fix(G.3): pre-collapse dungeon streaming at login/teleport — kill the login FPS ramp (#135)

On login (or teleport) into a dungeon, FPS started ~10 and climbed over ~30 s.
Root cause: the dungeon "collapse" (which shrinks the 25x25 streaming window to
the player's single dungeon landblock — AC dungeons have no neighbours) only
fires once the per-frame `insideDungeon` gate reads true, and that gate keys on
the physics CurrCell, which isn't set until the player is PLACED, which waits for
the dungeon landblock to hydrate. So during the whole hydration window NormalTick
bootstraps the full window — ~24 unrelated ocean-grid neighbour dungeons + their
~19k entities each — and the collapse only mops them up afterward. That mop-up is
the ramp.

Fix: trigger the SAME collapse early, the instant we recenter the streaming center
onto a sealed dungeon cell, before the first NormalTick.

- StreamingController.PreCollapseToDungeon(cx,cy): fires EnterDungeonCollapse
  early (idempotent). The expensive neighbour window is never enqueued.
- GameWindow.IsSealedDungeonCell(cellId): reads the EnvCell dat SeenOutside flag
  (CurrCell is null pre-placement) — the same flag ObjCell.SeenOutside and the
  per-frame gate use, so the early decision matches the eventual one. Distinguishes
  a real dungeon from a cottage/inn interior (SeenOutside → keeps its outdoor
  surround). Excludes the 0xFFFE/0xFFFF structural shell ids so an outdoor spawn id
  can't type-confuse a LandBlock record as an EnvCell.
- Hooks: OnLiveEntitySpawnedLocked (login) + OnLivePositionUpdated (teleport).
- Observer robustness: during a teleport PortalSpace hold the streaming observer
  follows the recentered destination, not the frozen pre-teleport position (which
  could drift >=2 landblocks off and trip ExitDungeonExpand). And
  _lastLivePlayerLandblockId is now filtered to the player guid (resolves the
  Phase A.1 TODO) so a stray NPC UpdatePosition can't drift the login-hold observer
  off the dungeon.

Faithful EARLY trigger of the existing AP-36 collapse mechanism, not a new
workaround — AP-36 amended in the same commit. Adversarially reviewed across
timing / threading / faithfulness lenses; 5 new tests including the real runtime
ordering (Tick bootstraps, then PreCollapse cancels). Core suite green (1463).

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

docs/architecture/retail-divergence-register.md

@@ -130,7 +130,7 @@ accepted-divergence entries (#96, #49, #50).
 | AP-32 | Cell shells DRAW +0.02 m above the dat EnvCell origin (`ShellDrawLiftZ`, z-fight vs coplanar terrain); retail draws at the origin verbatim. Split invariant: PHYSICS + visibility graph UNLIFTED (f35cb8b, **#119**-residual), every DRAW-space consumer of portal/cell geometry LIFTED (OutsideView color gate via `Build(drawLiftZ)`, seal/punch fans — **#130**) | `src/AcDream.App/Rendering/GameWindow.cs:5604` (const at `PortalVisibilityBuilder.ShellDrawLiftZ`) | Shell floors coplanar with terrain z-fight in our z-buffered frame; the 2 cm lift is the documented stand-in | A new draw-space consumer of portal/cell polygons that forgets the lift re-opens a 2 cm seam at horizontal aperture edges (the #130 top-edge strip, ~7 px at 2.4 m); a visibility consumer that picks up the LIFTED transform re-opens the #119-residual horizontal-portal side-cull | retail draws cell geometry at the dat EnvCell origin (no lift) |
 | 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 | `src/AcDream.App/Rendering/GameWindow.cs:6895` (predicate) + `src/AcDream.App/Streaming/StreamingController.cs` (collapse/expand) | 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 | 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 | ACE `LandblockManager.GetAdjacentIDs` (dungeons→empty) Landblock.cs:577-582; `IsDungeon` Landblock.cs:1264-1277 |
+| 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-35 | Point/spot lights use a single PER-PIXEL accumulation that ports `calc_point_light`'s `(1 − dist/falloff_eff)` LINEAR ramp (falloff_eff = Falloff × static_light_factor 1.3) + standard Lambert `N·L`; retail's path is PER-VERTEX Gouraud and additionally applies a half-Lambert wrap (`0.5·dist + N·L_vec`, lights surfaces down to `N·L ≥ −0.5`) and an x87-obscured normalization factor, neither ported | `src/AcDream.App/Rendering/Shaders/mesh_modern.frag:52` (+ `mesh.frag`; `LightInfoLoader.cs:81` folds 1.3 into Range) | The linear ramp is the user-visible fix (kills the hard-disc "spotlight" edge, #133 A7); the dropped wrap/normalization only re-shade the gradient slightly, and per-pixel vs per-vertex Gouraud chiefly differs on coarse geometry. Half-Lambert wrap + factor are an x87-decompile refinement (same artifact class as GetPowerBarLevel AP-24) | Surfaces facing slightly away from a torch (`−0.5 ≤ N·L < 0`) stay dark where retail's wrap lights them faintly; near-light gradient shading differs subtly from retail's per-vertex bake | `calc_point_light` 0x0059c8b0 (line 0x0059c9a2 ramp; 0x0059c925 wrap); static_light_factor 0x00820e24 |
 
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