.json`) | A LayoutDesc whose meter structure differs from the vitals 2-container/3-slice shape renders an empty/wrong meter — no oracle diff until the Plan-2 port lands | `UIElement_Meter::DrawChildren` @0x46fbd0; `docs/research/2026-06-15-layoutdesc-format.md` |
 | AP-38 | Chat transcript renders pre-split `ChatLog` lines 1:1; no in-element word-wrap at the panel's current pixel width | `src/AcDream.App/UI/UiText.cs` | Retail does in-element wrap via `UIElement_Text::SizeToFit`; our pre-split lines are always shorter than 440 px in practice; a line that overflows clips at the edge rather than wrapping | Very long server system messages (server shutdowns, broadcast announcements) clip rather than wrapping — no information loss, just visual truncation | `UIElement_Text::SizeToFit` @0x467980; `gmMainChatUI` layout |